Mathematical modeling of mass transfer in microvascular wall and interstitial space

The dynamics of macromolecular transport across the microvascular wall and into the adjoining interstitial space was studied in the hamster cheek pouch using intravital fluorescence microscopy in combination with digital image processing. Fluorescein isothiocyanate-labe led dextrans (FITC-Dx) of 70,000 and 150,000 daltons were used as tracers. In each experiment, the time-dependent extravasation of FITC-Dx from a leakage site in a blood vessel was videotaped for about 2 hours. The macromolecular transport from individual microvessels was quantified by digital video-image processing. Histograms of the light intensity distributions for selected fields at various times were obtained and then converted to the interstitial FITC-Dx concentrations using a newly developed in vivo calibration procedure. A one-dimensional unsteady-state model was developed to describe the dynamics of the macromolecular transport. Both molecular diffusion and convective transport in the microvascular wall as well as in the interstitial space were accounted for in the model. The experimental data were correlated using a non-linear regression algorithm incorporating the mathematical model in order to determine the diffusivity coefficients and average fluid velocity terms in the two regions. The diffusivity coefficients for FITC-Dx 70 were found to be 0.90±0.04x10-11 cm2/s in the microvascular wall, and 1.29±0.05x10-8 cm2/s in the interstitial space. The average fluid velocity term in both regions was found to be 2.05±0.05x10-8 cm/s. The corresponding transport parameters for FITC-Dx 150 were 0.27±0.02x10-11 cm2/s, 0.55±0.0SX10-8 cm2/s, and 1.71±0.48x10-8 cm/s, respectively. Using a similar experimental procedures, the extravasation of FITC-Dx 70 and FITC-Dx 150 was experimentally determined after a 5-minute topical application of calcium ionophore A23187 (7x10 7 M) which produced a transient increases in the rate of blood-tissue transport of large molecules. In this case, the diffusivity coefficients and average fluid velocity terms were found to be approximately two times and eight times higher, respectively, than the corresponding parameters obtained in the absence of the calcium ionophore A23187. The diffusivity coefficients and average fluid velocity terms so obtained were then used to quantify the role of the diffusive and convective mechanisms in the total solute flux through the microvascular wall and into the adjoining interstitial space. The macromolecular transport in the microvascular wall was found to be the limiting transport mechanism for the entire process. Within the microvascular wall, it appeared that the molecular diffusion mechanism dominated over convective transport in all the cases considered. However, in the presence of the calcium ionophore A23187 the convection term increased about three times if compared with the corresponding value in the absence of it. Within the interstitial space, diffusion appeared to be the dominating transport mechanism for all cases. It is expected that the proposed model and calibration procedure will be used in the future to describe the dynamics of macromolecular transfer across the microvascular wall and into the interstitial space on the basis of both molecular diffusion and convective transport mechanisms, thus contributing to the solution of the controversy regarding the nature of the transfer mechanism controlling the transport of macromolecules in living systems

Different Environmental Conditions in Genetic Algorithm

We propose an extended genetic algorithm (GA) with different local environmental conditions. Genetic entities, or configurations, are put on nodes in a ring structure, and location-dependent environmental conditions are applied for each entity. Our GA is motivated by the geographic aspect of natural evolution: Geographic isolation reduces the diversity in a local group, but at the same time, can enhance intergroup diversity. Mating of genetic entities across different environments can make it possible to search for broad area of the fitness landscape. We validate our extended GA for finding the ground state of three-dimensional spin-glass system and find that the use of different environmental conditions makes it possible to find the lower-energy spin configurations at relatively shorter computation time. Our extension of GA belongs to a meta-optimization method and thus can be applied for a broad research area in which finding of the optimal state in a shorter computation time is the key problem.Comment: 14 pages, 4 figure

Anti-inflammatory activity of hydrosols from Tetragonia tetragonoides in LPS-induced RAW 264.7 cells

The present study was performed to investigate the anti-inflammatory activity of Tetragonia tetragonoides hydro- sols (TTH) and its underlying mechanism in lipopolysaccharide (LPS)-induced RAW 264.7 cells. Gas chromatog- raphy (GC) coupled with mass spectrometry and retention index calculations showed that TTH were mainly com- posed of tetratetracontane (29.5 %), nonacosane (27.6 %), and oleamide (17.1 %). TTH significantly decreased the production of nitric oxide (NO), prostaglandin E2 (PGE2), interleukin (IL)-6, and IL-1β in LPS-stimulated RAW 264.7 cells. Consistent with these observations, TTH treatment decreased the protein expression levels of inducible NO synthase (iNOS) and cyclooxygenase-2 (COX-2). The molecular mechanism of its anti-inflamma- tory activity was found to be associated with inhibition of nuclear factor-kappa B (NF-κB) phosphorylation and nuclear translocation of NF-κB 65. Furthermore, TTH markedly suppressed the LPS-induced phosphorylation of mitogen-activated protein kinases (MAPKs). Taken together, these data indicate that TTH exerts an anti-inflam- matory activity by inhibiting the NF-κB and MAPK signaling pathways in LPS-stimulated RAW 264.7 cells

Generation of Reactive Oxygen Species (ROS) by Harmful Algal Bloom (HAB)-Forming Phytoplankton and Their Potential Impact on Surrounding Living Organisms

Most marine phytoplankton with relatively high ROS generation rates are categorized as harmful algal bloom (HAB)-forming species, among which Chattonella genera is the highest ROS-producing phytoplankton. In this review, we examined marine microalgae with ROS-producing activities, with focus on Chattonella genera. Several studies suggest that Chattonella produces superoxide via the activities of an enzyme similar to NADPH oxidase located on glycocalyx, a cell surface structure, while hydrogen peroxide is generated inside the cell by different pathways. Additionally, hydroxyl radical has been detected in Chattonella cell suspension. By the physical stimulation, such as passing through between the gill lamellas of fish, the glycocalyx is easily discharged from the flagellate cells and attached on the gill surface, where ROS are continuously produced, which might cause gill tissue damage and fish death. Comparative studies using several strains of Chattonella showed that ROS production rate and ichthyotoxicity of Chattonella is well correlated. Furthermore, significant levels of ROS have been reported in other raphidophytes and dinoflagellates, such as Cochlodinium polykrikoides and Karenia mikimotoi. Chattonella is the most extensively studied phytoplankton in terms of ROS production and its biological functions. Therefore, this review examined the potential ecophysiological roles of extracellular ROS production by marine microalgae in aquatic environment

Ultrathin, polarization-independent, and focus-tunable liquid crystal diffractive lens for augmented reality

Despite the recent advances in augmented reality (AR), which has shown the potential to significantly impact on our daily lives by offering a new way to manipulate and interact with virtual information, minimizing visual discomfort due to the vergence-accommodation conflict remains a challenge. Emerging AR technologies often exploit focus-tunable optics to address this problem. Although they demonstrated improved depth perception by enabling proper focus cues, a bulky form factor of focus-tunable optics prevents their use in the form of a pair of eyeglasses. Herein, we describe an ultrathin, focus-tunable liquid crystal (LC) diffractive lens with a large aperture, a low weight, and a low operating voltage. In addition, we show that the polarization dependence of the lens, which is an inherent optical property of LC lenses, can be eliminated using birefringent thin films as substrates and by aligning the optical axes of the birefringent substrates and LC at a specific angle. The polarization independence eliminates the need for a polarizer, thus further reducing the form factor of the optical system. Next, we demonstrate a prototype of AR glasses with addressable focal planes using the ultrathin lens. The prototype AR glasses can adjust the accommodation distance of the virtual image, mitigating the vergence-accommodation conflict without substantially compromising the form factor or image quality. This research on ultrathin lens technology shows promising potential for developing compact optical displays in various applications.Comment: 23 pages, 9 figure

Improved Sugar Production by Optimizing Planetary Mill Pretreatment and Enzyme Hydrolysis Process

This paper describes an optimization of planetary mill pretreatment and saccharification processes for improving biosugar production. Pitch pine (Pinus rigida) wood sawdust waste was used as biomass feedstock and the process parameters optimized in this study were the buffering media, the milling time, the enzyme quantity, and the incubation time. Glucose yields were improved when acetate buffer was used rather than citrate buffer. Initially, with each process variable tests, the optimal values were 100 minutes of milling, an enzyme concentration of 16 FPU/g-biomass, and a 12-hour enzymatic hydrolysis. Typically, interactions between these experimental conditions and their effects on glucose production were next investigated using RSM. Glucose yields from the Pinus rigida waste exceeded 80% with several of the conditions tested, demonstrating that milling can be used to obtain high levels of glucose bioconversion from woody biomass for biorefinery purposesopen

Strain-dependent lethal effects on abalone and haemolytic activities of the dinoflagellate Karenia mikimotoi

One of the clonal strains of Karenia mikimotoi NGU04 isolated from Kyushu Island in Japan, showed the most potent fish-killing activity in preliminary experiments. To evaluate shellfish toxicity, two species of juvenile abalone were exposed to the NGU04, and the toxicities were compared with those of two other K. mikimotoi strains. Of the two abalone species tested, N. gigantea showed a higher sensitivity to NGU04 than the hybrid abalone (N. discus hannai male × N. gigantea female) did. In comparative studies using N. gigantea, the NGU04 exhibited stronger toxicity on abalone than other strains. The cell-free culture supernatant and the ruptured cell suspension of the NGU04 showed no significant lethal effects on N. gigantea. The NGU04 showed a stronger haemolytic activity on rabbit erythrocytes than did the other two strains. Furthermore, the haemolytic activities of the NGU04 strain towards erythrocytes of four fish species were also stronger than those of other strains

Evaluation of the potential biological toxicities of aqueous extracts from red tide phytoplankton cultures in in vitro and in vivo systems

The biological toxic potentials of aqueous extracts from the dinophycean flagellates Gymnodinium impudicum and Alexandrium affine and the raphidophycean flagellate Chattonella ovata were examined in both in vitro and in vivo systems. Interestingly, the extract from A. affine was the only one that showed potent cytotoxicities towards HeLa, Vero, and Neuro-2a cells in a concentration- dependent manner. Mice given intraperitoneal injections of the extracts revealed that none of the extracts exhibited serious toxicities in mice. However, temporal body weight loss was observed in the mice injected with the extract from A. affine during the early stage, and the dramatic enlargement of spleens was also observed in the mice on the 7th day after injection. Since A. affine extract showed potent hemolytic activity in vitro towards mouse erythrocytes, hemolytic anemia may be a possible mechanism responsible for the splenomegaly in the mice injected with A. affine extract. Similar marginal effects were observed in the mice injected with the extract from C. ovata; however, no significant toxic or detrimental effects were detected in the mice injected with the extract from G. impudicum. These results suggest that the extract from G. impudicum may not be contaminated with detectable levels of biologically hazardous compounds and may be relatively safe compared with the other two extracts

Reevaluation of bactericidal, cytotoxic, and macrophage-stimulating activities of commercially available Fucus vesiculosus fucoidan

Polysaccharides prepared from marine algae sometimes contain contaminants such as polyphenols and endotoxins that may mislead their bona fide biological activities. In this study, we examined bioactive contaminants in commercially available fucoindan from Fucus vesiculosus, along with ascophyllan and fucoidan from Ascophyllum nodosum. F. vesiculosus fucoidan inhibited the growth of Vibrio alginolyticus in a concentration-dependent manner (0-1,000 μg mL?1). However, the antibacterial activity of the fucoidan significantly reduced after methanol-extraction, and the methanol-extract showed a potent antibacterial activity. The extract also showed cytotoxicity to RAW264.7 and U937 cells, and induced apoptotic nuclear morphological changes in U937 cells. These results suggest that the antibacterial activity of the fucoidan is partly due to the methanol-extractable contaminants that can also contribute to the cytotoxicity on RAW264.7 and U937 cells. On the other hand, the activities to induce secretion of nitric oxide and tumor necrosis factor-α from RAW264.7 cells were observed in the fucoidan even after methanol extraction, and the extract had no such activities. Our observations suggest that commercially available fucoidan should be purified prior to biochemical use