In order to maintain daily cycles, the circadian clock must tightly regulate the rhythms of thousands of mRNAs and proteins with the correct period, phase, and amplitude to ultimately drive the wide range of rhythmic biological processes. Recent genomic approaches have revolutionized our view of circadian gene expression and highlighted the importance of post-transcriptional regulation in driving mRNA rhythmicity. Even after transcripts are made from DNA, subsequent processing and regulatory steps determine when, where, and how much protein will be generated. These post-transcriptional regulatory mechanisms can add flexibility to overall gene expression and alter protein levels rapidly without requiring transcript synthesis, and are therefore beneficial for cells; however, the extent to which circadian post-transcriptional mechanisms contribute to rhythmic profiles throughout the genome and the mechanisms involved have not been fully elucidated. In this review, we will summarize how circadian genomics have revealed new insights into rhythmic post-transcriptional regulation in mammals, and discuss potential implications of such regulation in controlling many circadian-driven physiologies.
The first known cases of Middle East respiratory syndrome (MERS), associated with infection by a novel coronavirus (CoV), occurred in 2012 in Jordan but were reported retrospectively. The case first to be publicly reported was from Jeddah, in the Kingdom of Saudi Arabia (KSA). Since then, MERS-CoV sequences have been found in a bat and in many dromedary camels (DC). MERS-CoV is enzootic in DC across the Arabian Peninsula and in parts of Africa, causing mild upper respiratory tract illness in its camel reservoir and sporadic, but relatively rare human infections. Precisely how virus transmits to humans remains unknown but close and lengthy exposure appears to be a requirement. The KSA is the focal point of MERS, with the majority of human cases. In humans, MERS is mostly known as a lower respiratory tract (LRT) disease involving fever, cough, breathing difficulties and pneumonia that may progress to acute respiratory distress syndrome, multiorgan failure and death in 20 % to 40 % of those infected. However, MERS-CoV has also been detected in mild and influenza-like illnesses and in those with no signs or symptoms. Older males most obviously suffer severe disease and MERS patients often have comorbidities. Compared to severe acute respiratory syndrome (SARS), another sometimes- fatal zoonotic coronavirus disease that has since disappeared, MERS progresses more rapidly to respiratory failure and acute kidney injury (it also has an affinity for growth in kidney cells under laboratory conditions), is more frequently reported in patients with underlying disease and is more often fatal. Most human cases of MERS have been linked to lapses in infection prevention and control (IPC) in healthcare settings, with approximately 20 % of all virus detections reported among healthcare workers (HCWs) and higher exposures in those with occupations that bring them into close contact with camels. Sero-surveys have found widespread evidence of past infection in adult camels and limited past exposure among humans. Sensitive, validated reverse transcriptase real-time polymerase chain reaction (RT-rtPCR)-based diagnostics have been available almost from the start of the emergence of MERS. While the basic virology of MERS-CoV has advanced over the past three years, understanding of the interplay between camel, environment, and human remains limited.
Electronic supplementary material
The online version of this article (doi:10.1186/s12985-015-0439-5) contains supplementary material, which is available to authorized users.
Middle East respiratory syndrome; Coronavirus; MERS; Epidemiology; Diagnostics; Transmission
Sepsis-induced acute kidney injury (SAKI) remains an important challenge in critical care medicine. We reviewed current available evidence on prevention and treatment of SAKI with focus on some recent advances and developments. Prevention of SAKI starts with early and ample fluid resuscitation preferentially with crystalloid solutions. Balanced crystalloids have no proven superior benefit. Renal function can be evaluated by measuring lactate clearance rate, renal Doppler, or central venous oxygenation monitoring. Assuring sufficiently high central venous oxygenation most optimally prevents SAKI, especially in the post-operative setting, whereas lactate clearance better assesses mortality risk when SAKI is present. Although the adverse effects of an excessive “kidney afterload” are increasingly recognized, there is actually no consensus regarding an optimal central venous pressure. Noradrenaline is the vasopressor of choice for preventing SAKI. Intra-abdominal hypertension, a potent trigger of AKI in post-operative and trauma patients, should not be neglected in sepsis. Early renal replacement therapy (RRT) is recommended in fluid-overloaded patients’ refractory to diuretics but compelling evidence about its usefulness is still lacking. Continuous RRT (CRRT) is advocated, though not sustained by convincing data, as the preferred modality in hemodynamically unstable SAKI. Diuretics should be avoided in the absence of hypervolemia. Antimicrobial dosing during CRRT needs to be thoroughly reconsidered to assure adequate infection control.
Sepsis; Acute kidney injury; Septic acute kidney injury; Prevention; Treatment; Review
It is well established that glycogen depletion affects endurance exercise performance negatively. Moreover, numerous studies have demonstrated that post-exercise carbohydrate ingestion improves exercise recovery by increasing glycogen resynthesis. However, recent research into the effects of glycogen availability sheds new light on the role of the widely accepted energy source for adenosine triphosphate (ATP) resynthesis during endurance exercise. Indeed, several studies showed that endurance training with low glycogen availability leads to similar and sometimes even better adaptations and performance compared to performing endurance training sessions with replenished glycogen stores. In the case of resistance exercise, a few studies have been performed on the role of glycogen availability on the early post-exercise anabolic response. However, the effects of low glycogen availability on phenotypic adaptations and performance following prolonged resistance exercise remains unclear to date. This review summarizes the current knowledge about the effects of glycogen availability on skeletal muscle adaptations for both endurance and resistance exercise. Furthermore, it describes the role of glycogen availability when both exercise modes are performed concurrently.
Glycogen availability; Skeletal muscle; Adaptation; Endurance exercise; Resistance exercise
Human mesenchymal stem cells (hMSCs), also called mesenchymal stromal cells, have been of great interest in regenerative medicine applications because of not only their differentiation potential but also their ability to secrete bioactive factors that can modulate the immune system and promote tissue repair. This potential has initiated many early-phase clinical studies for the treatment of various diseases, disorders, and injuries by using either hMSCs themselves or their secreted products. Currently, hMSCs for clinical use are generated through conventional static adherent cultures in the presence of fetal bovine serum or human-sourced supplements. However, these methods suffer from variable culture conditions (i.e., ill-defined medium components and heterogeneous culture environment) and thus are not ideal procedures to meet the expected future demand of quality-assured hMSCs for human therapeutic use. Optimizing a bioprocess to generate hMSCs or their secreted products (or both) promises to improve the efficacy as well as safety of this stem cell therapy. In this review, current media and methods for hMSC culture are outlined and bioprocess development strategies discussed.
Lithium has been used as the gold standard in the treatment of major depressive and bipolar disorders for decades. Due to its narrow therapeutic index, lithium toxicity is a common clinical problem. Although risk factors for lithium intoxication seem to be well-described, lacking patient education and inexperience of treatment are assumed to contribute to the probability of lithium intoxication. A review of literature shows that the treatment of lithium intoxication has not been adequately studied or standardized. The aim of this literature review is to compile and present current evidence on the treatment of lithium intoxication and contribute to a standardization regarding general treatment recommendations as well as evidence on indication for extracorporeal methods. Against the background of this common and potentially life-threatening condition, the standardization of the treatment of lithium intoxication is definitely a task for the future.
Lithium; Intoxication; Affective disorders; Bipolar disorder; Treatment; Extracorporeal methods; Hemodialysis
maintain daily cycles, the circadian clock must tightly regulate
the rhythms of thousands of mRNAs and proteins with the correct period,
phase, and amplitude to ultimately drive the wide range of rhythmic
biological processes. Recent genomic approaches have revolutionized
our view of circadian gene expression and highlighted the importance
of post-transcriptional regulation in driving mRNA rhythmicity. Even
after transcripts are made from DNA, subsequent processing and regulatory
steps determine when, where, and how much protein will be generated.
These post-transcriptional regulatory mechanisms can add flexibility
to overall gene expression and alter protein levels rapidly without
requiring transcript synthesis and are therefore beneficial for cells;
however, the extent to which circadian post-transcriptional mechanisms
contribute to rhythmic profiles throughout the genome and the mechanisms
involved have not been fully elucidated. In this review, we will summarize
how circadian genomics have revealed new insights into rhythmic post-transcriptional
regulation in mammals and discuss potential implications of such regulation
in controlling many circadian-driven physiologies.
Mammalian circadian timekeeping arises
from a transcription-based
feedback loop driven by a set of dedicated clock proteins. At its
core, the heterodimeric transcription factor CLOCK:BMAL1 activates
expression of Period, Cryptochrome, and Rev-Erb genes, which feed back to repress
transcription and create oscillations in gene expression that confer
circadian timing cues to cellular processes. The formation of different
clock protein complexes throughout this transcriptional cycle helps
to establish the intrinsic ∼24 h periodicity of the clock;
however, current models of circadian timekeeping lack the explanatory
power to fully describe this process. Recent studies confirm the presence
of at least three distinct regulatory complexes: a transcriptionally
active state comprising the CLOCK:BMAL1 heterodimer with its coactivator
CBP/p300, an early repressive state containing PER:CRY complexes,
and a late repressive state marked by a poised but inactive, DNA-bound
CLOCK:BMAL1:CRY1 complex. In this review, we analyze high-resolution
structures of core circadian transcriptional regulators and integrate
biochemical data to suggest how remodeling of clock protein complexes
may be achieved throughout the 24 h cycle. Defining these detailed
mechanisms will provide a foundation for understanding the molecular
basis of circadian timing and help to establish new platforms for
the discovery of therapeutics to manipulate the clock.
Circadian clocks are self-sustaining
timekeepers found in almost
all organisms on earth. The filamentous fungus Neurospora
crassa is a preeminent model for eukaryotic circadian clocks.
Investigations of the Neurospora circadian clock
system have led to elucidation of circadian clock regulatory mechanisms
that are common to all eukaryotes. In this work, we will focus on
the Neurospora circadian oscillator mechanism with
an emphasis on the regulation of the core clock component FREQUENCY.
circadian clock is a global regulatory system that interfaces
with most other regulatory systems and pathways in mammalian organisms.
Investigations of the circadian clock–DNA damage response connections
have revealed that nucleotide excision repair, DNA damage checkpoints,
and apoptosis are appreciably influenced by the clock. Although several
epidemiological studies in humans and a limited number of genetic
studies in mouse model systems have indicated that clock disruption
may predispose mammals to cancer, well-controlled genetic studies
in mice have not supported the commonly held view that circadian clock
disruption is a cancer risk factor. In fact, in the appropriate genetic
background, clock disruption may instead aid in cancer regression
by promoting intrinsic and extrinsic apoptosis. Finally, the clock
may affect the efficacy of cancer treatment (chronochemotherapy) by
modulating the pharmacokinetics and pharmacodynamics of chemotherapeutic
drugs as well as the activity of the DNA repair enzymes that repair
the DNA damage caused by anticancer drugs.
β-defensin peptides are a large family of antimicrobial peptides. Although they kill microbes in vitro and interact with immune cells, the precise role of these genes in vivo remains uncertain. Despite their inducible presence at mucosal surfaces, their main site of expression is the epididymis. Recent evidence suggests that a major function of these peptides is in sperm maturation. In addition to previous work suggesting this, work at the MRC Human Genetics Unit, Edinburgh, has shown that homozygous deletion of a cluster of nine β-defensin genes in the mouse results in profound male sterility. The spermatozoa derived from the mutants had reduced motility and increased fragility. Epididymal spermatozoa isolated from the cauda region of the homozygous mutants demonstrated precocious capacitation and increased spontaneous acrosome reactions compared with those from wild-types. Despite this, these mutant spermatozoa had reduced ability to bind to the zona pellucida of oocytes. Ultrastructural examination revealed a disintegration of the microtubule structure of mutant-derived spermatozoa isolated from the epididymal cauda region, but not from the caput. Consistent with premature acrosome reaction and hyperactivation, spermatozoa from mutant animals had significantly increased intracellular calcium content. This work demonstrates that in vivo β-defensins are essential for successful sperm maturation, and that their disruption alters intracellular calcium levels, which most likely leads to premature activation and spontaneous acrosome reactions that result in hyperactivation and loss of microtubule structure of the axoneme. Determining which of the nine genes are responsible for the phenotype and the relevance to human sperm function is important for future work on male infertility.
acrosome reaction; antimicrobial; capacitation; epididymis; sperm; β-defensins
A variety of glycosylphosphatidylinositol (GPI)-linked proteins are acquired on spermatozoa from epididymal luminal fluids (ELF) during sperm maturation. These proteins serve roles in immunoprotection and in key steps of fertilization such as capacitation, acrosomal exocytosis and sperm-egg interactions. Their acquisition on sperm cells is mediated both by membrane vesicles (epididymosomes, EP) which were first reported to dock on the sperm surface, and by lipid carriers which facilitate the transfer of proteins associated with the membrane-free fraction of ELF. While the nonvesicular fraction is more efficient, both pathways are dependent on hydrophobic interactions between the GPI-anchor and the external lipid layer of the sperm surface. More recently proteomic and hypothesis-driven studies have shown that EP from several mammals carry transmembrane (TM) proteins, including plasma membrane Ca2+-ATPase 4 (PMCA4). Synthesized in the testis, PMCA4 is an essential protein and the major Ca2+ efflux pump in murine spermatozoa. Delivery of PMCA4 to spermatozoa from bovine and mouse EP during epididymal maturation and in vitro suggests that the docking of EP on the sperm surface precedes fusion, and experimental evidence supports a fusogenic mechanism for TM proteins. Fusion is facilitated by CD9, which generates fusion–competent sites on membranes. On the basis of knowledge of PMCA4's interacting partners a number of TM and membrane-associated proteins have been identified or are predicted to be present, in the epididymosomal cargo deliverable to spermatozoa. These Ca2+-dependent proteins, undetected in proteomic studies, play essential roles in sperm motility and fertility, and their detection highlights the usefulness of the hypothesis-driven approach.
epididymal maturation; epididymal secretory proteins; GPI-linked proteins; lipid carrier; membrane-associated proteins; PMCA4; transmembrane proteins
Ribonucleic acid (RNA) was previously thought to remain inside cells as an intermediate between genes and proteins during translation. However, it is now estimated that 98% of the mammalian genomic output is transcribed as noncoding RNAs, which are involved in diverse gene expression regulatory mechanisms and can be transferred from one cell to another through extracellular communication. For instance, microRNAs are 22-nucleotide-long noncoding RNAs that are generated by endonuclease cleavage of precursors inside the cells and are secreted as extracellular microRNAs to regulate target cell posttranscriptional gene expression via RNA interference. We and others have shown that different populations of microRNAs are expressed in distinct regions of the human epididymis and regulate the expression of target genes that are involved in the control of male fertility as indicated by knock-out mouse models. Importantly, some microRNAs, including the microRNA-888 (miR-888) cluster that is exclusively expressed in the reproductive system of human and nonhuman primates, are released in the sperm-surrounding fluid in the epididymis via extracellular vesicles, the so-called epididymosomes. In addition to interacting with the membrane of maturing spermatozoa, these extracellular vesicles containing microRNAs communicate with epithelial cells located downstream from their release site, suggesting a role in the luminal exocrine control of epididymal functions. Apart from their potential roles as mediators of intercellular communication within the epididymis, these extracellular microRNAs are potent molecular targets for the noninvasive diagnosis of male infertility.
Dicer; epididymis; exocrine factors; extracellular vesicles; intercellular communication; microRNAs; paracrine regulation; posttranscriptional gene regulation; seminal plasma; spermatozoa
Dicer1 is an RNase III enzyme necessary for microRNA (miRNA) biogenesis, as it cleaves pre-miRNAs into mature miRNAs. miRNAs are important regulators of gene expression. In recent years, several miRNA-independent roles of Dicer1 have been identified. They include the production of endogenous small interfering RNAs, detoxifying retrotransposon-derived transcripts, and binding to new targets; messenger RNAs and long noncoding RNAs. Further, in this review, the functional significance of Dicer1 in the male reproductive tract is discussed. Conditional Dicer1 knock-out mouse models have demonstrated a requisite role for Dicer in male fertility. Deletion of Dicer1 from somatic or germ cells in the testis cause spermatogenic problems rendering male mice infertile. The lack of Dicer1 in the proximal epididymis causes dedifferentiation of the epithelium, with unbalanced sex steroid receptor expression, defects in epithelial lipid homeostasis, and subsequent male infertility. In addition, Dicer1 ablation from the prostate leads to increased apoptosis of the differentiated luminal cells, followed by epithelial hypotrophy of the ventral prostate. However, further studies are needed to clarify which functions of Dicer1 are responsible for the observed phenotypes in the male reproductive tract.
Dicer 1; epididymis; prostate; seminal vesicle; testis; vas deferens
Cholesterol is a key molecule in the mammalian physiology of especial particular importance for the reproductive system as it is the common precursor for steroid hormone synthesis. Cholesterol is also a recognized modulator of sperm functions, not only at the level of gametogenesis. Cholesterol homeostasis regulation is crucial for posttesticular sperm maturation, and imbalanced cholesterol levels may particularly affect these posttesticular events. Metabolic lipid disorders (dyslipidemia) affect male fertility but are most of the time studied from the angle of endocrine/testicular consequences. This review will focus on the deleterious effects of a particular dyslipidemia, i.e., hypercholesterolemia, on posttesticular maturation of mammalian spermatozoa.
cholesterol; dyslipidemia; epididymis; fertility; posttesticular maturation; spermatozoa
The development of the Wolffian/epididymal duct is crucial for proper function and, therefore, male fertility. The development of the epididymis is complex; the initial stages form as a transient embryonic kidney; then the mesonephros is formed, which in turn undergoes extensive morphogenesis under the influence of androgens and growth factors. Thus, understanding of its full development requires a wide and multidisciplinary view. This review focuses on mouse models that display abnormalities of the Wolffian duct and mesonephric development, the importance of these mouse models toward understanding male reproductive tract development, and how these models contribute to our understanding of clinical abnormalities in humans such as congenital anomalies of the kidney and urinary tract (CAKUT).
epididymis; mesonephros; transgenic mice; Wolffian duct
polymers offer a powerful opportunity to develop theranostic
materials on the size scale of proteins that can provide targeting,
imaging, and therapeutic functionality. Achieving this goal requires
the presence of multiple targeting molecules, dyes, and/or drugs on
the polymer scaffold. This critical review examines the synthetic,
analytical, and functional challenges associated with the heterogeneity
introduced by conjugation reactions as well as polymer scaffold design.
First, approaches to making multivalent polymer conjugations are discussed
followed by an analysis of materials that have shown particular promise
biologically. Challenges in characterizing the mixed ligand distributions
and the impact of these distributions on biological applications are
then discussed. Where possible, molecular-level interpretations are
provided for the structures that give rise to the functional ligand
and molecular weight distributions present in the polymer scaffolds.
Lastly, recent strategies employed for overcoming or minimizing the
presence of ligand distributions are discussed. This review focuses
on multivalent polymer scaffolds where average stoichiometry and/or
the distribution of products have been characterized by at least one
experimental technique. Key illustrative examples are provided for
scaffolds that have been carried forward to in vitro and in vivo testing with significant biological
A significant number of patients with atrial fibrillation, treated with oral anticoagulants, present with an acute coronary syndrome. Many of these patients have an indication for coronary angiography. The introduction of non-vitamin K antagonist oral anticoagulants (NOACs) and the novel P2Y12 inhibitors has generated new uncertainty about the optimal treatment regimen, whether triple or dual therapy should be given and which is the most beneficial P2Y12 inhibitor (clopidogrel, ticagrelor, prasugrel). In this article, we will summarise the practical advice on the management of acute coronary syndrome patients requiring oral anticoagulants following the recent consensus document of the European Society of Cardiology (ESC) Working Group on Thrombosis in association with the European Heart Rhythm Association (EHRA) and ESC guidelines.
Oral anticoagulation; NOAC; Heparin; Bivalirudin; Prasugrel; Ticagrelor
Encouragingly, global rates of new tuberculosis (TB) cases have been falling since 2005, in line with the Millennium Development Goal targets; however, cases of multidrug-resistant (MDR-) and extensively drug-resistant TB (XDR-TB) have been increasing. Fifteen of the world's 27 high MDR- and XDR-TB burden countries are in the World Health Organization (WHO) European Region, of which 10 are in Eastern Europe (including Baltic and Caucasus countries). To address the MDR- and XDR-TB situation in the WHO European Region, a Consolidated Action Plan to Prevent and Combat M/XDR-TB (2011–2015) was developed for all 53 Member States and implemented in 2011. Since the implementation of the Action Plan, the proportion of MDR-TB appears largely to have levelled off among bacteriologically confirmed TB cases in high-burden countries with universal or near universal (>95%) first-line drug susceptibility testing (DST). The treatment success rate, however, continues to decrease. A contributing factor is the substantial proportion of MDR-TB cases that are additionally resistant to either a fluoroquinolone, a second-line injectable agent or both (XDR-TB); high-burden country proportions range from 12.6% to 80.4%. Proportions of XDR-TB range from 5% to 24.8%. Despite much progress in Eastern Europe, critical challenges remain as regards access to appropriate treatment regimens; patient hospitalisation; scale-up of laboratory capacity, including the use of rapid diagnostics and second-line DST; vulnerable populations; human resources; and financing. Solutions to these challenges are aligned with the Post-2015 Global TB strategy. As a first step, the global strategy should be adapted at regional and country levels to serve as a framework for immediate actions as well as longer-term ways forward.
MDR-TB; XDR-TB; epidemiology; review; European Region; WHO
Motivation: With the advent of relatively affordable high-throughput technologies, DNA sequencing of cancers is now common practice in cancer research projects and will be increasingly used in clinical practice to inform diagnosis and treatment. Somatic (cancer-only) single nucleotide variants (SNVs) are the simplest class of mutation, yet their identification in DNA sequencing data is confounded by germline polymorphisms, tumour heterogeneity and sequencing and analysis errors. Four recently published algorithms for the detection of somatic SNV sites in matched cancer–normal sequencing datasets are VarScan, SomaticSniper, JointSNVMix and Strelka. In this analysis, we apply these four SNV calling algorithms to cancer–normal Illumina exome sequencing of a chronic myeloid leukaemia (CML) patient. The candidate SNV sites returned by each algorithm are filtered to remove likely false positives, then characterized and compared to investigate the strengths and weaknesses of each SNV calling algorithm.
Results: Comparing the candidate SNV sets returned by VarScan, SomaticSniper, JointSNVMix2 and Strelka revealed substantial differences with respect to the number and character of sites returned; the somatic probability scores assigned to the same sites; their susceptibility to various sources of noise; and their sensitivities to low-allelic-fraction candidates.
Availability: Data accession number SRA081939, code at http://code.google.com/p/snv-caller-review/
Supplementary data are available at Bioinformatics online.
Motivation: Many biological systems operate in a similar manner across a large number of species or conditions. Cross-species analysis of sequence and interaction data is often applied to determine the function of new genes. In contrast to these static measurements, microarrays measure the dynamic, condition-specific response of complex biological systems. The recent exponential growth in microarray expression datasets allows researchers to combine expression experiments from multiple species to identify genes that are not only conserved in sequence but also operated in a similar way in the different species studied.
Results: In this review we discuss the computational and technical challenges associated with these studies, the approaches that have been developed to address these challenges and the advantages of cross-species analysis of microarray data. We show how successful application of these methods lead to insights that cannot be obtained when analyzing data from a single species. We also highlight current open problems and discuss possible ways to address them.