Mechanical characteristics of the canine thoracic duct: what are the driving forces of the lymph flow?

This study is designed to better understand the mode of lymph transport, particularly through the extrinsic pumping by external compression of the lymph vessel. The pressure-diameter relationship of lymphatic segments isolated from the canine thoracic duct was examined using a laser optical micrometer measurement system. Results revealed that the thoracic duct displayed a high extensibility or compliance in the physiological pressure range, yet became progressively less so with increasing internal pressure. The calculated incremental circumferential modulus of the thoracic duct under physiological pressure (range of 2 to 6 cm H2O) showed values ranging from 1.2 x 10(4) to 3.61 x 10(5) dyn/cm2. At a pressure of 35 cm H2O, the modulus reached a limiting value of approximately 6.0 x 10(6) dyn/cm2. In the physiological pressure range, the relative wall thickness (h/R0) of the canine thoracic duct was approximately 3.5%, which was much lower than that reported for canine arterial segments and similar in value to that of the canine jugular vein. In conclusion, the pressure-diameter curve of the canine thoracic duct was shown to resemble that of venous vessels. However, the circumferential elastic modulus of the thoracic duct wall was lower than the moduli of veins, proving that lymphatics are more compliant than veins. This suggests lymph flow in the thoracic duct may be better promoted by external compression of the lymphatic vessel.     

Neural correlates of the attentional blink

Attending to a visual event can lead to functional blindness for other events in the visual field. This limit in our attentional capacities is exemplified by the attentional blink (AB), which refers to the transient but severe impairment in perceiving the second of two temporally neighboring targets. Using functional magnetic resonance imaging (fMRI), we observed predominantly right intraparietal and frontal cortex activations associated with the AB. We further demonstrate that an AB can be elicited by both temporal and spatial distractor interference on an attended target and that both of these interference mechanisms activate the same neural circuit. These results suggest that a (right) parietofrontal network previously implicated in attentional control and enhancement is also a locus of capacity-limited processing of visual information.     

The Major Yolk Protein Vitellogenin Interferes with the Anti-Plasmodium Response in the Malaria Mosquito Anopheles gambiae

When taking a blood meal on a person infected with malaria, female Anopheles gambiae mosquitoes, the major vector of human malaria, acquire nutrients that will activate egg development (oogenesis) in their ovaries. Simultaneously, they infect themselves with the malaria parasite. On traversing the mosquito midgut epithelium, invading Plasmodium ookinetes are met with a potent innate immune response predominantly controlled by mosquito blood cells. Whether the concomitant processes of mosquito reproduction and immunity affect each other remains controversial. Here, we show that proteins that deliver nutrients to maturing mosquito oocytes interfere with the antiparasitic response. Lipophorin (Lp) and vitellogenin (Vg), two nutrient transport proteins, reduce the parasite-killing efficiency of the antiparasitic factor TEP1. In the absence of either nutrient transport protein, TEP1 binding to the ookinete surface becomes more efficient. We also show that Lp is required for the normal expression of Vg, and for later Plasmodium development at the oocyst stage. Furthermore, our results uncover an inhibitory role of the Cactus/REL1/REL2 signaling cassette in the expression of Vg, but not of Lp. We reveal molecular links that connect reproduction and immunity at several levels and provide a molecular basis for a long-suspected trade-off between these two processes.     

Neutrophils exhibit distinct phenotypes toward chitosans with different degrees of deacetylation: implications for cartilage repair

Introduction  

Osteoarthritis is characterized by the progressive destruction of cartilage in the articular joints. Novel therapies that promote resurfacing of exposed bone in focal areas are of interest in osteoarthritis because they may delay the progression of this disabling disease in patients who develop focal lesions. Recently, the addition of 80% deacetylated chitosan to cartilage microfractures was shown to promote the regeneration of hyaline cartilage. The molecular mechanisms by which chitosan promotes cartilage regeneration remain unknown. Because neutrophils are transiently recruited to the microfracture site, the effect of 80% deacetylated chitosan on the function of neutrophils was investigated. Most studies on neutrophils use preparations of chitosan with an uncertain degree of deacetylation. For therapeutic purposes, it is of interest to determine whether the degree of deacetylation influences the response of neutrophils to chitosan. The effect of 95% deacetylated chitosan on the function of neutrophils was therefore also investigated and compared with that of 80% deacetylated chitosan.