Acute kidney injury in the elderly: predisposition to chronic kidney disease and vice versa.

There have been considerable advances in the past few years in our understanding of how chronic kidney disease (CKD) predisposes to acute kidney injury (AKI) and vice versa. This review shows, however, that few studies have focused on the elderly or conducted stratified analysis by age. It does appear that elderly patients with estimated glomerular filtration rate (eGFR) 45-59 ml/min/1.73 m(2) are at higher risk for AKI compared with their counterparts with eGFR >60 ml/min/1.73 m(2). This is a similar relationship to that seen in younger patients, although effect size appears smaller. As the incidence of AKI has been increasing over the past several years, the proportion of elderly patients surviving after AKI has also been increasing. Since AKI heightens the risk for the development and acceleration of CKD, this implies significant public health concerns with regard to the absolute number of elderly persons developing incident CKD

Endocidal Regulation of Secondary Metabolites in the Producing Organisms

Secondary metabolites are defined as organic compounds that are not directly involved in the normal growth, development, and reproduction of an organism. They are widely believed to be responsible for interactions between the producing organism and its environment, with the producer avoiding their toxicities. In our experiments, however, none of the randomly selected 44 species representing different groups of plants and insects can avoid autotoxicity by its endogenous metabolites once made available. We coined the term endocides (endogenous biocides) to describe such metabolites that can poison or inhibit the parent via induced biosynthesis or external applications. Dosage-dependent endocides can selectively induce morphological mutations in the parent organism (e.g., shrubbiness/dwarfism, pleiocotyly, abnormal leaf morphogenesis, disturbed phyllotaxis, fasciated stems, and variegation in plants), inhibit its growth, development, and reproduction and cause death than non-closely related species. The propagule, as well as the organism itself contains or produces adequate endocides to kill itself

Understanding Excitation Energy Quenching in IsiA

Cyanobacteria are photoautotrophic organisms that contribute a significant amount of global primary productivity. They are found in freshwater, marine and even some extremely severe environments. Among those environments, iron deficiency is one of the most common stress conditions in cyanobacterial habitats. To survive, cyanobacteria have evolved and developed several strategies to alleviate the damage caused by iron deficiency. Iron stress-inducible protein (IsiA) is a chlorophyll-binding membrane protein found in cyanobacteria grown in iron-deficient conditions. During the past decades, considerable effort has been put on understanding how IsiA functions to help cyanobacteria survive iron deficiency. It has been reported that IsiA forms various ring-shaped complexes with PSI (PSIx-IsiAy) or by itself (IsiA aggregate). While coupled with PSI (PSIx-IsiAy), the IsiA protein serves as an accessary antenna for PSI, which increases the absorption cross-section by 60% compared with the PSI trimer. IsiA aggregate, instead, dissipates excess light energy to prevent the cells from photodamage. Although these functions have been discovered and demonstrated in vivo and in vitro, the detailed mechanisms, especially the non-photochemical quenching process in IsiA, were not well understood. In this study, the excitation energy quenching process in IsiA was investigated by time-resolved spectroscopy, and we proposed that IsiA dissipate excitation energy via a cysteine-mediated quenching process. Site-directed mutagenesis was performed to replace this critical cysteine (C260) in IsiA with a valine. This single amino acid substitution in IsiA results in the defective IsiA that no longer quenches excitation energy but still functions as light-harvesting antenna for PSI. Interestingly, this IsiA mutant grew faster than the wild type in the presence of iron under high light, suggesting a more efficient use of light energy due to the abolishment of a photoprotective mechanism. Sharing a similar structure with IsiA, CP43, an intrinsic antenna of PSII, has not been reported being involved in excitation energy quenching process. We attempted to introduce this cysteine-mediated quenching process into CP43 to directly provide photoprotection to the reaction center of PSII. The mutant CP43 phenotypes showed a 25% lower quantum efficiency of PSII and barely grew photoautotrophically, implying an inefficient energy transfer to the reaction center of PSII caused by the introduction of an extrinsic quenching process

Space group symmetry fractionalization in a chiral kagome Heisenberg antiferromagnet

The anyonic excitations of a spin-liquid can feature fractional quantum numbers under space-group symmetries. Detecting these fractional quantum numbers, which are analogs of the fractional charge of Laughlin quasiparticles, may prove easier than the direct observation of anyonic braiding and statistics. Motivated by the recent numerical discovery of spin-liquid phases in the kagome Heisenberg antiferromagnet, we theoretically predict the pattern of space group symmetry fractionalization in the kagome lattice chiral spin liquid. We provide a method to detect these fractional quantum numbers in finite-size numerics which is simple to implement in DMRG. Applying these developments to the chiral spin liquid phase of a kagome Heisenberg model, we find perfect agreement between our theoretical prediction and numerical observations.Comment: 5 pages plus appendi

Criteria for Evaluating Authentication Systems

User authentication is an important component of information security. It is critical in addressing many concerns that consumers and business have over the risk of identity theft. However, there is no systematic method to measure how good an authentication mechanism is in a given business context. This paper outlines nine criteria businesses can use to assess authentication systems. With these criteria, businesses are better equipped to select authentication systems that meet the needs of both their organization and their customers, and provide better protection against identity theft and other computer crimes

Evolution of the speech‐ready brain: The voice/jaw connection in the human motor cortex

A prominent model of the origins of speech, known as the “frame/content” theory, posits that oscillatory lowering and raising of the jaw provided an evolutionary scaffold for the development of syllable structure in speech. Because such oscillations are nonvocal in most nonhuman primates, the evolution of speech required the addition of vocalization onto this scaffold in order to turn such jaw oscillations into vocalized syllables. In the present functional MRI study, we demonstrate overlapping somatotopic representations between the larynx and the jaw muscles in the human primary motor cortex. This proximity between the larynx and jaw in the brain might support the coupling between vocalization and jaw oscillations to generate syllable structure. This model suggests that humans inherited voluntary control of jaw oscillations from ancestral species, but added voluntary control of vocalization onto this via the evolution of a new brain area that came to be situated near the jaw region in the human motor cortex