bluuebunny/crossref_metadata_2025_split huggingface dataset:
Inflammation and Microvascular and Macrovascular Endothelial Dysfunction in Rheumatoid Arthritis: Effect of Treatment
Authors: FOSTER WILL , CARRUTHERS DAVID , LIP GREGORY Y.H. , BLANN ANDREW D. 
Published: February 2010

Objective.To determine whether abnormalities in microvascular and macrovascular function in rheumatoid arthritis (RA) are associated with plasma markers [von Willebrand factor (VWF)] of endothelial dysfunction and inflammation [C-reactive protein (CRP)] and whether the abnormalities would be altered by treatment. Endothelial dysfunction and inflammation in RA may contribute to adverse cardiovascular events. Although endothelial dysfunction in RA has been demonstrated by altered plasma markers, the relationships with macrovascular and microvascular function are relatively unexplored.Methods.We recruited 66 patients with chronic RA, 48 community controls (CC), and 25 patients with diabetes and hypertension as a disease control group (DC). Subjects had venous blood sampled for plasma markers, and underwent laser Doppler perfusion imaging of forearm skin (to assess microvascular circulation) following acetylcholine and sodium nitroprusside iontophoresis, to assess endothelium-dependent and endothelium-independent responses, respectively. Brachial artery flow-mediated dilatation assessed endothelial dysfunction in a macrovascular bed. A subgroup of 29 patients with RA were assessed pretherapy and after 2–4 weeks of antirheumatic therapy.Results.As expected, patients with RA had higher CRP, erythrocyte sedimentation rate (ESR), and VWF. Endothelium-independent vasoreactivity was abnormal in RA, and this correlated negatively with CRP. All aspects of microvascular function were abnormal in the DC compared to the CC. Macrovascular function was preserved in RA but was abnormal in the DC group. Four weeks of antiinflammatory therapy reduced CRP and ESR but had no effect on any vascular function index in the patients with RA.Conclusion.Patients with RA have abnormal endothelium-independent microvascular function that correlates with inflammation but is not altered by short-term antiinflammatory therapy.
Enzyme Specificity and Selectivity
Authors: Hedstrom Lizbeth 
Published: February 2010

Abstract

Enzymes are exquisitely selective catalysts, capable of choosing a single substrate from a sea of similar compounds. Importantly, specificity is most manifest in the rate that a substrate reacts rather than the affinity of substrate binding. Specificity arises from the three‐dimensional structure of the enzyme‐active site, which is complementary to the transition state of the reaction. In some cases, a good substrate induces an active conformation that is not available to a poor substrate. Enzymes can also contain a second ‘proofreading’ site that further increases selectivity. Specificity is also evident in the way that enzymes control the decomposition of unstable intermediates, restricting their conformation so that the reaction is channelled down one pathway, to yield a single product. Lastly, it is important to recognize that enzyme selectivity is not absolute; the optimization of ‘promiscuous’ activities is an efficient route to the evolution of new enzymes.

Key concepts

Specificity is most manifest in the rate that a substrate reacts rather than the affinity of substrate binding.

The value of
k
cat
/K
m
is used to assess specificity.

The enzyme‐active site is complementary to the transition state, with key residues perfectly aligned to promote the reaction.

A good substrate can induce an active enzyme conformation that is not accessed by a poor substrate.

Some enzymes contain additional active sites that catalyse proofreading reactions, further enhancing specificity.

Enzymes control reaction outcomes by restricting the conformation of substrates and high‐energy intermediates; this is called stereoelectronic control.

Enzyme specificity is not absolute; new enzymes evolve via the optimization of ‘promiscuous’ activities.
Plant–Water Relations
Authors: Passioura John B 
Published: February 2010

Abstract

Plant–water relations concern how plants control the hydration of their cells, including the collection of water from the soil, its transport within the plant and its loss by evaporation from the leaves. The water status of plants is usually expressed as ‘water potential’, which has units of pressure, is always negative, and in simple form is the algebraic sum of the hydrostatic pressure and the osmotic pressure of water. Flow of water through plant and soil over macroscopic distances is driven by gradients in hydrostatic pressure. Over microscopic distances (e.g. across semipermeable membranes) it is driven by gradients in water potential. Evaporation of water from leaves is primarily controlled by stomata, and if not made good by the flow of water from soil through the plant to the leaves, results in the plants wilting. Resistances to this flow are still not well understood.

Key concepts:

Plants perform best when they are turgid, that is when the water within their cells has a positive hydrostatic pressure.

Leaves often transpire several times their own volume of water each day, but the net loss is usually small owing to the inflow of water drawn up the plant from the soil, this flow being known as the ‘transpiration stream’.

The water status of a plant is expressed as ‘water potential’, the chemical potential of water divided by the volume of 1 mole of water to give units of pressure.

Water potential (ψ) comprises two main components, hydrostatic pressure (
P
) and osmotic pressure (π), such that ψ=
P
−π.

The flows of water through plant and soil are driven by gradients in hydrostatic pressure over macroscopic distances, by differences in water potential across semipermeable membranes or by diffusion as water vapour from the leaves to the atmosphere.

Resistance to these flows, and the factors influencing them, vary markedly as the transpiration stream moves from soil, across the roots, longitudinally in the xylem and eventually through the tissue of the leaves to the evaporating surfaces within the leaf.
Syringomyelia and Related Diseases
Authors: Heiss John D , Oldfield Edward H 
Published: February 2010

Abstract

Syringomyelia is an uncommon medical condition in which a cyst (syrinx) develops in the spinal cord. Untreated, the syrinx will displace, injure and destroy the spinal cord, resulting in neurological deterioration in the affected region of the body. The Chiari I malformation is the most frequent cause of syringomyelia. Symptoms of paralysis, sensory loss and chronic pain usually develop during the second through the fifth decades of life in these patients. Syringomyelia may also develop months to years after trauma or meningitis. The natural history of syringomyelia is typically one of gradual, stepwise neurological deterioration over many years. The objective of surgical treatment of syringomyelia is to eliminate the syrinx and prevent progression of spinal cord dysfunction, known as myelopathy. Syringomyelia usually resolves after surgical treatment that eliminates the effects of the underlying condition by opening the CSF (cerebrospinal fluid) pathways at the foramen magnum or spinal canal.

Key concepts:

Syringomyelia is a cyst within the spinal cord that results in dysfunction of the spinal cord, which is known as myelopathy.

The fluid within the syrinx is chemically identical to normal cerebrospinal fluid (CSF) when there is an associated condition that obstructs the CSF pathway at the foramen magnum or within the spinal canal.

The fluid within the syrinx has a protein content that is in excess to that of normal CSF when the syrinx is associated with a tumour within the spinal cord (an intramedullary tumour).

The syrinx injures sensory nerve cell bodies (posterior horn cells) near the centre of the spinal cord and results in loss of sensation, uncomfortable sensations known as dysesthesias and perception of pain in the anatomic region supplied by the sensory nerves.

The syrinx injures motor nerves cell bodies (anterior horn cells) near the centre of the spinal cord and results in loss of strength and atrophy in the muscles supplied by those nerves.

The syrinx may expand over time to compress the long tracts of neurons that pass to the inferior part of the spinal cord and disrupt their function, resulting in spasticity, paralysis and loss of sensation in the lower extremities.

Treatment of syringomyelia requires a surgical procedure that successfully addresses the condition that causes syringomyelia, by opening obstructed CSF pathways or by removing a spinal cord tumour.

Successful treatment of syringomyelia arrests the progression of syringomyelia but results in limited improvement in signs and symptoms of spinal cord injury.

Because treatment of syringomyelia can prevent disease progression, but cannot restore neurons lost to the disease, early diagnosis and treatment is the key to maintain optimal function.
Computed Tomography
Authors: Shaw Ashley S , Dixon Adrian K 
Published: February 2010

Abstract

Computed tomography (CT) comprises an X‐ray tube and a bank of detectors that rotate around a patient, taking multiple exposures from different angles. The data from the detectors, essentially a density map of the body, is reconstructed to form an image which may be manipulated to any plane. The development of CT during the 1970s heralded the start of sophisticated cross‐sectional imaging. Such cross‐sectional images have, in turn, revolutionized the diagnostic investigation for many clinical conditions and demand for imaging grows inexorably; in 2006, an estimated 62 million CT studies were performed in the United States alone, almost five times the number in 1990. Increasingly, the radiation dose involved in CT has become a major issue and, alongside high‐speed imaging, is the focus of current developments.

Key Concepts:

The first CT machine was built in the early 1970s by Sir Godfrey Hounsfield.

CT comprises an X‐ray tube and a bank of detectors rotating around a patient to produce a dataset from which an image can be reconstructed.

Current technology enables rapid acquisition (<10 s) of submillimetre resolution images.

The contrast adjacent structures may be enhanced by the administration of oral, intravascular or rectal contrast medium.

CT images may be displayed in any plane and manipulated in a number of ways depending on the clinical indication.

There are innumerable indications for CT across many clinical specialties, with many other investigations becoming obsolete.

CT exposes patients to a relatively high dose of radiation; efforts should be made to ensure that the investigation is necessary and that the technique employed uses the lowest dose possible while answering the clinical problem.

Dual‐energy CT enables one to determine the chemical composition of structures in addition to their morphology.

There is currently extensive research in the use of CT perfusion imaging, adding functional information to the anatomical detail.

CT machines are often combined with nuclear medicine machines to give hybrid functional and anatomical information.
Base Flipping
Authors: Cheng Xiaodong , Roberts Richard J 
Published: February 2010

Abstract

Base flipping involves the rotation of backbone bonds in double‐stranded
deoxyribonucleic acid
(DNA) to expose an out‐of‐stack base, which can then be a substrate for an enzyme‐catalysed chemical reaction or for a specific protein‐binding interaction. The phenomenon is fully established structurally and experimentally for
DNA methyltransferases
, for several key DNA repair enzymes, and for a few nonenzymatic DNA‐binding proteins involved in the DNA methylation and repair pathways, and is likely to prove general for enzymes or proteins that require access to unpaired, mismatched, damaged or modified bases. Recent results suggest that it may also be involved in the initial opening of a DNA helix during the initiation of transcription.

Key Concept:

Base flipping is a key mechanism used by many DNA and RNA modifying enzymes, including DNA repair enzymes, to gain access to one or more bases in a double helix.
Hydrogen Bonds in Proteins: Role and Strength
Authors: Hubbard Roderick E , Kamran Haider Muhammad 
Published: February 2010

Abstract

Hydrogen bonds provide most of the directional interactions that underpin protein folding, protein structure and molecular recognition. The core of most protein structures is composed of secondary structures such as α helix and β sheet. This satisfies the hydrogen‐bonding potential between main chain carbonyl oxygen and amide nitrogen buried in the hydrophobic core of the protein. Hydrogen bonding between a protein and its ligands (protein, nucleic acid, substrate, effector or inhibitor) provides a directionality and specificity of interaction that is a fundamental aspect of molecular recognition. The energetics and kinetics of hydrogen bonding therefore need to be optimal to allow the rapid sampling and kinetics of folding, conferring stability to the protein structure and providing the specificity required for selective macromolecular interactions.

Key concepts:

A hydrogen bond is formed by the interaction of a hydrogen atom that is covalently bonded to an electronegative atom (donor) with another electronegative atom (acceptor).

Hydrogen bonding confers rigidity to the protein structure and specificity to intermolecular interactions.

The accepted (and most frequently observed) geometry for a hydrogen bond is a distance of less than 2.5 Å (1.9 Å) between hydrogen and the acceptor and a donor‐hydrogen‐acceptor angle of between 90° and 180° (160°).

During protein folding, the burial of hydrophobic side‐chains requires intramolecular hydrogen bonds to be formed between the main chain polar groups.

The most stable conformations of polypeptide chains that maximize intrachain hydrogen‐bonding potential are α helices and β sheets.

Specificity in molecular recognition is driven by the interaction of complementary hydrogen‐bonding groups on interacting surfaces.
Molecular Genetics of Myocardial Infarction
Authors: Yamada Yoshiji 
Published: February 2010

Abstract

Myocardial infarction (MI) is an important clinical problem because of its large contribution to mortality. The main causal and treatable risk factors for MI include hypertension, dyslipidaemia, diabetes mellitus, chronic kidney disease and smoking. In addition to these risk factors, recent studies have shown the importance of genetic factors and interactions between multiple genes and environmental factors. Genetic linkage analyses of families and sib‐pairs as well as candidate gene association studies have implicated several loci and many candidate genes in predisposition to coronary heart disease (CHD) or MI. Recent genome‐wide association studies demonstrated that single nucleotide polymorphisms (SNPs) at chromosome 9p21.3 or other loci were associated with CHD or MI. Such studies may provide insight into the function of implicated genes as well as into the role of genetic factors in the development of CHD and MI.

Key concepts

Twin and family studies have established that CHD aggregates in families, with a family history of early onset CHD being considered a risk factor for the disease.

Genes responsible for familial hypercholesterolaemia and Tangier disease are the prototypical examples of causal genes for Mendelian disorders associated with CHD and MI.

Several genome‐wide linkage analyses of families or sib‐pairs have identified chromosomal loci linked, or genetic variations that confer susceptibility, to MI, acute coronary syndrome (ACS) or CHD.

Various association studies of unrelated individuals have identified genetic variations that confer susceptibility to MI or CHD. Numerous candidate genes have been implicated, but those that show reproducible associations between risk alleles and CHD or MI in replication studies are few.

A genome‐wide association study (GWAS) and subsequent analysis have suggested that the lymphotoxin alpha gene is important in the pathogenesis of coronary atherosclerosis and thrombosis.

Four independent GWAS have identified SNPs at chromosome 9p21.3 that were associated with CHD or MI in several white cohorts.

In addition, several GWAS identified SNPs associated with CHD or MI at various chromosomal loci.

Identification of susceptibility genes for CHD and MI and clarification of the functional relevance of genetic variants to these conditions will contribute to the prevention, early diagnosis and treatment of CHD and MI.
“Lachkabinett” und “großes Fest” der Physiker. Walter Grotrians “physikalischer Einakter” zu Max Plancks 80. Geburtstag
Authors: Hoffmann Dieter , Rößler Hole , Reuther Gerald 
Published: February 2010

Abstract“Funhouse” and “Big Celebration” of the Physicists. Walter Grotrian's „Physical One‐Act Play”︁ for Max Planck's 80th Birthday. On the occasion of Max Planck's 80th birthday on April 23, 1938, a “big celebration of the physicists” (großes Fest der Physiker) was celebrated at the Harnack‐House in Berlin. The festivities were organized by the German Physical Society. Part of the ceremony was a “Physical One‐act‐play” (Physikalischer Einakter) written by the Potsdam astrophysicist Walter Grotrian. The actors of the humorous play were chief protagonists in the development of quantum theory such as Debye, Sommerfeld and Heisenberg. In this essay we analyze Grotrian's drama against the background of both the festive event and the professional and social setting of the physicists. We argue that below the level of comedy a number of characteristic and normally unexpressed aspects of the epistemic culture of the German physics by the end of the nineteen‐thirties is treated in the play.
Cd(II), Pb(II) and Zn(II) Removal from Contaminated Water by Biosorption Using Activated Sludge Biomass
Authors: Ahmad Anwar , Ghufran Rumana , Faizal Wan Mohd. 
Published: February 2010

AbstractBiosorption using activated sludge biomass (ASB) as a potentially sustainable technology for the treatment of wastewater containing different metal ions (Cd(II), Pb(II) and Zn(II)) was investigated. ASB metal uptake clearly competed with protons consumed by microbial biomass compared with control tests with non‐activated sludge biomass. Biosorption tests confirmed maximum exchange between metal ions and protons at pH 2.0–4.5. It was revealed by the study that the amount of metal ions released from the biomass increased with biomass sludge concentration. The result showed that maximum absorption of metal ions was observed for Cd(II) at pH 3.5, Pb(II) at pH 4.0, and pH 4.5 for Zn(II) ions. The maximum absorption capacities of ASB for Cd(II), Pb(II) and Zn(II) were determined to be 59.3, 68.5 and 86.5%, respectively. The biosorption of heavy metals was directly proportional to ASB stabilization corresponding to a reduction in heavy metals in the order of Cd < Pb < Zn. The order of increase of biosorption of metal ions in ASB was Zn(II) < Pb(II) < Cd(II), and this was opposite to that of non active sludge. The results indicate that ASB is a sustainable tools for the bioremediation of Cd(II), Pb(II) and Zn(II) ions from industrial sludge and wastewater treatment plants.
Improved Model of Lanosterol 14α‐Demethylase by Ligand‐Supported Homology Modeling: Validation by Virtual Screening and Azole Optimization
Authors: Sheng Chunquan , Wang Wenya , Che Xiaoying , Dong Guoqiang , Wang Shengzheng , Ji Haitao , Miao Zhenyuan , Yao Jianzhong , Zhang Wannian 
Published: February 2010

AbstractLanosterol 14α‐demethylase (CYP51) is an important target for antifungal drugs. An improved three‐dimensional model of CYP51 from Candida albicans (CACYP51) was constructed by ligand‐supported homology modeling and molecular dynamics simulations. The accuracy of the constructed model was evaluated by its performance in a small‐scale virtual screen. The results show that known CYP51 inhibitors were efficiently discriminated by the model, and it performed better than our previous CACYP51 model. The active site of CACYP51 was characterized by multiple copy simultaneous search (MCSS) calculations. On the basis of the MCSS results, a series of novel azoles were designed and synthesized, and they showed good in vitro antifungal activity with a broad spectrum. The MIC80 value of four of these compounds against C. albicans is 0.001 μg mL−1, indicating that they are promising leads for the discovery of novel antifungal agents.
Bio‐interfaces—Interaction of PLL/HA Thick Films with Nanoparticles and Microcapsules
Authors: Skirtach Andre G. , Volodkin Dmitry V. , Möhwald Helmuth 
Published: February 2010

AbstractThe interaction of biocompatible, exponentially grown films composed of poly‐L‐lysine (PLL) and hyaluronic acid (HA) polymers with gold nanoparticles and microcapsules is studied. Both aggregated and non‐aggregated nanoparticle states are achieved; desorption of PLL accounts for aggregation of nanoparticles. The presence of aggregates of gold nanoparticles on films enables remote activation by near‐infrared irradiation due to local, nanometer confined heating. Thermally shrunk microcapsules, which are remarkably monodisperse upon preparation but gain polydispersity after months of storage, are also adsorbed onto films. PLL polymers desorbed from films interact with microcapsules introducing a charge imbalance which leads to an increase of the microcapsule size, thus films amplify this effect. Multifunctional, biocompatible, thick gel films with remote activation and release capabilities are targeted for cell cultures in biology and tissue engineering in medicine.
Soil water dynamics along a tree diversity gradient in a deciduous forest in Central Germany
Authors: Krämer Inga , Hölscher Dirk 
Published: February 2010

AbstractThis study aimed to investigate whether soil water dynamics differ along a tree species diversity gradient. The 12 study plots in the Hainich National Park, Germany, were composed of up to 11 tree species. Fagus sylvatica formed the monospecific plots. Mixed forest plots consisted of a variable admixture of other broad‐leaved deciduous tree species such as Tilia spp., Fraxinus excelsior, Carpinus betulus, and Acer pseudoplatanus. Volumetric soil water content and soil water potential were measured for about two and a half years. Overall patterns of soil water dynamics were similar in all study plots. However, during a desiccation period in summer 2006, significant correlations between soil water in the upper soil and tree species diversity of the 12 study plots were observed. At the beginning of this period, soil water was extracted at higher rates in the species‐rich plots than in the beech‐dominated plots. However, later during the desiccation period, when atmospheric evaporative demand was higher, only the beech‐dominated stands were able to increase soil water extraction. In plots of high tree species diversity, soil water reserves were already low and soil water extraction reduced. Possible explanations for high water extraction rates in mixed species plots at the beginning of the desiccation period include species‐specific characteristics such as high maximum water use rate of some species, enhanced exploitation of soil water resources in mixed stands (complementarity effect), and additional water use of the herb layer, which increased along the tree species diversity gradient. Copyright © 2010 John Wiley & Sons, Ltd.