Anal Chem Insights [JOURNAL]
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109 papers
Development and validation of a HPLC method to determine griseofulvin in rat plasma: application to pharmacokinetic studies.
Wei B, Liang D, Bates TR
Anal Chem Insights · 2008 Aug · PMID 19609394 · Full text
A simple, specific, sensitive, and rapid high performance liquid chromatography (HPLC) method for the determination of griseofulvin in small volumes of rat plasma was developed and validated using warfarin as an internal...
A simple, specific, sensitive, and rapid high performance liquid chromatography (HPLC) method for the determination of griseofulvin in small volumes of rat plasma was developed and validated using warfarin as an internal standard. Biological sample preparation involved simple extraction with acetonitrile, followed by dilution with aqueous mobile phase buffer (20 mM sodium dihydrogen phosphate, pH 3.5) to eliminate any chromatographic solvent effects. Griseofulvin and warfarin were baseline separated and quantitated on a C(18) reversed phase column (4.6 x 150 mm, 3.5 microm), using a mobile phase composed of a 20 mM aqueous solution of sodium dihydrogen phosphate-acetonitrile (55:45, v/v, pH 3.5) delivered at a flow rate of 1.0 mL/min, and with fluorescence detection (lambda(excitation) = 300 nm, lambda(emission) = 418 nm). The method was proven to be linear over a plasma griseofulvin concentration range of 10 to 2500 ng/mL with a mean correlation coefficient of 0.9996. The intra-day and inter-day accuracy (relative error) were in the range of 0.89% to 9.26% and 0.71% to 7.68%, respectively. The within-day precision (coefficient of variation) was less than 3.0% and the between-day precision was less than 7.5%. The mean recovery of griseofulvin from rat plasma was found to be 99.2%. The limit of detection (LOD) and the limit of quantification (LOQ) of griseofulvin were determined to be 1 ng/mL and 10 ng/mL, respectively. The developed method was successfully applied to quantitatively assess the pharmacokinetics of griseofulvin in rats following a single 50 mg/kg oral dose of the drug.
Micellar electrokinetic chromatographic study of the separation of an aromatase inhibitor and a tryciclic antidepressant in the breast cancer treatment.
Flores JR, Salcedo AM, Fernández LM
Anal Chem Insights · 2008 Aug · PMID 19609393 · Full text
Micellar electrokinetic chromatography (MEKC) was investigated for the simultaneous determination of letrozole, imipramine and their metabolites in human urine samples over a concentration range of therapeutic interest....
Micellar electrokinetic chromatography (MEKC) was investigated for the simultaneous determination of letrozole, imipramine and their metabolites in human urine samples over a concentration range of therapeutic interest. Experimental parameters such as pH of the running electrolyte, sodium dodecylsulphate (SDS) concentration, borate concentration, voltage, etc were investigated. Under optimal conditions of 25 mM SDS, 15 mM borate buffer (pH 9.2), 15% 2-propanol, as background electrolyte; 28 kV and 40 degrees C, as voltage and cartridge temperature, respectively; resolution between the peaks was greater than 1.7. Before the determination, a solid phase extraction (SPE) procedure with a C(18) cartridge was optimized. Good linearity, accuracy, precision, robustness and ruggedness were achieved and detection limits of 12.5 ng/mL for letrozole and its metabolite and 37.5 ng/mL, were obtained for imipramine and their metabolites. Real determinations of these analytes in two patient urines were carried out. Sensitivity achieved in this method is sufficient to perform kinetic studies in humans.
A simple and selective spectrophotometric method for the determination of trace gold in real, environmental, biological, geological and soil samples using bis (salicylaldehyde) orthophenylenediamine.
Soomro R, Ahmed MJ, Memon N … +1 more , Khan H
Anal Chem Insights · 2008 Aug · PMID 19609392 · Full text
A simple high sensitive, selective, and rapid spectrophotometric method for the determination of trace gold based on the rapid reaction of gold(III) with bis(salicylaldehyde)orthophenylenediamine (BSOPD) in aqueous and m...
A simple high sensitive, selective, and rapid spectrophotometric method for the determination of trace gold based on the rapid reaction of gold(III) with bis(salicylaldehyde)orthophenylenediamine (BSOPD) in aqueous and micellar media has been developed. BSOPD reacts with gold(III) in slightly acidic solution to form a 1:1 brownish-yellow complex, which has an maximum absorption peak at 490 nm in both aqueous and micellar media. The most remarkable point of this method is that the molar absorptivities of the gold-BSOPD complex form in the presence of the nonionic TritonX-100 surfactant are almost a 10 times higher than the value observed in the aqueous solution, resulting in an increase in the sensitivity and selectivity of the method. The apparent molar absorptivities were found to be 2.3 x 10(4) L mol(-1) cm(-1) and 2.5 x 10(5) L mol(-1) cm(-1) in aqueous and micellar media, respectively. The reaction is instantaneous and the maximum absorbance was obtained after 10 min at 490 nm and remains constant for over 24 h at room temperature. The linear calibration graphs were obtained for 0.1-30 mg L(-1) and 0.01-30 mg L(-1) of gold(III) in aqueous and surfactant media, respectively. The interference from over 50 cations, anions and complexing agents has been studied at 1 mg L(-1) of Au(III); most metal ions can be tolerated in considerable amounts in aqueous micellar solutions. The Sandell's sensitivity, the limit of detection and relative standard deviation (n = 9) were found to be 5 ng cm(-2), 1 ng mL(-1) and 2%, respectively in aqueous micellar solutions. Its sensitivity and selectivity are remarkably higher than that of other reagents in the literature. The proposed method was successfully used in the determination of gold in several standard reference materials (alloys and steels), environmental water samples (potable and polluted), and biological samples (blood and urine), geological, soil and complex synthetic mixtures. The results obtained agree well with those samples analyzed by atomic absorption spectrophotometry (AAS).
Microalbuminuria measured by three different methods, blood pressure and cardiovascular risk factors in elderly Swedish males.
Florvall G, Basu S, Helmersson J … +1 more , Larsson A
Anal Chem Insights · 2008 Sep · PMID 19609391
Microalbuminuria is associated with hypertension and is a strong risk factor for subsequent chronic disease, both renal and coronary heart disease (CHD), Presently there are several methods available for measurement of m...
Microalbuminuria is associated with hypertension and is a strong risk factor for subsequent chronic disease, both renal and coronary heart disease (CHD), Presently there are several methods available for measurement of microalbuminuria. The aim of this study was to evaluate if the three different methods gave similar information or if one of the assays were superior to the others. Blood pressure, inflammatory markers and cardiovascular mortality and morbidity were correlated with urine albumin analysed with a point-of-care testing (POCT) instrument, nephelometric determination of albumin and albumin/creatinine ratio in elderly males. The study population consisted of 103 diabetic and 603 nondiabetic males (age 77 years) in a cross-sectional study. We analyzed urine albumin with a HemoCue Urine Albumin POCT instrument and a ProSpec nephelometer and albumin/creatinine ratio. There were strong correlations between both systolic and diastolic blood pressure and all three urine albumin methods (p < 0.0001). There were also significant correlations between the different urine albumin measurements and serum amyloid A component, high-sensitivity C-reactive protein and interleukin-6. The three different urine albumin methods studied provided similar information in relation to cardiovascular disease. There was a strong correlation between systolic and diastolic blood pressure and microalbuminuria in both the whole study population and in nondiabetic males emphasizing the role of hypertension in glomerular damage. The good correlation between the studied urine albumin measurements show that all three methods can be used for monitoring urine albumin excretion.
High-performance liquid chromatographic method for determination of phenytoin in rabbits receiving sildenafil.
Khedr A, Moustafa M, Abdel-Naim AB … +2 more , Alahdal A, Mosli H
Anal Chem Insights · 2008 Apr · PMID 19609390 · Full text
A validated high-performance liquid chromatographic (HPLC) method for determination of phenytoin (PHN), para-hydroxy metabolite of phenytoin (POH) and sildenafil (SIL) in rabbit plasma is described. The method is based o...
A validated high-performance liquid chromatographic (HPLC) method for determination of phenytoin (PHN), para-hydroxy metabolite of phenytoin (POH) and sildenafil (SIL) in rabbit plasma is described. The method is based on extraction on Sep-Pak C18 solid support using ethyl acetate and ether as eluents and monitoring at 220 nm. The extracted samples were analyzed by HPLC using Agilent Zorbax Extended C(18) column (150 mm x 4.6 mm internal diameter) and isocratic elution with a mobile phase consist of 29% acetonitrile and 71% sodium acetate solution (0.02 M, pH 4.6). The method was fully validated for linearity and range, selectivity, precision, stability, recovery, and robustness. The linearity of the method was in the range of 0.15 to 39 microg /ml for PHN and 0.15 to 33 microg/ml for both POH and SIL. Limits of detection (LOD) of PHN, POH, and SIL were 0.15 +/- 0.01, 0.15 +/- 0.01, and 0.15 +/- 0.01 microg/ml, respectively. The % recovery of PHN, POH, and SIL from rabbit plasma were, 101.88 +/- 0.12, 99.16 +/- 0.25, and 99.49 +/- 0.33, respectively. The method was applied on plasma collected from rabbits at different time intervals after receiving 30 mg/kg PHN-Na with (and without) 8 mg/kg SIL citrate.
Determination of key intermediates in cholesterol and bile acid biosynthesis by stable isotope dilution mass spectrometry.
Yoshida T, Honda A, Miyazaki H … +1 more , Matsuzaki Y
Anal Chem Insights · 2008 Mar · PMID 19609389 · Full text
For more than a decade, we have developed stable isotope dilution mass spectrometry methods to quantify key intermediates in cholesterol and bile acid biosynthesis, mevalonate and oxysterols, respectively. The methods ar...
For more than a decade, we have developed stable isotope dilution mass spectrometry methods to quantify key intermediates in cholesterol and bile acid biosynthesis, mevalonate and oxysterols, respectively. The methods are more sensitive and reproducible than conventional radioisotope (RI), gas-chromatography (GC) or high-performance liquid chromatography (HPLC) methods, so that they are applicable not only to samples from experimental animals but also to small amounts of human specimens. In this paper, we review the development of stable isotope dilution mass spectrometry for quantifying mevalonate and oxysterols in biological materials, and demonstrate the usefulness of this technique.
Optimized and validated spectrophotometric methods for the determination of enalapril maleate in commercial dosage forms.
Rahman N, Haque SM
Anal Chem Insights · 2008 Mar · PMID 19609388 · Full text
Four simple, rapid and sensitive spectrophotometric methods have been proposed for the determination of enalapril maleate in pharmaceutical formulations. The first method is based on the reaction of carboxylic acid group...
Four simple, rapid and sensitive spectrophotometric methods have been proposed for the determination of enalapril maleate in pharmaceutical formulations. The first method is based on the reaction of carboxylic acid group of enalapril maleate with a mixture of potassium iodate (KIO(3)) and iodide (KI) to form yellow colored product in aqueous medium at 25 +/- 1 degrees C. The reaction is followed spectrophotometrically by measuring the absorbance at 352 nm. The second, third and fourth methods are based on the charge transfer complexation reaction of the drug with p-chloranilic acid (pCA) in 1, 4-dioxan-methanol medium, 2, 3-dichloro 5, 6-dicyano 1, 4-benzoquinone (DDQ) in acetonitrile-1,4 dioxane medium and iodine in acetonitrile-dichloromethane medium. Under optimized experimental conditions, Beer's law is obeyed in the concentration ranges of 2.5-50, 20-560, 5-75 and 10-200 microg mL(-1), respectively. All the methods have been applied to the determination of enalapril maleate in pharmaceutical dosage forms. Results of analysis are validated statistically.
Detecting the site of phosphorylation in phosphopeptides without loss of phosphate group using MALDI TOF mass spectrometry.
Jagannadham MV, Nagaraj R
Anal Chem Insights · 2008 Feb · PMID 19609387 · Full text
Phosphopeptides with one and four phosphate groups were characterized by MALDI mass spectrometry. The molecular ion of monophosphopeptide could be detected both as positive and negative ions by MALDI TOF with delayed ext...
Phosphopeptides with one and four phosphate groups were characterized by MALDI mass spectrometry. The molecular ion of monophosphopeptide could be detected both as positive and negative ions by MALDI TOF with delayed extraction (DE) and in the reflector mode. The tetraphospho peptide could be detected in linear mode. When MS/MS spectra of the monophospho peptides were obtained in a MALDI TOF TOF instrument by CID, b and y ions with the intact phosphate group were observed, in addition the b and y ions without the phosphate group. Our study indicates that it is possible to detect phosphorylated peptides with out the loss of phosphate group by MALDI TOF as well as MALDI TOF TOF instruments with delayed extraction and in the reflector mode.
Understanding structural features of microbial lipases--an overview.
Mala JG, Takeuchi S
Anal Chem Insights · 2008 Mar · PMID 19609386 · Full text
The structural elucidations of microbial lipases have been of prime interest since the 1980s. Knowledge of structural features plays an important role in designing and engineering lipases for specific purposes. Significa...
The structural elucidations of microbial lipases have been of prime interest since the 1980s. Knowledge of structural features plays an important role in designing and engineering lipases for specific purposes. Significant structural data have been presented for few microbial lipases, while, there is still a structure-deficit, that is, most lipase structures are yet to be resolved. A search for 'lipase structure' in the RCSB Protein Data Bank (http://www.rcsb.org/pdb/) returns only 93 hits (as of September 2007) and, the NCBI database (http://www.ncbi.nlm.nih.gov) reports 89 lipase structures as compared to 14719 core nucleotide records. It is therefore worthwhile to consider investigations on the structural analysis of microbial lipases. This review is intended to provide a collection of resources on the instrumental, chemical and bioinformatics approaches for structure analyses. X-ray crystallography is a versatile tool for the structural biochemists and is been exploited till today. The chemical methods of recent interests include molecular modeling and combinatorial designs. Bioinformatics has surged striking interests in protein structural analysis with the advent of innumerable tools. Furthermore, a literature platform of the structural elucidations so far investigated has been presented with detailed descriptions as applicable to microbial lipases. A case study of Candida rugosa lipase (CRL) has also been discussed which highlights important structural features also common to most lipases. A general profile of lipase has been vividly described with an overview of lipase research reviewed in the past.
Solid-phase extraction and reverse-phase HPLC: application to study the urinary excretion pattern of benzophenone-3 and its metabolite 2,4-dihydroxybenzophenone in human urine.
Gonzalez H, Jacobson CE, Wennberg AM … +2 more , Larkö O, Farbrot A
Anal Chem Insights · 2008 Jan · PMID 19609385 · Full text
BACKGROUND: Benzophenone-3 (BZ-3) is a common ultraviolet (UV) absorbing compound in sunscreens. It is the most bioavailable species of all UV-absorbing compounds after topical application and can be found in plasma and...
BACKGROUND: Benzophenone-3 (BZ-3) is a common ultraviolet (UV) absorbing compound in sunscreens. It is the most bioavailable species of all UV-absorbing compounds after topical application and can be found in plasma and urine. OBJECTIVES: The aim of this study was to develop a reverse-phase high performance liquid chromatography (HPLC) method for determining the amounts BZ-3 and its metabolite 2,4-dihydroxybenzophenone (DHB) in human urine. The method had to be suitable for handling a large number of samples. It also had to be rapid and simple, but still sensitive, accurate and reproducible. The assay was applied to study the urinary excretion pattern after repeated whole-body applications of a commercial sunscreen, containing 4% BZ-3, to 25 healthy volunteers. METHODS: Each sample was analyzed with regard to both conjugated/non-conjugated BZ-3 and conjugated/non-conjugated DHB, since both BZ-3 and DHB are extensively conjugated in the body. Solid-phase extraction (SPE) with C8 columns was followed by reverse-phase HPLC. For separation a Genesis C18 column was used with an acethonitrile-water mobile phase and the UV-detector was set at 287 nm. RESULTS: The assay was linear r(2) > 0.99, with detection limits for BZ-3 and DHB of 0.01 micromol L(-1) and 0.16 micromol L(-1) respectively. Relative standard deviation (RSD) was less than 10% for BZ-3 and less than 13% for DHB. The excretion pattern varied among the human volunteers; we discerned different patterns among the individuals. CONCLUSIONS: The reverse-phase HPLC assay and extraction procedures developed are suitable for use when a large number of samples need to be analyzed and the method fulfilled our objectives. The differences in excretion pattern may be due to differences in enzyme activity but further studies, especially about genetic polymorphism, need to be performed to verify this finding.
Direct enantiomeric resolution of betaxolol with application to analysis of pharmaceutical products.
Hefnawy MM, Sultan MA, Al-Shehri MM
Anal Chem Insights · 2007 Feb · PMID 19690633
A high-performance liquid chromatographic (HPLC) method has been developed for the separation and determination of S- and R-enantiomers of betaxolol in tablets and ophthalmic preparations. Baseline resolution was achieve...
A high-performance liquid chromatographic (HPLC) method has been developed for the separation and determination of S- and R-enantiomers of betaxolol in tablets and ophthalmic preparations. Baseline resolution was achieved by using teicoplanin macrocyclic antibiotic chiral stationary phase (CSP) known as Chirobiotic T with fluorescence detection at excitation/emission wavelengths 275/305 nm. The polar ionic mobile phase (PIM) consists of methanol-glacial acetic acid-triethylamine, (100:0.020:0.025, v/v/v) has been used at a flow rate of 1.5 ml/min. All analytes with S-(-)-atenolol as internal standard were conducted at ambient temperature. The method is highly specific where another coformulated compounds did not interfere. The stability of betaxolol enantiomers under different degree of temperature also studied. The results showed that it is stable for at least 7 days at 70 degrees C. The method validated for its linearity, accuracy, precision and robustness. Experimental design was used during validation to evaluate method robustness. Using the chromatographic conditions described, S- and R-betaxolol were well resolved with mean retention times of 11.3 and 12.6 min, respectively. Linear response (r > 0.997) was observed over the range of 10-500 ng/ml of betaxolol enantiomers, with detection limit of 5 ng/ml. The recoveries of S- and R-betaxolol from tablets and ophthalmic preparation ranged from 97.4 to 101.4% and 98.0 to 102.0%, respectively. The mean relative standard deviation (R.S.D.%) for both enantiomers were 1.1-1.4% and 1.3-1.7% in tablets and ophthalmic solution, respectively.
The use of ion chromatography for the determination of clean-in-place-200 (CIP-200) detergent traces.
Resto W, Roque J, Rey R … +2 more , Colón H, Zayas J
Anal Chem Insights · 2007 Feb · PMID 19690632
Anion chromatography with conductivity detection was chosen as the analytical technique for the development of a cleaning validation method for clean-in-place (CIP) detergents. The method was developed and validated for...
Anion chromatography with conductivity detection was chosen as the analytical technique for the development of a cleaning validation method for clean-in-place (CIP) detergents. The method was developed and validated for the determination of traces of the detergent CIP-200. It was shown to be linear with a squared correlation coefficient (r(2)) of 0.9999 and the accuracy experiments presented average recoveries of 88.2% (area response factor) from stainless steel surfaces. The repeatability was found to be 1.6% and an intermediate precision of 1.9% across the range. The method was also shown to be sensitive with an average Detection Limit (DL) of 0.23 ppm and a Quantitation Limit (QL) of 0.70 ppm based on the amount of phosphate in the detergent sample. The phosphate signal was well resolved from typical ions encountered in water samples or any other interference presented from swabs and surfaces. The method was applied to cleaning validation samples and proved to be suitable for rapid and reliable quality control.
Solid phase extraction for monitoring of occupational exposure to Cr (III).
Shahtaheri SJ, Khadem M, Golbabaei F … +1 more , Rahimi-Froushani A
Anal Chem Insights · 2007 Dec · PMID 19662187
Chromium is an important constituent widely used in different industrial processes for production of various synthetic materials. For evaluation of workers' exposure to trace toxic metal of Cr (III), environmental and bi...
Chromium is an important constituent widely used in different industrial processes for production of various synthetic materials. For evaluation of workers' exposure to trace toxic metal of Cr (III), environmental and biological monitoring are essential processes, in which, preparation of samples is one of the most time-consuming and error-prone aspects prior to analysis. The use of solid-phase extraction (SPE) has grown and is a fertile technique of sample preparation as it provides better results than those produced by liquid-liquid extraction (LLE). SPE using mini columns filled with XAD-4 resin was optimized regarding to sample pH, ligand concentration, loading flow rate, elution solvent, sample volume, elution volume, amount of resins, and sample matrix interferences. Chromium was retained on solid sorbent and was eluted with 2 M HNO(3) followed by simple determination of analytes by using flame atomic absorption spectrometry. Obtained recoveries of metal ion were more than 92%. The optimized procedure was also validated with three different pools of spiked urine samples and showed a good reproducibility over six consecutive days as well as six within-day experiments. Through this study, suitable results were obtained for relative standard deviation, therefore, it is concluded that, this optimized method can be considered to be successful in simplifying sample preparation for trace residue analysis of Cr in different matrices for evaluation of occupational and environmental exposures. To evaluate occupational exposure to chromium, 16 urine samples were taken, prepared, and analyzed based on optimized procedure.
Hazard identification on a single cell level using a laser beam.
Wu XZ, Kato T, Tsuji Y … +1 more , Terada S
Anal Chem Insights · 2007 Dec · PMID 19662186
This research shows a novel method for hazard identification of a chemical and UV light on a single cell level with a laser probe beam. The laser probe beam was passed through interface of cell membrane/culture medium of...
This research shows a novel method for hazard identification of a chemical and UV light on a single cell level with a laser probe beam. The laser probe beam was passed through interface of cell membrane/culture medium of a cultured human hepatoblastoma cell line HepG2. Deflection of the laser probe beam, which was induced by changes in concentration gradients due to the active materials movement across the cell membrane, was monitored. When a toxic hazard existed, a living cell was expected to be killed or injured, or cellular behaviors to be changed greatly. Then, the changing deflection signal from the living cell would become unchanged or altered in a different way. This was successfully demonstrated with cytotoxicity of UV light and H(2)O(2). Most of the cultured HepG2 cells showed changing deflection signals after 10 min illumination of UV-visible light longer than 370 nm, while almost all HepG2 cells showed unchanged deflection signal after 10 min illumination of UV-visible light with wavelength longer than 330 nm. The results suggested that UV light between 330-370 nm could kill the cells. Additions of H(2)O(2) solution with different concentrations to the cell cultures caused the changing deflection signal from a living cell either unchanged or changed in different trend, suggesting toxicity of H(2)O(2) to the cells. The results from the beam deflection detection agreed well with those obtained by the conventional trypane blue method.
UV-Vis spectrophotometrical and analytical methodology for the determination of singlet oxygen in new antibacterials drugs.
Zoltan T, Vargas F, Izzo C
Anal Chem Insights · 2007 Nov · PMID 19662185
We have determined and quantified spectrophotometrically the capacity of producing reactive oxygen species (ROS) as (1)O(2) during the photolysis with UV-A light of 5 new synthesized naphthyl ester derivates of well-know...
We have determined and quantified spectrophotometrically the capacity of producing reactive oxygen species (ROS) as (1)O(2) during the photolysis with UV-A light of 5 new synthesized naphthyl ester derivates of well-known quinolone antibacterials (nalidixic acid (1), cinoxacin (2), norfloxacin (3), ciprofloxacin (4) and enoxacin (5)). The ability of the naphthyl ester derivatives (6-10) to generate singlet oxygen were detecting and for the first time quantified by the histidine assay, a sensitive, fast and inexpensive method. The following tendency of generation of singlet oxygen was observed: compounds 7 > 10 > 6 > 8 > 9 >> parent drugs 1-5.
A practical approach to red blood cell folate analysis.
Piyathilake CJ, Robinson CB, Cornwell P
Anal Chem Insights · 2007 Nov · PMID 19662184
The measurement of folate in red blood cells (RBCs) is preferred since it reflects long-term folate status in the body compared to plasma/serum folate which may be influenced by recent dietary intake. The commonly accept...
The measurement of folate in red blood cells (RBCs) is preferred since it reflects long-term folate status in the body compared to plasma/serum folate which may be influenced by recent dietary intake. The commonly accepted technique for RBC folate analysis involves preparation of a hemolysate using a fresh whole blood sample. Hematocrit and plasma folate concentrations are needed to calculate RBC folate values. Because of the need for immediate access to a laboratory where processing can be performed, it may not be practical to assess RBC folate status using this method in field-based epidemiological studies. It is however, feasible to isolate packed RBSs from a blood sample under these conditions. The purpose of this study is to validate RBC folate analysis using packed red cells by comparing the RBC folate values obtained by hemolysate method (routine assay) with those obtained by using packed RBCs (new assay) in the same individuals (n = 50) using the folate microbiological assay. The correlation between plasma folate and the routine RBC folate assay (r = 0.58, p = 0.001) and the correlation between plasma folate and the new RBC folate assay was statistically significant (r = 0.55, p = 0.001). The correlation between RBC folate by the routine assay and new assay was also statistically significant (r = 0.78, p < 0.001). We conclude that measurement of folate in packed RBC is a practical approach in assessing long-term folate status in field-based and or larger scale epidemiological studies where an immediate access to a laboratory is unavailable for necessary sample processing for the routine RBC folate assay.
NS-187 (INNO-406), a Bcr-Abl/Lyn dual tyrosine kinase inhibitor.
Niwa T, Asaki T, Kimura S
Anal Chem Insights · 2007 Nov · PMID 19662183
Protein kinases catalyze the transfer of the gamma-phosphoryl group of adenosine triphosphate (ATP) to the hydroxyl groups of protein side chains, and they play critical roles in regulating cellular signal transduction a...
Protein kinases catalyze the transfer of the gamma-phosphoryl group of adenosine triphosphate (ATP) to the hydroxyl groups of protein side chains, and they play critical roles in regulating cellular signal transduction and other biochemical processes. They are attractive targets for today's drug discovery and development, and many pharmaceutical companies are intensively developing various kinds of protein kinase inhibitors. A good example is the recent success with the Bcr-Abl tyrosine kinase inhibitor imatinib mesylate (Gleevec) in the treatment of chronic myeloid leukemia. Though imatinib has dramatically improved the treatment of Bcr-Abl-positive chronic myeloid leukemia, resistance is often found in patients with advanced-stage disease. Several mechanisms have been proposed to explain this resistance, including point mutations within the Abl kinase domain, amplification of the bcr-abl gene, overexpression of the corresponding mRNA, increased drug efflux mediated by P-glycoprotein, and activation of the Src-family kinase (SFK) Lyn. We set out to develop a novel drug whose affinity for Abl is higher than that of imatinib and whose specificity in inhibiting Lyn is higher than that of SFK/Abl inhibitors such as dasatinib (Sprycel) or bosutinib (SKI-606). Our work has led to the development of NS-187 (INNO-406), a novel Abl/Lyn dual tyrosine kinase inhibitor with clinical prospects. To provide an overview of how a selective kinase inhibitor has been developed, this review presents chemical-modification studies carried out with the guidance of molecular modeling, the structural basis for the high potency and selectivity of NS-187 based on the X-ray structure of the NS-187/Abl complex, and the biological profiling of NS-187, including site-directed mutagenesis experiments.
Possible impact of salivary influence on cytokine analysis in exhaled breath condensate.
Ichikawa T, Matsunaga K, Minakata Y … +8 more , Yanagisawa S, Ueshima K, Akamatsu K, Hirano T, Nakanishi M, Sugiura H, Yamagata T, Ichinose M
Anal Chem Insights · 2007 Oct · PMID 19662182
BACKGROUND: Exhaled breath condensate (EBC) is thought to contain substances of the lower airway epithelial lining fluid (ELF) aerosolized by turbulent flow. However, contamination by saliva may affect the EBC when colle...
BACKGROUND: Exhaled breath condensate (EBC) is thought to contain substances of the lower airway epithelial lining fluid (ELF) aerosolized by turbulent flow. However, contamination by saliva may affect the EBC when collected orally. OBJECTIVE: The purpose of this study was to compare the cytokine expression levels in EBC with those in saliva, and to clarify the influence of saliva on cytokine measurements of EBC. METHODS: EBC and saliva samples were obtained from 10 adult subjects with stable asthma. To estimate differences in the contents of substances between EBC and saliva, the total protein concentration of each sample was measured. Further, we also measured the total protein concentration of ELF obtained from another patient group with suspected lung cancer using a micro sampling probe during bronchoscopic examination and roughly estimated the dilution of EBC by comparing the total protein concentration of EBC and ELF from those two patient groups. The cytokine expression levels of EBC and saliva from asthmatic group were assessed by a cytokine protein array. RESULTS: The mean total protein concentrations in EBC, saliva and ELF were 4.6 microg/ml, 2,398 microg/ml and 14,111 microg/ml, respectively. The dilution of EBC could be estimated as 1:3000. Forty cytokines were analyzed by a cytokine protein array and each cytokine expression level of EBC was found to be different from that of saliva. Corrected by the total protein concentration, all cytokine expression levels of EBC were significantly higher than those of saliva. CONCLUSION: These results suggest that the salivary influence on the cytokine assessment in EBC may be negligible.
Role of 99mTc-(V)DMSA in detecting tumor cell proliferation.
Al-Saeedi F
Anal Chem Insights · 2007 Dec · PMID 19662181
Pentavalent technetium-99m dimercaptosuccinic acid ((99m)Tc-(V)DMSA) is a tumor-seeking agent which was introduced to evaluate, image, and manage many types of cancers. In this review, the beginning of, and the most rece...
Pentavalent technetium-99m dimercaptosuccinic acid ((99m)Tc-(V)DMSA) is a tumor-seeking agent which was introduced to evaluate, image, and manage many types of cancers. In this review, the beginning of, and the most recent applications of using this agent was appraised. The relation with tumor cell detection and proliferation was reported and several mechanisms of uptake of (99m)Tc-(V)DMSA in tumor cells are described.
Enantioselective gas chromatographic separation of racemic N-alkylated barbiturates: application of C11-Chirasil-Dex as chiral stationary phase in GC.
Ghanem A
Anal Chem Insights · 2007 Sep · PMID 19662180
Chirasil-beta-Dex containing an undecamethylene spacer (C11-Chirasil-Dex) was synthesized and used as chiral stationary phase (CSP) in enantioselective gas chromatography (GC). The versatility of the new stationary phase...
Chirasil-beta-Dex containing an undecamethylene spacer (C11-Chirasil-Dex) was synthesized and used as chiral stationary phase (CSP) in enantioselective gas chromatography (GC). The versatility of the new stationary phase in the simultaneous enantiomeric separation of a set of N-alkylated barbiturates is demonstrated.
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