Profiling the Essential Nature of Lipid Metabolism in Asexual Blood and Gametocyte Stages of Plasmodium falciparum.

During its life cycle, Plasmodium falciparum undergoes rapid proliferation fueled by de novo synthesis and acquisition of host cell lipids. Consistent with this essential role, Plasmodium lipid synthesis enzymes are emerging as potential drug targets. To explore their broader potential for therapeutic interventions, we assayed the global lipid landscape during P.

Origin of robustness in generating drug-resistant malaria parasites.

Biological robustness allows mutations to accumulate while maintaining functional phenotypes. Despite its crucial role in evolutionary processes, the mechanistic details of how robustness originates remain elusive. Using an evolutionary trajectory analysis approach, we demonstrate how robustness evolved in malaria parasites under selective pressure from an antimalarial drug inhibiting the folate synthesis pathway.

Tricks in Plasmodium's molecular repertoire--escaping 3'UTR excision-based conditional silencing of the chloroquine resistance transporter gene.

In the human malaria parasite Plasmodium falciparum, the major determinant of chloroquine resistance, P. falciparum chloroquine resistance transporter (pfcrt), likely plays an essential role in asexual blood stages, thus precluding conventional gene targeting approaches. We attempted to conditionally silence the expression of its ortholog in Plasmodium berghei (pbcrt) through Flp recombinase-mediated excision of the 3'untranslated region (UTR) during mosquito passage.

Normalization of the lymph node T cell stromal microenvironment in lpr/lpr mice is associated with SU5416-induced reduction in autoantibodies.

The vascular-stromal elements of lymph nodes can play important roles in regulating the activities of the lymphocytes within. During model immune responses, the vascular-stromal compartment has been shown to undergo proliferative expansion and functional alterations. The state of the vascular-stromal compartment and the potential importance of this compartment in a spontaneous, chronic model of autoimmunity have not been well studied.

Diversity-Oriented Synthesis Yields a Novel Lead for the Treatment of Malaria.

Here, we describe the discovery of a novel antimalarial agent using phenotypic screening of Plasmodium falciparum asexual blood-stage parasites. Screening a novel compound collection created using diversity-oriented synthesis (DOS) led to the initial hit. Structure-activity relationships guided the synthesis of compounds having improved potency and water solubility, yielding a subnanomolar inhibitor of parasite asexual blood-stage growth.

In vitro and in vivo activity of solithromycin (CEM-101) against Plasmodium species.

With the emergence of Plasmodium falciparum infections exhibiting increased parasite clearance times in response to treatment with artemisinin-based combination therapies, the need for new therapeutic agents is urgent. Solithromycin, a potent new fluoroketolide currently in development, has been shown to be an effective, broad-spectrum antimicrobial agent. Malarial parasites possess an unusual organelle, termed the apicoplast, which carries a cryptic genome of prokaryotic origin that encodes its own translation and transcription machinery.

Quantitative assessment of Plasmodium falciparum sexual development reveals potent transmission-blocking activity by methylene blue.

Clinical studies and mathematical models predict that, to achieve malaria elimination, combination therapies will need to incorporate drugs that block the transmission of Plasmodium falciparum sexual stage parasites to mosquito vectors. Efforts to measure the activity of existing antimalarials on intraerythrocytic sexual stage gametocytes and identify transmission-blocking agents have, until now, been hindered by a lack of quantitative assays. Here, we report an experimental system using P.

Identifying apicoplast-targeting antimalarials using high-throughput compatible approaches.

Malarial parasites have evolved resistance to all previously used therapies, and recent evidence suggests emerging resistance to the first-line artemisinins. To identify antimalarials with novel mechanisms of action, we have developed a high-throughput screen targeting the apicoplast organelle of Plasmodium falciparum. Antibiotics known to interfere with this organelle, such as azithromycin, exhibit an unusual phenotype whereby the progeny of drug-treated parasites die.

Taking Charge: Feeding Malaria via Anion Channels.

The human malaria parasite Plasmodium falciparum increases red blood cell membrane permeability during infection to allow for import of nutrients and other solutes. Nguitragool et al. (2011) have now identified parasite-encoded CLAG3 proteins as key components of the import channel located on the erythrocyte membrane.

Fibroblast-type reticular stromal cells regulate the lymph node vasculature.

The lymph node vasculature is essential to immune function, but mechanisms regulating lymph node vascular maintenance and growth are not well understood. Vascular endothelial growth factor (VEGF) is an important mediator of lymph node endothelial cell proliferation in stimulated lymph nodes. It is expressed basally in lymph nodes and up-regulated upon lymph node stimulation, but the identity of VEGF-expressing cells in lymph nodes is not known.

In vitro evaluations of antimalarial drugs and their relevance to clinical outcomes.

Plasmodium falciparum resistance to the former first-line antimalarials chloroquine and sulfadoxine/pyrimethamine has reached critically high levels in many malaria-endemic regions. This has spurred the introduction of several new artemisinin-based combination therapies (ACTs) that display excellent potency in treating drug-resistant malaria. Monitoring for the emergence of drug resistant P.

Advances in understanding the genetic basis of antimalarial drug resistance.

The acquisition of drug resistance by Plasmodium falciparum has severely curtailed global efforts to control malaria. Our ability to define resistance has been greatly enhanced by recent advances in Plasmodium genetics and genomics. Sequencing and microarray studies have identified thousands of polymorphisms in the P.

Regulation of lymph node vascular growth by dendritic cells.

Lymph nodes grow rapidly and robustly at the initiation of an immune response, and this growth is accompanied by growth of the blood vessels. Although the vessels are critical for supplying nutrients and for controlling cell trafficking, the regulation of lymph node vascular growth is not well understood. We show that lymph node endothelial cells begin to proliferate within 2 d of immunization and undergo a corresponding expansion in cell numbers.

Requirements for follicular exclusion and competitive elimination of autoantigen-binding B cells.

Results from several mouse tolerance models indicate that autoreactive B cells in peripheral lymphoid organs develop an anergic phenotype, migrate to the boundary between the T cell zone and the B cell follicle (T/B boundary), and undergo rapid cell death. We have used B cells from mice that are double-transgenic for soluble hen egg lysozyme (HEL) and an Ig that recognizes HEL with a high affinity to characterize the mechanisms underlying the migration and elimination of autoreactive B cells. In contrast to the situation for acutely activated B cells, we find that anergic B cells have reduced levels of CXCR5, the receptor for the follicular chemokine, CXCL13, and this contributes to their exclusion from follicles.

Chemokine requirements for B cell entry to lymph nodes and Peyer's patches.

B cell entry to lymph nodes and Peyer's patches depends on chemokine receptor signaling, but the principal chemokine involved has not been defined. Here we show that the homing of CXCR4-/- B cells is suppressed in CCL19 (ELC)- and CCL21 (SLC)-deficient paucity of lymph node T cells mice, but not in wild-type mice. We also find that CXCR4 can contribute to T cell homing.

Balanced responsiveness to chemoattractants from adjacent zones determines B-cell position.

B lymphocytes re-circulate between B-cell-rich compartments (follicles or B zones) in secondary lymphoid organs, surveying for antigen. After antigen binding, B cells move to the boundary of B and T zones to interact with T-helper cells. Despite the importance of B--T-cell interactions for the induction of antibody responses, the mechanism causing B-cell movement to the T zone has not been defined.

Recognition of nucleoside triphosphates during RNA-catalyzed primer extension.

In support of the idea that certain RNA molecules might be able to catalyze RNA replication, a ribozyme was previously generated that synthesizes short segments of RNA in a reaction modeled after that of proteinaceous RNA polymerases. Here, we describe substrate recognition by this polymerase ribozyme. Altering base or sugar moieties of the nucleoside triphosphate only moderately affects its utilization, provided that the alterations do not disrupt Watson-Crick pairing to the template.

Follicular stromal cells and lymphocyte homing to follicles.

Follicular dendritic cells (FDCs), the best defined stromal cell subset within lymphoid follicles, play a critical role in presenting intact antigen to B lymphocytes. The discovery that many follicular stromal cells make B-lymphocyte chemoattractant (BLC), a CXC chemokine that attracts CXCR5+ cells, provides a basis for understanding how motile B cells come into contact with stationary FDCs. Here we review our work on BLC and discuss properties of BLC-expressing follicular stromal cells.

Meanings of state hospital nursing. I: Facing challenges.

The purpose of this study was to describe the meaning of work for nurses employed in two state psychiatric hospitals. Nurses at both hospitals participated in designing and carrying out the research. In Phase I, nurses described situations in which they had been observers or participant observers and the way that they understood what was occurring in the situations described.

A B-cell-homing chemokine made in lymphoid follicles activates Burkitt's lymphoma receptor-1.

Secondary lymphoid organs (spleen, lymph nodes and Peyer's patches) are divided into compartments, such as B-cell zones (follicles) and T-cell zones, which provide specialized environments for specific steps of the immune response. Migration of lymphocyte subsets into these compartments is essential for normal immune function, yet the molecular cues guiding this cellular traffic are poorly defined. Chemokines constitute a family of chemotactic cytokines that have been shown to direct the migration of leukocytes during inflammation and which may be involved in the constitutive homing of lymphocytes into follicles and T-cell zones.

RNA-catalysed RNA polymerization using nucleoside triphosphates.

The hypothesis that certain RNA molecules may be able to catalyse RNA replication is central to current theories of the early evolution of life. In support of this idea, we describe here an RNA that synthesizes RNA using the same reaction as that employed by protein enzymes that catalyse RNA polymerization. In the presence of the appropriate template RNA and nucleoside triphosphates, the ribozyme extends an RNA primer by successive addition of up to six mononucleotides.