Proton relaxation times in human red bone marrow by volume selective magnetic resonance spectroscopy

In hematological diseases the composition of red bone marrow shows alterations. The relaxation timesT ₁ andT ₂ of water and lipids in human hemopoietic bone marrow of 14 normal volunteers and 10 patients with acute leukemia and bone marrow carcinosis are determined using a double spin echo spectroscopy sequencein vivo. The volumes of interest (VOI) of (13 mm)³ in the center of vertebral bodies are examined using different measurement parameters. ForT ₁ measurements an inversion-recovery method is used.T ₂ is evaluated from spectra with differentTE. T ₁ (water) is found in a range between 1000 and 1700 ms,T ₁ (lipids) in a range between 260 and 320 ms in healthy volunteers.T ₂ (water) is determined between 32 and 65 ms. In some cases phase distortions of the water signals occur in the spectra. Water flow within the VOI may be a possible reason.T ₂ (lipids) is evaluated between 73 and 91 ms. The patients with acute leukemia exhibit clearly reduced lipid signals in their spectra. Lipid relaxation times could not be determined in these cases.T ₂ (water) is prolonged in acute leukemia to 51–98 ms.T ₁ (water) was not significantly different from values of healthy volunteers in our measurements. Results are discussed in comparison to relaxometric data from imaging and STEAM spectroscopic methods of other authors.     

Supramolecular fluorophores for biological studies: phenylene vinylene-amino acid amphiphiles

We report here on a family of self-assembling fluorescent organic amphiphiles with a biomolecular L-lysine hydrophile and a photonically active phenylene vinylene hydrophobe. Unlike conventional amphiphiles, these segmented dendrimers feature a rigid, branched hydrophobe, and have packing characteristics controlled by the ratio of cross-sectional areas of the hydrophobe and hydrophile. In dilute solution, the amphiphiles form supramolecular aggregates, which are easily taken in by cells through an endocytic pathway, and have no discernible effect on cell proliferation or morphology. An analogous pyrene-based amphiphile was cytotoxic, suggesting that cell survival may be linked either to the self-assembling nature of the amphiphiles, or to the specific properties of the phenylene vinylene segment. The combination of photonic and biological components in these amphiphiles provides great potential for applications in sensing or delivery of molecules to intracellular targets.     

Two-proton correlations in the target fragmentation region of nuclear collisions at 200A GeV

Correlations between protons are studied in the target fragmentation region of reactions of protons and¹⁶O with C, Cu, Ag, Au and of³²S with Al and Au at 200A GeV. The emitted protons were measured with the Plastic Ball detector in the WA80 experiment at the CERN SPS. The comparison of the correlation function with calculations, assuming a spherical, gaussian shaped source with a lifetime τ=0 fm/c, allows the extraction of radius parameters. The values are very close to those expected from the geometry of the target nuclei and increase with the target mass as αA _Target ^1/3 . Even in proton induced reactions the whole target nucleus is involved. The dependence of the radii on centrality, polar angleθ _lab, and energy, and their relation to measured proton yields are presented.     

Heritability of Stroop and flanker performance in 12-year old children

Background  

There is great interest in appropriate phenotypes that serve as indicator of genetically transmitted frontal (dys)function, such as ADHD. Here we investigate the ability to deal with response conflict, and we ask to what extent performance variation on response interference tasks is caused by genetic variation. We tested a large sample of 12-year old monozygotic and dizygotic twins on two well-known and closely related response interference tasks; the color Stroop task and the Eriksen flanker task. Using structural equation modelling we assessed the heritability of several performance indices derived from those tasks.