A technique for computing dose volume histograms for structure combinations

Graphical displays of three-dimensional dose distribution data are often too complex to be easily assimilated and interpreted for the evaluation of radiation treatment plans. Histograms showing dose versus volume are convenient and useful tools for summarizing dose distribution information throughout the entire volume of a given anatomic structure. They can quickly highlight characteristics such as dose uniformity and hot and cold spots, and can be used to produce statistics including tumor control and normal tissue complication probabilities. To obtain a dose volume histogram for a given structure, it may be necessary to examine its spatial relationships with neighboring structures. They may overlap, be completely disjoint, or one may be contained within another. To resolve potential ambiguities, a procedure has been developed that assigns hierarchies to anatomical structures for the purpose of histogram calculation. The hierarchy assigned to each structure is used to determine the structure within which a given dose matrix point is considered to lie. In this manner, regions of structure intersection are assigned to one object or another, and dose volume histograms can be calculated for each structure separately. From this framework, addition and subtraction of histograms can also be performed. Details of the algorithm are presented along with an example using patient data.     

Evidence for high-velocity smooth pursuit in the trained cat

It is generally accepted that in cats smooth pursuit velocity of the eye never exceeds a few degrees per second. This is in contrast with observations in primates, where smooth pursuit velocity can reach values as high as 100°/s. Cats were trained to fixate and pursue spots of light appearing on a translucent screen. Spots were moved in the horizontal and vertical planes at different constant velocities up to 80°/s. Eye position was recorded with the sclerai search coil technique. Naive cats did not pursue moving targets with high efficiency. Smooth eye movement velocity saturated at 5°/s. After a few days of training, smooth-pursuit eye velocity increased with target velocity and saturated at 25°/s on average. However, velocities twice as high have been observed frequently. When the target was unexpectedly extinguished, smooth eye movement velocity dropped to values close to 0°/s in approximately 350 ms. After a short training period (usually 5 times the same target presentation), the eye continued to move smoothly until the target reappeared. These data suggest that smooth pursuit eye movements of the cat are qualitatively similar to those of primates, but reach lower velocities and are more variable in their characteristics.     

Effect of titanium surface topography on macrophage activation and secretion of proinflammatory cytokines and chemokines

The macrophage has a major role in normal wound healing and the reparative process around implants. Murine macrophage-like cells RAW 264.7 were used to investigate the effect of titanium surfaces on macrophage activation and secretion of proinflammatory cytokines [interleukin (IL)-1 beta, IL-6, and tumor necrosis factor (TNF)-alpha] and chemokines (monocyte chemoattractant protein-1 and macrophage inflammatory protein-1 alpha). Four topographies were used: those produced by mechanically polishing, coarse sand blasting, acid etching, and sandblasting and acid etching (SLA). Macrophages were plated on the four titanium surfaces at a population density of 5 x 10(5) cells/mL/well. Tissue culture plastic and tissue culture plastic plus lipopolysaccharide (LPS) served as negative and positive control, respectively. In addition, all surfaces were tested for their effects on macrophages in the presence of LPS. Supernatants were collected for assays after 6, 24, and 48 h and the numbers of macrophages attached to the surfaces were quantified using the DAPI (4,6-di-amidino-2-phenylindole) assay. Cytokine and chemokine levels were measured with sandwich enzyme-linked immunosorbent assays. Statistical comparison between the surfaces and the controls was determined by using the two-way analysis of variance including interaction effect (two tailed and p < or = 0.05). Unstimulated macrophages increased their secretion of the proinflammatory cytokine (TNF-alpha) when attached to rough surfaces (acid etching and SLA, p < or = 0.05). In macrophages stimulated with LPS, the roughest surface SLA produced higher levels of IL-1 beta, IL-6, and TNF-alpha at 24 and 48 h than all other surfaces (p < or = 0.05). Surface topography also modulated the secretion of the chemokines monocyte chemoattractant protein-1 and macrophage inflammatory protein-1 alpha by macrophages. Unstimulated macrophages attached to the SLA surface down-regulated their production of chemokines (p < or = 0.05) whereas LPS-stimulated macrophages attached to the SLA surface up-regulated their production (p < or = 0.05). Moreover, the SLA surface was found to act synergistically with LPS as well as the combination of blasting and etching features of the SLA surface resulted in significant release of proinflammatory cytokines and chemokines by stimulated macrophages at 24 and 48 h (p < or = 0.05). This in vitro study has demonstrated that surface topography, in particular the SLA surface, modulated expression of proinflammatory cytokines and chemokines by macrophages in a time-dependent manner.     

CD39 activity correlates with stage and inhibits platelet reactivity in chronic lymphocytic leukemia

Background  

Chronic lymphocytic leukemia (CLL) is characterized by accumulation of mature appearing lymphocytes and is rarely complicated by thrombosis. One possible explanation for the paucity of thrombotic events in these patients may be the presence of the ecto-nucleotidase CD39/NTDPase-1 on the surface of the malignant cells in CLL. CD39 is the major promoter of platelet inhibition in vivo via its metabolism of ADP to AMP. We hypothesize that if CD39 is observed on CLL cells, then patients with CLL may be relatively protected against platelet aggregation and recruitment and that CD39 may have other effects on CLL, including modulation of the disease, via its metabolism of ATP.     

Evaluation of R-Mix shell vials for the diagnosis of viral respiratory tract infections.

Respiratory viruses cause significant morbidity and mortality. The management of these infections can be improved by a rapid diagnosis and administration of available virus-specific therapy. The goal of this study was to compare R-Mix, an engineered tissue monolayer for rapid shell vial (SV) diagnosis of viral respiratory infections, with conventional tissue culture (TC) and conventional respiratory SV (primary rhesus monkey kidney (RhMK) and Hep2 monolayers). The primary outcome measure was sensitivity for detection of influenza A and B, respiratory syncytial virus, parainfluenza 1-3, and adenovirus. The study was performed in two phases: (1) the three methods were compared using 250 nasal washes from children with lower respiratory tract infections; (2) a modified R-Mix SV harvesting schedule (SV were harvested at 24 and 120 h) was compared with TC and conventional RhMK/Hep2 SV using 311 respiratory specimens. A total of 110 viruses were identified in the first and 55 in the second phase. Diagnostic accuracies of R-Mix harvested at 24, 48, and 120 h were 98%, whereas for TC varied between 99 and 100%, and for RhMK/Hep2 SV between 98 and 99%. Sensitivities of R-Mix harvested at 24, 48, and 120 h were 26, 75, and 47%, respectively, whereas for TC varied between 60 and 94%, and for RhMK/Hep2 SV between 62 and 85%. R-Mix harvested at 48 h represent a valuable substitute for RhMK/Hep2 SV because they have comparable sensitivities and diagnostic accuracies, but R-Mix offers several technical advantages. In contrast, R-Mix harvested at 24h did not seem a very useful diagnostic tool. The utility of R-Mix harvested at 120 h, which accelerated the diagnosis of 16% of positive specimens in study phase 2, needs further investigation.