New Papers Offer Insights Into Process Of Malarial Drug Resistance Science Daily (press release) - Nov 26, 2008 In the papers, Ferdig points out that development of the malaria parasite Plasmodium falciparum in the blood is driven by a number of different genes ...
Mutations in the Plasmodium falciparum cytochrome b gene are ... 7thSpace Interactive (press release), NY - Nov 20, 2008 Fixed-dose combination antimalarial drugs have played an increasingly important role in the treatment and chemoprophylaxis of falciparum malaria since the ...
Experimental conditions affect the outcome of Plasmodium... 7thSpace Interactive (press release), NY - Nov 24, 2008 Platelet-mediated clumping of Plasmodium falciparum-infected erythrocytes (IE) is a parasite adhesion phenotype that has been associated with severe malaria...
Auditory assessment of patients with acute uncomplicated ... 7thSpace Interactive (press release), NY - Nov 5, 2008 ... mefloquine (25 mg/kg) in patients with acute uncomplicated falciparum malaria treated at the Shoklo Malaria Research Unit, on the Thai-Burmese border. ...
Extensive dynamics of Plasmodium falciparum densities, stages and ... 7thSpace Interactive (press release), NY - Nov 21, 2008 Individuals living in areas of high malaria transmission often have different Plasmodium falciparum clones detected in the peripheral blood over time. ...
Evaluation of the efficacy and safety of artemether-lumefantrine ... 7thSpace Interactive (press release), NY - Nov 27, 2008 The six-dose regimen of artemether-lumefantrine (AL) is now considered the gold standard for the treatment of uncomplicated Plasmodium falciparum malaria. ...
Pyrethroid resistance in the major malaria vector Anopheles ... 7thSpace Interactive (press release), NY - Nov 28, 2008 Of the 436 An. arabiensis females, 0.5% were positive for Plasmodium falciparum infection. WHO diagnostic tests on wild populations showed resistance to the ...
Study sheds new light into process of malarial drug resistance Thaindian.com, Thailand - Nov 27, 2008 Michael Ferdig, a biologist at the University of Notre Dame, pint out that the development of Plasmodium falciparum in the blood is driven by a number of ...
Effect of treating Schistosoma haematobium infection on Plasmodium... 7thSpace Interactive (press release), NY - Nov 17, 2008 Methods: IgG1 and IgG3 antibody responses directed against Schistosoma haematobium crude adult worm antigen (WWH) and Plasmodium falciparum antigens ...
Malarial parasites have become drug resistant The Statesman, India - Nov 12, 2008 The other half of the cases are testing positive with malignant malaria, commonly caused by Plasmodium falciparum, the most lethal malaria parasite. ...
Source: Google News
Recent News and Articles on the Keywords: falciparum + malaria + 0.17 Related to the article below (Last Update: 8/7/2008)
One more falls victim to malaria Times of India, India - Aug 1, 2008 Civic officials said a 75-year-old man from Khar (W) died of falciparum malaria on Thursday. He was admitted to Bhabha Hospital in Bandra on July 10. ...
Malaria On The Increase In The UK Science Daily (press release) - Jul 9, 2008 The researchers also note a worrying trend in cases of the potentially fatal falciparum malaria which have increased steady over the past 20 years in the UK ...
Falciparum malaria increases in the UK TropIKA, Switzerland - Jul 12, 2008 About a dozen people now die in the UK every year as a result of malaria caused by Plasmodium falciparum. This is a tiny fraction of the estimated one ...
New weakness found in malaria Cordis News, Belgium - Dr Higgins studied a malarial protein, called PfEMP1 (Plasmodium falciparum erythrocyte membrane protein 1), which is found on the surface of infected red ...
Shortfall In Current Funding Commitments To Halve Malaria... Medical News Today, UK - Jul 25, 2008 The study revealed that every year, about US $1billion are sent towards the 1.4 billion people exposed to stable P. falciparum malaria risk. ...
UK Malaria cases increasing as travellers ignore prophylaxis Nursing Times, UK - Jul 16, 2008 It was found that 41% of all cases of malaria, and 65% of cases of P. falciparum malaria, occurred in London, whereas 68% cases of P. vivax were reported in ...
… -Benflumetol and Artesunate-Mefloquine in Treatment of MultidrugResistant Falciparum Malaria - M van Vugt, A Brockman, B Gemperli, C Luxemburger, … - Antimicrobial Agents and Chemotherapy, 1998 - aac.highwire.org ... 11%) that were on AB and 24 (7.8%) that were on AM (P = 0.17). ... AM and AB proved to
be effective treatments for acute, uncomplicated falciparummalaria in the ...
Parasite-induced permeation of nucleosides in Plasmodium falciparum malaria - JM Upston, AM Gero - BBA-Biomembranes, 1995 - Elsevier ... presence of NBMPR (1 /xM) was 0.17 ___ 0.01 ... which would selectively enter only malaria
infected cells ... on D-adenosine transport in P. falciparum infected and ...
Coma scales for children with severe falciparum malaria - C Newton, T Chokwe, JA Schellenberg, PA Winstanley … - Transactions of the Royal Society of Tropical Medicine and …, 1997 - Elsevier ... 0.10 0.10 Knc 0.46 0.30 Verbal PAa 0.57 O-63 DRb 0.07 0.17 Knc 0.46 ... learned and useful
as an assessment of the overall sever- ity of falciparummalaria in a ...
Researchers have determined how Plasmodium falciparum can turn on one cloaking gene and keep dozens of others silent until each is needed in turn.
Their findings, published in the journal Nature, reveal the mechanism of action of the genetic machinery thought to be the key to the parasite's survival.
Malaria kills an estimated 2.7 million people annually worldwide, 75 percent of them children in Africa.
> A DNA sequence near the start of a cloaking gene, known as the gene's promoter, not only turns up production of its protein, but also keeps all other cloaking genes under wraps, according to Alan Cowman and Brendan Crabb, HHMI international research scholars at the Walter and Eliza Hall Institute of Medical Research in Melbourne, Australia, and their co-authors. " The promoter is all you need for activation and silencing," Cowman said. " It's the main site of action where everything is happening."
Malaria parasites enter human blood from infected mosquitoes. The organisms invade and promptly remodel red blood cells. They decorate the surface of the cells they occupy with a protein called PfEMP1, made by the var gene family.
Using this versatile surface protein, the parasite evades the host's immune system using two basic strategies. First, the protein sticks infected red blood cells to the blood vessel lining, removing the infected cells from circulation, where they would probably be destroyed.
But the protein cannot protect the parasite from patrolling immune cells, which eventually detect the invader and recruit troops to fight it. So, during a malaria infection, a small percentage of each generation of parasites switches to a different version of PfEMP1 that the body has never seen before. In its new disguise, Plasmodium falciparum can invade more red blood cells and cause another wave of fever, headaches, nausea, and chills.
Many children do not survive malaria long enough to develop immunity. And without continuous exposure, hard-won immunity may disappear. For example, adults in Papua New Guinea who move to work in the mining industry, which is in mountainous regions that are mosquito-free, lose their immunity within a short time, he said.
The diverse genetic sequences of the 60 var cloaking genes all code for remarkably similar protein structures, the malaria researcher added. The genes are generally found at the ends of P. falciparum's 14 chromosomes, although some of them cluster in internal regions.
In April 2005, Cowman, Crabb, and colleagues showed that var genes are regulated by the chromosome packaging, which unwraps one gene to be expressed at a time and literally packs away the inactive genes. In chromosomes, DNA can be encased so securely by some proteins that other proteins cannot access the nucleic acid for transcription, a process known as epigenetic silencing.
In their new paper, the researchers show that the activation of a var gene promoter is all it takes to trigger both the production that gene's protein and the epigenetic silencing of the 59 other var genes. As in a previous study, they found that the physical location of the promoter within the nucleus seems to make a difference. The genetic activity occurred at the edge of the nucleus, with the activated promoter surrounded by chromosome ends containing silenced var genes.
To do this research, the scientists had to master the difficult technique of cloning large DNA sequences with a var promoter attached to various genes, inserting them into plasmid vectors, and introducing them into red blood cells infected by malaria parasites.
In one experiment, they set up a system where var gene expression could be studied using drug selection rather than the immune pressure that is normally needed to select variants in the field. Using this system they found that the information required for switching var genes on and off was contained within a promoter and that when active this could silence all of the var genes in the parasite.
" This is the first time anyone has actually been able to infiltrate an antigenic variation program," Cowman said. "We forced the cell to switch our gene on and others off." Their system can be used to study blood samples from people in the field to determine how they gain immunity over time.
Kirk Deitsch's lab at Cornell University found that a piece of shared DNA -- discarded in the process of translating the protein from its genetic instructions--was a key regulator of var gene silencing and activation. The HHMI researchers confirmed that this gene segment caused tighter packaging for the silenced genes, but they also showed that it wasn't vital.
The researchers are continuing to disassemble the var gene machinery, piece by piece. They want to identify the proteins that unpack and activate the promoter region and learn more about the other proteins in the nuclear compartment that make it the prime spot for var gene activation. Eventually, they think their work may lead to new types of therapies that interfere with the parasite's immune evasion strategies.
