Interaction Of New Kinase Inhibitor Drugs With Multi-drug Resistance (MDR) Transporter Proteins.
Funder
National Health and Medical Research Council
Funding Amount
$411,000.00
Summary
Multidrug transporter proteins are remarkable molecular pumps that expel a wide variety of drugs and toxins from cells. They are located at strategic sites where they eliminate harmful substances from the body or prevent them being absorbed from our diet in the first place. Multidrug transporters are also found at natural barriers within the body where they protect vulnerable tissue compartments, including the brain, cerebrospinal fluid, testes and, in preganant women, the foetus. Nevertheless, ....Multidrug transporter proteins are remarkable molecular pumps that expel a wide variety of drugs and toxins from cells. They are located at strategic sites where they eliminate harmful substances from the body or prevent them being absorbed from our diet in the first place. Multidrug transporters are also found at natural barriers within the body where they protect vulnerable tissue compartments, including the brain, cerebrospinal fluid, testes and, in preganant women, the foetus. Nevertheless, multidrug transporters sometimes interfere with drug therapy. They can prevent efficient absorption of drugs, increase the rate of drug elimination from the body, or prevent drug access to some tissues . Moreover, the activity of the transporters is quite variable, both between patients and within the same patient over time. This makes it difficult to provide optimal drug doses, particularly when treating cancer, where the drugs must be given at the maximum tolerated dose. The presence of drug transporter proteins in tumour cells can prevent entry of anticancer drugs, rendering them resistant to treatment. This is the main cause of failure in chemotherapy. This project will investigate a class of very promising new anticancer drugs, kinase inhibitors, to determine whether they are pumped by multidrug transporters, whether they alter the amounts of drug transporters in cells, and whether they alter transporter activity. We will also determine the consequences that follow from this for drug therapy. This information will help clinicians to rationally optimise therapy with the new drugs, to identify in advance both favourable (synergistic) and unfavourable (harmful) drug interactions in combination chemotherapy, to optimise drug doses and to minimise toxic side effects. The information will also add to our general understanding of drug absorption and elimination, and to the basic science of the remarkable multidrug transporter proteins.Read moreRead less
Developing Synergisers Of The Antimalarial Drug, Chloroquine, For The Treatment Of Chloroquine-resistant P. Falciparum.
Funder
National Health and Medical Research Council
Funding Amount
$243,000.00
Summary
Malaria is a debilitating parasitic disease that is responsible for the deaths of about two million children each year. As drugs, such as chloroquine, become increasingly useless due to the development of parasite resistance, there is an urgent need to understand the mode of action of and the molecular basis of resistance to existing antimalarials and to design affordable treatments that can replace chloroquine. It is known that some compounds, that have only poor antimalarial activity themselve ....Malaria is a debilitating parasitic disease that is responsible for the deaths of about two million children each year. As drugs, such as chloroquine, become increasingly useless due to the development of parasite resistance, there is an urgent need to understand the mode of action of and the molecular basis of resistance to existing antimalarials and to design affordable treatments that can replace chloroquine. It is known that some compounds, that have only poor antimalarial activity themselves, can synergise the action of chloroquine. This may involve the inhibition of the activity of proteins that directly or indirectly extrude chloroquine from its site of action in the parasite's digestive apparatus. Unfortunately, thechloroquine synergisers examined to date have been too toxic to be useful in vivo. In preliminary studies we have identified some compounds that would be suitable for use in malaria patients, including a widely used antimalarial drug, primaquine, that can synergise the activity of chloroquine against chloroquine-resistant parasites. We will attempt to understand the molecular basis of this interaction. This will allow us to define optimal combinations of chloroquine and a resistance-reversing quinoline for use treating malaria. This could extend the clinical life of this important antimalarial drug. The information obtained may also help to design novel antimalarial drugs.Read moreRead less
The PH Of The Malaria Parasite's Digestive Vacuole And Its Role In Antimalarial Drug Resistance
Funder
National Health and Medical Research Council
Funding Amount
$210,990.00
Summary
Malaria is an infectious disease that infects an estimated 300-500 million people and kills an estimated 1.5-2.7 million people annually. The microscopic parasite responsible for the disease is becoming increasingly resistant to most of the antimalarial drugs presently available. However the mechanisms by which it does so are very poorly understood. The malaria parasite invades the red blood cells of its victim. Once itside, it sets about consuming the contents of the cell, ingesting them and de ....Malaria is an infectious disease that infects an estimated 300-500 million people and kills an estimated 1.5-2.7 million people annually. The microscopic parasite responsible for the disease is becoming increasingly resistant to most of the antimalarial drugs presently available. However the mechanisms by which it does so are very poorly understood. The malaria parasite invades the red blood cells of its victim. Once itside, it sets about consuming the contents of the cell, ingesting them and depositing them in a small acidic compartment called the digestive vacuole. Many of the antimalarial drugs presently in use target this compartment and interfere with the processes going on inside it. There is evidence that resistance to antimalarial drugs arises as a result of changes in this compartment, though what these changes are, and how they occur remains a mystery. This work focuses on the mechanisms involved in controlling the acidity of the parasite's digestive vacuole. We have preliminary evidence that parasites showing different levels of antimalarial drug resistance have different levels of acidity in their vacuoles, and that this may be due to differences in the rate at which acid leaks from this compartment. The aim of this work is to obtain a detailed understanding on the mechanisms by which the acidity of the parasite's digestive vacuole is regulated and to gain some insight into whether and how these mechanisms might differ between drug-resistant and drug-sensitive parasites. By so doing, this work might be expected, in the long term, to provide a basis for the devolpment of new drugs with which to combat this deadly and increasingly threatening disease.Read moreRead less
Development Of Novel Hybrid Antibiotics For The Treatment Of Hospital And Community Acquired Drug Resistant Gram-Negative And Gram-Postitive Bacterial Infections
Funder
National Health and Medical Research Council
Funding Amount
$715,076.00
Summary
Drug resistant bacteria now pose a serious and growing threat to human health. Many bacteria have developed new resistance mechanisms such that most common antibiotics no longer can protect patients from serious, life-threatening infection. We will modify two existing antibiotics, colistin and carbapenem (a penicillin), to convert it into a more powerful antibiotic that targets resistant bacteria.
The Na+-H+ Exchanger And H+-pumping Pyrophosphatases Of The Malaria Parasite
Funder
National Health and Medical Research Council
Funding Amount
$664,604.00
Summary
Malaria is an infectious disease caused by a single-celled parasite. The disease kills up to 2 million people each year and the parasite is becoming increasingly resistant to available drugs. This work focuses on the mechanisms by which the parasite controls its internal ion concentrations. These mechanisms may be new drug targets, and they may also play a role in antimalarial drug resistance. For both of these reasons it is important that we understand them.
Interactions Between The Malaria Parasite's Chloroquine Resistance Transporter And Antimalarial Drugs
Funder
National Health and Medical Research Council
Funding Amount
$485,641.00
Summary
The malaria parasite is a single-celled organism which invades the red blood cells of its host. The aim of this project is to characterize the parasite protein responsible for conferring resistance to chloroquine, and to study its interaction with other antimalarial drugs. The parasite's susceptibility to chloroquine, and other drugs, is altered by small changes in this protein. This work will advance our understanding of the increasingly widespread phenomenon of antimalarial drug resistance.
The Mechanism Of Action Of New 5-nitroimidazole Drugs Which Are Effective Against Metronidazole-resistant Giardia
Funder
National Health and Medical Research Council
Funding Amount
$292,216.00
Summary
We have discovered new 5-nitroimidazole drugs which can overcome giardial resistance to metronidazole, the most prescribed 5-nitroimidazole drug to treat giardiasis. We will focus on defining mechanisms of action of these new 5-nitroimidazole drugs in the anaerobic gut protozoan parasite Giardia. Using biochemical techniques, we will determine whether our potent new drugs are activated more efficiently by the same mechanisms as metronidazole or by novel enzyme pathways in the parasite.