111In–L–LDL and 153Gd–L–LDL as radiotracers for detection of AR4‐2J rat pancreatic tumors

Pancreatic cancer has an extremely poor prognosis, due, in part, to lack of methods for early diagnosis. The present study was designed to evaluate the potential of labeling low‐density lipoprotein (LDL) with a radionuclide using a lipid chelating agent, bis(stearylamide) of diethylenetriaminepentaacetic acid (L), to detect pancreatic tumors by gamma‐scintigraphy. Previous studies indicated that the difficulty of visualization of pancreatic tumors was due to their poor vascularization. This study compares the ability of two radiotracers, ¹¹¹In–L–LDL and ¹⁵³Gd–L–LDL to target highly vascularized rat pancreatic tumors (AR4‐2J) implanted in nude mice. Biodistribution studies showed that the tumor uptake of ¹¹¹In–L–LDL and ¹⁵³Gd–L–LDL tracers was twofold and fivefold higher respectively than with the controls (¹¹¹In citrate and ¹⁵³Gd citrate respectively). These tracers would thus be suitable for scintigraphic imaging. We show here that LDL could be employed as a delivery system for tracers such as ¹¹¹In or ¹⁵³Gd when these two radionuclides are complexed by a lipid‐chelating anchor, and that ¹¹¹In–L–LDL and ¹⁵³Gd–L–LDL enabled better visualization of the pancreatic tumor tissues, with a better result with ¹⁵³Gd–L–LDL. Copyright © 2004 John Wiley & Sons, Ltd.     

The oxime bond formation as an efficient tool for the conjugation of ruthenium complexes to oligonucleotides and peptides

A convenient method for the conjugation of ruthenium complex on oligonucleotides and peptides through chemoselective oxime linkage is reported. Novel Ru(II) complexes sustaining an aminooxy containing ligand were prepared and efficiently coupled with the oligonucleotides and peptides functionalized with the complementary reactive aldehyde group. The method described herein could be a useful tool for preparing a broad range of metal complex-oligonucleotide and peptide conjugates.     

Xanthones and other constituents of Allanblackia monticola (Guttiferae)

A xanthone derivative, 3,6,7-trihydroxy-1-methoxyxanthone has been isolated from the stem bark of Allanblackia monticola together with other known compounds, 2,6-dihydroxy-1-methoxyxanthone, allanxanthone A, epicathechin and oleanolic acid acetate. The structure of the new compound was elucidated by spectroscopic methods.     

Microrobotics and MEMS-based fabrication techniques for scaffold-based tissue engineering

Scaffold based tissue engineering strategies use cells, biomolecules and a scaffold to promote the repair and regeneration of tissues. Although scaffold-based tissue engineering approaches are being actively developed, most are still experimental, and it is not yet clear what defines an ideal scaffold/cell construct. Solid free form fabrication (SFF) techniques can precisely control matrix architecture (size, shape, interconnectivity, branching, geometry and orientation). The SFF methods enable the fabrication of scaffolds with various designs and material compositions, thus providing a control of mechanical properties, biological effects and degradation kinetics. This paper reviews the application of micro-robotics and MEMS-based fabrication techniques for scaffold design and fabrication. It also presents a novel robotic technique to fabricate scaffold/cell constructs for tissue engineering by the assembly of microscopic building blocks.     

Retronasal Aroma of Beef Pate Analyzed by a Chewing Simulator

In retronasal aroma, the targeted aroma compounds are released from food during chewing. The changes in the food structures during chewing strongly influence the release of the compounds, therefore affecting the perception of food. Here, the relationship between retronasal aroma and food deliciousness based on the physicochemical properties of aroma compounds was examined. We considered the consumption of solid foods and the effect of oral parameters in elderly people. Beef pate was used as a model food sample to study the effect of the release of aroma compounds under controlled in vitro mastication and salivation conditions using a chewing simulator. We identified the effects of coexisting ingredients such as beef fat on the time course behavior of the release of aroma compounds. In particular, the release of the middle types of aromas was significantly faster with stronger chewing force, and higher with a high fat content of the sample. In addition, a larger release intensity was observed when soy proteins were partially substituted for beef proteins. Using an appropriate model saliva, a change in the salting-out effect from the saliva composition was found to be a factor, which could explain the lowering of aroma sensation in an elderly person.     

Long-term carrier-envelope phase stability from a grating-based, chirped pulse amplifier

We demonstrate a carrier-envelope phase (CEP) stabilized, chirped pulse laser amplifier that exhibits greatly improved intrinsic long-term CEP stability compared with that of other amplifiers. This system employs a grating-based stretcher and compressor and a cryogenically cooled laser amplifier. Single-shot carrier envelope phase noise measurements are also presented that avoid underestimation of this parameter caused by fringe averaging and represent a rigorously accurate upper limit on CEP noise.     

Optimal acoustic fields in compact thermoacoustic refrigerators

Thermoacoustic refrigerators have been developed during the last 15 years, employing quasi-standing resonant acoustic waves inside fluid-filled cavities to transfer heat along a stack region. Because higher efficiency can be reached when a significant travelling wave component exists in the resonator, specific resonant thermoacoustic devices have been designed allowing to adjust more or less the ratio of travelling and standing wave components. However, the acoustic pressure field and the particle velocity field do not appear to be the optimal ones, for the thermal quantities of interest. Thus, it is the aim of the paper to present a new kind of thermoacoustic standing wave-like device which allows to control easily and independently the pressure field and the particle velocity field, after investigating the optimal acoustic field, in the stack region, for the main parameters of interest, i.e. the temperature gradient, the thermoacoustic heat flow and the coefficient of performance.     

Cell refractive index tomography by digital holographic microscopy

For what we believe to be the first time, digital holographic microscopy is applied to perform optical diffraction tomography of a pollen grain. Transmission phase images with nanometric axial accuracy are numerically reconstructed from holograms acquired for different orientations of the rotating sample; then the three-dimensional refractive index spatial distribution is computed by inverse radon transform. A precision of 0.01 for the refractive index estimation and a spatial resolution in the micrometer range are demonstrated.     

Neutral Community Theory: How Stochasticity and Dispersal-Limitation Can Explain Species Coexistence

Neutral community theory explains biodiversity, i.e. the coexistence of several species, as the result of a stochastic balance between immigration and extinction on a local level, and between speciation and extinction on a regional level. The most popular model, presented by Hubbell in 2001, has seen many analytical developments in recent years, which can be used in model analysis, model testing and model comparison. We review these developments here, and present alternative derivations and shine previously unnoticed lights on them.     

Self-activated luminescence in zinc-sulfo-selenide crystals

The orange luminescence at 2.15eV of As-grown ZnS_0.52Se_0.48crystals has been studied. The peak energy, halfwidth and Gaussian band shape exhibit a temperature dependence which is similar to that of the self-activated (SA) luminescence of ZnS at 2.66 eVand to that of ZnSe at 2.03 eV, and which can be described satisfactorily by a configurational coordinate model. However, optically detected magnetic resonance experiments at 1.8 K show that the luminescence is due to the recombination of an electron thermally released from a donor state with a hole trapped at an A-center acceptor state. The temperature dependence of the thermoluminescence spectra above 77 K and their spectral shift under additional IR exposure are also consistent with radiative recombination involving distant donor-acceptor pairs.