Tirilazad mesylate protects stored erythrocytes against osmotic fragility

Advances in our understanding of nematode ion channels as potential anthelmintic targets

Ion channels are specialized multimeric proteins that underlie cell excitability. These channels integrate with a variety of neuromuscular and biological functions. In nematodes, the physiological behaviors including locomotion, navigation, feeding and reproduction, are regulated by these protein entities. Majority of the antinematodal chemotherapeutics target the ion channels to disrupt essential biological functions. Here, we have summarized current advances in our understanding of nematode ion channel pharmacology. We review cys-loop ligand gated ion channels (LGICs), including nicotinic acetylcholine receptors (nAChRs), acetylcholine-chloride gated ion channels (ACCs), glutamate-gated chloride channels (GluCls), and GABA (γ-aminobutyric acid) receptors, and other ionotropic receptors (transient receptor potential (TRP) channels and potassium ion channels). We have provided an update on the pharmacological properties of these channels from various nematodes. This article catalogs the differences in ion channel composition and resulting pharmacology in the phylum Nematoda. This diversity in ion channel subunit repertoire and pharmacology emphasizes the importance of pursuing species-specific drug target research. In this review, we have provided an overview of recent advances in techniques and functional assays available for screening ion channel properties and their application.

High throughput screening technologies for ion channels

Ion channels are involved in a variety of fundamental physiological processes, and their malfunction causes numerous human diseases. Therefore, ion channels represent a class of attractive drug targets and a class of important off-targets for in vitro pharmacological profiling. In the past decades, the rapid progress in developing functional assays and instrumentation has enabled high throughput screening (HTS) campaigns on an expanding list of channel types. Chronologically, HTS methods for ion channels include the ligand binding assay, flux-based assay, fluorescence-based assay, and automated electrophysiological assay. In this review we summarize the current HTS technologies for different ion channel classes and their applications.

Clinical consequences of red cell storage in the critically ill

Red cell (RBC) transfusions are a potentially life-saving therapy employed during the care of many critically ill patients to replace losses in hemoglobin to maintain oxygen delivery to vital organs. During storage, RBCs undergo a series of biochemical and biomechanical changes that reduce their survival and function. Additionally, accumulation of other biologic by-products of RBC preservation may be detrimental to recipients of blood transfusions. Laboratory studies and an increasing number of observational studies have raised the possibility that prolonged RBC storage adversely affects clinical outcomes. In this article, the laboratory and animal experiments evaluating changes to RBCs during prolonged storage are reviewed. Subsequently, the clinical studies that have evaluated the clinical consequences of prolonged RBC storage are reviewed. These data suggest a possible detrimental clinical effect associated with the transfusion of stored RBCs; randomized clinical trials further evaluating the clinical consequences of transfusing older stored RBCs are required.

Red cell storage lesion: The potential impact of storage-induced CD47 decline on immunomodulation and the survival of leucofiltered red cells

Red blood cells undergo major biochemical and biomechanical changes during storage that could effect their post transfusion performance. Biochemical effects include changes in 2,3-diphosphoglycerate (2,3-DPG), ATP, and calcium levels, as well as metabolic modulation and release of Annexin V, a cytosolic component of blood cells, as a global marker of cellular injury and fragmentation. Biomechanical changes include alterations in cellular membrane, shape changes, phospholipid content, phospholipid asymmetry, and antigenic markers. Although the extent of these changes under various storage conditions has been well documented, their clinical effects remain unclear. In the current era of universal leucodepletion, the immunomodulatory effects of some essential markers such as CD47 and phosphatidyl serine become the focus of interest as highlighted in this manuscript.

Effects of storage on efficacy of red cell transfusion: When is it not safe?

OBJECTIVE

To review the literature on red blood cell storage and its relationship to the efficacy of transfusion.

RESULTS

Well-documented changes occur to the red blood cell product during ex vivo storage. These changes include a reduction in red blood cell deformability, altered red blood cell adhesiveness and aggregability, and a reduction in 2,3-diphosphoglycerate and ATP. Bioactive compounds with proinflammatory effects also accumulate in the storage medium. These changes reduce posttransfusion viability of red blood cells. The clinical effects beyond posttransfusion viability are uncertain, but a growing body of evidence suggests that the storage lesion may reduce tissue oxygen availability, have proinflammatory and immunomodulatory effects, and influence morbidity and mortality. There are no published randomized, control trials examining the effect of storage duration on morbidity and mortality. Leukoreduction improves the quality of stored red blood cell products and in some studies has been shown to reduce morbidity and mortality.

CONCLUSION

Although storage duration influences the quality of red blood cell product, there is currently insufficient evidence to advocate shorter storage periods for red blood cell products.

Effects of membrane partitioning and other physical chemical properties on the apparent potency of "membrane active" compounds evaluated using red blood cell lysis assays

The membrane-destabilizing properties of Amphotericin B and Zwittergent were used as benchmark compounds for examining in detail their membrane-altering effects in a series of human red blood cell lysis assays. The procedures included examining dose responses and the effects of different cell concentrations on potency in rbc lysis assays. In order to enhance detection of subtle membrane effects, we also used a range of NaCl concentrations to osmotically stress the rbc's. Using the benchmark compounds, a set of conditions was developed for examination of subtle membrane effects that may be applied to series of compounds with suspected membrane-perturbation activity. A group of experiments was defined that allow detection of the most important membrane-modifying behaviors among a diverse group of compounds. From an initial screen of bacterial growth inhibition over 150 compounds were examined for membrane-altering properties using the limited experimental protocols developed from the benchmark compounds. Several dose-response patterns were observed as useful for classifying compounds based on their tendency to alter membrane integrity and to partition into the lipids of membranes, as well as their propensity to form aggregates or precipitates. The methods may prove generally useful for distinguishing compounds whose primary activity is membrane destabilization from more interesting and useful pharmacological mechanisms of action.

The red cell storage lesion and its implication for transfusion

Storage of red blood cells in preservative medium is associated with metabolic, biochemical and molecular changes to erythrocytes collectively referred to as the "storage lesion." In addition to corpuscular injury, bioreactive substances including cytokines and lipids accumulate in the medium during storage. We review evidence for those storage related changes and potential clinical implications for red blood cell transfusion.