Quantitative assessment of bone marrow hematopoiesis using parametric magnetic resonance imaging

Spatial maps of the percentage cellularity in pelvic bone marrow were calculated at a resolution of 15.6 mm3 from six volunteers and 10 patients treated for documented hematologic disease using a three-point Dixon MRI pulse sequence. The percentage cellularity calculation was aided by analyzing a two-dimensional feature space consisting of the apparent water fraction (Wa), and the T2 relaxation time of water (T2w). An extracellular water fraction was assigned to each voxel on the basis of a two-component T2w algorithm. In six cases, the method was compared to results obtained from core biopsies or aspirates of the posterior iliac crest. The results indicate that segmentation schemes that combine high-quality phase-contrast imaging with nuclear relaxation time measurements can potentially identify the true fractional marrow volume occupied by hematopoietic elements in a variety of clinical situations.     

Studies on the transmission of vibrations in human organism exposed to low-frequency whole-body vibration

Investigations were carried out in a group of 20 males with a definite morpho-physiological type, at two selected ranges of acceleration values chosen according to ISO criteria in the range of 2-20 Hz. In the subjects exposed to vibration the values of vibration acceleration were measured in different points along the spine at the levels of S3, L3, Th7, C3 and at the vertex. The investigations demonstrated that the frequency is the parameter of crucial significance for the propagation of vibrations in the human organism. Vibration within the frequency range up to 12 Hz affects the whole human organism, while the vibrations above 12 Hz have only a local effect.     

Pup and object carrying by maternally and nonmaternally behaving female albino rats (Rattus norvegicus).

Pups and toys (rubber dropper-bulbs) were presented to 48 nulliparous and 10 lactating female albino Sprague-Dawley rats either together (choice test) or in separate tests. Regardless of their reproductive state, Ss fell into 3 categories according to their behavior: (a) Postpartum Ss as well as virgins that behaved maternally picked up pups much faster than toys, carried more pups than toys, gathered young into the nest, but scattered toys outside the nest site. (b) Virgins that carried young spontaneously but did not show any other elements of maternal behavior picked up pups and toys after equal latencies, carried pups and toys in equal numbers, and scattered both the pups and the toys about the floor of the cage. (c) Virgins that ignored pups did not carry young, but they did show high levels of toy carrying and dispersed the toys about the cage. It is proposed that the term retrieving should be limited, by its definition, to those cases in which the objects are carried to a specific location. Thus, pup retrieval was seen exclusively in Ss that showed maternal behavior (i.e., crouching, pup licking), because only these Ss carried pups consistently to the nest. On the other hand, pup carrying shown by nonmaternally behaving Ss and toy carrying shown by all Ss are both cases of scattered, nondirected object carrying, rather than retrieving. (13 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Preparation of ultrathin amorphous ice films for cryo-electron microscopy

Electron microscopy of biological macromolecules embedded in vitrified ice films suffers from serious problems caused by excessive inelastic scattering, beam-induced movements of the specimen, deformation of the molecules by adsorption at the water-air interface and insufficient mechanical stability of the films. We have built an environmental chamber to control temperature and humidity independently in order to produce ultrathin water films (< 20 nm) spanning holes with diameters of 20 μm to 1 mm. The surface tension of the water films was reduced by adding lipid monolayers, thus prolonging the usable time for thinning of the film and avoiding adsorption artefacts in the embedded material. After cryofixation in ethane a carbon film was evaporated on each side of the specimen to stabilize the ultrathin ice—lipid film. Mechanical stability and charging effects could successfully be reduced by this preparation method. Collapsing water films could be cryofixed and the shape of the hole was analysed. By the eccentricity of the elliptical holes an estimation could be made of the burst velocity of the rim of the hole and of the cooling rate of the cryofixation process.     

Quantification of VX vapor in ambient air by liquid chromatography isotope dilution tandem mass spectrometric analysis of glass bead filled sampling tubes

An analysis method has been developed for determining low parts-per-quadrillion by volume (ppqv) concentrations of nerve agent VX vapor actively sampled from ambient air. The method utilizes glass bead filled depot area air monitoring system (DAAMS) sampling tubes with isopropyl alcohol extraction and isotope dilution using liquid chromatography coupled with a triple-quadrupole mass spectrometer (LC/MS/MS) with positive ion electrospray ionization for quantitation. The dynamic range was from one-tenth of the worker population limit (WPL) to the short-term exposure limit (STEL) for a 24 L air sample taken over a 1 h period. The precision and accuracy of the method were evaluated using liquid-spiked tubes, and the collection characteristics of the DAAMS tubes were assessed by collecting trace level vapor generated in a 1000 L continuous flow chamber. The method described here has significant improvements over currently employed thermal desorption techniques that utilize a silver fluoride pad during sampling to convert VX to a higher volatility G-analogue for gas chromatographic analysis. The benefits of this method are the ability to directly analyze VX with improved selectivity and sensitivity, the injection of a fraction of the extract, quantitation using an isotopically labeled internal standard, and a short instrument cycle time.