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Articles 31 - 46 of 46

Full-Text Articles in Immunology and Infectious Disease

Artemether-Lumefantrine Selects For Malaria Parasites With Decreased Lumefantrine Sensitivity Although Parasites Remain Sensitive To This Regimen In Tororo, Uganda, P. Tumwebaze, J. Bloome, O. Byaruhanga, C. Nakazibwe, A. Walakira, J. Okiring, S. L. Nsobya, Roland A. Cooper, P. J. Rosenthal Nov 2012

Artemether-Lumefantrine Selects For Malaria Parasites With Decreased Lumefantrine Sensitivity Although Parasites Remain Sensitive To This Regimen In Tororo, Uganda, P. Tumwebaze, J. Bloome, O. Byaruhanga, C. Nakazibwe, A. Walakira, J. Okiring, S. L. Nsobya, Roland A. Cooper, P. J. Rosenthal

Roland A. Cooper

Artemisinin-based combination therapies (ACTs) may select for malaria parasites with decreased drug sensitivity. We studied the sensitivity of parasites from children enrolled in treatment and prevention trials in Tororo, Uganda from June, 2010 to February, 2012. When Plasmodium falciparum malaria was diagnosed, blood was obtained, parasites (286 isolates) were cultured with serial dilutions of chloroquine (CQ), monodesethylamodiaquine (AQ), quinine (QN), dihydroartemisinin (DHA), lumefantrine (LM), or piperaquine (PQ) for 72 h, and ex vivo sensitivities were assessed by HRP-2-based ELISA. Sensitivities (nM) to CQ (median IC50 486.2; IQR 206.5-748.8), AQ (83.3; 58.4-132.4), PQ (20.3; 7.6-47.5) and QN (126.4; 74.9-196.3) varied widely; …


Regulation Of Anti-Plasmodium Immunity By A Litaf-Like Transcription Factor In The Malaria Vector Anopheles Gambiae, Ryan C. Smith, Abraham G. Eappen, Andrea J. Radtke, Marcelo Jacobs-Lorena Oct 2012

Regulation Of Anti-Plasmodium Immunity By A Litaf-Like Transcription Factor In The Malaria Vector Anopheles Gambiae, Ryan C. Smith, Abraham G. Eappen, Andrea J. Radtke, Marcelo Jacobs-Lorena

Ryan C. Smith

The mosquito is the obligate vector for malaria transmission. To complete its development within the mosquito, the malaria parasite Plasmodium must overcome the protective action of the mosquito innate immune system. Here we report on the involvement of the Anopheles gambiae orthologue of a conserved component of the vertebrate immune system, LPS-induced TNFα transcription factor (LITAF), and its role in mosquito anti-Plasmodium immunity. An. gambiae LITAF-like 3 (LL3) expression is up-regulated in response to midgut invasion by both rodent and human malaria parasites. Silencing of LL3 expression greatly increases parasite survival, indicating that LL3 is part of an anti-Plasmodium defense …


Ex Vivo Drug Sensitivity Of Malaria Parasites Under Selective Pressure In Tororo, Uganda, P. K. Tumebaze, O. Byaruhanga, J. Okiring, S. L. Nsobya, R. A. Cooper, P. J. Rosenthal Nov 2011

Ex Vivo Drug Sensitivity Of Malaria Parasites Under Selective Pressure In Tororo, Uganda, P. K. Tumebaze, O. Byaruhanga, J. Okiring, S. L. Nsobya, R. A. Cooper, P. J. Rosenthal

Roland A. Cooper

Artemisinin-based combination therapies (ACTs) are standard treatments for uncomplicated malaria in Africa. ACTs provide highly effective treatment, and regular use may offer protection against malaria in high risk populations. However, increased use of ACTs may select for parasites with decreased sensitivity. We studied the ex vivo sensitivity of malaria parasites collected from children enrolled in treatment and prevention trials in Tororo, Uganda from June, 2010 to August, 2011. When P. falciparum malaria was diagnosed, blood was obtained, parasites were cultured with serial dilutions of chloroquine (CQ), monodesethylamodiaquine (AQ), quinine (QN), dihydroartemisinin (DHA), lumefantrine (LM), and piperaquine (PQ) for 72 hours, …


The Armadillo Repeat Protein Pf16 Is Essential For Flagellar Structure And Function In Plasmodium Male Gametes, Ursula Straschil, Arthur M. Talman, David J. P. Ferguson, Karen A. Bunting, Zhengyao Xu, Elizabeth Bailes, Robert E. Sinden, Anthony A. Holder, Elizabeth F. Smith Sep 2010

The Armadillo Repeat Protein Pf16 Is Essential For Flagellar Structure And Function In Plasmodium Male Gametes, Ursula Straschil, Arthur M. Talman, David J. P. Ferguson, Karen A. Bunting, Zhengyao Xu, Elizabeth Bailes, Robert E. Sinden, Anthony A. Holder, Elizabeth F. Smith

Dartmouth Scholarship

Malaria, caused by the apicomplexan parasite Plasmodium, threatens 40% of the world's population. Transmission between vertebrate and insect hosts depends on the sexual stages of the life-cycle. The male gamete of Plasmodium parasite is the only developmental stage that possesses a flagellum. Very little is known about the identity or function of proteins in the parasite's flagellar biology. Here, we characterise a Plasmodium PF16 homologue using reverse genetics in the mouse malaria parasite Plasmodium berghei. PF16 is a conserved Armadillo-repeat protein that regulates flagellar structure and motility in organisms as diverse as green algae and mice. We show that …


Identification Of Novel Antimalarials From Marine Natural Products For Lead Discovery, Stephenie M. Alvarado Jan 2010

Identification Of Novel Antimalarials From Marine Natural Products For Lead Discovery, Stephenie M. Alvarado

Electronic Theses and Dissertations

An estimated 500 million cases of malaria occur each year. The increasing prevalence of drug resistant strains of Plasmodium in most malaria endemic areas has significantly reduced the efficacy of current antimalarial drugs for prophylaxis and treatment of this disease. Therefore, discovery of new, inexpensive, and effective drugs are urgently needed to combat this disease. Marine biodiversity is an enormous source of novel chemical entities and has been barely investigated for antimalarial drug discovery. In an effort to discover novel therapeutics for malaria, we studied the antimalarial activities of a unique marine-derived peak fraction library provided by Harbor Branch Oceanographic …


Chloroquine Susceptibility And Reversibility In A Plasmodium Falciparum Genetic Cross, Jigar J. Patel, Drew Thacker, John C. Tan, Perri Pleeter, Lisa Checkley, Joseph M. Gonzales, Bingbing Deng, Paul D. Roepe, Roland A. Cooper, Michael T. Ferdig Jan 2010

Chloroquine Susceptibility And Reversibility In A Plasmodium Falciparum Genetic Cross, Jigar J. Patel, Drew Thacker, John C. Tan, Perri Pleeter, Lisa Checkley, Joseph M. Gonzales, Bingbing Deng, Paul D. Roepe, Roland A. Cooper, Michael T. Ferdig

Biological Sciences Faculty Publications

Mutations in the Plasmodium falciparum chloroquine (CQ) resistance transporter (PfCRT) are major determinants of verapamil (VP)-reversible CQ resistance (CQR). In the presence of mutant PfCRT, additional genes contribute to the wide range of CQ susceptibilities observed. It is not known if these genes influence mechanisms of chemosensitization by CQR reversal agents. Using quantitative trait locus (QTL) mapping of progeny clones from the HB3 x Dd2 cross, we show that the P. falciparum multidrug resistance gene 1 (pfmdr1) interacts with the South-East Asia-derived mutant pfcrt haplotype to modulate CQR levels. A novel chromosome 7 locus is predicted to contribute …


Lipid Targets Of The Antimalarial Trioxanes In Plasmodium Falciparum, Carmony Leah Hartwig Jul 2009

Lipid Targets Of The Antimalarial Trioxanes In Plasmodium Falciparum, Carmony Leah Hartwig

Biological Sciences Theses & Dissertations

Malaria is among the most debilitating diseases of man. The protozoan parasite, Plasmodium falciparum, causes over a million annual fatalities. The antimalarial trioxanes, exemplified by artemisinin, are among the few pharmaceuticals for which clinical resistance has not become widespread. Artemisinin is a naturally occurring sesquiterpene lactone, containing a unique endoperoxide pharmacophore. Despite extensive study, the precise antimalarial mechanism of action of trioxanes remains elusive. Heme iron-mediated cleavage of the endoperoxide within the parasite digestive vacuole is hypothesized to generate cytotoxic metabolites capable of alkylating heme and damaging cellular macromolecules. The hypothesis of this research is that the endoperoxide pharmacophore …


Quantitative Dissection Of Clone-Specific Growth Rates In Cultured Malaria Parasites, Heather B. Reilly Ayala, Hongjian Wang, John A. Steuter, Anastasia M. Marx, Michael T. Ferdig Dec 2007

Quantitative Dissection Of Clone-Specific Growth Rates In Cultured Malaria Parasites, Heather B. Reilly Ayala, Hongjian Wang, John A. Steuter, Anastasia M. Marx, Michael T. Ferdig

Faculty Publications - Department of Biological & Molecular Science

Measurement of parasite proliferation in cultured red blood cells underpins many facets of malaria research, from drug sensitivity assays to assessing the impact of experimentally altered genes on parasite growth, virulence, and fitness. Pioneering efforts to grow Plasmodium falciparum in cultured red blood cells revolutionized malaria research and spurred the development of semi-high throughput growth assays using radio-labeled hypoxanthine, an essential nucleic acid precursor, as a reporter of whole-cycle proliferation (Trager and Jensen, 1976; Desjardins et al., 1979). Use of hypoxanthine (Hx) and other surrogate readouts of whole-cycle proliferation remains the dominant choice in malaria research. While amenable to high-throughput …


The Plasmodium Falciparum Chloroquine Resistance Transporter, Pfcrt, Mediates The Activity Of Chloroquine-Resistance Reversal Agents In The Malaria Parasite, Kristin Lane Oct 2007

The Plasmodium Falciparum Chloroquine Resistance Transporter, Pfcrt, Mediates The Activity Of Chloroquine-Resistance Reversal Agents In The Malaria Parasite, Kristin Lane

Biological Sciences Theses & Dissertations

Chloroquine (CQ) resistant Plasmodium falciparum is a serious problem affecting 3.2 billion people in over 100 countries today. Most endemic malarious countries are among the poorest in the world and lack the resources to replace the inexpensive and highly effective CQ. CQ resistance (CQR) reversal agents are a potentially inexpensive solution to restoring CQ efficacy. CQR reversal agents are drugs that have little to no antimalarial activity alone, but in combination with CQ, they increase dmg accumulation in the parasite and enhance the sensitivity to CQ in CQR parasites. PfCRT is a putative transporter located on the parasite digestive vacuole …


Design, Synthesis, And Evaluation Of 10-N-Substituted Acridones As Novel Chemosensitizers In Plasmodium Falciparum, Jane X. Kelly, Martin J. Smilkstein, Roland A. Cooper, Kristin D. Lane, Robert A. Johnson, Aaron Janowsky, Rozalia A. Dodean, David J. Hinrichs, Rolf Winter, Michael Riscoe Jan 2007

Design, Synthesis, And Evaluation Of 10-N-Substituted Acridones As Novel Chemosensitizers In Plasmodium Falciparum, Jane X. Kelly, Martin J. Smilkstein, Roland A. Cooper, Kristin D. Lane, Robert A. Johnson, Aaron Janowsky, Rozalia A. Dodean, David J. Hinrichs, Rolf Winter, Michael Riscoe

Biological Sciences Faculty Publications

A series of novel 10-N-substituted acridones, bearing alkyl side chains with tertiary amine groups at the terminal position, were designed, synthesized, and evaluated for the ability to enhance the potency of quinoline drugs against multidrug-resistant (MDR) Plasmodium falciparum malaria parasites. A number of acridone derivatives, with side chains bridged three or more carbon atoms apart between the ring nitrogen and terminal nitrogen, demonstrated chloroquine (CQ)-chemosensitizing activity against the MDR strain of P. falciparum (Dd2). Isobolograrn analysis revealed that selected candidates demonstrated significant synergy with CQ in the CQ-resistant (CQR) parasite Dd2 but only additive (or indifferent) interaction in the CQ-sensitive …


Intellectual Property Management Strategies To Accelerate The Development And Access Of Vaccines And Diagnostics: Case Studies On Pandemic Influenza, Malaria And Sars, Anatole Krattiger, Stanley P. Kowalski, Robert Eiss, Anthony Taubman Apr 2006

Intellectual Property Management Strategies To Accelerate The Development And Access Of Vaccines And Diagnostics: Case Studies On Pandemic Influenza, Malaria And Sars, Anatole Krattiger, Stanley P. Kowalski, Robert Eiss, Anthony Taubman

Law Faculty Scholarship

Achieving global access to vaccines, diagnostics, and pharmaceuticals remains a challenge. Throughout the developing world, intellectual property (IP) constraints complicate access to critically essential medical technologies and products. Vaccines for malaria and pandemic strains of influenza, as well as diagnostic and vaccine technologies for SARS, are not only relevant to global public health but are particularly critical to the needs of developing countries. A global access solution is urgently needed. This article offers a timely case‐by‐case analysis of preliminary patent landscape surveys and formulates options via patent pools and other forms of creative IP management to accelerate development and access. …


Pfcg2, A Plasmodium Falciparum Protein Peripherally Associated With The Parasitophorous Vacuolar Membrane, Is Expressed In The Period Of Maximum Hemoglobin Uptake And Digestion By Trophozoites, Roland A. Cooper, Janni Papakrivos, Kristen D. Lane, Hisashi Fujioka, Klaus Lingelbach, Thomas E. Wellems Nov 2005

Pfcg2, A Plasmodium Falciparum Protein Peripherally Associated With The Parasitophorous Vacuolar Membrane, Is Expressed In The Period Of Maximum Hemoglobin Uptake And Digestion By Trophozoites, Roland A. Cooper, Janni Papakrivos, Kristen D. Lane, Hisashi Fujioka, Klaus Lingelbach, Thomas E. Wellems

Roland A. Cooper

A Plasmodium falciparum gene closely linked to the chloroquine resistance locus encodes PfCG2, a predicted 320-330kDa protein. In the parasitized erythrocyte, PfCG2 expression rises sharply in the trophozoite stage and is detected in electron-dense patches along the parasitophorous vacuolar membrane (PVM), in the cytoplasm and in the digestive vacuole (DV). Results of extraction and partitioning experiments show that PfCG2 is a peripheral membrane protein. Exposure of trophozoite-infected erythrocytes to trypsin-containing buffer after streptolysin O permeabilization indicates that PfCG2 is exposed to the erythrocyte cytosol at the outer face of the PVM. PfCG2 is highly susceptible to hydrolysis by aspartic and …


Pfcrt Is More Than The Plasmodium Falciparum Chloroquine Resistance Gene: A Functional And Evolutionary Perspective, Roland A. Cooper, Carmony L. Hartwig, Michael T. Ferdig May 2005

Pfcrt Is More Than The Plasmodium Falciparum Chloroquine Resistance Gene: A Functional And Evolutionary Perspective, Roland A. Cooper, Carmony L. Hartwig, Michael T. Ferdig

Roland A. Cooper

Genetic, physiological and pharmacological studies are gradually revealing the molecular basis of chloroquine resistance (CQR) in the malaria parasite, Plasmodium falciparum. Recent highlights include the discovery of a key gene associated with resistance, pfcrt (Plasmodium falciparum chloroquine resistance transporter; PfCRT), encoding a novel transporter, and the characterization of global selective sweeps of haplotypes containing a K76T amino acid change within this protein. Little is known about the cellular mechanism by which resistant parasites escape the effects of chloroquine (CQ), one of the most promising drugs ever deployed, due in part to an unresolved mechanism of action. The worldwide spread of …


Proteomic Approaches To Studying Drug Targets And Resistance In Plasmodium, R. A. Cooper, D. J. Carucci Feb 2004

Proteomic Approaches To Studying Drug Targets And Resistance In Plasmodium, R. A. Cooper, D. J. Carucci

Roland A. Cooper

Ever increasing drug resistance by Plasmodium falciparum, the most virulent of human malaria parasites, is creating new challenges in malaria chemotherapy. The entire genome sequences of P. falciparum and the rodent malaria parasite, P. yoelii yoelii are now available. Extensive genome sequence data from other Plasmodium species including another important human malaria parasite, P. vivax are also available. Powerful research techniques coupled to genomic resources are needed to help identify new drug and vaccine targets against malaria. Applied to Plasmodium, proteomics combines high-resolution protein or peptide separation with mass spectrometry and computer software to rapidly identify large numbers of proteins …


Plasmepsin 4, The Food Vacuole Aspartic Proteinase Found In All Plasmodium Spp. Infecting Man, John B. Dame, Charles A. Yowell, Levi Omara-Opyene, Jane M. Carlton, Roland A. Cooper, Tang Li Jul 2003

Plasmepsin 4, The Food Vacuole Aspartic Proteinase Found In All Plasmodium Spp. Infecting Man, John B. Dame, Charles A. Yowell, Levi Omara-Opyene, Jane M. Carlton, Roland A. Cooper, Tang Li

Roland A. Cooper

Plasmepsins are aspartic proteinases of the malaria parasite, and seven groups of plasmepsins have been identified by comparing genomic sequence data available for the genes encoding these enzymes from Plasmodium falciparum, Plasmodium vivax, Plasmodium knowlesi, Plasmodium berghei, and Plasmodium yoelii. The food vacuole plasmepsins typified by plasmepsin 4 from P. falciparum (PfPM4) constitute one of these groups. Genes encoding the ortholog of PfPM4 have been cloned from Plasmodium ovale, Plasmodium malariae, and P. vivax. In addition, P. falciparum contains three paralagous food vacuole plasmepsins or plasmepsin-like enzymes that appear to have arisen by gene duplication, plasmepsins 1 (PfPM1), 2 (PfPM2) …


Dr. Nott's Theory Of Insect Causation Of Disease, William A. Riley Sep 1914

Dr. Nott's Theory Of Insect Causation Of Disease, William A. Riley

Harold W. Manter Laboratory: Library Materials

Excerpt:

The danger in using isolated sentences from an article as a basis for interpreting the author's theories, is generally recognized, but sometimes the most careful workers fall into the trap. Once the mistaken interpretation is published, it may be copied over and over again until it rises to the dignity of a dogma.

A striking illustration is afforded by the practical unanimity with which writers on the subject of insects and disease credit Dr. Josiah Nott with being the earliest to formulate definitely the theory of mosquito transmission of yellow fever.

Nuttall, in his classic monograph On the Role …