bluuebunny/crossref_metadata_2025 huggingface dataset:
Is There Synchronicity in Nitrogen Input and Output Fluxes at the Noland Divide Watershed, a Small N-Saturated Forested Catchment in the Great Smoky Mountains National Park?
Authors: Van Miegroet H. , Creed I.F. , Nicholas N.S. , Tarboton D.G. , Webster K.L. , Shubzda J. , Robinson B. , Smoot J. , Johnson D. W. , Lindberg S. E. , Lovett G. , Nodvin S. , Moore S.
Published: March 2005

High-elevation red spruce [Picea rubens Sarg.]-Fraser fir [Abies fraseri (Pursh.) Poir] forests in the Southern Appalachians currently receive large nitrogen (N) inputs via atmospheric deposition (30 kg N ha�1 year�1) but have limited N retention capacity due to a combination of stand age, heavy fir mortality caused by exotic insect infestations, and numerous gaps caused by windfalls and ice storms. This study examined the magnitude and timing of the N fluxes into, through, and out of a small, first-order catchment in the Great Smoky Mountains National Park. It also examined the role of climatic conditions in causing interannual variations in the N output signal. About half of the atmospheric N input was exported annually in the streamwater, primarily as nitrate (NO3-N). While most incoming ammonium (NH4-N) was retained in the canopy and the forest floor, the NO3-N fluxes were very dynamic in space as well as in time. There was a clear decoupling between NO3-N input and output fluxes. Atmospheric N input was greatest in the growing season while largest NO3-N losses typically occurred in the dormant season. Also, as water passed through the various catchment compartments, the NO3-N flux declined below the canopy, increased in the upper soil due to internal N mineralization and nitrification, and declined again deeper in the mineral soil due to plant uptake and microbial processing. Temperature control on N production and hydrologic control on NO3-N leaching during the growing season likely caused the observed inter-annual variation in fall peak NO3-N concentrations and N discharge rates in the stream.
Nitrogen Cycling in a Norway Spruce Plantation in Denmark — A SOILN Model Application Including Organic N Uptake
Authors: Beier Claus , Eckersten Henrik , Gundersen Per
Published: March 2005

A dynamic carbon (C) and nitrogen (N) circulation model, SOILN, was applied and tested on 7�years of control data and 3 years of manipulation data from an experiment involving monthly N addition in a Norway spruce (Picea abies, L. Karst) forest in Denmark. The model includes two pathways for N uptake: (1) as mineral N after mineralisation of organic N, or (2) directly from soil organic matter as amino acids proposed to mimic N uptake by mycorrhiza. The model was parameterised and applied to the data from the control plot both with and without the organic N uptake included. After calibration, the model�s performance was tested against data from the N-addition experiment by comparing model output with measurements. The model reproduced well the overall trends in C and N pools and the N concentrations in soil solutions in the top soil layers whereas discrepancies in soil-solution concentrations in the deeper soil layers are seen. In the control data, the needle-N concentration was well reproduced except for small underestimations in some years because of drought effects not included in the model. In the N-addition experiment, SOILN reproduces the observed changes; in particular, the changes in needle-N concentrations and the overall distribution within the ecosystem of the extra added 3.5 g N m�2 year�1 parallel the observations. When organic N uptake is included, the simulations indicate that in the control plot receiving c. 1.9 g N m�2 year�1, the organic N uptake in average supplies 35% of the total plant N uptake. By addition of an extra 35 kg N ha�1 year�1, the organic N uptake is reduced to 16% of the total N uptake. Generally, inclusion of the pathway for organic N uptake improves model performance compared with observations for both C and N. This is because mineral N uptake alone implies a larger mineralisation rate, leading to bigger concentrations of N in the soil and soil water, bigger N losses, and net loss of c. 100 kg C ha�1 year�1, thereby causing depletion of the organic soil layer.
Limitations of Improved Nitrogen Management to Reduce Nitrate Leaching and Increase Use Efficiency
Authors: Baker James L.
Published: March 2005

The primary mode of nitrogen (N) loss from tile-drained row-cropped land is generally nitrate-nitrogen (NO3-N) leaching. Although cropping, tillage, and N management practices can be altered to reduce the amount of leaching, there are limits as to how much can be done. Data are given to illustrate the potential reductions for individual practices such as rate, method, and timing of N applications. However, most effects are multiplicative and not additive; thus it is probably not realistic to hope to get overall reductions greater than 25 to 30% with in-field practices alone. If this level of reduction is insufficient to meet water quality goals, additional off-site landscape modifications may be necessary.
Biomechanics of Heading a Soccer Ball: Implications for Player Safety
Authors: Babbs Charles F.
Published: March 2005

To better understand the risk and safety of heading a soccer ball, the author created a set of simple mathematical models based upon Newton�s second law of motion to describe the physics of heading. These models describe the player, the ball, the flight of the ball before impact, the motion of the head and ball during impact, and the effects of all of these upon the intensity and the duration of acceleration of the head. The calculated head accelerations were compared to those during presumably safe daily activities of jumping, dancing, and head nodding and also were related to established criteria for serious head injury from the motor vehicle crash literature. The results suggest heading is usually safe but occasionally dangerous, depending on key characteristics of both the player and the ball. Safety is greatly improved when players head the ball with greater effective body mass, which is determined by a player�s size, strength, and technique. Smaller youth players, because of their lesser body mass, are more at risk of potentially dangerous headers than are adults, even when using current youth size balls. Lower ball inflation pressure reduces risk of dangerous head accelerations. Lower pressure balls also have greater “touch” and “playability”, measured in terms of contact time and contact area between foot and ball during a kick. Focus on teaching proper technique, the re-design of age-appropriate balls for young players with reduced weight and inflation pressure, and avoidance of head contact with fast, rising balls kicked at close range can substantially reduce risk of subtle brain injury in players who head soccer balls.
The Evolution of the Neural Basic Helix-Loop-Helix Proteins
Authors: Vervoort Michel , Ledent Valerie
Published: March 2005

Basic Helix-Loop-Helix (bHLH) transcription factors control various aspects of the formation of the nervous system in the metazoans. In Drosophila some bHLH (such as the achaete-scuteatonal, and amos genes) act as proneural genes, directing ectodermal cells toward a neural fate. Their vertebrate orthologs, however, probably do not assume such a neural determination function, but rather control the decision made by neural precursors to generate neurons and not glial cells, as well as the progression of neuronal precursors toward differentiation into mature neurons. The proneural function of Drosophila bHLH genes may be an innovation that occurs in the evolutive lineage that leads to arthropods. In addition, although neural bHLH appear to be involved in the specification of neuronal identities, they probably do not confer by themselves neuronal type-specific properties to the cells. Rather, neural bHLH allow neural cells to correctly interpret specification and positional cues provided by other factors. Although bHLH genes are often expressed in complementary subsets of neural cells and/or expressed sequentially in those cells, the coding regions of the various neural bHLH appear largely interchangeable. We propose that the specific expression patterns have been acquired, following gene duplications, by subfunctional-ization, i.e., the partitioning of ancestral expression patterns among the duplicates and, by extension, we propose that subfunctionalization is a key process to understand the evolution of neural bHLH genes.
U.S. Science Politics are Top Headlines in Both Journals
Authors: Haley Shauna M.
Published: March 2005

Nature and Science open the news week with an introduction to U.S. President Bush’s choice for the nation’s science advisor post as their top subject. Both journals also report in their second slots on the same administration’s difficulties developing national stem cell and cloning policies.
Air Pollution and Forest Health: Establishing Cause and Effect in the Forest
Authors: Manning William J.
Published: March 2005

I participated in a NATO Advanced Research Workshop titled “Effects of Air Pollution on Forest Health and Biodiversity in Forests of the Carpathian Mountains,” in Stara Lesna, Slovakia from May 22–26, 2001. Researchers from Canada, Czech Republic, Poland, Romania, Slovakia, Ukraine, and the U.S. met to present their results from a three-year cooperative study of tree health and air quality monitoring in forests of the Carpathian Mountains in Central Europe. Much of the work reported related to assessing the crown condition of trees in permanent plots in natural or managed (planted) forests in the mountains. The endpoint was tree condition, with results extrapolated to the forests in the Carpathian range. From this I learned that, of the 50,000 trees evaluated, European beech (Fagus sylvatica) was the most healthy, while Norway spruce (Picea abies) (the principal forest tree) and white fir (Abies alba) sustained crown defoliation of up to 12.8%. The cause of this crown defoliation and tree decline was usually attributed to “air pollution” as a generic term and an automatic assumption. It is well known that deposition of heavy metals and acidic sulfur and nitrogen compounds can cause tree decline and predispose affected trees to bark beetles and climatic damage. Chemical analyses can also be done to detect metals and sulfur compounds in trees and soils. Sometimes these analyses were done, but most often the assumption was that crown defoliation was caused by air pollution. The assumption was that given sufficient exposure to high enough concentrations of toxic elements, sooner or later there will be a visible adverse response.
Recent Advances in Photoluminescence Detection of Fingerprints
Authors: Menzel E. Roland
Published: March 2005

Photoluminescence detection of latent fingerprints has over the last quarter century brought about a new level of fingerprint detection sensitivity. The current state of the art is briefly reviewed to set the stage for upcoming new fingerprint processing strategies. These are designed for suppression of background fluorescence from articles holding latent prints, an often serious problem. The suppression of the background involves time-resolved imaging, which is dealt with from the perspective of instrumentation as well as the design of fingerprint treatment strategies. These focus on lanthanide chelates, nanocrystals, and nanocomposites functionalized to label fingerprints.
Atmospheric Deposition of Nitrogen and Sulphur Compounds in the Czech Republic
Authors: Zapletal Milos
Published: March 2005

Estimates of dry and wet deposition of nitrogen and sulphur compounds in the Czech Republic for the years 1994 and 1998 are presented. Deposition has been estimated from monitored and modeled concentrations in the atmosphere and in precipitation, where the most important acidifying compounds are sulphur diOxide, nitrogen Oxides, ammonia, and their reaction products. Measured atmospheric concentrations of SO2, NOx, NH3, and aerosol particles (SO42-, NO3–, and NH4+), along with measured concentrations of SO42-, NO3–, and NH4+in precipitation, weighted by precipitation amounts, were interpolated with Kriging technique on a 10- x 10-km grid covering the whole Czech Republic. Wet deposition was derived from concentration values for SO42-, NO3–, and NH4+in precipitation and from precipitation amounts. Dry deposition was derived from concentrations of gaseous components and aerosol in the air, and from their deposition velocities. A multiple resistance model was used for calculation of SO2, NOx, and NH3deposition velocities. Deposition velocities of particles were parameterized. It was estimated that the annual average deposition of SOxin the Czech Republic decreased from 1384 to 1027 mol H+ha-1a-1between 1994 and 1998. The annual average NOydeposition was estimated to be 972 and 919 mol H+-1a-1in 1994 and 1998, respectively. The annual average NHxdeposition was estimated to be 887 mol H+-1a-1and 779 mol H+-1a-1in 1994 and 1998, respectively. It was estimated that the annual average of the total potential acid deposition decreased from 3243 to 2725 mol H+-1a-1between 1994 and 1998. Sulphur compounds (SOx) contributed about 38%, Oxidized nitrogen species (NOy) 34%, and reduced nitrogen species (NHx) 28% to the total potential acid deposition in 1998. The wet deposition contributed 42% to the total potential acid deposition in 1998.
Bermudagrass Management in the Southern Piedmont U.S. IV. Soil Surface Nitrogen Pools
Authors: Franzluebbers Alan J. , Stuedemann John A.
Published: March 2005

The fate of nitrogen (N) applied in forage-based agricultural systems is important for understanding the long-term production and environmental impacts of a particular management strategy. We evaluated the factorial combination of three types of N fertilization (inorganic, crimson clover [Trifolium incarnatum L.] cover crop plus inorganic, and chicken [Gallus gallus] broiler litter pressure and four types of harvest strategy (unharvested forage, low and high cattle [Bos Taurus] grazing pressure, and monthly haying in summer) on surface residue and soil N pools during the first 5 years of ̒Coastal̓ bermudagrass (Cynodon dactylon [L.] Pers.) management. The type of N fertilization used resulted in small changes in soil N pools, except at a depth of 0 to 2 cm, where total soil N was sequestered at a rate 0.2 g ‧ kg–1‧ year–11 greater with inorganic fertilization than with other fertilization strategies. We could account for more of the applied N under grazed systems (76–82%) than under ungrazed systems (35–71%). As a percentage of applied N, 32 and 48% were sequestered as total soil N at a depth of 0 to 6 cm when averaged across fertilization strategies under low and high grazing pressures, respectively, which was equivalent to 6.8 and 10.3 g ‧ m–2‧ year–1. Sequestration rates of total soil N under the unharvested-forage and haying strategies were negligible. Most of the increase in total soil N was at a depth of 0 to 2 cm and was due to changes in the particulate organic N (PON) pool. The greater cycling of applied N into the soil organic N pool with grazed compared with ungrazed systems suggests an increase in the long-term fertility of soil.
Effects of Brash Removal After Clear Felling on Soil and Soil-Solution Chemistry and Field-Layer Biomass in an Experimental Nitrogen Gradient
Authors: Ring E. , Hogbom L. , Nohrstedt H.A.
Published: March 2005

Biofuels, such as brash from forest fellings, have been proposed as an alternative energy source. Brash removal may affect the sustainability of forest production, e.g., through a change in the availability of cations and N in the soil. We report initial effects of brash removal on inorganic N content in humus and mineral soil, soil-solution chemistry, and field-layer biomass after clear felling an N-fertilisation experiment in central Sweden. The experiment comprised six different fertiliser levels, ranging from 0 to 600 kg N ha�1. Urea was given every 5th year during 1967 to 1982 to replicated plots, giving total doses of 0 to 2400 kg N ha�1. Clear felling took place in 1995, 13 years after the last fertilisation. The removal of brash decreased the NO3� content in the humus layer after clear felling. A decrease in the NO3� concentration of the soil solution was indicated during most of the study period as well. No effect of the previous N fertilisation was found in the humus layer, but in the mineral soil there was an increase in NO3� content for the highest N dose after clear felling (p = 0.06). The soil-solution chemistry and the field-layer biomass showed an irregular pattern with no consistent effects of brash removal or previous fertilisation.
Anthropogenic Effects on Forest Ecosystems at Various Spatio-Temporal Scales
Authors: Bredemeier Michael
Published: March 2005

The focus in this review of long-term effects on forest ecosystems is on human impact. As a classification of this differentiated and complex matter, three domains of long-term effects with different scales in space and time are distinguished: 1- Exploitation and conversion history of forests in areas of extended human settlement 2- Long-range air pollution and acid deposition in industrialized regions 3- Current global loss of forests and soil degradation.

There is an evident link between the first and the third point in the list. Cultivation of primary forestland — with its tremendous effects on land cover — took place in Europe many centuries ago and continued for centuries. Deforestation today is a phenomenon predominantly observed in the developing countries, yet it threatens biotic and soil resources on a global scale. Acidification of forest soils caused by long-range air pollution from anthropogenic emission sources is a regional to continental problem in industrialized parts of the world. As a result of emission reduction legislation, atmospheric acid deposition is currently on the retreat in the richer industrialized regions (e.g., Europe, U.S., Japan); however, because many other regions of the world are at present rapidly developing their polluting industries (e.g., China and India), “acid rain” will most probably remain a serious ecological problem on regional scales. It is believed to have caused considerable destabilization of forest ecosystems, adding to the strong structural and biogeochemical impacts resulting from exploitation history.

Deforestation and soil degradation cause the most pressing ecological problems for the time being, at least on the global scale. In many of those regions where loss of forests and soils is now high, it may be extremely difficult or impossible to restore forest ecosystems and soil productivity. Moreover, the driving forces, which are predominantly of a demographic and socioeconomic nature, do not yet seem to be lessening in strength. It can only be hoped that a wise policy of international cooperation and shared aims can cope with this problem in the future.
Uranium Speciation and Bioavailability in Aquatic Systems: An Overview
Authors: Markich Scott J.
Published: March 2005

The speciation of uranium (U) in relation to its bioavailability is reviewed for surface waters (fresh- and seawater) and their sediments. A summary of available analytical and modeling techniques for determining U speciation is also presented. U(VI) is the major form of U in oxic surface waters, while U(IV) is the major form in anoxic waters. The bioavailability of U (i.e., its ability to bind to or traverse the cell surface of an organism) is dependent on its speciation, or physicochemical form. U occurs in surface waters in a variety of physicochemical forms, including the free metal ion (U4+or UO22+) and complexes with inorganic ligands (e.g., uranyl carbonate or uranyl phosphate), and humic substances (HS) (e.g., uranyl fulvate) in dissolved, colloidal, and/or particulate forms. Although the relationship between U speciation and bioavailability is complex, there is reasonable evidence to indicate that UO22+and UO2OH+are the major forms of U(VI) available to organisms, rather than U in strong complexes (e.g., uranyl fulvate) or adsorbed to colloidal and/or particulate matter. U(VI) complexes with inorganic ligands (e.g., carbonate or phosphate) and HS apparently reduce the bioavailability of U by reducing the activity of UO22+and UO2OH+. The majority of studies have used the results from thermodynamic speciation modeling to support these conclusions. Time-resolved laser-induced fluorescence spectroscopy is the only analytical technique able to directly determine specific U species, but is limited in use to freshwaters of low pH and ionic strength. Nearly all of the available information relating the speciation of U to its bioavailability has been derived using simple, chemically defined experimental freshwaters, rather than natural waters. No data are available for estuarine or seawater. Furthermore, there are no available data on the relationship between U speciation and bioavailability in sediments. An understanding of this relationship has been hindered due to the lack of direct quantitative U speciation techniques for particulate phases. More robust analytical techniques for determining the speciation of U in natural surface waters are needed before the relationship between U speciation and bioavailability can be clarified.
Potential Trace Metal–Organic Complexation in the Atmosphere
Authors: Okochi Hiroshi , Brimblecombe Peter
Published: March 2005

It is possible that metal–organic complexation enhances the uptake of gaseous organic compounds and the solubility of metals in aerosols and atmospheric water. We investigated potential atmospheric organic ligands and the enhanced uptake of hydroxy-, oxo-, and dicarboxylic acids as well as dicarbonyls into atmospheric aqueous aerosol. We examined complexation with transition metals (iron, manganese, nickel, copper, zinc) and lead on the basis of available references and our experimental data. Humic-like substances are most likely ligands in the atmosphere, although this is a poorly characterized material. A number of polycarboxylic acids and hydroxy forms (e.g., citric and tartronic acids) effectively complex metals such as copper in atmospheric aerosols. The simple equilibrium model calculations show that the effect of the complexation on the gas–aqueous phase partition of gaseous atmospheric ligands is quite small for the ligands with the high physical Henry’s law constants, e.g., dicarboxylic acids represented by oxalic acid, even if they have high affinity with metal ions. The lower Henry’s law constants of the α-dicarbonyls, such as glyoxal and methylglyoxal, mean that the complexation could lead to profound increases in their partition into the aqueous phase. Despite quantum mechanical arguments for copper–glyoxal complexes, experiments showed no evidence of complexation between either hydrated or unhydrated α-dicarbonyls and the cupric ion. By contrast the β-dicarbonyl, malondialdehyde, has properties that would allow it to partition into atmospheric water via the complexation with metal ions under some conditions.
Recent Developments in the Methods of Estimating Shooting Distance
Authors: Zeichner Arie , Glattstein Baruch
Published: March 2005

A review of developments during the past 10 years in the methods of estimating shooting distance is provided. This review discusses the examination of clothing targets, cadavers, and exhibits that cannot be processed in the laboratory. The methods include visual/microscopic examinations, color tests, and instrumental analysis of the gunshot residue deposits around the bullet entrance holes. The review does not cover shooting distance estimation from shotguns that fired pellet loads.
Can Drug–Drug Interactions Be Predicted fromIn VitroStudies?
Authors: Kremers Pierre
Published: March 2005

Potential drug–drug interactions as well as drug–xenobiotic interactions are a major source of clinical problems, sometimes with dramatic consequences. Investigation of drug–drug interactions during drug development is a major concern for the drug companies while developing new drugs.

Our knowledge of the drug-metabolising enzymes, their mechanism of action, and their regulation has made considerable progress during the last decades. Various efficientin vitroapproaches have been developed during recent years and powerful computer-based data handling is becoming widely available. All these tools allow us to initiate, early in the development of new chemical entities, large-scale studies on the interactions of drugs with selective cytochrome P-450 (CYP) isozymes, drug receptors, and other cellular entities. Standardisation and validation of these methodological approaches significantly improve the quality of the data generated and the reliability of their interpretation.

The simplicity and the low costs associated with the use ofin vitrotechniques have made them a method of choice to investigate drug–drug interactions. Promising successes have been achieved in the extrapolation of in vitro data to thein vivosituation and in the prediction of drug–drug interaction. Nevertheless, linkingin vitroandin vivostudies still remains fraught with difficulties and should be made with great caution.
An Interactive Database of Cocaine-Responsive Gene Expression
Authors: Freeman Willard M. , Dougherty Kathryn E. , Vacca Sally E. , Vrana Kent E.
Published: March 2005

The postgenomic era of large-scale gene expression studies is inundating drug abuse researchers and many other scientists with findings related to gene expression. This information is distributed across many different journals, and requires laborious literature searches. Here, we present an interactive database that combines existing information related to cocaine-mediated changes in gene expression in an easy-to-use format. The database is limited to statistically significant changes in mRNA or protein expression after cocaine administration. The Flash-based program is integrated into a Web page, and organizes changes in gene expression based on neuroanatomical region, general function, and gene name. Accompanying each gene is a description of the gene, links to the original publications, and a link to the appropriate OMIM (Online Mendelian Inheritance in Man) entry. The nature of this review allows for timely modifications and rapid inclusion of new publications, and should help researchers build second-generation hypotheses on the role of gene expression changes in the physiology and behavior of cocaine abuse. Furthermore, this method of organizing large volumes of scientific information can easily be adapted to assist researchers in fields outside of drug abuse.
Hypothesis: Ran GTPase-Based Potential Therapeutic Interventions Against Lethal Microbial Infections
Authors: Wong Peter M.C.
Published: March 2005

Host innate immune response represents a vital immediate defense against infections by a diverse group of microorganisms that include bacteria, viruses, and fungi. Many types of cell surface receptors in mammalian cells specifically recognize particular groups of microorganisms and transmit response signals to the nuclei via multiple signal transduction pathways. These signaling pathways must merge at some point and are likely to be redundant, as the host innate immune response to many microorganisms is remarkably similar; it is characterized by the production of proinflammatory cytokines such as TNFα, IL-1, and IL-6 by the principal cell types – macrophages and dendritic cells. Since these cytokines influence greatly the magnitude of the cascade of inflammatory events, the proportion and the actual amount of each among the cytokine group may be a characteristic of each type of infections. Immune modulation by systematically up-regulate or down-modulate these cytokines would conceivably have major therapeutic potential. We have recently shown that two alleles of Ran cDNAs – RanT/n and RanC/d – may possess these characteristics. Thus the applica-tion of Ran to the treatment of septic shock, lethal anthrax shock, or adenovirus-induced toxicities may open up many interesting possibilities in the future.
Screening and Selection of Hypoallergenic Buckwheat Species
Authors: Nair Arun , Adachi Taiji
Published: March 2005

Both common buckwheat (Fagopyrum esculentum) flour and meal cause an allergy in sensitive patients, and if unnoticed, it can be fatal. It has become a potential occupational hazard for some mill workers. The development of hypoallergenic buckwheat would be more efficient if natural mutants for allergenic protein are detected. A screening and selection method was developed using SDS-PAGE coupled with PCR techniques. SDS-PAGE analysis of 14 different species of buckwheat revealed thatF. lineareandF. urophyllumlack the 22-kDa major allergenic protein. PCR-based screening with specific primers for sequences encoding the allergenic protein was also effective in distinguishing the allergen-deficient species.
Cell Death and Ageing – A Question of Cell Type
Authors: Jansen-Dürr Pidder
Published: March 2005

Replicative senescence of human cells in primary culture is a widely accepted model for studying the molecular mechanisms of human ageing. The standard model used for studying human ageing consists of fibroblasts explanted from the skin and grown intoin vitrosenescence. From this model, we have learned much about molecular mechanisms underlying the human ageing process; however, the model presents clear limitations. In particular, a long-standing dogma holds that replicative senescence involves resistance to apoptosis, a belief that has led to considerable confusion concerning the role of apoptosis during human ageing. While there are data suggesting that apoptotic cell death plays a key role for ageingin vitroand in the pathogenesis of various age-associated diseases, this is not reflected in the current literature onin vitrosenescence. In this article, I summarize key findings concerning the relationship between apoptosis and ageingin vivoand also review the literature concerning the role of apoptosis during in vitro senescence. Recent experimental findings, summarized in this article, suggest that apoptotic cell death (and probably other forms of cell death) are important features of the ageing process that can also be recapitulated in tissue culture systems to some extent. Another important lesson to learn from these studies is that mechanisms ofin vivosenescence differ considerably between various histotypes.
The TGF-β Family: Signaling Pathways, Developmental Roles, and Tumor Suppressor Activities
Authors: Johnson Aaron N. , Newfeld Stuart J.
Published: March 2005

Intercellular communication is a critical process for all multicellular organisms, and communication among cells is required for proper embryonic development and adult physiology. Members of the Transforming Growth Factor-β (TGF-β) family of secreted proteins communicate information between cells via a complex signaling pathway, and family members are capable of inducing a wide range of cellular responses. The purpose of this review is to provide the reader with a broad introduction to our current understanding of three aspects of the TGF-β family. These are the molecular mechanisms utilized by TGF-β signaling pathways, the developmental roles played by TGF-β family members in a variety of species, and the growing list of cancers in which various TGF-β signaling pathways display tumor suppressor activity.
Environmental Radionuclides in Surface Soils of Vietnam
Authors: Hien P.D. , Hiep H.T. , Quang N.H. , Luyen T.V. , Binh N.T. , Ngo N.T. , Long N. Q. , Bac V. T.
Published: March 2005

A database on238U,232Th,40K, and137Cs in surface soils was established to provide inputs for the assessment of the collective dose to the population of Vietnam and to support soil erosion studies using137Cs as a tracer. A total of 292 soil samples was taken from undisturbed sites across the territory and the concentrations of radionuclides were determined by gamma spectrometry method. The multiple regression of137Cs inventories against characteristics of sampling locations allowed us to establish the distribution of137Cs deposition density and its relationship with latitude and annual rainfall. The137Cs deposition density increases northward and varies from 178 Bq m–2to 1,920 Bq m–2. High rainfall areas in the northern and central parts of the country have received considerable137Cs inputs exceeding 600 Bq m–2, which is the maximum value that can be expected for Vietnam from the UNSCEAR global pattern. The mean activity concentrations of naturally occurring radionuclides238U,232Th, and40K are 45, 59, and 401 Bq kg–1, respectively, which entail an average absorbed dose rate in air of 62 nGy h–1, which is about 7% higher than the world average.
Regulation of Apoptosis in African Swine Fever Virus–Infected Macrophages
Authors: Zsak Laslo , Neilan John G.
Published: March 2005

A number of viruses have evolved antiapoptotic mechanisms to promote infected-cell survival, either to ensure efficient productive viral replication or to promote long-term survival of virus-infected cells. Recent studies identified critical African swine fever virus genes involved in the complex regulation of ASFV-host interactions. Here we review the present knowledge of the recently identified ASFV genes with special attention to those which affect viral virulence, host range, and pathogenesis by regulating viral-induced apoptotic mechanisms.
Microscopic Photosensitization: A New Tool to Investigate the Role of Mitochondria in Cell Death
Authors: Lum May-Ghee , Minamikawa Tetsuhiro , Nagley Phillip
Published: March 2005

Active involvement of mitochondria in cell death has been well-documented, but local apoptotic signaling between subsets of mitochondria has been poorly explored to date. Using mitochondrially localized CMXRos as a photosensitizer coupled to laser irradiation by confocal laser scanning microscopy, we demonstrate that partial irradiation of about half the mitochondria in human 143B TK–cells induces rapid loss of mitochondrial membrane potential (ΔΨm) in nonirradiated mitochondria. Cells so partially irradiated show apoptotic indications, including mobilization of cytochrome c and binding of annexin V within 2 h following irradiation. The loss of ΔΨm in nonirradiated mitochondria did not occur in cells photoirradiated in the absence of CMXRos. Increasing the proportion of irradiated mitochondria in each cell (up to about 50%) generated a correspondingly greater percentage of cells in which nonirradiated mitochondria lost ΔΨm and which also showed apoptotic indications. Only at the highest level of irradiation (global for all mitochondria in one cell) were signs of necrosis evident (judged by uptake of propidium iodide). Because laser irradiation is specific to the subpopulation of mitochondria targeted, the data imply that a signal emanating from irradiated mitochondria is processed by their nonirradiated counterparts. We conclude that intermitochondrial signaling occurs in the subcellular response to induction of apoptosis.
8-Chloro-cAMP-Related Changes on Mice Uteri
Authors: Actis Andrea , Croci Maximo , Levin Emanuel , Bergoc Rosa
Published: March 2005

Histopathological effects of cAMP analog (8-Chloro-cAMP), tamoxifen, and medroxyprogesterone, alone or combined, upon BALB/c mice uteri are reported. 8-Chloro-cAMP diminished uterine weight, but did not modify its histopathology or estral cycle significantly. Tamoxifen diminished uterine weight showing cystic hyperplasia and an estral cycle arrested at diestrus. Medroxyprogesterone increased uterine weight, caused a swelling of the endometrium and a pseudopregnancy estrus. When combined with 8-Chloro-cAMP, tamoxifen or medroxyprogesterone always had a predominant effect. We concluded that the effects of 8-Chloro-cAMP on mice uteri did not cause significant changes on its histopathology, but diminished its weight.
Developmental and Activity Dependent Regulation of Ionotropic Glutamate Receptors at Synapses
Authors: Molnar Elek , Isaac John T.R.
Published: March 2005

Glutamate receptors mediate the majority of excitatory responses in the central nervous system. The establishment and refinement of glutamatergic synaptic connections depend on the concerted actions of a-amino-3-hydroxy-5-methyl-isoxazole-4-propionate (AMPA),N-methyl-D-aspartate (NMDA), and kainate (KA) type ionotropic glutamate receptors (iGluRs) and G-protein coupled metabotropic receptors. While a lot remains to be clarified, the most is known about the mechanisms by which the iGluR subtypes are targeted and how this is influenced by synaptic activity on both short and long time scales. Changes in their subunit compositions are also input specific and developmentally regulated. The identification of key molecular components of the postsynaptic density (PSD) and novel proteins that influence receptor targeting and clustering have started to reveal the underlying molecular mechanisms of the trafficking and targeting of iGluRs. Here we discuss the evidence that these basic mechanisms are used during developmental synaptic plasticity.
Calcitonin Gene-Related Peptide (CGRP) in Cerebrovascular Disease
Authors: Edvinsson Lars
Published: March 2005

Cerebral blood vessels are innervated by sensory nerves that store several neurotransmitters among which calcitonin gene-related peptide (CGRP) is the most abundant. In primary headaches, there is a clear association between the head pain and the release of CGRP. In cluster headache there is an additional release of vasoactive intestinal peptide (VIP).

In connection with administration of triptans, the headache subsides and the neuropeptide release normalises, in part via a presynaptic effect.

In subarachnoid hemorrhage (SAH), CGRP is released to counterbalance the blood-induced vasospasm. In severe cases, the stored CGRP may be exhausted while infusion of CGRP may limit cerebral vasospasm. Thus, interactions with the trigeminovascular system at CGRP receptors may be a useful target for understanding of cerebrovascular disease and to design novel treatments.
Crystal Structures of Tcl1 Family Oncoproteins and Their Conserved Surface Features
Authors: Petock John M. , Torshin Ivan Y. , Wang Yuan-Fang , Du Bois Garrett C. , Croce Carlo M. , Harrison Robert W. , Weber Irene T.
Published: March 2005

Members of the TCL1 family of oncogenes are abnormally expressed in mature T-cell leukemias and B-cell lymphomas. The proteins are involved in the coactivation of protein kinase B (Akt/PKB), a key intracellular kinase. The sequences and crystal structures of three Tcl1 proteins were analyzed in order to understand their interactions with Akt/PKB and the implications for lymphocyte malignancies. Tcl1 proteins are ~15 kD and share 25—80% amino acid sequence identity. The tertiary structures of mouse Tcl1, human Tcl1, and Mtcp1 are very similar. Analysis of the structures revealed conserved semi-planar surfaces that have characteristics of surfaces involved in protein-protein interactions. The Tcl1 proteins show differences in surface charge distribution and oligomeric state suggesting that they do not interact in the same way with Akt/PKB and other cellular protein(s).
Purification of Peroxisomes Using a Density Barrier in a Swinging-Bucket Rotor
Authors: Graham John
Published: March 2005

In iodixanol, peroxisomes are the densest organelle in the light mitochondrial fraction and are therefore easily separated from the other components (lysosomes, mitochondria, etc.) in a preformed isosmotic continuous gradient. Because of the large difference in density between peroxisomes and the next densest organelle (mitochondria), a density barrier is effective. The resolution of the peroxisomes is far superior than that in sucrose and, unlike in Percoll®, there is no contamination from endoplasmic reticulum.
The Role of High Density Lipoproteins in Thrombosis
Authors: Cuchel Marina , Rader Daniel J.
Published: March 2005

Lipids and lipoproteins, as well as factors involved in hemostasis and thrombosis, play a central role in the pathogenesis of cardio- and cerebrovascular disease. In recent years it has become clear that a strong association exists between coagulation factors and plasma lipoproteins. Anionic phospholipids are necessary for the optimal activity of both pro- and anticoagulant enzymatic complexes. Cell membranes have traditionally been considered to provide the essential lipid-containing surfaces. However, in light of recent studies, plasma lipoproteins are also believed to provide appropriate surfaces to support coagulation. While triglyceride-rich lipoproteins and oxidized low-density lipoproteins are associated with a procoagulant profile, high-density lipoproteins (HDL) may have an anticoagulant effect. This paper reviews scientific data on the potential role of HDL as modulator of thrombotic processes.
Semisynthesis of Ribonuclease A using Intein-Mediated Protein Ligation
Authors: Arnold Ulrich , Hinderaker Matthew P. , Raines Ronald T.
Published: March 2005

The introduction of non-natural amino acid residues or modules into proteins provides a new means to explore the basis for conformational stability, folding/unfolding behavior, or biological function. We exploited intein-mediated protein ligation to produce a semisynthetic ribonuclease A. Of the 124 residues of RNase A, residues 1–94 were linked to an intein. After expression of the fusion protein and thiol-induced cleavage, the RNase A(1–94) fragment possessed a C-terminal thioester. A peptide identical to the C-terminal residues 95–124 of RNase A (with residue 95 being cysteine) was successfully ligated to that thioester thereby reconstituting full-length wild-type RNase A. In mass spectrometry, this semisynthetic RNase A proved to be undistinguishable from the control protein, namely recombinant wild-type RNase A. Recombinant wild-type RNase A was obtained by expression of RNase A(1–124)–intein fusion protein followed by thiol-induced cleavage and hydrolysis of the thioester. Both proteins showed thermal stabilities (Tm) and catalytic activities comparable to the wild-type enzyme, indicating that both proteins folded properly. These results might serve as basis for the semisynthesis of RNase A variants containing non-natural modules in the aforementioned peptide.
The Accumulation of Deficits with Age and Possible Invariants of Aging
Authors: Mitnitski Arnold B. , Mogilner Alexander J. , MacKnight Chris , Rockwood Kenneth
Published: March 2005

This paper extends a method of apprising health status to a broad range of ages from adolescence to old age. The “frailty index” is based on the accumulation of deficits (symptoms, signs, disease classifications) as analyzed in the National Population Health Survey, a representative Canadian population sample (n = 81,859). The accumulation of deficits has both an age-independent (background) component and an age-dependent (exponential) component, akin to the well-known Gompertz-Makeham model for the risk of mortality. While women accumulate more deficits than men of the same age, on average, their rate of accumulation is lower, so the difference in the level of deficits between men and women decreases with age. Two possible invariants of the process of accumulation of deficits were found: (1) the age at which the average proportion of deficits coincides for men and women is 94 years, which closely matches thespecies-specific lifespan in humans(95 ± 2); (2) the value of the frailty index (proportion of deficits), which corresponds to that age (0.18). The similarity between mortality kinetics and the accumulation of deficits (frailty kinetics), and the coincidence of the time parameters in the frailty and mortality models make it possible to express mortality risk in terms of accumulated deficits. This provides a simple and accessible tool that might have potential in a number of biomedical applications.
High Dose Cyclophosphamide Treatment for Autoimmune Disorders
Authors: Brodsky Robert A.
Published: March 2005

High-dose cyclophosphamide (200 mg/kg) was initially developed as a conditioning regimen for allogeneic bone marrow transplantation. Recently, high-dose cyclophosphamide without bone marrow transplantation has been employed as a method to induce durable treatment-free remissions in severe aplastic anemia and a variety of other severe autoimmune disorders. The premise underlying this approach is that high-dose cyclophosphamide is maximally immunosuppressive, but not myeloablative. Early hematopoietic stem cells are spared the cytotoxicity of cyclophosphamide because of their high levels of aldehyde dehydrogenase, an enzyme that confers resistance to the drug. Conversely, autoimmune effector cells (T cells, B cells, and NK cells) are exquisitely sensitive to high-dose cyclophosphamide because of their relatively low levels of aldehyde dehydrogenase. Intensive investigation is underway to determine which autoimmune disorders will most benefit and where in the natural history of these diseases to employ this rapidly developing therapy.
A New All-Season Passive Sampling System for Monitoring H2S in Air
Authors: Tang Hongmao , Sandeluk James , Lin Linda , Lown J. WIlliam
Published: March 2005

A new Maxxam All-Season Passive Sampling system for monitoring H2S in air has been developed. This passive sampling system employs the same approaches as the Maxxam All-Season Passive Sampling Systems for monitoring SO2, NO2, and O3reported previously. This system has been extensively tested in the lab (temperature from -20 to 20°C, relative humidity from 30 to 84%, and wind speed from 0.5 to 150 cm/s) and validated in field studies. Comparing measurements obtained with the use of the new passive sampling system with equivalent measurement with the use of an active filter pack H2S sampler yielded an accuracy of greater than 85%. The new H2S passive sampling system can be used to measure ambient H2S concentrations ranging from 0.02 to 7 ppb based on a 1-month exposure period. There is no significant interference found from other sulfur compounds in air. This system has been used in many air monitoring projects.
Use of Thermodynamic Orientors to Assess the Efficiency of Ecosystems: A Case Study in the Lagoon of Venice
Authors: Bastianoni Simone
Published: March 2005

So-called orientors have been introduced at the interface between ecology and thermodynamics. Two have been chosen here to compare the characteristics of five ecological systems: exergy, which is related to the degree of organization of a system and represents the biogeochemical energy of a system, and emergy, which is defined as the total amount of solar energy directly or indirectly required to generate a product or a service. They represent two complementary aspects of a system: the actual state and the past work needed to reach that state. The ratio of exergy to the emergy flow indicates the efficiency of an ecosystem in producing or maintaining its organization.

The main system under study is a portion of the Venice Lagoon, which is used as a fish farming basin. Four other aquatic ecosystems were considered for comparison. Results show that the ecosystem within the Venice Lagoon is the one with the highest efficiency in transforming the available inputs in organization of the system. This fact is due to human intervention, which is very limited but also very effective.