Capillary electrophoretic detection in apolipoprotein E genotyping

We describe the application of capillary electrophoresis to detect DNA fragments, obtained after amplifying a part of the apolipoprotein E (apoE) gene with polymerase chain reaction (PCR). Compared to conventional agarose slab gel electrophoresis (AGE), CE appears the method of choice with regard to resolution and sensitivity, to detect DNA fragments in the range of 20-100 base pairs. Especially discrimination between apoE2/E2 and apoE2/E3 genotypes is more reliable with CE than with AGE, this being of great clinical value in the diagnosis of familiary dysbetalipoproteinemia.     

An improved error bound for a finite element approximation of a model for phase separation of a multi-component alloy

Using the approach of Rulla (1996 SIAM J. Numer. Anal. 33, 68-87)for analysing the time discretization error and assuming moreregularity on the initial data, we improve on the error boundderived by Barrett and Blowey (1996 IMA J. Numer. Anal. 16,257-287) for a fully practical piecewise linear finite elementapproximation with a backward Euler time discretization of amodel for phase separation of a multi-component alloy.     

The Stark effect in the 6snf Rydberg series of barium

The Stark effect has been studied in the odd-parity 6snf^1,3F₃ Rydberg series of barium with high-resolution laser-atomic-beam spectroscopy. Scalar and tensor polarizabilities have been measured of 6snf¹F₃ levels with n=11–30 and of 6snf³F₃ levels withn = 12 ? 40. The contributions of the adjacent even-parity Rydberg levels to these polarizabilities have been calculated as far as data are available. This results in important additional information on the only partly known 6sng^1,3G₄ series and confirms the perturbation of these series atn = 24 by a 5d7dJ= 4 level. A tentative three-channel quantum-defect-theory analysis of the^1,3G₄ series has been performed. It is shown that reported level energies of the 6snd^1,3D₂ series are systematically 0.14 cm^?1 too high.     

In vivo C magnetic resonance spectroscopy of a human brain tumor after application of C-1-enriched glucose

Objectives

As a unique tool to assess metabolic fluxes noninvasively, ¹³C magnetic resonance spectroscopy (MRS) could help to characterize and understand malignancy in human tumors. However, its low sensitivity has hampered applications in patients. The aim of this study was to demonstrate that with sensitivity-optimized localized ¹³C MRS and intravenous infusion of [1-¹³C]glucose under euglycemia, it is possible to assess the dynamic conversion of glucose into its metabolic products in vivo in human glioma tissue.

Materials and Methods

Measurements were done at 3 T with a broadband single RF channel and a quadrature ¹³C surface coil inserted in a ¹H volume coil. A ¹H/¹³C polarization transfer sequence was applied, modified for localized acquisition, alternatively in two (50 ml) voxels, one encompassing the tumor and the other normal brain tissue.

Results

After about 20 min of [1-¹³C]glucose infusion, a [3-¹³C]lactate signal appeared among several resonances of metabolic products of glucose in MR spectra of the tumor voxel. The resonance of [3-¹³C]lactate was absent in MR spectra from contralateral tissue. In addition, the intensity of [1-¹³C]glucose signals in the tumor area was about 50% higher than that in normal tissue, likely reflecting more glucose in extracellular space due to a defective blood–brain barrier. The signal intensity for metabolites produced in or via the tricarboxylic acid (TCA) cycle was lower in the tumor than in the contralateral area, albeit that the ratios of isotopomer signals were comparable.

Conclusion

With an improved ¹³C MRS approach, the uptake of glucose and its conversion into metabolites such as lactate can be monitored noninvasively in vivo in human brain tumors. This opens the way to assessing metabolic activity in human tumor tissue.     

Finite element approximation of a model for phase separation of a multi-component alloy with a concentration-dependent mobility matrix

We consider a model for phase separation of a multi-componentalloy with a concentration-dependent mobility matrix and logarithmicfree energy. In particular we prove that there exists a uniquesolution for sufficiently smooth initial data. Further, we provean error bound for a fully practical piecewise linear finiteelement approximation in one and two space dimensions. Finallynumerical experiments with three components in one space dimensionare presented.