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The potential of 3-(4-sulfo-1,8-naphthalimido)propyl-modified silyl silica gel (SNAIP) as a mixed-mode stationary phase for capillary electrochromatography (CEC) was investigated for the separation of charged analytes, taking four amino acids (tyrosine, phenylalanine, tryptophan, histidine) as model analytes. The elution process of these charged analytes in CEC with SNAIP was dominated by a combination of both electrophoretic process and chromatographic process involving hydrophobic as well as electrostatic interactions. In order to study the retention mechanism, the CEC retention factor k* and the velocity factor ke* were measured for the amino acids, which allowed the assessment of the respective contribution from the differential processes underlying the separation. Migration and retention could be mediated by changing various mobile phase compositions, including buffer pH, buffer concentration, and concentration of organic solvent. Based on the results obtained by separation of the amino acids, the separation of eight peptides (Gly-Val, Gly-Phe, Gly-Ile, Gly-His, Gly-Lys, Lys-Lys, Gly-Gly-Gly, Gly-Gly-His) was attempted. A good separation was achieved under an isocratic elution with a mobile phase consisting of 35 mM phosphate buffer (pH 3.8) and 40% methanol., (Copyright 2004 WILEY-VCH Verlag GmbH & Co.)

A highly sensitive HPLC method was developed for the determination of xenoestrogenic compound, bisphenol A (BPA) in human breast milk samples. After a two-step liquid-liquid extraction, BPA was derivatized with fluorescent labeling reagent, 4-(4,5-diphenyl-1H-imidazol-2-yl)benzoyl chloride (DIB-Cl). The excess fluorescent reagent could be removed effectively using a column-switching system. The separation of DIB-BPA from endogenous materials in milk was carried out on two C(18) columns and fluorescence intensity was monitored at 475 nm with the excitation of 350 nm. A good linearity (r = 0.994) was observed of BPA in the concentration range of 0.2-5.0 ng mL(-1) in breast milk, and the detection limit was 0.11 ng mL(-1) at a signal-to-noise ratio of 3. Intra- and inter-day precision (RSD, %) were less than 8.7 and 10.4, respectively. Twenty-three breast milk samples of healthy lactating women were analyzed for the BPA concentration; the mean value was 0.61 +/- 0.20 ng mL(-1), with no correlation to the lipid content of milk samples.

A novel chemiluminescence (CL) assay method for lipase (triacylglycerol lipase, E.C.3.1.1.3) activity was developed by using the lauric acid ester of 2-(4-hydroxyphenyl)-4,5-diphenylimidazole (HDI) as a substrate. The method is based on the enhanced CL reaction of luminol-hydrogen peroxide-horseradish peroxidase (HRP) with HDI that is liberated from the substrate by enzymatic hydrolysis. To simplify the assay procedure, both the hydrolysis of the substrate and the enhanced CL reaction were performed in the same reaction mixture. Lipases from Candida cylindracea and porcine pancreas were successfully determined with the detection limits (blank signal + 3 SD) of 0.05 and 50.0 mU/tube, respectively. The method is simple and rapid, permitting the completion of single assay within 5 min. The reproducibilities obtained with replicate assays were relative standard deviations (RSDs) of <=> 4.7% for within-day and <=> 6.0% for between-day assays.

A novel packing material, 3-(4-sulfo-1,8-naphthalimido)propyl-modified silyl silica gel (SNAIP), was prepared for the use as a stationary phase of capillary electrochromatography (CEC). The sulfonic acid groups on SNAIP stationary phase contributed to the generation of electroosmotic flow (EOF) at low pH and served as a strong cation-exchanger. In CEC with SNAIP, a mixed-mode separation was predicted, comprising hydrophobic and electrostatic interactions as well as electrophoretic migration process. In order to understand the retention mechanism on SNAIP, effects of buffer pH, concentration, and mobile phase composition on EOF mobility and the retention factors of barbiturates and benzodiazepines were systematically investigated. Moreover, the retention behavior of barbiturates on SNAIP was investigated and compared with those on octadecyl silica (ODS), phenyl-bonded silica, and 3-(1,8-naphthalimido)propyl-modified silyl silica gel to confirm the presence of pi-pi interaction on its retention mechanism. It was observed that a column efficiency was more than 85,000 N/m for retained compounds and the relative standard deviations for the retention times of EOF marker, thiourea, and five barbiturates were below 2.5% (n = 4). Under an applied voltage of 20 kV and a mobile phase consisted of 5 mM phosphate (pH 3.8) and 40% methanol, the baseline separation of five barbiturates was achieved within 3 min.

A black-colored and well-circumscribed renal tumor in a 71-year-old woman is reported. The tumor was unique in that it was rich in vasculature and exclusively composed of perivascular epithelioid clear cells. Morphological features were reminiscent of conventional renal cell carcinoma (RCC). However, immunohistochemical examinations showed that the tumor cells did not express any epithelial markers, but diffusely and intensely expressed a melanocytic marker, gp-100/HMB-45. Another striking feature of the tumor was a large amount of cytoplasmic pigment that made the tumor wholly black. The pigment was not stained with Berlin-blue, completely bleached with potassium permanganate, and stained with Fontana-Masson staining, which suggests that the pigment was melanin. Morphological features and immunohistochemical findings indicated that the present tumor was an extreme example of a perivascular epithelioid clear cell tumor with a large amount of melanin, which has not been previously reported. One should be aware of the pure form of perivascular epithelioid clear cell tumor of the kidney because it is sometimes very difficult to differentiate this tumor from conventional RCC. Immunohistochemical examinations and the presence of cytoplasmic melanin can help the differentiation.

This paper describes a highly sensitive and selective method for the determination of hydroxylated polycyclic aromatic hydrocarbons (PAHs-OH) in airborne particulates. PAHs-OH were extracted from airborne particulates with ethanol by ultrasonication. The extractant was further cleaned up by solid phase extraction (SPE) with an aminopropylsilica cartridge, and subsequently analyzed by reversed-phase high-performance liquid chromatography with fluorescence detection. 2-Hydroxy-1-acetonaphthone was used as an internal standard. By the proposed method, 2-hydroxyfluorene and 1-hydroxypyrene were identified in airborne particulates and their concentrations were determined for the first time.

This paper describes a high-performance liquid chromatographic (HPLC) method for the determination of polycyclic aromatic hydrocarbons (PAHs) in milk samples. The method involves a liquid-liquid extraction procedure after saponification of milk samples with sodium hydroxide. Reproducible determination with highly sensitive detection was attained by HPLC with fluorescence detection using 1,2-bis(9-anthryl)ethane as an internal standard. The detection limits of 12 kinds of PAHs ranged from 1.3 to 76 ng/kg milk at a signal/noise ratio of 3. By the proposed method, the presence of 12 and 11 kinds of PAHs could be confirmed in commercial milk and human milk samples, respectively. The average concentrations of total PAHs (mean+/-SD, micro g/kg) were found to be 0.99+/-0.37 for commercial milk (n=14), 2.01+/-0.30 for infant formula (n=3) and 0.75+/-0.47 for human milk (n=51). High correlation coefficients between the concentrations of total PAHs and triglyceride were observed for commercial milk (r=0.659) and human milk (r=0.645).

A HPLC method was developed for the simultaneous determination of organic peroxides and hydrogen peroxide with peroxyoxalate chemiluminescence (PO-CL) detection following on-line UV irradiation. Organic peroxides [i.e., benzoyl peroxide (BP), tert.-butyl hydroperoxide (BHP), tert.-butyl perbenzoate (BPB), cumene hydroperoxide (CHP)] were UV irradiated (254 nm, 15 W) to generate hydrogen peroxide, which was determined by PO-CL detection. The conditions for UV irradiation and PO-CL detection were optimized by a flow injection analysis (FIA) system. Generation of hydrogen peroxide from peroxides with on-line UV irradiation also was confirmed by the FIA system by incorporating an enzyme column reactor immobilized with catalase. The separation of four organic peroxides and hydrogen peroxide by HPLC was accomplished isocratically on an ODS column within 30 min. The detection limits (signal-to-noise ratio=3) were 1.1 microM for hydrogen peroxide, 6.8 microM for BP, 31.3 microM for BHP, 7.5 microM for BPB and 1.3 microM for CHP. The proposed method was applied to the determination of BP in wheat flour.

Bisbenzimidazole-capped cyclodextrins, capable of forming supramolecules, harvest chemical energy from the oxidation reaction of a bis(aryl)oxalate and emit light two orders of magnitude more efficiently than fluorescein does.

A sensitive column-switching HPLC method with fluorescence detection was developed for the determination of bisphenol A (BPA) in human blood serum and ascitic fluid samples. 4-(4,5-Diphenyl-1H-imidazol-2-yl)benzoyl chloride (DIB-Cl) was used as the fluorescent label, and the excess reagent was removed by a column-switching technique. Liquid-liquid extraction with chloroform was used for the pretreatment of serum and ascitic fluid samples. BPA in both the samples could be determined in the concentration range of 0.1-7.0 ppb with the detection limit of 0.04 ppb at a signal-to-noise ratio of 3. The recoveries of BPA spiked to serum and ascitic fluid were 78.6 and 77.7%, respectively. The mean concentrations of BPA (n=9) in maternal and umbilical cord blood sera obtained from healthy pregnant women were 0.46+/-0.20 and 0.62+/-0.13 ppb, respectively. BPA levels (n=21) in blood sera and ascitic fluid obtained from the patients with sterility were also determined to be 0.46+/-0.20 and 0.56+/-0.19 ppb, respectively. Relationships of BPA concentrations were observed between maternal and umbilical cord blood serum samples (r=0.626), as well as blood serum and ascitic fluid samples (r=0.785).

Electrical stimulation of the cerebral peduncle or oral mechanical or chemical stimulation induced rhythmical jaw movements (RJM) in the anesthetized rat. Extracellular recording was made from the pontomedullary reticular neurons in relation to RJM. The RJM-related activity was classified to a tonic, a transient and a phase-dependent rhythmical activities (116, 92 and 45 neurons, respectively). We found that the neurons showing the phase-dependent activities discharged exclusively or almost exclusively during RJM without responding to at least one of three kinds of RJM-inducing stimulation. Fourteen neurons were activated by all kinds of RJM-inducing stimulation and majority of them showed weak or no change in activity during RJM, although some showed the transient or the rhythmical activity during RJM. We propose that the phase-dependent rhythmical activity is necessary to generate RJM since any stimulation-induced RJM was reversibly blocked by microinjection of lidocaine or glutamate receptor blocking agents into the brainstem site concentrated by this type of neurons. No other type of activity was observed exclusively during RJM.

Liposarcomas are the most common of the malignant soft tissue tumors arising in the mediastinum and retroperitoneum. We have treated patients for round cell liposarcoma, an unusual histologic subtype, which is reported to be histologically mistaken for Ewing's sarcoma, lymphoma and other round cell neoplasms. The successful resection of a 2,300-g round cell liposarcoma of the omentum was recently performed at our hospital. Ultrastructural observations of this tumor are characterized by massive proliferation of the mitochondria in addition to the presence of lipid vacuoles in tumor cells. To our knowledge, no description of substantial mitochondrial proliferation in round cell liposarcoma has appeared previously in the literature; therefore, this is the first case report of histopathologic, cytopathologic and electron microscopic observations on this extremely rare tumor.