Neuropeptide Y infusion decreases plasma renin activity in postmyocardial infarction rats.

We wished to determine if chronic neuropeptide Y (NPY) infusion (1 ng/min for 1 week by Alzet minipump) could decrease plasma renin activity (PRA) and norepinephrine (NE) in a rat myocardial infarction (MI) model of moderate compensated congestive heart failure (CHF). CHF was produced by prior (6-8 weeks) ligation of the left coronary artery; control rats were sham-operated. Carotid arterial blood was drawn for PRA and NE in conscious unrestrained rats that had been instrumented 24 h earlier. MI rats had increased PRA as compared with sham-operated rats [8.73 +/- 1.27 vs. 5.10 +/- 0.91 ng angiotensin (AI) I/ml.h, mean +/- SE]. During chronic NPY infusion, PRA was reduced to normal in the MI group (4.78 +/- 0.91) but was not affected in the sham group (5.65 +/- 0.51). Plasma NE was altered similarly, but the changes did not reach statistical significance. These data suggest that NPY has the capacity to restrain renin release in moderate compensated CHF.

Immunology taught by lung dendritic cells.

Dendritic cells (DCs) are leukocytes specialised in the uptake, processing, and presentation of antigen and fundamental in regulating both innate and adaptive immune functions. They are mainly localised at the interface between body surfaces and the environment, continuously scrutinising incoming antigen for the potential threat it may represent to the organism. In the respiratory tract, DCs constitute a tightly enmeshed network, with the most prominent populations localised in the epithelium of the conducting airways and lung parenchyma. Their unique localisation enables them to continuously assess inhaled antigen, either inducing tolerance to inoffensive substances, or initiating immunity against a potentially harmful pathogen. This immunological homeostasis requires stringent control mechanisms to protect the vital and fragile gaseous exchange barrier from unrestrained and damaging inflammation, or an exaggerated immune response to an innocuous allergen, such as in allergic asthma. During DC activation, there is upregulation of co-stimulatory molecules and maturation markers, enabling DC to activate naïve T cells. This activation is accompanied by chemokine and cytokine release that not only serves to amplify innate immune response, but also determines the type of effector T cell population generated. An increasing body of recent literature provides evidence that different DC subpopulations, such as myeloid DC (mDC) and plasmacytoid DC (pDC) in the lungs occupy a key position at the crossroads between tolerance and immunity. This review aims to provide the clinician and researcher with a summary of the latest insights into DC-mediated pulmonary immune regulation and its relevance for developing novel therapeutic strategies for various disease conditions such as infection, asthma, COPD, and fibrotic lung disease.

Indoleamine 2,3-dioxygenase-expressing mature human monocyte-derived dendritic cells expand potent autologous regulatory T cells.

A comprehensive understanding of the complex, autologous cellular interactions and regulatory mechanisms that occur during normal dendritic cell (DC)-stimulated immune responses is critical to optimizing DC-based immunotherapy. We have found that mature, immunogenic human monocyte-derived DCs (moDCs) up-regulate the immune-inhibitory enzyme, indoleamine 2,3-dioxygenase (IDO). Under stringent autologous culture conditions without exogenous cytokines, mature moDCs expand regulatory T cells (Tregs) by an IDO-dependent mechanism. The priming of resting T cells with autologous, IDO-expressing, mature moDCs results in up to 10-fold expansion of CD4(+)CD25(bright)Foxp3(+)CD127(neg) Tregs. Treg expansion requires moDC contact, CD80/CD86 ligation, and endogenous interleukin-2. Cytofluorographically sorted CD4(+) CD25(bright)Foxp3(+) Tregs inhibit as much as 80% to 90% of DC-stimulated autologous and allogeneic T-cell proliferation, in a dose-dependent manner at Treg:T-cell ratios of 1:1, 1:5, and as low as 1:25. CD4(+)CD25(bright)Foxp3(+) Tregs also suppress the generation of cytotoxic T lymphocytes specific for the Wilms tumor antigen 1, resulting in more than an 80% decrease in specific target cell lysis. Suppression by Tregs is both contact-dependent and transforming growth factor-beta-mediated. Although mature moDCs can generate Tregs by this IDO-dependent mechanism to limit otherwise unrestrained immune responses, inhibition of this counter-regulatory pathway should also prove useful in sustaining responses stimulated by DC-based immunotherapy.

First day of an oil spill on the open sea: early mass transfers of hydrocarbons to air and water.

During the first hours after release of petroleum at sea, crude oil hydrocarbons partition rapidly into air and water. However, limited information is available about very early evaporation and dissolution processes. We report on the composition of the oil slick during the first day after a permitted, unrestrained 4.3 m(3) oil release conducted on the North Sea. Rapid mass transfers of volatile and soluble hydrocarbons were observed, with >50% of ≤C17 hydrocarbons disappearing within 25 h from this oil slick of <10 km(2) area and <10 μm thickness. For oil sheen, >50% losses of ≤C16 hydrocarbons were observed after 1 h. We developed a mass transfer model to describe the evolution of oil slick chemical composition and water column hydrocarbon concentrations. The model was parametrized based on environmental conditions and hydrocarbon partitioning properties estimated from comprehensive two-dimensional gas chromatography (GC×GC) retention data. The model correctly predicted the observed fractionation of petroleum hydrocarbons in the oil slick resulting from evaporation and dissolution. This is the first report on the broad-spectrum compositional changes in oil during the first day of a spill at the sea surface. Expected outcomes under other environmental conditions are discussed, as well as comparisons to other models.

Measurement of the mechanical power of walking by satellite positioning system (GPS).

PURPOSE: This descriptive article illustrates the application of Global Positioning System (GPS) professional receivers in the field of locomotion studies. The technological challenge was to assess the external mechanical work in outdoor walking. METHODS: Five subjects walked five times during 5 min on an athletic track at different imposed stride frequency (from 70-130 steps x min(-1)). A differential GPS system (carrier phase analysis) measured the variation of the position of the trunk at 5 Hz. A portable indirect calorimeter recorded breath-by-breath energy expenditure. RESULTS: For a walking speed of 1.05 +/- 0.11 m x s(-1), the vertical lift of the trunk (43 +/- 14 mm) induced a power of 46.0 +/- 20.4 W. The average speed variation per step (0.15 +/- 0.03 m x s(-1)) produced a kinetic power of 16.9 +/- 7.2 W. As compared with commonly admitted values, the energy exchange (recovery) between the two energy components was low (39.1 +/- 10.0%), which induced an overestimated mechanical power (38.9 +/- 18.3 W or 0.60 W x kg(-1) body mass) and a high net mechanical efficiency (26.9 +/- 5.8%). CONCLUSION: We assumed that the cause of the overestimation was an unwanted oscillation of the GPS antenna. It is concluded that GPS (in phase mode) is now able to record small body movements during human locomotion, and constitutes a promising tool for gait analysis of outdoor unrestrained walking. However, the design of the receiver and the antenna must be adapted to human experiments and a thorough validation study remains to be conducted.

Species-specific population structure in rock-specialized sympatric cichlid species in Lake Tanganyika, East Africa.

Species richness and geographical phenotypic variation in East African lacustrine cichlids are often correlated with ecological specializations and limited dispersal. This study compares mitochondrial and microsatellite genetic diversity and structure among three sympatric rock-dwelling cichlids of Lake Tanganyika, Eretmodus cyanostictus, Tropheus moorii, and Ophthalmotilapia ventralis. The species represent three endemic, phylogenetically distinct tribes (Eretmodini, Tropheini, and Ectodini), and display divergent ecomorphological and behavioral specialization. Sample locations span both continuous, rocky shoreline and a potential dispersal barrier in the form of a muddy bay. High genetic diversity and population differentiation were detected in T. moorii and E. cyanostictus, whereas much lower variation and structure were found in O. ventralis. In particular, while a 7-km-wide muddy bay curtails dispersal in all three species to a similar extent, gene flow along mostly continuous habitat appeared to be controlled by distance in E. cyanostictus, further restricted by site philopatry and/or minor habitat discontinuities in T. moorii, and unrestrained in O. ventralis. In contrast to the general pattern of high gene flow along continuous shorelines in rock-dwelling cichlids of Lake Malawi, our study identifies differences in population structure among stenotopic Lake Tanganyika species. The amount of genetic differentiation among populations was not related to the degree of geographical variation of body color, especially since more phenotypic variation is observed in O. ventralis than in the genetically highly structured E. cyanostictus.