Real-time fusion of endoscopic views with dynamic 3-D cardiac images: a phantom study

Minimally invasive robotically assisted cardiac surgical systems currently do not routinely employ 3-D image guidance. However, preoperative magnetic resonance and computed tomography (CT) images have the potential to be used in this role, if appropriately registered with the patient anatomy and animated synchronously with the motion of the actual heart. This paper discusses the fusion of optical images of a beating heart phantom obtained from an optically tracked endoscope, with volumetric images of the phantom created from a dynamic CT dataset. High quality preoperative dynamic CT images are created by first extracting the motion parameters of the heart from the series of temporal frames, and then applying this information to animate a high-quality heart image acquired at end systole. Temporal synchronization of the endoscopic and CT model is achieved by selecting the appropriate CT image from the dynamic set, based on an electrocardiographic trigger signal. The spatial error between the optical and virtual images is 1.4 +/- 1.1 mm, while the time discrepancy is typically 50-100 ms. Index Terms-Image guidance, image warping, minimally invasive cardiac surgery, virtual endoscopy, virtual reality.     

The switch mechanism of the cell death mode from apoptosis to necrosis in menadione-treated human osteosarcoma cell line 143B cells

Time-dependent changes in the cell death mode from apoptosis to necrosis were studied in cultured 143B cells treated with menadione, an anti-cancerous drug, excluding a possible involvement of "secondary necrosis." The population of apoptotic cells judged by FITC-Annexin V and propidium iodide (PI) double staining reached its maximum at 6 hours after 100 microM menadione treatment followed by an abrupt decrease thereafter, while that of necrotic cells continuously increased reaching 90% at 24 hours. Electron microscopically, cells attached to the culture dish at 6 hours after the treatment consisted of two different types of cells: cells with typical apoptotic features occupying the major population and those with condensed nuclei and swollen cytoplasm. Cells attached to the culture dish at 8 hours after the treatment consisted exclusively of those with condensed nuclei and swollen cytoplasm. Mitochondria in these cells showed various structural changes: those swollen to various degrees with deposition of flocculent densities, or those with highly condensed matrix. Distinct decreases both in intracellular levels of ATP and caspase-3-like activities and remarkable elevations of intracellular levels of superoxide, which were partly suppressed by NAD(P)H oxidase inhibitors, occurred at 6 hours after the treatment. These results may suggest that distinct increases of the intracellular level of superoxide derived from plasma membrane NAD(P)H oxidase besides that from mitochondria have triggered the transition of cell death mode from apoptosis to necrosis. Transition of highly condensed mitochondria to extremely swollen ones may reflect necrotic processes in menadione-treated cells. The present study strongly suggests that time-dependent study is essential using the electron microscopic technique to analyze detailed processes in the changes of the cell death mode.     

Multicolour micropatterning of thin films of dry gels

Micropatterning of surfaces with several chemicals at different spatial locations usually requires multiple stamping and registration steps. Here, we describe an experimental method based on reaction-diffusion phenomena that allows for simultaneous micropatterning of a substrate with several coloured chemicals. In this method, called wet stamping (WETS), aqueous solutions of two or more inorganic salts are delivered onto a film of dry, ionically doped gelatin from an agarose stamp patterned in bas relief. Once in conformal contact, these salts diffuse into the gelatin, where they react to give deeply coloured precipitates. Separation of colours in the plane of the surface is the consequence of the differences in the diffusion coefficients, the solubility products, and the amounts of different salts delivered from the stamp, and is faithfully reproduced by a theoretical model based on a system of reaction-diffusion partial differential equations. The multicolour micropatterns are useful as non-binary optical elements, and could potentially form the basis of new applications in microseparations and in controlled delivery.     

Ultrastructural basis for the transition of cell death mode from apoptosis to necrosis in menadione-treated osteosarcoma 143B cells

Time-dependent ultrastructural changes of menadione-treated human osteosarcoma 143B cells were correlated with those in their stainability to Annexin V and propidium iodide (PI). Populations of both apoptotic (Annexin V(+)/PI(-)) and necrotic (Annexin V(+)/PI(+)) cells, judged by flow cytometry, began to increase at 2 h after menadione treatment. The former reached a maximum at 6 h followed by abrupt decreases thereafter, while the latter continued to increase. Electron microscopically, cells obtained at 6 h after the menadione treatment consisted of mixed populations of cells with typical apoptotic features and those with a mixture of apoptotic and necrotic features, while cells obtained at 8-24 h consisted exclusively of cells with a mixture of apoptotic and necrotic features. Thus, necrotic cells, as judged by flow cytometry, were in a transitional state of cell death mode from apoptosis to necrosis and are thus designated as 'intermediate cells'. Lack of apoptotic bodies, judged by flow cytometric analysis on sub-G1 nuclei and by electron microscopy in menadione-treated cells, suggested that the transition of cell death mode from apoptosis to necrosis occurred before the apoptotic processes were completed. Effects of N-acetylcysteine and Z-VAD-fmk on menadione-induced ultrastructural changes were also studied.     

Relationships between Tg and cohesive energy: 1. Dependence of Tg on the composition of copolymers

The possibility of expressing the glass transition temperature of copolymers and homopolymers with an n-alkyl side chain as a function of two parameters (cohesive energy and steric factor) is discussed. An empirical equation representing these two factors is proposed. Calculated values are in good agreement with literature data for the investigated systems.     

The CD200 Regulates Inflammation in Mice Independently of TNF-α Production

Inflammatory bowel disease is characterized by the infiltration of immune cells and chronic inflammation. The immune inhibitory receptor, CD200R, is involved in the downregulation of the activation of immune cells to prevent excessive inflammation. We aimed to define the role of CD200R ligand-CD200 in the experimental model of intestinal inflammation in conventionally-reared mice. Mice were given a dextran sodium sulfate solution in drinking water. Bodyweight loss was monitored daily and the disease activity index was calculated, and a histological evaluation of the colon was performed. TNF-α production was measured in the culture of small fragments of the distal colon or bone marrow-derived macrophages (BMDMs) cocultured with CD200⁺ cells. We found that Cd200^−/− mice displayed diminished severity of colitis when compared to WT mice. Inflammation significantly diminished CD200 expression in WT mice, particularly on vascular endothelial cells and immune cells. The co-culture of BMDMs with CD200⁺ cells inhibited TNF-α secretion. In vivo, acute colitis induced by DSS significantly increased TNF-α secretion in colon tissue in comparison to untreated controls. However, Cd200^−/− mice secreted a similar level of TNF-α to WT mice in vivo. CD200 regulates the severity of DSS-induced colitis in conventionally-reared mice. The presence of CD200⁺ cells decreases TNF-α production by macrophages in vitro. However, during DDS-induced intestinal inflammation secretion of TNF-α is independent of CD200 expression.     

Effect of CO<Subscript>2</Subscript> addition on lignite gasification in a CFB reactor: A pilot-scale study

The addition of carbon dioxide to the gasification media during lignite gasification is introduced. The paper presents thermodynamic grounds of CO₂ enhanced gasification using a simplified equilibrium model. Experimental tests conducted using a pilot-scale circulating fluidized bed gasifier are discussed. Detailed analysis of the CO₂/C ratio on process conditions, namely on the process gas composition, lower heating value and H₂/CO ratio, is provided. Process gas composition implies that the gas is suitable for heat and power generation. Alternatively, CO₂ enhanced gasification could be considered as a carbon capture and utilization technology when external, renewable heat supply to the process is used. The results thus obtained are the initial step toward development of the CO₂ enhanced gasification process.     

The second evolution of ionic liquids: from solvents and separations to advanced materials--energetic examples from the ionic liquid cookbook

In this Account of the small portion of the recent research in ionic liquids (ILs) by the Rogers Group, we fast forward through the first evolution of IL research, where ILs were studied for their unique set of physical properties and the resulting potential for tunable "green solvents", to the second evolution of ILs, where the tunability of the cation and anion independently offers almost unlimited access to targeted combinations of physical and chemical properties. This approach is demonstrated here with the field of energetic ionic liquids (EILs), which utilizes this design flexibility to find safe synthetic routes to ILs with high energy content and targeted physical properties.     

Bivalent peptides as models for multimeric targets of PDZ domains

PDZ domains are among the most common modules in eukaryotic, including human, genomes. They are found exclusively in large, multidomain cytosolic proteins--often with other domains that belong to a variety of families--and are involved in a plethora of physiological and pathophysiological events. PDZ domains mediate protein-protein interactions by binding to solvent-exposed and extended C-terminal short fragments of membrane-associated proteins, such as receptors and ion channels. Most of what is known about the mechanisms of target binding by PDZ domains is inferred from studies that involve isolated recombinant PDZ domains and short synthetic peptides that represent the targets. These binary systems constitute an obvious oversimplification and disregard factors such as noncanonical modes of binding and enhanced affinity due to multimeric interactions mediated by clusters and oligomers of PDZ-domain-containing proteins. We have tested whether the interaction between a dimeric form of PDZ domain that mimics a functional dimeric guanine nucleotide exchange factor, PDZ-RhoGEF (PDZ-containing RhoA-specific guanine nucleotide exchange factor) or LARG (leukemia-associated RhoA specific guanine nucleotide exchange factor), and a bivalent peptide that mimics the dimer of the plexin B receptor, could enhance the interaction between the two moieties. Peptide dimerization was achieved by cross-linking the N-terminal ends of peptides attached to Wang resin with poly(ethylene glycol) spacers (30-45 Angstroms in length). The interaction of dimeric PDZ domains with dimeric peptides resulted in an up to 20-fold increase in affinity compared to the simple binary system. This is consistent with the notion that multimerization of both receptors and PDZ-containing proteins might constitute an important regulatory mechanism.