Enzyme-catalysed hydrolysis of L-amino acid esters in a low water organic solvent studied by isothermal calorimetry

Isothermal calorimetry and UV-visible spectrophotometry have been used to study the thermochemistry of the enzyme-catalyzed hydrolysis of hydrophobic L-amino acid esters in organic solvents with low water content at 298 K. The p-nitrophenyl esters of Z-L-tyrosine and Z-L-phenylalanine were used as model hydrophobic substrates. Acetonitrile was used as a model organic solvent. A special preparation protocol of the reactants in the calorimetric vessel was applied in order to determine the heat effects accompanying the enzyme-catalyzed hydrolysis reaction in organic mixtures with low water content and the Tris buffer ionization enthalpies over the whole range of water content in acetonitrile. It was found that the molar enthalpy of the hydrolysis of p-nitrophenyl esters and buffer ionization enthalpy depend significantly and similarly on the water content in acetonitrile. However, the reaction enthalpy corrected for the buffer ionization enthalpy does not depend on the water content in organic solvent mixtures. An explanation of the effect of the selected organic solvent on the thermochemical parameters was provided on the basis of the IR spectroscopic data for the hydrogen bond network of water in acetonitrile. The results obtained show that the state of water in organic solvents is an important factor that determines the reaction enthalpy as well as buffer ionization enthalpy. © 2008 Springer Science+Business Media, LLC

Dew formation on the surface of biological soil crusts in central European sand ecosystems

Dew formation was investigated in three developmental stages of biological soil crusts (BSC), which were collected along a catena of an inland dune and in the initial substrate. The Penman equation, which was developed for saturated surfaces, was modified for unsaturated surfaces and used for prediction of dewfall rates. The levels of surface saturation required for this approach were predicted using the water retention functions and the thicknesses of the BSCs. During a first field campaign (2–3 August 2011), dewfall increased from 0.042 kg m<sup>−2</sup> for the initial sandy substrate to 0.058, 0.143 and 0.178 kg m<sup>−2</sup> for crusts 1 to 3, respectively. During a second field campaign (17–18 August 2011), where dew formation was recorded in 1.5 to 2.75-h intervals after installation at 21:30 CEST, dewfall increased from 0.011 kg m<sup>−2</sup> for the initial sandy substrate to 0.013, 0.028 and 0.055 kg m<sup>−2</sup> for crusts 1 to 3, respectively. Dewfall rates remained on low levels for the substrate and for crust 1, and decreased overnight for crusts 2 and 3 (with crust 3 > crust 2 > crust 1 throughout the campaign). Dew formation was well reflected by the model response. The suggested mechanism of dew formation involves a delay in water saturation in near-surface soil pores and extracellular polymeric substances (EPS) where the crusts were thicker and where the water capacity was high, resulting in elevated vapor flux towards the surface. The results also indicate that the amount of dewfall was too low to saturate the BSCs and to observe water flow into deeper soil. Analysis of the soil water retention curves revealed that, despite the sandy mineral matrix, moist crusts clogged by swollen EPS pores exhibited a clay-like behavior. It is hypothesized that BSCs gain double benefit from suppressing their competitors by runoff generation and from improving their water supply by dew collection. Despite higher amounts of dew, the water availability to the crust community decreases with crust development, which may be compensated by ecophysiological adaptation of crust organisms, and which may further suppress higher vegetation or mosses

Current Status of Musculoskeletal Trauma Care Systems Worldwide

BACKGROUND AND RATIONALE Although general trauma care systems and their effects on mortality reduction have been studied, little is known of the current state of musculoskeletal trauma delivery globally, particularly in low-income (LI) and low middle-income (LMI) countries. The goal of this study is to assess and describe the development and availability of musculoskeletal trauma care delivery worldwide. MATERIALS & METHODS A questionnaire was developed to evaluate different characteristics of general and musculoskeletal trauma care systems, including general aspects of systems, education, access to care and pre- and posthospital care. Surgical leaders involved with musculoskeletal trauma care were contacted to participate in the survey. RESULTS Of the 170 surveys sent, 95 were returned for use for the study. Nearly 30 percent of surgeons reported a formalized and coordinated trauma system in their countries. Estimates for the number of surgeons providing musculoskeletal trauma per one million inhabitants varied from 2.6 in LI countries to 58.8 in high-income countries. Worldwide, 15% of those caring for musculoskeletal trauma are fellowship trained. The survey results indicate a lack of implemented musculoskeletal trauma care guidelines across countries, with even high-income countries reporting less than 50% availability in most categories. Seventy-nine percent of the populations from LI countries were estimated to have no form of health care insurance. Formalized emergency medical services were reportedly available in only 33% and 50% of LI and LMI countries, respectively. Surgeons from LI and LMI countries responded that improvements in the availability of equipment (100%), number and locations of trauma-designated hospitals (90%), and physician training programs (88%) were necessary in their countries. The survey also revealed a general lack of resources for postoperative and rehabilitation care, irrespective of the country's income level. CONCLUSION This study addresses the current state of musculoskeletal trauma care delivery worldwide. These results indicate a greater need for trauma system development and support, from prehospital through posthospital care. Optimization of these systems can lead to better outcomes for patients after trauma. This study represents a critical first step toward better understanding the state of musculoskeletal trauma care in countries with different levels of resources, developing strategies to address deficiencies, and forming regional and international collaborations to develop musculoskeletal trauma care guidelines

Evaluating the Risk of Air Pollution to Forests in Central and Eastern Europe

Foliar damage to trees by air pollution in Central and Eastern Europe has been a major scientific and political issue. Emissions of toxic gases such as sulfur dioxide and nitrogen oxides can have wide-ranging effects on local and regional vegetation that can be compounded by other environmental stresses to plant growth. Since uptake and physiological effects of these gases on tree leaves are largely mediated by stomata, surrogate methods for estimating pollutant conductances into leaves and forest canopies may lead to risk assessments for major vegetation types that can then be used in regional planning. Management options to ameliorate or mitigate air pollutant damage to forests and losses in productivity are likely to be more difficult to widely implement than on-the-stack emissions abatement, Informed management and policy decisions regarding Central and Eastern European forests are dependent on the development of quantitative tools and models for risk assessment of the effects of atmospheric pollutants on ecosystem health and productivity