Plasma circulating fibrinogen stability and moderate beer consumption

Moderate beer consumption (MBC) is cardioprotective: it positively influences plasma lipid levels and plasma antioxidant activity in beer-consuming individuals. The connection between MBC and blood coagulation is not clearly defined. Forty-two volunteers were equally divided into experimental (EG) and control (CG) groups following coronary bypass surgery. For 30 consecutive days, only patients of the EG consumed 330 mL of beer per day (about 20 g of alcohol). A comprehensive clinical investigation of 42 patients was done. Blood samples were collected before and after the investigation for a wide range of laboratory tests. The plasma fibrinogen was denatured with 8 M urea and intrinsic fluorescence (IF), hydrophobicity and differential scanning calorimetry (DSC) were used to reveal possible qualitative changes. After 30 days of moderate beer consumption, positive changes in the plasma lipid levels, plasma anticoagulant and plasma antioxidant activities were registered in patients of the EG group. In 17 out of 21 patients of the same group, differences in plasma circulating fibrinogen's (PCF), secondary and tertiary structures were found. The stability of fibrinogen, expressed in thermodynamic parameters, has shown that the loosening of the structure takes place under ethanol and urea denaturation. Also fluorescence stability of PCF was decreased. No changes in the lipid levels, anticoagulant and antioxidant activity or changes in PCF were detected in patients of CG. In conclusion, for the first time after a short term of moderate beer consumption some qualitative changes in the plasma circulating fibrinogen were detected: differences in the emission peak response, fluorescence intensity and all thermodynamic data. Together, with the decrease in the PCF concentration it may lead to an elevation of the blood anticoagulant activity.     

Genetic variability in forced and voluntary endurance exercise performance in seven inbred mouse strains.

The goal of this study was to characterize the genetic contribution to both forced and voluntary exercise performance and to determine whether performance in these two paradigms is controlled by similar genetic influences. There were marked strain differences in treadmill exercise performance, with Swiss Webster (SW) and FVB/NJ mice showing elevated performance and C57BL/6J animals showing decreased performance compared with all other strains. There was no apparent relationship between treadmill performance and voluntary wheel performance, with the exception of SW mice, which demonstrated high performances on both the treadmill and the voluntary wheel. Numerous properties were measured to attempt to understand the basis for these differences in exercise performance. DBA/1J and SW mice exhibited significantly greater cardiac contractility than all other analyzed strains. Conversely, BALB/cByJ mice exhibited significantly reduced cardiac contractility compared with all other strains. Expression of molecular indicators of hypertrophy (atrial natriuretic factor and beta-myosin heavy chain) was significantly elevated in DBA/2J myocardium compared with all other analyzed strains.     

Stability in simple grazing models: effects of explicit functions

A class of simple models of a grazed pasture is based on the assumption that the dynamics of green biomass can be expressed as a balance between rates of growth and consumption, both of which are functions only of the total amount of green biomass present. Graphical analysis, using only the general shape of these functions, has shown that the pasture may be either continuously or discontinuously stable under grazing. Further results require explicit specification of these functions. Four growth functions and four consumption functions are considered here and their mathematical and biological properties discussed. The stability properties of the 16 models resulting from combinations of these functions are compared by plotting the isoclines of zero pasture growth, and by obtaining expressions in terms of the parameters for some critical points and quantities. Both methods show considerable similarity between the models in their qualitative behaviour and in the role of certain parameters in determining critical values. There are substantial differences in quantitative predictions of critical values and particularly of the boundary between continuous and discontinuous stability. In the absence of an ungrazable residual, some models are discontinuously stable in the whole parameter space, others only in a limited region of it-albeit the region in which most real systems may be.     

Interactive effects of fire and grazing on structure and diversity of Mediterranean grasslands

Abstract. The separate and combined effects of fire and cattle grazing on structure and diversity of productive Mediterranean grasslands in northern Israel were examined within a set of climatically and edaphically similar sites. Cover and height of green and dry plants in winter, and species richness and diversity in spring, were measured in paired transects on both sides of cattle fences, and on both sides of boundaries of both incidental and experimentally lit fires. Early in the first growing season after a fire, plant cover as well as height of green plants were reduced, compared to unburnt grassland. These structural effects of fire were similar to the effects of grazing, but they were greater in ungrazed than in grazed grasslands, indicating a fire-grazing interaction. The effects of fire were considerably attenuated in the second growing season after the fire. Species richness and diversity tended to be higher in grazed than in adjacent ungrazed grasslands. Richness consistently increased after a fire only in grazed grasslands with a strong perennial component. In ungrazed grasslands, and in predominantly annual grasslands, fires reduced species richness and diversity at least as often as they increased it. Fire and grazing should be regarded as two agents with distinct and interactive effects on the community, rather than as two alternative mechanisms of a general disturbance factor.     

Estimating multiple benefits from vegetation in mediterranean ecosystems

Ecosystems of the Mediterranean region are characterized by a heterogeneous and dynamic landscape mosaic of vegetation formations that provide diverse benefits: agro pastoral products, ecosystem services, and other utilities. Valuation of these benefits in different states of the ecosystem is an important step towards conservation, decision making, and land management. Yet, studies of this kind are scarce, especially cases dealing with more than one benefit. Multiple benefits evaluation is not straightforward; it involves many difficulties and questions which have no agreed solutions, e.g. estimation, common currency, and optimal solution. In this study we present a methodology for the estimation of three benefits in different components of Mediterranean woody vegetation in Israel. Densities of geophyte wildflowers, honey flowers, and fleshy fruits as food for birds were measured within five vegetation components defined by dominant plant functional types, in four sites with different disturbance histories. Each benefit was measured in its own units. The results showed significant differences between vegetation states in values of each benefit. Therefore, it is possible to calculate the contributions of different cover components for these three benefits. Furthermore, this indicates that it is possible to estimate the level of benefits at larger scales as a first approximation, by considering only the composition of the vegetation cover. The values for the three benefits were standardized to illustrate the question of multiple benefits valuation. This method does not lead to an optimization, but can nevertheless provide a useful tool toward conservation and rational management by land managers and policy makers.     

The effect of shrub clearing and grazing on the composition of a Mediterranean plant community: functional groups versus species

Abstract. Fuel-breaks to impede the spread of fires in Mediterranean woody vegetation are created by clearing of shrubs, followed by very intensive cattle grazing before the fire season. The present research analysed the effects of these two disturbance types on herbaceous community composition at the functional group and the species level, by using canonical discriminant ordination analysis and by categorical modeling methods. Grazing caused an increase in the abundance of small species, geophytes, and species with an early flowering period that ends before the grazing period. The abundance of many different species increased as a result of clearing. However, no association was found between positive or negative response to clearing and any species attribute tested. Several a priori functional groups defined by life form and family showed responses to either grazing or clearing. Links between these responses and individual species attributes are discussed. The results emphasize the different nature of the two disturbances: grazing as a selective agent, and shrub clearing as a generalized one. It also stresses the importance of the plant architecture and the morphological and phenological niche in determining community composition under extremely intensive grazing conditions.