DP-CAR offers a high R0 resectability rate and may potentially achieve complete local control in selected patients. The persisting early hepatic recurrence may indicate DP-CAR for the treatment of less advanced disease.

The CT scan is most useful in making the diagnosis of intussusception. Colonic lesions should be resected without reduction. Small bowel lesions should be reduced only in patients in whom a benign diagnosis has been strongly suggested preoperatively or in patients in whom resection may result in short gut syndrome.

We describe a highly sensitive and specific method for the quantification of key regulatory oxysterols in biological samples. This method is based upon a stable isotope dilution technique by liquid chromatography-tandem mass spectrometry (LC-MS/MS). After alkaline hydrolysis of human serum (5 ml) or rat liver microsomes (1 mg protein), oxysterols were extracted, derivatized into picolinyl esters, and analyzed by LC-MS/MS using the electrospray ionization mode. The detection limits of the picolinyl esters of 4b-hydroxycholesterol, 7a-hydroxycholesterol, 22R-hydroxycholesterol, 24S-hydroxycholesterol, 25-hydroxycholesterol, 27-hydroxycholesterol, and 24S,25-epoxycholesterol were 2-10 fg (5-25 amol) on-column (signal-to-noise ratio 5 3). Reproducibilities and recoveries of these oxysterols were validated according to one-way layout and polynomial equation, respectively. The variances between sample preparations and between measurements by this method were calculated to be 1.8% to 12.7% and 2.9% to 11.9%, respectively. The recovery experiments were performed using rat liver microsomes spiked with 0.05 ng to 12 ng of oxysterols, and recoveries of the oxysterols ranged from 86.7% to 107.3%, with a mean recovery of 100.6%. This method provides reproducible and reliable results for the quantification of oxysterols in small amounts of biological samples. Supplementary key words liquid chromatography-tandem mass spec-Biological samples contain a large number of oxysterols (1), and most of them are formed from cholesterol by enzymatic oxidation (2 -6) ( Fig. 1) or autoxidation (7). By contrast, the oxysterol 24S,25-epoxycholesterol is not derived from cholesterol but is produced de novo from acetyl-CoA via a shunt in the mevalonate pathway (8).These oxysterols are important molecules for preserving lipid homeostasis in the body. 7a-Hydroxycholesterol is a product of CYP7A1, which is the rate-limiting enzyme in the classic bile acid biosynthetic pathway. 27-Hydroxycholesterol, 24S-hydroxycholesterol, 4b-hydroxycholesterol, 22R-hydroxycholesterol, and 24S,25-epoxycholesterol are effective endogenous ligands of the nuclear receptors liver X receptor a (LXRa) and LXRb (9-11). In addition, 27-hydroxycholesterol (12), 25-hydroxycholesterol (13), and 24S,25-epoxycholesterol (14) are known to downregulate the cholesterol biosynthetic pathway, presumably by blocking the processing of the sterol-regulatory element binding protein.GC-MS has historically been used for the analyses of oxysterols in serum and tissues (1, 15) because the sensitivity and specificity of conventional GC with flame ionization detector is not sufficient to quantify oxysterols in biological samples. However, GC-MS is still not an ideal method, especially for the analysis of 24S,25-epoxycholesterol, because this epoxycholesterol does not survive the temperature required for GC analysis (16). Another approach to quantifying oxysterols in biological samples was HPLC with ultraviolet (UV) detection after derivatization to the D 4 -3-ketones (16-19). Thi...

We have developed a highly sensitive and specific method for the analysis of serum sterol profiles. Sterols in 1 ml of dried serum were derivatized into picolinyl esters (3b-picolinate) and analyzed by liquid chromatographytandem mass spectrometry (LC-MS/MS) using the electrospray ionization (ESI) mode. In addition to cholesterol, 19 cholesterol precursors, cholestanol, campesterol, sitosterol, and sitostanol were identified simultaneously. Quantitative analyses for the picolinyl esters of 11 available sterols were performed, and detection limits were found to be less than 1 pg on-column. Reproducibilities and recoveries of 8 noncholesterol sterols were validated according to one-way layout and polynomial equation, respectively. The variances between sample preparations and between measurements by this method were calculated to be 1.6% to 8.2% and 2.5% to 16.5%, respectively. The recovery experiments were performed using 1 ml aliquots of normal human serum spiked with 1 ng to 6 ng of sterols, and recoveries of the sterols ranged from 88.1% to 102.5% with a mean recovery of 98.1%. The present method provides reliable and reproducible results for the identification and quantification of neutral sterols, especially in small volumes of blood samples, which is useful for serological diagnosis of inherited disorders in cholesterol metabolism and for noninvasive evaluation of cholesterol biosynthesis and absorption in humans.-Honda, A., K. Yamashita, H. Miyazaki, M. Shirai, T. Ikegami, G. Xu, M. Numazawa, T. Hara, and Y. Matsuzaki. Highly sensitive analysis of sterol profiles in human serum by LC-ESI-MS/MS.

A new application of the time-resolved transient grating method for measuring the enthalpy and reaction volume changes in a photochemical reaction is described in detail. From the temporal profile of the signal, these quantities can be determined independently in one particular solvent at a temperature and a pressure. The advantages of this method become clear by a comparison with the previously used photothermal methods, such as the thermal lens and photoacoustic methods. The partial molar volumes of carbon monoxide as well as the reaction volume changes of the photodissociation of diphenylcyclopropenone in several alkanes and aqueous solution are measured, and its solvent dependence is discussed in terms of the isothermal compressibility of the matrix.