Chromatographic separation of fullerenes.
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Journal Article↗
Biomedical subjects
Yoshihiro Saito
Publications and source records attributed to Yoshihiro Saito.
Development of miniaturized sample preparation with fibrous extraction media.
Introducing fine polymeric filaments as the extraction medium, a miniaturized sample preparation technique for micro-column liquid chromatography (micro-LC) has been developed along with the investigation of a reproducible preparation scheme of the extraction capillary. The polymeric filaments were packed longitudinally into either a fused-silica capillary or a polyether ether ketone (PEEK) capillary of appropriate dimensions, and the extraction capillary was installed to the injection valve in micro-LC system. The number of packed filaments should be precisely counted before the packing process to make sure the reproducible preparation of the extraction capillary. With conventional stationary phase materials for open-tubular gas chromatography, polymeric coating to the surface of the filaments was also studied in order to further enhance the extraction performance and selectivity. Coated with the polymeric material suitable for the extraction of particular analyte, a dramatic improvement on the extraction power was obtained. The results suggest that the future possibility of novel tailored fibrous extraction medium with an appropriate coating on it, especially for the analysis of complex sample matrices.
Chromatography, Liquid↗
Phase II study of bi-weekly docetaxel and carboplatin with concurrent thoracic radiation therapy followed by consolidation chemotherapy with docetaxel plus carboplatin for stage III unresectable non-small cell lung cancer.
OBJECTIVE: Docetaxel and carboplatin (DC) have demonstrated activity as radiation sensitizers in pre-clinical studies. The aim of this phase II study was to evaluate the efficacy and toxicity of DC with concurrent thoracic radiation therapy (TRT) followed by consolidation chemotherapy with DC for stage III unresectable non-small cell lung cancer (NSCLC). PATIENTS AND METHODS: Thirty-three previously untreated patients with inoperable, locally advanced (LA) NSCLC received docetaxel 30 mg/m2 over 1 h and carboplatin at an AUC of 3 every 2 weeks for six courses--four courses during concurrent chemoradiotherapy and two courses following completion of radiotherapy. Concurrent TRT was performed in 2-Gy daily fractions to a total dose of 60 Gy. RESULTS: Among 32 evaluable patients, the overall response rate was 91%, with two complete responses (CR) and 27 partial responses (PR). Median survival time by intention-to-treat analysis was 27 months, with survival rates of 76% at 1 year and 61% at 2 years. Serious side effects were generally limited to grade 3 neutropenia in 6%, grades 3 and 4 pulmonary toxicity in 6 and 3%, respectively, and grade 3 esophagitis in 3% of patients. CONCLUSIONS: DC with concurrent TRT followed by consolidation chemotherapy was highly active with manageable toxicity in patients with stage III unresectable NSCLC.
Adult↗
A modified method using static head-space gas chromatography for determining the stability constants of 1-alkanol/alpha-cyclodextrin complexation.
A modification of the conventional static head-space gas chromatography method (SHSGC method) to determine stability constants for 1-alkanol/alpha-CD inclusion complexes was investigated. The 1 : 1 stability constants determined by this modified SHSGC method are in reasonable agreement with the corresponding values reported previously. The modified SHSGC method precludes the necessity of the calibration curve by the use of Henry's law constant of guest. Consequently, the modified SHSGC method is more advantageous than the conventional SHSGC method because the experimental time required for determination of the stability constant is markedly reduced.
Calibration↗
Effects of bedtime vs. morning administration of the long-acting lipophilic angiotensin-converting enzyme inhibitor trandolapril on morning blood pressure in hypertensive patients.
Cardiovascular events occur most frequently in the morning. To study the effects of the long-acting lipophilic angiotensin-converting enzyme (ACE) inhibitor trandolapril on morning blood pressure (BP), we performed ambulatory BP monitoring (ABPM) before and after administration of trandolapril just before going to bed (bedtime-administered group: n=17) or in the morning (morning-administered group: n=20) in 37 hypertensive patients. Both sets of ABPM data were available in 30 patients. The 24-h systolic BP (SBP) levels were significantly decreased by 7.2 mmHg in the morning-administered group (p=0.02) and by 5.2 mmHg in the bedtime-administered group (p=0.04). In the bedtime-administered group, prewaking SBP (the average of the 2-h SBP values just before waking) and morning SBP (the average of the 2-h SBP values just after waking) were significantly decreased by 11 mmHg (p=0.005) and by 8.4 mmHg (p=0.03), respectively. On the other hand, in the morning-administered group, the reduction of prewaking SBP (3.9 mmHg, n.s.) and morning SBP (6.6 mmHg, n.s.) did not reach the level of statistical significance. However, the differences in the reductions of prewaking and morning SBPs between the two groups were not statistically significant. There was no additional reduction of the nighttime lowest BP in either administration group. In conclusion, bedtime administration of the long-acting ACE inhibitor trandolapril seems to be a safe and effective means of controlling morning BP in hypertensive patients without an excessive fall in nocturnal BP.
Aged↗
Polymer-coated fibrous stationary phases in packed-capillary gas chromatography.
Fibrous synthetic polymers have been introduced as the support material for packed capillaries in gas chromatography. The filaments of the polymers were packed longitudinally into a fused-silica capillary, followed by the conventional coating process for open-tubular capillaries. With various polysiloxane-based polymeric materials coated onto these filaments, it was demonstrated that the retentivity was significantly improved over conventional wall-coated capillaries of the same length and that the selectivity can be tuned by selecting different coating materials chosen for the various purposes. The results clearly showed the contribution of the fibrous support and the polymer-coating to the retention of analytes. They also showed the bright possibility for a novel usage of fine fibrous polymers as the support material, which can be combined with a newly-synthesized coating materials designed for particular separations.
Journal Article↗
Polymer-coated fibrous materials as the stationary phase in packed capillary gas chromatography.
Synthetic polymer filaments have been introduced as the support material in packed capillary gas chromatography (GC). The filaments of the heat-resistant polymers, Zylon, Kevlar, Nomex, and Technora, were longitudinally packed into a short fused-silica capillary, followed by the conventional coating process for open-tubular GC columns. The separation of several test mixtures such as n-alkylbenzenes and n-alkanes was carried out with these polymer-coated fiber-packed capillary columns. With the coating by various polymeric materials on the surface of these filaments, the retentivity was significantly improved over the parent fiber-packed column (without polymer coating) as well as a conventional open-tubular capillary of the same length. The results demonstrated a good combination of Zylon as the support and poly(dimethylsiloxane)-based materials as the coating liquid-phase for the successful GC separation of n-alkanes and polycyclic aromatic hydrocarbons (PAHs), while successful applications for other separations such as poly(ethylene glycol) coating for the separation of alcohols were also obtained. From the results it has been suggested that the selectivity of the fiber-packed column could be tuned by selecting different coating materials, indicating the promising possibility for a novel usage of fine fibrous polymers as the support material that can be combined with newly synthesized coating materials specially designed for particular separations. Taking advantage of good thermal stability of the fibers, the column temperature could be elevated to higher than 350 degrees C with the combination of a short metallic capillary.
Journal Article↗
Better success of retinal reattachment with long-standing gas tamponade in highly myopic eyes.
BACKGROUND: To evaluate the efficacy of long-term gas tamponade after pars plana vitrectomy (PPV) for retinal detachment (RD) due to a macular hole (MH) in highly myopic eyes. METHODS: A retrospective study was conducted at two institutions. The study included 25 highly myopic eyes with RD resulting from a MH. C3F8 gas tamponade was used in 13 eyes (C3F8 gas group), and SF6 gas tamponade was used in 12 eyes (SF6 gas group) following PPV. C3F8 gas has a longer half-life time in the vitreous cavity than SF6 gas. The main outcome measures were the anatomic reattachment rate and the visual acuity (VA). Follow-up periods were at least 24 months. RESULTS: The anatomic reattachment rate and MH closure following the initial surgery were significantly higher in the C3F8 gas group (100%) than in the SF6 gas group (66.7%; P=0.039). The differences in the postoperative VAs were not significant both for all eyes and only for eyes with initial anatomic success. (P=0.42 and P=0.54, respectively). In addition, no significant difference was found in the improvement of VA both for all eyes and for the initial success eyes (P=0.66 and P=0.56, respectively). CONCLUSION: We conclude that the longer duration of tamponade with C3F8 gas results in a higher rate of successful closure and that C3F8 gas tamponade is an effective treatment for MH with RD in highly myopic eyes.
Aged↗
Miniaturized sample preparation combined with liquid phase separations.
Miniaturized sample preparation methods designed as the sample pretreatment for liquid phase separations, such as liquid chromatography, capillary electrophoresis and capillary electrochromatography, have been reviewed especially for the on-line coupling of the sample preparation process and the separation process. The development of the desorption interfaces for the effective combining of the sample preparation and subsequent liquid phase separations is briefly described along with the applications of the combined analytical systems to the analysis of complex sample mixtures such as biological and environmental matrices. Novel use of fine polymeric filaments as the extraction medium for microscale liquid phase separation methods are investigated and a comparison is made with other sample preparation techniques. Polymer coating onto the fibrous material is also introduced to further develop microscale sample preparation methods with improved extraction performance. Several other microscale sample preparation methods having a potential compatibility to the liquid phase separations are also described for future applications of these techniques.
Chromatography, Liquid↗
Polymer-coated fibrous extraction medium for sample preparation coupled to microcolumn liquid-phase separations.
Polymer-coated fibrous material has been introduced as the extraction medium for a miniaturized sample preparation method being coupled with microcolumn liquid chromatography. The preconcentration and the subsequent liquid chromatographic separation of tricyclic antidepressants (TCAs) drugs, amitriptyline, imipramine, nortriptyline and desipramine, was carried out with the hyphenated system. Several basic experimental parameters, such as extraction and separation conditions, were investigated along with the applicability of the method for the analysis of biological fluids. The results clearly showed that the on-line coupled system could be a powerful tool for the analysis of complex mixtures in biological matrix without a large solvent consumption and specially designed instruments. The lowest limit of quantification was quite acceptable for the analysis of TCAs in clinical and forensic situations.
Antidepressive Agents, Tricyclic↗
Solubilization of (+)-limonene by anionic/cationic mixed surfactant systems.
The combined effects of sodium n-octyl sulfate (SOS) and cetyltrimethylammonium bromide (CTAB) on the solubilization of (+)-limonene in aqueous solution were studied using a headspace gas chromatography technique. The findings showed the mixing of SOS and CTAB resulted in positive synergistic effects on the solubility of (+)-limonene. The positive synergistic effects are explained from the perspective of the phase behavior of this mixed surfactant system.
Alkanesulfonic Acids↗
Complexation of butylbenzenes with 2-hydroxypropyl-cyclodextrins in aqueous solution.
The stability constants for the inclusion of butylbenzenes (BBs) with 2-hydroxypropyl-cyclodextrins (2HP-CDs) in aqueous solution have been determined using the static head-space method. The 1:1 stability constants were obtained by this method. For the complexation of BBs by 2HP-alpha-CD, the order of stability constants was n-BB > isoBB > tert-BB. In contrast, the order for complexation of BBs by 2HP-beta-CD was the opposite: tert-BB > isoBB > n-BB. The order of the stability constants by 2HP-gamma-CD was similar to that of 2HP-beta-CD, but the values of the stability constants were not significantly different in the BB types. In addition, the binding effects are discussed in relation to the different alkyl groups of BBs.
2-Hydroxypropyl-beta-cyclodextrin↗
Effects of poly(ethylene glycol) (PEG) chain length of PEG-lipid on the permeability of liposomal bilayer membranes.
The effects of poly(ethylene glycol) (PEG) chain length of PEG-lipid on the membrane characteristics of liposomes were investigated by differential scanning calorimetry (DSC), freeze-fracture electron microscopy (FFEM), fluorescence polarization measurement and permeability measurement using carboxyfluorescein (CF). PEG-liposomes were prepared from mixtures of dipalmitoyl phosphatidylcholine (DPPC) and distearoyl phosphatidylethanolamines with covalently attached PEG molecular weights of 1000, 2000, 3000 and 5000 (DSPE-PEG). DSC and FFEM results showed that the addition of DSPE-PEG to DPPC in the preparation of liposomes caused the lateral phase separation both in the gel and liquid-crystalline states. The fluidity in the hydrocarbon region of liposomal bilayer membranes was not significantly changed by the addition of DSPE-PEG, while that in the interfacial region was markedly increased. From these results, it was anticipated that the CF leakage from PEG-liposomes is accelerated compared with DPPC liposomes. However, CF leakage from liposomes containing DSPE-PEG with a 0.060 mol fraction was depressed compared with regular liposomes, and the leakage decreased with increasing PEG chain length. Furthermore, the CF leakage from liposomes containing DSPE-PEG with a 0.145 mol fraction was slightly increased compared with that of liposomes containing DSPE-PEG with a 0.060 mol fraction. It is suggested that the solute permeability from the PEG-liposomes was affected by not only properties of the liposomal bilayer membranes such as phase transition temperature, phase separation and membrane fluidity, but also the PEG chain of the liposomal surface.
Lipid Bilayers↗
A botulism case of a 12-year-old girl caused by intestinal colonization of Clostridium botulinum type Ab.
We encountered a 12-year-old girl, who had contracted food-borne botulism, and subsequently suffered from obstinate constipation for more than half a year. Even on hospital day 122, Clostridium botulinum and its toxin were detected in her stool specimens. The potency of the toxin of the blood serum sampled before treatment was 20 mouse minimum lethal dose per ml. The toxin in the blood had a molecular size equivalent to that of type A botulinum neurotoxin. On hospital day 250, the patient's serum detoxified type A neurotoxin. We confirmed that the patient had food-borne botulism caused by C. botulinum type Ab, followed by intestinal colonization-type botulism.
Botulinum Toxins↗
A spot test for aqueous phosphate by color band formation.
Phosphate is generally analyzed by color intensity of phosphoantimonylmolybdenum blue (PAMB): especially by a spot test based on spectrophotometric or visual determination. Visual determination is one of the simplest and most inexpensive methods; however, it is believed to be of low precision. In this work, we have developed an alternative phosphate spot test, where phosphate concentration is measured by the color band length of PAMB formed in a detection tube similar to a gas detection tube. The color band is formed by the entrapment of the hydrophobic ion pair of PAMB and quaternary ammonium ions in the column; we demonstrated that this color band length correlates quantitatively with the phosphate concentration. In order to optimize the measurement performance, systematic investigations have been carried out for various experimental parameters such as phosphate concentration, preparation conditions of the column packing material, the type of support material (either silica-gel or PVC), the solution feeding conditions (filtration or penetration), and volume of the sample solution. The effects from some co-existing components were also studied for the measurement of real samples. Determination of phosphate concentrations in actual wastewaters was successfully carried out by this method, indicating that the quantification range achievable was of 3-18 mg PO(4) L(-1) without dilution prior to the analysis. No interference was observed from suspended solid (SS) and organic pollutants (COD, TOC) during the wastewater analysis. Because of the simplicity and rapid processing of the samples (not requiring any special instruments) this newly developed method can be applied to the on-site analysis of wastewater.
Chromatography↗
Polymer-coated synthetic fibers designed for miniaturized sample preparation process.
Miniaturized sample preparation technique for complex sample matrices has been developed with a polymer-coated fibrous extraction medium. Several hundreds of fine fibrous materials were packed longitudinally into a fused-silica capillary followed by a polymeric coating on it to prepare the extraction capillary. The extraction capillary was installed in a liquid chromatograph as a sample loop of the injection valve. The on-line coupled sample preparation/separation system demonstrated a good validity for the analysis of phthalates in real river and wastewater samples. The lowest limits of quantification for several phthalates were less than 1 ng/ml. The effect of polymeric coating to the filaments on the extraction power was also investigated.
Chromatography, High Pressure Liquid↗
On-line coupling of miniaturized solid-phase extraction and microcolumn liquid-phase separations.
On-line coupling of miniaturized solid-phase extraction methods and microcolumn separation techniques are reviewed. A conventional solid-phase micro-extraction device and fiber-in-tube solid-phase extraction was employed as the sample preparation method. In the fiber-in-tube technique, a novel fibrous polymeric material was introduced as the extraction medium for the microscale sample preparation step which could be directly coupled with microcolumn liquid-phase separation systems, such as microcolumn liquid chromatography, capillary electrophoresis, and capillary electrochromatography. The applications of these hyphenated systems, consisting of the sample preparation and separation processes, are also reviewed.
Capillary Action↗
Miniaturized solid-phase extraction as a sample preparation technique for the determination of phthalates in water.
Miniaturized solid-phase extraction (SPE) has been developed and successfully employed for the determination of organic species in water samples by liquid chromatography (LC). The method is based on the concept of a microscale extraction technique using a fused-silica capillary column for gas chromatography (GC), so-called in-tube solid-phase microextraction (SPME). The extraction conditions, such as the extraction time and flow-rate for the extraction and desorption process, were investigated as well as the effect of the internal structure of the extraction capillary on the efficiency. By inserting a stainless steel wire into the extraction capillary to reduce the internal volume of the capillary with the same surface area of the coating, an improved extraction and pre-concentration effects were obtained. Further pre-concentration was accomplished by the extraction device with a novel fiber-in-tube configuration. The direct coupling of the extraction method with a LC system has made it possible to determine low levels of phthalates in water samples without high consumption of organic solvents. The system developed must have potential applications for the analysis of environmental and biological samples in aqueous sample matrices.
Capillary Action↗