Showing posts with label medicine. Show all posts
Showing posts with label medicine. Show all posts

Tuesday, August 31, 2010

A new treatment

A new anti-malarial drug may soon progress to clinical trials. This new treatment "is made from simple organic molecules and will be cheaper to mass produce compared to existing therapies."

Malaria is widespread and deadly. Many of the nearly 250 million people who contract the malaria parasite each year do not have access or cannot afford adequate treatment. Drugs that are easy and cheap to produce and distribute may save many of the nearly one million lives that are lost each year due to malaria infection.

With the goal of easing the cost of malaria eradication on poor countries and individuals, the research "team at Liverpool" has "created a synthetic drug based on the chemical structure of artemisinin, an extract of a Chinese herb commonly used in malaria treatment. The new drug, which can be taken orally, is more potent than naturally derived artemisinin."

"Malaria affects the world's poorest countries and hospitals are unable to afford expensive treatments. The problem with current artemisinin-based therapies is their limited availability, poor oral absorption and high cost. We have created a new drug that is easily absorbed by the body, chemically stable and highly potent. It is made from very simple organic materials and therefore will be more cost-effective to mass produce than current therapies," says Professor Paul O'Neill.

Artemisinin is known to interact with a substance inside parasite-infected red blood cells, causing a chain of events that destroys malaria. The treatment, however, is difficult to mass produce and can be chemically unstable in the body. Scientists have now found a way of creating the most reactive part of artemisinin synthetically and fusing it with a cage-like structure made of organic molecules to make the drug more chemically stable. The stability of the chemical structure in the body makes the drug last longer, reducing the chance of the parasite reappearing.


Source:
University of Liverpool (2010, August 16). New drug treatment for malaria?. ScienceDaily. Retrieved August 31, 2010, from http://www.sciencedaily.com­ /releases/2010/08/100816095715.htm

Friday, July 23, 2010

Antibiotics prevent malaria

Preventative malaria "treatment with affordable and safe antibiotics...has the potential to act as a 'needle-free' natural vaccine against malaria", according to a study published in the journal, Science Translation Medicine. This type of treatment "may likely provide an additional valuable tool for controlling and/or eliminating malaria in resource-poor settings."

During research, the multinational team "found that infection with malaria parasites during administration of preventative antibiotics developed a vaccine-like immunity against re-infection."

Approximately one million people die from malaria each year and nearly half of the world's population is at risk of contracting malaria, a mosquito-transmitted parasite. "Only an estimated 10 to 100 parasites per mosquito bite invade the liver where they replicate. About a week after infection, tens of thousands of parasites are released into the bloodstream where they are responsible for malaria's recurring fevers and cause life-threatening complications."

The proposed treatment attacks parasites "during their passage into the liver of the infected host. The "researchers showed that the antibiotics caused a cellular defect in malaria parasites...This action did not prevent parasite replication in the liver but blocked the malaria parasite's fatal conversion to the disease causing blood stage. The very late arrest of parasites in the liver allowed the immune system to mount a robust defense against subsequent infections." In this way, the body produces results that are comparable to vaccines that use weakened varieties of the parasite.

Further reading:
London School of Hygiene & Tropical Medicine (LSHTM) (2010, July 23). 'Needle-free' intervention as natural vaccine against malaria. ScienceDaily. Retrieved July 23, 2010, from http://www.sciencedaily.com­ /releases/2010/07/100723112711.htm

Friday, May 7, 2010

Quiescence

How does a vampire avoid that which kills him? He plays dead.

Plasmodium falciparum, a deadly disease known as malaria, proves just as apt to play dead as a fictive vampire facing the sunlight. Humans had a secret weapon against malaria. "Artemisinin (ART), a substance extracted from a Chinese plant," was "the first-line drug for malaria," since other compounds lost their efficacy from overuse and parasite mutation. Artermisinin-based Combination Therapies (ACT) were "the most effective treatment for malaria, achieving a 95% cure rate."

Then, malaria played dead.

In July 2009, artemisinin-resistant malaria was identified in South East Asia. Scientists, desperate to determine how malaria avoided their once brutal weapon, ran laboratory studies.

Françoise Benoit-Vical and his team at Laboratoire de Chimie de Coordination (CNRS) "sought to isolate ART-resistant strains in an experimental manner. This feat was achieved at the end of 2009 when the scientists managed to obtain a strain of Plasmodium falciparum that was resistant to this compound and some of its derivatives, and the first to be adapted to in vitro culture." In the process, the "researchers also identified and characterized a new mode of parasite resistance. To evade the action of ART, Plasmodium falciparum arrested its development and entered a so-called state of quiescence [temporary inactivity]. It thus functioned at a slow metabolic rate until the drug was eliminated", at which time, it would reawaken and wreak havoc again.

"Malaria still continues to kill nearly a million people each year throughout the world. There is no vaccine against this infectious disease", which is caused by a blood parasite and transmitted by mosquitoes."

This study demonstrated "a novel resistance mechanism" and provides "important tool that will allow a clearer understanding of the mechanisms of resistance to antimalarial drugs". Scientists plan further studies in order to "identify the genes responsible for the acquisition of ART resistance."

Sources:
Physorg.com. "How the parasite responsible…" 5 May 2010. http://www.physorg.com/news192300284.html
Witkowski B, Leličvre J, López Barragán MJ, Laurent V, Su XZ, Berry A, Benoit-Vical F. "Increased tolerance to artemisinin in Plasmodium falciparum is mediated by a quiescence mechanism." Antimicrobial Agents and Chemotherapy. Mai 2010.

Tuesday, April 6, 2010

Drugmakers work together

Two drugmakers, Crucell NV and GlaxoSmithKline PLC, "will work together on a new malaria vaccine composed of two drugs", which they previously were developing separately.

According to Crucell, "malaria kills about 900,000 people a year, making it one of the deadliest diseases in the world."

The companies worked together "to research a Crucell vaccine in preclinical studies, and want to begin testing their combined vaccine on humans. They said the preclinical research shows the drugs may work better together than they do separately."

"The experimental vaccine combines a GlaxoSmithKline vaccine", called RTS,S/AS, with a developing vaccine by Crucell, which "involves placing a section of genetic material from a virus or parasite into larger 'vehicle' particle similar to the virus that causes the common cold. Crucell says that creates immunity to the disease, and works better against severe infectious diseases than older methods of vaccine creation".

Source:
Associated Press. "Crucell and Glaxo will combine malaria vaccines." Via Forbes. http://www.forbes.com/feeds/ap/2010/04/06/business-health-care-us-crucell-glaxosmithkline_7490454.html

Sunday, March 21, 2010

Flying vaccinators

Everyone hates mosquitoes, right? But, what if a mosquito bite vaccinated you against malaria, a deadly disease that infects approximately 250 million people each year? "New research published in Insect Molecular Biology reveals that mosquito genetic engineering may turn the transmitter into a natural 'flying vaccinator', providing a new strategy for biological control over the disease."

The study, led by Shigeto Yoshida from Jichi Medical University, "targets the saliva gland of the Anopheles stephensi mosquitoes, the main vectors of human malaria."

"For the past decade it has been theorized that genetic engineering of the mosquito could create a 'flying vaccinator,' raising hopes for their use as a new strategy for malaria control. However so far research has been limited to a study of the insect's gut and the 'flying vaccinator' theory was not developed."

Mosquito bites offer a free and easy way to administer a vaccine. Continued "exposure to bites" is expected to produce "high levels of protective immunity, through natural boosting, for a life time. So the insect shifts from being a pest to being beneficial," according to Yoshida.

"While 'flying vaccinator' theory may now be scientifically possible the question of ethics hangs over the application of the research. A natural and uncontrolled method of delivering vaccines, without dealing with dosage and consent, alongside public acceptance to the release of 'vaccinating' mosquitoes, provide barriers to this method of disease control."

Is this idea too dangerous to be beneficial, or is it just radical enough to help eliminate malaria? The world has yet to decide.

Source:
Wiley-Blackwell (2010, March 19). 'Flying vaccinator': Can genetically engineered mosquitoes provide a new strategy against malaria?. ScienceDaily. Retrieved March 21, 2010, from http://www.sciencedaily.com­ /releases/2010/03/100318192658.htm

Sunday, March 14, 2010

Protective barrier

Malaria is a parasite that affects many organisms, yet mosquitoes can carry the disease without it triggering an immune response. How?

"Scientists. . . have found that when the mosquito takes a blood meal, that act triggers two enzymes to form a network of crisscrossing proteins around the ingested blood. The formation of this protein barrier, the researchers found, is part of the normal digestive process that allows so-called "healthy" or commensal gut bacteria to grow without activating mosquito immune responses."

"But there is a downside: The barrier also prevents the mosquito's immune defense system from clearing any disease-causing agents that may have slipped into the blood meal, such as the Plasmodium malaria parasite, which in turn can be passed on to humans." However, scientists believe that disrupting "the protein barrier. . . can trigger mosquito immune defenses to intervene and protect the insect from infection." It is possible that the mosquito's immune defenses will combat and eliminate malaria parasites before they are passed on to humans. Researchers are investigating a vaccine that "would generate antibodies" in humans which, "after a mosquito feeds on" the vaccinated human, "could disrupt the barrier, reduce parasite survival in the mosquito and prevent malaria transmission."

Source:

NIH/National Institute of Allergy and Infectious Diseases (2010, March 14). Barrier in mosquito midgut protects invading pathogens. ScienceDaily. Retrieved March 14, 2010, from http://www.sciencedaily.com¬ /releases/2010/03/100311175043.htm

Saturday, February 20, 2010

Battling malaria

"Scientists battling malaria have earned a major victory", according to a Nature Genetics study. "Combating malaria resistance is nothing short of an arms race," says author and pediatrics professor, Dr. Philip Awadalla, from the Universite de Montreal. "As the malaria pathogen evolves, researchers must evolve with it to find ways to counter the disease."

Every year approximately 250 million people contract malaria. "Malaria is transmitted when people are bitten by infected mosquitoes. According to the World Health Organization, malaria symptoms include fever, headaches, vomiting and appear within 10 to 15 days after an infected mosquito bite." If left "untreated, malaria can be life-threatening" and may kill "an estimated five million people yearly." At the current level of malaria treatment one million people die annually, and most of those who die are young children.

The team at Universite de Montreal is deciphering the deadly parasite in an effort to eradicate the disease. This "international group of researchers has used genomics [study of organisms' genomes] to decode the blueprint of Plasmodium falciparum -- a strain of malaria most resistant to drugs that causes the most deaths around the world. The discovery may lead to advanced pharmaceuticals to fight the disease and prevent drug resistance".


"The team decoded 200 malaria samples from Asia, Africa, Central America, South America and Papua New Guinea. Their goal was to identify how Plasmodium falciparum strains were becoming resistant to the eight anti-malaria drugs currently available." The team noted how there is "substantial genetic differences in malaria around the world. What has occurred is a combination of genetic drift, where genes segregated over space and time from differential environments, immune pressures and exposures to drugs."

Research discovered that "Plasmodium falciparum recombined fastest in Africa...New clues garnered by this study...will allow pharmaceutical companies to create treatments that target the evolving malaria genome."

Sources:


Mu et al. Plasmodium falciparum genome-wide scans for positive selection, recombination hot spots and resistance to antimalarial drugs. Nature Genetics, 2010; DOI: 10.1038/ng.528

University of Montreal (2010, February 18). Genomic warfare to counter malaria drug resistance. ScienceDaily. Retrieved February 20, 2010, from http://www.sciencedaily.com¬ /releases/2010/02/100216140146.htm

Tuesday, February 16, 2010

Chemical paths


Frequent use and misuse of antimalarials [drugs that fight malaria] can lead to malaria parasites that are resistant to existing treatments. For this reason, there "is an urgent need for new drugs to combat malaria". "Researchers report that they have discovered -- and now know how to exploit -- an unusual chemical reaction mechanism that allows malaria parasites and many disease-causing bacteria to survive."

The same research team from the University of Illinois, led by Eric Oldfield, developed an inhibitor of a pivotal chemical reaction. This inhibitor may fight malaria [and other bacterial and parasitic diseases] in a manner that is different from the traditional medicines. The situation is dire, according to Oldfield. "The parasites that cause malaria also have become resistant to quinine, chloroquine and now, artemisinin, three common treatments for the disease."

"The new study focuses on an essential chemical pathway that occurs in malaria parasites and in most bacteria but not in humans or other animals, making it an ideal drug target." An enzyme, known as IspH, promotes the assembly of a "class of compounds, called isoprenoids, which are essential to life" and prove to be necessary to the bacteria and parasites that cause disease.

"Isoprenoids are the largest class of compounds on the planet," Oldfield said. "There are over 60,000 of them. Cholesterol is an isoprenoid. The orange beta-carotene in carrots is an isoprenoid. And bacterial cell walls are made using isoprenoids." After a decade of research, scientists believe that they understand the structure and function of IspH and hope that it will "allow them to find a way to... shut down production of isoprenoids in the disease-causing bugs," thereby reducing their numbers.

"We're really at the initial, key stage, which is understanding structure and function and getting clues for inhibitors -- drug leads," he said. "But there are a finite number of proteins unique to bacteria and malaria parasites that can be targeted for the development of new drugs. And everyone agrees that this enzyme, IspH, is a tremendous target."

Further research:
Eric Oldfield et al. Bioorganometallic mechanism of action, and inhibition, of IspH. Proceedings of the National Academy of Sciences, Feb 15, 2010. http://www.news.illinois.edu/WebsandThumbs/Oldfield,Eric/0215pnas.200911087.pdf
The National Institute of General Medical Sciences at the National Institutes of Health funded this research.


Source:

University of Illinois at Urbana-Champaign (2010, February 16). New weapon to fight disease-causing bacteria, malaria developed. ScienceDaily. Retrieved February 16, 2010, from http://www.sciencedaily.com¬ /releases/2010/02/100215173944.htm

Photo source:
http://insciences.org/article_album_file.php?article_id=8350&articlemedia_id=1069

Friday, February 12, 2010

Substandard Medicines

"A high percentage of medicines circulating on national markets", in ten Sub-Saharan African countries, "are of substandard quality and thus may contribute to the growth of drug-resistant strains of Plasmodium falciparum, the most virulent form of malaria." First results of the "large-scale study of key antimalarial medicines" were released for Madagascar, Senegal, and Uganda by the Promoting the Quality of Medicines (PQM) Program, a USAID-funded program.

"Within Madagascar, Senegal and Uganda, the study" focused "on artemisinin-based combination therapy (ACT) products, currently the WHO's recommended form of first-line treatment for uncomplicated malaria, and sulfadoxine-pyrimethamine (SP) products, often used for preventative treatment of malaria during pregnancy." Researchers collected samples from "public and regulated private sectors" and from "informal markets, as many patients obtain their medicines from these sources."

"Substandard and counterfeit versions of antimalarial medicines are highly problematic throughout Africa, Asia and Latin America because of the direct threat they pose to the lives of individual patients as well as their contribution to the development of drug-resistant strains of these diseases." The "study found that approximately 44 percent of sampled medicines from Senegal, 30 percent of samples from Madagascar, and 26 percent of samples from Uganda that underwent full quality control laboratory testing failed such testing and were thus substandard."

"Substandard" medicines are classified as "those that do not meet the quality specifications set for them, primarily because they do not contain the correct amount of the active ingredient(s), do not dissolve properly in the body or include unacceptable levels of potentially harmful impurities." According to the released results, "[n]o samples in the full study completely lacked the active ingredient(s). The results also showed that, as a general rule, when a brand passed or failed in one country, it would also pass or fail in other countries. This indicates that the problem of quality is created at the source, rather than during passage through the distribution chain."

Substandard medicines were not limited to informal markets, and their point of sale varied by country. "In Madagascar, for instance, poor quality medicines appear to be widespread across regions and not limited to any particular type of distributor [public, private, or informal]. In Uganda, samples fared much better in the public sector than in the country's private sector. Despite overall failure rates, this was one of the bright spots the study revealed; in Uganda's public sector, all ACT and SP samples passed quality tests."

The purpose of this study was reveal "the prevalence of substandard antimalarials in Sub-Saharan Africa, which are believed to contribute to antimicrobial resistance of Plasmodium falciparum. Already, Plasmodium falciparum has become resistant to traditional" treatments "such as chloroquine, and more recently to SP products. The sustainability of treatment success depends to a large extent on preventing Plasmodium falciparum's exposure to incomplete doses of these medicines to minimize the possibility of the emergence of drug resistance."

Source:
US Pharmacopeia (2010, February 10). One-third of antimalarial medicines sampled in three African nations found to be substandard. http://vocuspr.vocus.com/vocuspr30/Newsroom/ViewAttachment.aspx?SiteName=USPharm&Entity=PRAsset&AttachmentType=F&EntityID=108111&AttachmentID=f2e22216-44a5-41a2-a9bc-464b7a98e3bf

Malaria vaccine to protect pregant women

"Each year, 25 million pregnant women in sub-Saharan Africa run the risk of contracting malaria." Women who become infected during their first pregnancy are at the most risk for severe anemia and poor fetal growth. "The malaria parasites accumulate in the placenta, resulting in children being born prematurely and underweight." Maternal malaria causes the death of approximately 200,000 infants and 10,000 women each year

"Researchers at the University of Copenhagen have become the first in the world to synthesize the entire protein that is responsible for life-threatening malaria in pregnant women and their unborn children. The protein known as VAR2CSA enables malaria parasites to accumulate in the placenta and can therefore potentially be used as the main component in a vaccine to trigger antibodies that protect pregnant women against malaria. The research team is now planning to test the efficacy of the protein-based vaccine on humans."

"The hope is that within 10 years all African girls could be vaccinated against maternal malaria, thereby preventing more than 200,000 deaths a year." The vaccine "elicits antibodies that stop the [malaria] parasite from binding to the placenta." Laboratory testing is underway, and the vaccine can already be tested in animals.

"These antibodies seem to be effective at preventing the parasite from accumulating in the placental tissue. The next step is to investigate whether we can elicit the same antibodies and so protect against the disease by vaccinating humans. Then the vaccine will be a reality."

Source:

University of Copenhagen (2010, February 5). Vaccine to protect pregnant women from contracting malaria?. ScienceDaily. Retrieved February 12, 2010, from http://www.sciencedaily.com­ /releases/2010/02/100204144433.htm

Sunday, February 7, 2010

Lost Code


Although made of few parts, the complete DNA content or genome of a species is extensive and complicated. Plasmodium falciparum, "the most deadly form of malaria", has about 5,300 genes. "Up until now, scientists [had] a good understanding of the gene functions for only about half" of the genes.


Plasmodium falciparum is a tiny parasite that infects the blood of mammals through mosquito bites and is responsible for approximately 1 million human deaths each year. "Using transcriptional profiling," a process by which "gene expression (activity) patterns" are revealed, the research team lead by Prof Zbynek Bozdech (Nanyang Technological University) "has successfully uncovered the gene functions for almost the entire genome, with more than 90 percent of the gene functions from the previously unknown half now better understood."


"Transcriptional profiling is the measurement of the activity of thousands of genes at once," in order to "create a global picture of cellular function. These profiles can, for example, distinguish between cells that are actively dividing, or show how the cells react to a particular treatment. This outcome in infectious disease pathology could potentially be the decade's big breakthrough as it has yielded critical information about how the malaria parasite...responds to existing compounds with curative potential."


"Preventing malaria infection is important because resistance to anti-malaria drugs is a growing problem worldwide. There is currently no vaccine for malaria, which is widespread in poorer countries where it remains a hindrance to economic development. Also of growing concern to scientists is the confirmation of the first signs of resistance to the only affordable treatment left in the global medicine cabinet for malaria: Artemisinin."


"In successfully using transcriptional profiling to study the behavior of the malaria parasite, ...researchers have ventured into the unknown and paved the way for future breakthroughs in healthcare."

Sources:
Gastin, George. "GenomeGradient.jpg" [Photo hosted by wikimedia, shared under CC license] http://commons.wikimedia.org/wiki/File:Genome_gradient.jpg

Nanyang Technological University (2010, February 6). World's first in-depth study of the malaria parasite genome. ScienceDaily. Retrieved February 7, 2010, from http://www.sciencedaily.com /releases/2010/02/100205102607.htm

Saturday, February 6, 2010

Protective immunity

Every year approximately a million people die from malaria, a treatable blood disease, and most of those who die are children under the age of five. "A new vaccine to prevent the deadly malaria infection has shown promise to protect the must vulnerable patients--young children--against the disease."

The results found by the international research team, led by the University of Maryland School of Medicine's Center for Vaccine Development (CVD) and the Malaria Research and Training Center at the University of Bamako in Mali, excites the medical community. "In a new study of the vaccine in young children in Mali, researchers found it stimulated strong and long-lasting immune responses. In fact, the antibody levels the vaccine produced in the children were as high or even higher than the antibody levels found in adults who have naturally developed protective immune responses to the parasite over lifelong exposure to malaria."

"In areas of the world such as Africa, where malaria is particularly rampant, the young are most vulnerable to the disease since they have not built up the same natural immunity as adults. A child dies of malaria every 30 seconds, according to the World Health Organization. There are about 300 million malaria cases worldwide each year, resulting in more than one million deaths, most of them African children."

Malaria is a parasite, "spread to humans through mosquito bites". At this time, "no approved vaccine to protect against the condition" exists, although "using bed nets or killing mosquitoes with insecticides can prevent infection. The parasite is treatable using medications, though drug resistance is a relatively common problem. Eradicating the disease has become a priority for scientists and health officials worldwide. An effective and broadly protective vaccine is a key step toward that goal."

This "vaccine, based on a single strain of the falciparum malaria parasite -- the most common and deadliest form of the parasite found in Africa -- targets malaria in the blood stage. The blood stage is the period after the mosquito bite, when the parasite multiplies in the blood, causing disease and death." Before this discovery, "other blood stage vaccines" existed, but none of them exhibited "the ability to prevent malaria disease."

In addition to preventing malaria, the vaccine (at all three tested doses) "proved to be safe and well tolerated" in each of the 100 Malian children administered with the drug. A new trial is already planned to test more subjects and to examine "whether the vaccine -- though it is based on a single strain of malaria -- can protect against the broad array of malaria parasites that exist."

Sources:
University of Maryland Medical Center (2010, February 6). New malaria vaccine is safe and protective in children, scientists find. ScienceDaily. Retrieved February 6, 2010, from http://www.sciencedaily.com­ /releases/2010/02/100203201425.htm

Wednesday, February 3, 2010

Lethal Weapon

"Mankind may finally have a weapon to fight two of the world's deadliest diseases." A new vaccine may prove to be a "lethal weapon against malaria" and cholera. Each year approximately a million people die from malaria and cholera sickens hundreds of thousands. Currently, "no FDA approved vaccine to prevent malaria, a mosquito-borne illness" exists. "Only one vaccine to fight cholera, a diarrheal illness that is common in developing countries and can be fatal" is on the market. "The lone vaccine is too expensive to prevent outbreaks in developing countries after floods, and children lose immunity within three years of getting the current vaccine."

Recently, a "University of Central Florida biomedical researcher has developed what promises to be the first low-cost dual vaccine against malaria and cholera."

Led by Henry Daniell, the "team genetically engineered tobacco and lettuce plants to produce the vaccine. Researchers gave mice freeze-dried plant cells (orally or by injection) containing the vaccine. They then challenged the mice with either the cholera toxin or malarial parasite…Untreated rodents contracted diseases quickly, but the mice who received the plant-grown vaccines showed long-lasting immunity for more than 300 days (equivalent to 50 human years)."

In addition to this vaccine, Daniell's lab has "created vaccines against anthrax and black plague that generated a congratulatory call from the top U.S. homeland security official and was featured on the Discovery Channel."

But, why lettuce? "Producing vaccines in plants is less expensive than traditional methods because it requires less labor and technology," Daniell said.

"We're talking about producing mass quantities for pennies on the dollar," he said. "And distribution to mass populations would be easy because it could be made into a simple pill, like a vitamin, which many people routinely take now. There is no need for expensive purification, cold storage, transportation or sterile delivery via injections."

"For Daniell, his research is more than his day job. His passion to find vaccines for the world's top 10 diseases as defined by the World Health Organization comes from growing up in India. He watched many of his childhood friends contract malaria, cholera and other diseases."

"I'm not done yet," he claims. "I still have more diseases to attack."

Source:
University of Central Florida (2010, January 27). New vaccine could be lethal weapon against malaria, cholera. ScienceDaily. Retrieved February 3, 2010, from http://www.sciencedaily.com¬ /releases/2010/01/100126101421.htm

Sunday, January 31, 2010

Digestive enzymes

"Malaria causes more than two million deaths each year, but an expert multinational team battling the global spread of drug-resistant parasites has made a breakthrough in the search for better treatment" (McGill). Examining the way malaria parasites reproduce, a team led by John Dalton, has identified "a plan of attack" to develop new and urgently needed treatments, which combat malaria.

The secret lies in how the parasites propagate. "Malaria parasites live inside our red blood cells and feed on proteins". They break down the proteins to "use the proceeds (amino acids) as building blocks for their own proteins". Once they "a sufficient size they divide and burst out of the red cell, entering another and repeating the process until severe disease or death occurs."

Specialized digestive enzymes of the parasites "enable them to undertake this process." Researchers have now developed three-dimensional structures of these two enzymes and "demonstrated how drugs can be designed to disable the enzymes."

"By blocking the action of these critical parasite enzymes, we have shown that the parasites can no longer survive within the human red blood cell," Dalton explains. "The team is putting their findings into action immediately and is already pursuing anti-malarial drug development."

Publications: The discovery will be published in the Proceedings of the National Academy of Sciences, and is the result of collaboration including Australia’s Queensland Institute of Medical Research, Monash University and the University of Western Sydney, Wroclaw University of Technology in Poland and the University of Virginia in the U.S.

Read more about digestive enzymes and malaria

Source:
McGill University (2010, January 29). Breakthrough could lead to new treatment for malaria. ScienceDaily. Retrieved January 31, 2010, from http://www.sciencedaily.com¬ /releases/2010/01/100128165850.htm

Friday, January 8, 2010

Alarm amid medicine shortage

Kenya's rainy season is the most dangerous for contracting malaria, a deadly disease carried by mosquitoes, and children are the most susceptible. "A shortage of malaria drugs for children has hit hospitals as fears of an outbreak of the disease loom following heavy rains in various parts of the country."

"The Kenya Medical Supplies Agency said stocks of the drugs were running low, but were in the process of being procured and could be delivered by the beginning of February." The Chief executive, John Munyu, is hopeful that the crisis will be avoided because deliveries are continuing. He indicated that "adult malarial drugs are already being supplied after a reported shortage in parts of the country."

The minister of medical services, Anyang' Nyong'o, claims that "the shortage of drugs was caused by inadequate funding by the Treasury." The "budget for Health ministries was laughable when compared to that for the Ministry of Education", he says. This is not the first shortage that Kenya has suffered in recent years. Antibiotics used to treat cholera "were nearly exhausted due to last year's outbreak".

Still, Nyong'o is confident that disaster will be avoided. He says, "I do not envisage any crisis because the government is already adding stocks to what is already there in the health facilities. That is mere replenishment."

Ogo, Kenneth. "Children's malaria drugs run out." Daily Nation. 7 January 2010.

Sunday, January 3, 2010

Critically weakened

What happens when a vampire does not feed on human blood?

If you believe the tales spun in Vampire Diaries, then the once-deadly creature becomes significantly weakened, looses the ability to affect the human brain, and is generally much less threatening than his human blood consuming counterpart. The same is true for the variety of parasite that Dr Andrea Crisanti is studying in an attempt to find a malaria vaccine.

Malaria, a mosquito-borne disease that affects 300-500 million people each year, is caused by infection with Plasmodium parasites. The deadly disease kills approximately one million people every year, most of whom are children and pregnant women, is treatable and preventable. The search for a malaria vaccine is well under way, but the "number of life cycle changes" that the parasites undergo increase "the challenges of malarial vaccine development." In other words, because the malaria parasites change and adapt rapidly, a workable vaccine is difficult to develop.

However, recent research by Crisanti and her colleagues "have found that weakened Plasmodium elicits a protective immune response." This means that clinically and genetically weakened parasites may be used for vaccine development. Crisanti's team targeted Plasmepsin 4, "a digestive enzyme that is critical for Plasmodium growth and survival within the host red blood cells." Research showed that parasites without the critical digestive enzyme "were significantly less virulent than their wild-type [define: normal] counterparts."

Furthermore, "infection with plasmepsin 4-deficient parasites, in contrast to infection with wild-type Plasmodium, did not induce cerebral complications", which means that infection with the weaker parasite produces a less severe illness than an ordinary malaria infection. Also, parasites without the digestive enzyme "induced strong protective immune responses against secondary immunization with wild-type Plasmodium." This weakened parasite may provide a model for comparing genetically-weakened malarial vaccines.

Dr. Crisanti and colleagues conclude that "it is possible, by engineered inactivation of parasite proteins, to generate attenuated blood stage parasites that are capable of inducing protective immunity against blood-stage infection. Such parasites should be powerful tools in elucidating parasite-derived factors that cause severe disease and should provide additional insight into factors that are required to induce protective immunity."

Source:
American Journal of Pathology (2009, December 31). Weakened Plasmodium generates protective immunity. ScienceDaily. Retrieved January 3, 2010, from http://www.sciencedaily.com¬ /releases/2009/12/091230193211.htm

Wednesday, October 28, 2009

Antimalarial side effects

In early October, a study comparing the side effects of commonly prescribed malaria medication was conducted by a team led by Dr. Frederique Jacquerioz at Tulane University. "The review looked at eight clinical trials" of commonly prescribed anti-malarials. Both "atovaquone-proguanil -- sold under the brand-name Malarone -- and doxycycline appear to have fewer side effects" than the other drugs tested. "With these two drugs, there is lower risk of nausea, stomach pain and other gastrointestinal side effects, and also neurological and psychiatric side effects, such as dizziness, sleep disturbances, anxiety and depression."

No drugs produced side effects that were considered life-threatening or required hospitalization; however, the investigators did discover a disturbing link between mefloquine and patient death. They uncovered "published case reports linking mefloquine to 22 deaths, including five suicides." It is important to note that "no other anti-malaria drugs have been linked to deaths when taken at prescribed doses".

Mefloquine is still an effective anti-malarial and may be safely prescribed to patients who have previously taken it without adverse effects. Doctors believe that risk of death is higher for patients who fail to take mefloquine when they should than the risk of serious side effects.

"[S]evere reactions to mefloquine are rare, noted Dr. Andrea Boggild of Toronto General Hospital in Canada, who was not involved in the study. In a written statement, Boggild said that severe neurological and psychiatric symptoms develop in just one out of every 6,000 to 10,000 people who take the drug."

In regard to antimalarial side effects, the Jacquerioz says this: "The main message is that you have to take some malaria chemoprophylaxis (preventive treatment) if you go to an endemic area". Malaria kills approximately one-million people each year, and an estimated ten-thousand to thirty-thousand travelers develop malaria annually.

"Boggild advised people who are planning a trip to a malaria-endemic area to talk with a healthcare provider who specializes in travel medicine about how to best protect themselves."

Source:
Reuters Health. " Two anti-malaria drugs have fewer side effects". Wednesday, October 7, 2009.

Wednesday, October 21, 2009

Genetic Diversity

"Scientists and health officials worldwide have made eradication of" malaria "a priority, with an effective and broadly protective vaccine a critical step toward that goal. Malaria -- a parasite spread to humans through mosquito bites -- is prevented by avoiding mosquito bites using bed nets or by killing mosquitoes with insecticides. The parasite is treatable using medications, although drug resistance is a relatively common problem. According to the World Health Organization, a child dies of malaria every 30 seconds" (University). Currently, "no approved vaccine for malaria" exists, but "various experimental vaccines are in development" (University). As of now, "vaccines directed against the blood stages of Plasmodium falciparum malaria [a deadly strain] are intended to prevent the parasite from invading and replicating within host cells. No blood-stage malaria vaccine has shown clinical efficacy in humans" (Takala).

"Researchers at the University of Maryland School of Medicine Center for Vaccine Development (CVD) have charted the extreme genetic differences that occur over time in the most dangerous malaria parasite in the world" (University). They "examined the extent and within-host dynamics of genetic diversity in the blood-stage malaria vaccine" and concluded that this "extreme diversity may pose a serious obstacle" to the creation of an effective vaccine.

"The CVD study suggests that developing a broadly protective vaccine for malaria may be challenging because the parasite's genetic makeup is so variable, constantly changing" (University).

Sources:
Takala, Shannon L. et al. "Extreme Polymorphism in a Vaccine Antigen and Risk of Clinical Malaria: Implications for Vaccine Development." Sci Transl Med 14 October 2009:
Vol. 1, Issue 2, p. 2ra5.

University of Maryland Medical Center. "Extreme Genetic Variability In Malaria Parasite Found." ScienceDaily 15 October 2009. 21 October 2009 .

Wednesday, October 7, 2009

Fungus reduces malaria transmission

"Biopesticides containing a fungus that is pathogenic to mosquitoes may be an effective means of reducing malaria transmission, particularly if used in combination with insecticide-treated bednets" (Public). Mosquito adaptation and resistance to insecticides is a major hindrance to malaria eradication. "In developing strategies to control malaria...there is increased interest in biological methods that do not cause instant" mosquito or parasite death. Instead, scientists are searching for preventative measures, which "have sublethal and lethal effects at different ages and stages in the mosquito life cycle", with the hope that these more mild approaches will be more effective in the long run than the aggressive techniques used in the past. (Hancock).

"[A]ccording to a modelling study conducted by Dr. Penelope Hancock from Imperial College London," incorporating fungal biopesticides "may substantially reduce malaria transmission rates and help manage insecticide resistance...Efficient combinations of interventions may allow each to be used at lower levels, and slow the development of resistance in the mosquito population" (Public).


Sources:
Hancock, Penelope A. "Combining Fungal Biopesticides and Insecticide-Treated Bednets to Enhance Malaria Control".

Public Library of Science. "Control Of Mosquito Vectors Of Malaria May Be Enhanced By A New Method Of Biocontrol." ScienceDaily 1 October 2009. 7 October 2009 .

Tuesday, September 8, 2009

Herbal medicine

"An ancient Chinese folk medicine that's effective against malaria also might be a potent cancer-fighting candidate, scientists at the University of Washington say" (Hill). "A derivative of the sweet wormwood plant used since ancient times to fight malaria and shown to precisely target and kill cancer cells may someday aid in stopping breast cancer before it gets a toehold" (Harril). "Artemisia annua...has shown favorable...results" against "breast cancer and prostate cancer" (Artemisinin).

"The substance, artemisinin, appeared to prevent the onset of breast cancer in rats that had been given a cancer-causing agent." Artemisinin is "selectively toxic to cancer cells" (Harril). "The compound appears to be extremely" harmful "to cancer cells but had little impact on normal cells," according to the researchers (Hill).

"The properties that make artemisinin an effective antimalarial agent also appear responsible for its anti-cancer clout. When artemisinin comes into contact with iron, a chemical reaction ensues that spawns free radicals -- highly reactive chemicals that, when formed inside a cell, attack the cell membrane and other structures, killing the cell...The malaria parasite can't eliminate iron in the blood cells it eats, and stores it. Artemisinin makes that stored iron toxic to the parasite...The same appears to be true for cancer. Because they multiply so rapidly, most cancer cells have a high rate of iron uptake. Their surfaces have large numbers of receptors, which transport iron into the cells. That appears to allow the artemisinin to selectively target and kill the cancer cells, based on their higher iron content" (Harril). "In addition," artemisinin has already "been shown to be safe" in humans, as is evident in malaria patients who have taken the drug (Hill). Artemisnin may provide an alternative for harsh chemotherapy in some cancer cases.


Sources
:
“Artemisinin Herbal Extract Cures Malaria, Breast Cancer and Leukemia”. Associated Content. 29 March 2009.

Harril, Rob. “Malaria drug may help prevent breast cancer, study shows”. University Week. Jan. 12, 2006

Hill, Richard. The Oregonian, 28 Nov 2001 p C12.

Koresby Online. Artemisinin Annua. (Photo)