Gene Therapy Experiment Creates Biological Pacemakers

Researchers at a heart institute in California have synthesised biological pacemakers that could potentially replace mechanical pacemaker implants for patients suffering from irregular heartbeats.

                                                                                                        

After nearly 12 years of research, a team of cardiologists at the Cedars-Sinai Heart Institute, LA, have managed to create "pacemaker" tissue from heart muscle cells in living pigs with heart arrhythmias. The success of the research contributes to a reinforcement in the larger field of somatic therapy - non-inherent genetic manipulation of vegetative cells (non-sex cells) in an organism. The Director of the Cardiogenetics-Familial Arrhythmia Clinic, Dr Eugenio Cingolani, believes the implications of this breakthrough are wide and could be very beneficial: 

      "It is possible that one day, we might be able to save lives by replacing hardware with an injection of genes."

The minimally-invasive experiment involved the insertion of a specific gene into the cardiac tissue of certain pigs with conditions that caused them to have very slow or irregular heart rates. The gene in question is the T Box 18 (TBX18), which is involved in the embryonic development of the heart. A catheter was used to access the heart tissue inside the test-subject pigs, and the gene was transfered through an artificial adenovirus - a basic, medium-sized, non-enveloped virus. The adenovirus would have been injected into the tissue and would have incorporated the TBX18 gene into the cardiac cells' DNA. A transformation would have taken place, changing the virus-infected cardiac tissue into a "pacemaker" for the heart, the Sino-atrial (SA) node. This new SA tissue would have begun to send out regular electrical signals, causing the hearts of the pigs to contract at a normal, healthy rate.

The 14 day study looked at the adenovirus-infected pigs alongside non-infected pigs with the same heart conditions. After the first day the transformed pigs were already observed to have stronger, faster heartbeats compared to the other pigs. The research is already being branded a huge success amongst scientific communities, and because the procedure is so minimally invasive scientists are looking at more complex applications. For example babies with congenital heartblock could be treated before they are even born, reducing the complications after birth.

The full scientific paper was published by Science Translational Medicine, and can be found on their website (Link below).

Sources:

• LINK TO SCIENTIFIC PAPER http://stm.sciencemag.org/content/6/245/245ra94.abstract?sid=7b6dce60-bb1e-4dd3-99a0-c8716aa8854b
• http://www.medicalnewstoday.com/articles/279760.php
• http://www.bbc.co.uk/news/health-28325370
• http://www.ncbi.nlm.nih.gov/gene/9096
• Image of heart retrieved from  http://www.citruscardiology.org/arrhythmias.html

Aspirin - A New Field for Cancer Treatment?

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We live in an age where 1 in 3 people will develop cancer in their lifetime. For the majority of us it's our worst fear, according to statistics released by Cancer Research UK. New classes of drugs and treatment methods are being studied every year to combat many forms of the disease, but several studies are now claiming that a new form of treatment comes from the most commonly prescribed drug in the world.

Aspirin, or Acetyl-salicylic acid, derives from a reaction between salicylic acid and an acetyl group. 
The drug blocks the action of the Cycloxygenase (COX) enzyme by binding to serine residues near their active sites. COX converts arachidonic acid into prostaglandins, lipid-like compounds that work with other substances to cause pain and inflammation. When COX is inhibited, the body's inflammatory response is suppressed.

Cancer Explained

Quoting a publication from Yale: 
"Cancer results from the outgrowth of a clonal population of cells from tissue."*
Cancer can be caused in many ways regarding what a body is exposed to (E.g. Smoking, alcohol, unbalanced diets etc.). However, a cell can turn cancerous through either 2 fundamental pathways:

1. Genetic mutation; a series of random genetic "accidents" that can turn normal cell-growth genes (protogenes) into cancerous genes (oncogenes). Because of this randomness, no two cancers are genetically identical.
2. Tumour Viruses. That's right, some viruses can manipulate cell division control systems when integrating their foreign DNA into a host's genome.

When a cell becomes cancerous it rejects it's ability to kill itself after so many divisions. This "cell suicide" is called Apoptosis, and is a critical part in the life cycle of a cell.
When apoptosis is inhibited in a cell, it carries on dividing to form a cluster of abnormal cells referred to as a tumour. This tumour can stay within the tissue it originated from (a benign tumour) or spread to other tissues (a malignant tumour). A tumour that is malignant can invade all types of tissue - this can include organs, the circulatory system and even bones. These invasions cause all sorts of different problems that compromise the life of the suffering individual.

Aspirin treatment against Breast Cancer

Because of it's ability to suppress inflammation, Aspirin has been loosely coupled with cancer treatment in studies conducted over the last 5 years. Some researchers believe that aspirin, by blocking inflammatory chemicals that fuel cancer growth in cells, can help reduce and prevent the spread of a cancer.A recent study out of Glasgow University claims evidence that a tiny 75mg daily dose of Aspirin can increase breast cancer survival rates by nearly 60 per cent. The study consisted of 4627 women diagnosed with breast cancer, with 1000 of the women taking the aspirin every day for 10 years. Not only did the results show a 58% increase in breast cancer survival within the aspirin-prescribed group, but these participants were reported to have been less likely to die from any illness compared to the rest of the women in the study. Saying this, a latest study on aspirin treatment for breast cancer has produced results that shows that their participants were actually more likely to die on the regular aspirin dose.

Aspirin treatment against Pancreatic Cancer

Scientists at Yale University set up a research project in 2005 which was soon to be one of the largest ever studies on Aspirin's effects. Just over 1000 individuals in Connecticut hospitals were asked about doses of aspirin they had taken in the past. 362 of the patients interviewed had been newly diagnosed with pancreatic cancer, and the rest were "healthy" individuals used as a control for the study. The results of the study suggested that long term doses of aspirin had halved the risk of pancreatic cancer for many patients - people who regularly took 75-325mg doses of the drug from at least 3 years before the study was conducted had a 48% lower risk of developing pancreatic cancer. Furthermore, the results went on the show that people who had been regularly taking aspirin for 20 years before the study had a 60% lower risk of developing the cancer.
However, it is worth noting that a lot of the patients observed were taking aspirin regularly as a prescription for cardiovascular disease, or cardiovascular disease prevention. Rather than a direct link between aspirin and pancreatic cancer, CVD treatment and even genetics could play a more predominant role in this anti-cancer claim. Also, a large study conducted in 2004 went against these findings completely and produced results showing that taking aspirin could actually increase the risk of developing pancreatic cancer in women.

Aspirin treatment against Bowel/Digestive Cancer

A research team from Leiden UMC, Netherlands analysed tumour tissue from patients that suffered from colon cancer, and had undergone surgery between 2002 and 2008. As common with this type of cancer, most of the 999 patients in the study were diagnosed at the later stages of the disease.

Of these patients, 182 took a low, regular dose of aspirin. During the study 37.9% of these participants died as a result of colon cancer, whereas 48.5% of the patients who didn't use aspirin died from the cancer. These researchers believed that aspirin, by targeting COX found in gastrointestinal tract, reduced the inflammation of cancerous cells consequently reducing the spread of the cancer in the patients.                                                       

The claims that a common drug that has been around for hundreds of years can prevent or even treat cancer are certainly worth looking in to, when given the evidence of these studies. Nonetheless, for as many studies claiming aspirin is a "miracle" anti-cancer drug, there are just as many claiming the contrary. There are many crucial points surrounding this area of oncology, one being common in many other areas of the field: every cancer is different. What may work for one individual's cancer may not work as well for another's, or even prove fatal. Additionally, aspirin comes with many potential side effects. The drug causes blood platelets to become less sticky and prevents clotting, which could lead to stomach ulcers, haemorrhages or even strokes when used regularly.

For now, evidence for or against this type of treatment is inconclusive. Should anyone consider taking a regular dose of aspirin, they should first see about consulting their doctor.










Sources:

• * http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1994795/
• http://www.cancerresearchuk.org/
• http://www.labmuffin.com/2012/06/is-aspirin-mask-same-as-beta-hydroxy.html
• http://osteoarthritis.about.com/od/osteoarthritismedications/a/cyclooxygenase.htm
• http://science.education.nih.gov/supplements/nih1/cancer/guide/understanding1.htm
• http://www.dailymail.co.uk/health/article-2678610/How-aspirin-halve-risk-dying-breast-cancer-Powerful-effects-drugs-seen-women-taking-small-doses.html
• http://www.theguardian.com/science/2014/jun/26/low-dose-aspirin-risk-pancreatic-cancer
• http://www.medicalnewstoday.com/articles/274834.php
• Image of colon cancer retrieved from http://healthsciencedegree.info/colon-cancer-cells/
• Image of cancer lab retrieved from http://www.ludwigcancerresearch.org/sites/default/files/styles/lab
  _main_image/public/media/lab-images/Ludwig_Constantinescu_Lab
  .jpg?itok=g_Yz70ex

Significant Rise in Genetically Resistant "Super Rats"

The UK and mainland Europe is experiencing an extreme rise in poison-resistant rats, according to studies conducted at the University of Huddersfield.

Research team leader and Head of Applied Sciences at the university, Dr Dougie Clarke, stresses that the use of common rat poisons are not effective for many populations of rats in some English and Scottish counties. 
“The fact we've tested 17 counties and every single one of them has got resistant rats was an amazing find to us. We didn't even expect to have every single county having resistant rats.”. The resistance is said to be the cause of natural selection after generations of exposure to rodenticides such as Warafin, Bromodiolone and Difenacoum.

Natural selection has caused mutations in the genomes of European rat populations that make them less susceptible to poisons like Warafin. Although several different mutations are prominent in different populations, the alleles all seem to be dominant. Studies over the past few years have also shown that although the mutant rats are resistant to the poison, they still become Vitamin K deficient. In fact, the resistant homozygous rats are prone to lethal haemorrhages after exposure to Warafin. This is an example of overdominant natural selection, where the heterozygous mutants seem to have the best survival advantage.

The research, funded by several British and European pest control organisations, looks at the VKORC1 gene which codes for the production of a subunit in the protein Vitamin K epoxide reductase. VKOR catalyses the reduction of Vitamin K 2,3-epoxide to Vitamin K, an amine that plays a crucial part in blood coagulation. Rodenticides like Warafin inhibit VKORC1 at it's active site (thought to comprise of 4 cysteine residues and either 1 serine or threonine residue), causing a vitamin K deficiency. Rats exposed to Warafin die from either arterial calcification or mass uncontrolled bleeding.
The genomes in the research were studied through PCR cloning, a technique that uses DNA polymerase and restriction enzymes to amply strands of genetic material. This process is very fast and gives a more accurate, quantitative result. 

The exact results of the study are not yet published, as the full details and methodology have been sent to the government in confidential reports.



Sources:

• http://en.wikipedia.org/wiki/Vitamin_K_epoxide_reductase
• http://www.independent.co.uk/news/uk/home-news/invincible-mutant-superrats-spreading-across-the-uk-9567486.html
• http://www.uscnk.com/directory/Vitamin-K-Epoxide-Reductase-Complex-Subunit-1(VKORC1)-6899.htm
• http://www.sciencemag.org/site/products/pcr.xhtml
• Kohn, M.H., Price, R.E., Pelz, H.J. (2008). A cardiovascular phenotype in warfarin-resistant Vkorc1 mutant rats. Artery Research, 2 (4) 138-147. doi: 0.1016/j.artres.2008.09.002.
• Wadelius, M., Chen, L.Y., Downes, K., Ghori, J., Hunt, S., Eriksson, N. ... Deloukas, P. (2005). Common VKORC1 and GGCX polymorphisms associated with warfarin dose. The Pharmacogenomics Journal, 5 (4) 262-270. doi: 10.1038/sj.tpj.6500313.

PROFILES: Trypanosomal Disease: Description, Mechanisms of Infection, Treatments

Summary

Trypanosomes are a genus of protozoa (a type of single-celled organism with a nucleus) that are parasitic to animals and humans (Turnbull, 2001). Relatively common around the world, only some species of trypanosoma are harmful to their hosts (University of Bristol, 2009).

Trypanosomes are transmitted by hematophagous insects. They are the cause of African sleeping sickness and Chagas disease which both have a latent and a chronic infection stage that attacks the nervous system. Treatment administered is aggressive and encompasses a mortality risk, although there aren’t many other alternative treatments. Supportive care is a better and cheaper option for financially challenged patients or for sufferers in developing countries (Wiser, 2011).
Trypanosomes are Zooflagellates; typical protozoans that feed by absorption or engulfing their food (Rogers, 2011). They have a flagellum for motility, and a kinetoplast. These are organelles that house the DNA of the “power stations” of the cell - the mitochondria.
Trypanosomes have several developmental stages in their life cycle (Aus. Society for Parasitology, 2010):

1. Amastigote- No flagellum or undulating membrane (Aus. Society for Parasitology, 2010).
2. Promastigote- Kinetoplast is located in the rear of the cell, and there is a developing flagellum (See Figure 1) (Aus. Society for Parasitology, 2010).
3. Epimastigote- Kinetoplast is located in the rear of the cell. There is a developed flagellum and undulating membrane. This phase is prominent when the organism is in the vector’s salivary gland (Aus. Society for Parasitology, 2010).
4. Trypomastigote- Kinetoplast is located at the front of the cell. There is a developed flagellum and a long undulating membrane. This phase occurs when the organism is in the host (Aus. Society for Parasitology, 2010).

Human African Trypanosomiasis

Probably the most well-known form of Trypanosomal disease, HAT was first documented and diagnosed in 1901 (Turnbull, 2001). There are several species of trypanosoma that cause the disease, Trypanosoma gambiense being identified first in Central Africa (Turnbull, 2001). T. rhodesiense was later discovered in Zimbabwe, when a person who had never travelled to a T. gambiense endemic region was shown to have a trypanosomal infection in a blood smear test (Turnbull, 2001). These two trypanosomes are often classed as sub-species of T. Brucei (which causes a similar disease in animals, Nagana), as all three are identical in morphological terms (Wiser, 2011). Despite this being the case, genetic techniques have shown that the species in question are assuredly different from one another on a molecular level (Wiser, 2011).

Studies suggest the following mechanism of infection takes place when the vector, the tsetse fly, feeds on a potential human host. The epimastigote trypanosome swims out of the fly’s salivary gland, obtaining entry into the bite site (Turnbull, 2001). Once there, it begins to replicate rapidly, forming a painless sore called a chancre (Turnbull, 2001). T. gambiense is slow in reaching the next stage of its life cycle - the infection can sit in the sore for years before migrating into the body-systems – whereas T. rhodesiense’s infection develops at a much faster rate from this point (Moore, 2013). Either way, at this point in the infection the host may only suffer mild symptoms (e.g. muscle aches and a fever).
The next stage of infection involves the protozoa developing into trypomastigotes and migrating into 
the circulatory system through the local lymph tissue (Turnbull, 2001). These tiny organisms can then be found all over the host’s body.
Due to the infection of the lymph system, the nodes swell up (Winterbottom’s Sign) (Aus. Society for Parasitology, 2010) from a massive influx of B-lymphocyte immune system cells. Trypanosomes burst and release their toxic compounds, causing other immune system cells known as macrophages to release chachetin, a tumour-necrosis factor, causing weight loss, fatigue and a muscle wasting (Wiser, 2011).
Just like the progression from the chancre, the time it takes for the parasite to cross into the Central Nervous System (CNS) varies between species. T. rhodesiense’s invasion is very fast, in most cases taking less than a month (Aus. Society for Parasitology, 2010).
Sometimes patients die from other causes (e.g. swelling of the heart) before the parasite reaches the CNS due to the rapid progression of the species. T. gambiense, however, takes over the brain and nervous system slowly causing insomnia, general mood changes and brain inflammations; haemorrhages and cerebral oedemas. This strain of the disease progresses over years, and eventually leads to a coma or death through other minor intervening diseases (Aus. Society for Parasitology, 2010).
When the trypanosome population in the host reaches the stationary phase of their growth, they change back into epimastigotes to prepare for the infection of another tsetse fly (Martin, 2003). When the fly bites the infected host the trypanosomes swim up its proboscis and into the mid-gut, meaning the parasite can spread to other hosts (Wiser, 2011).
Now in the vector, the amino acid Proline is used alongside glucose in aerobic cell-respiration, and the volume of mitochondria increases. These changes are referred to as procyclism (Wiser, 2011). It takes around a week for these procyclic trypanosomes to pass through the vector, towards the salivary glands. Once there they transform back into epimastigotes and use their flagella to cling on to epithelial cells, ready to enter another host all over again (Wiser, 2011).

American Trypanosomiasis

In 1911, Carlos Chagas discovered a similar disease to African sleeping sickness in the Americas which he named Chagas’ Disease. The species was found in a child that suffered from a fever, anaemia and lymphatic swelling (Tolan, 2013) - symptoms all found in the African Trypanosomiasis. American Trypanosomiasis is found across central and southern America, spanning from southern USA to the very south of Argentina (Tolan, 2013). The disease is the number one cause of heart failure in central and southern America (Burleigh, 2013).
The parasite, T.cruzi, is mainly transmitted by the blood-sucking Triatomine bug although a variety of other hematophagous (blood sucking) insects can act as vectors (Wiser, 2011). T. cruzi’s infection process is quite different to that of the T. Brucei species (See Figure 3):
The trypanosomes reside in the vector’s gut, and rather than migrating to the salivary glands they are egested out when the fly lands on a host to feed (Wiser, 2011). Infection is caused when the faeces containing the trypanosomes are rubbed into the irritative bite wound.
The trypanosome burrows into the mucous membrane and meets the influx of macrophages and lymphocytes. Some of the parasitic cells are engulfed by these immune system cells, and others enter the local tissue through a lysosome (Tolan, 2013). The trypomastigotes escapes its lysosomal vacuole by releasing a very active hemolytic protein which disrupts the vacuole membrane (Tanowitz et al., 1992). The population of the parasites then transform into simple amastigotes (Bell, 1995), replicate within their host cells, and after 4 days they are released as trypomastigotes (Wiser, 2011). After this first round of intracellular replication, trypomastigotes are found in the blood and can reinvade other cells around the body (Bell, 1995), specifically cardiac, nervous and smooth muscle tissue (Tolan, 2013).
The heart is the main target organ for T. cruzi – the parasite can reside in the cardiac and nervous tissue for years without being detected (Wiser, 2011). This is known as the acute stage of Chagas’ Disease (Tolan, 2013). A tell-tale sign of this stage is Romana’s sign – the swelling or inflammation of the eye (conjunctivitis) due to trypanosomes in the eye’s mucous membrane (Wiser, 2011). A swelling can also occur around the vector bite site. This is called a Chagoma and is similar to African trypanosomiasis’s chancre.
The chronic stage is reached when more than 20% of the nervous tissue in the heart is damaged causing conduction problems, arrhythmias and congestive heart failure (Tanowitz et al., 1992). The stage begins with trypanosomes being found in the spinal fluid – a sign of neural invasion (Tanowitz et al., 1992). As the heart walls become thinner, an aneurysm (bulge in blood vessels) forms in the atria (Wiser, 2011), and the organ swells causing symptoms of Dilated Congestive Cardiomyopathy (Tanowitz et al., 1992). Death usually occurs through congestive heart failure, a rhythm disturbance or thrombosis (Wiser, 2011). 
Because American Trypanosomiasis targets the muscular and nervous tissue in general, and not just the heart, other autonomic systems are affected. Damage similar to the thinning heart walls occurs in the Gastrointestinal (GI) tract, causing nerve loss and problems with moving and absorbing food (Tolan, 2013). These symptoms can be recognised by high levels of muscle sensitivity and over contraction (Tubraikh & Ali, 2010).

Treatment

Treatment of African and American trypanosomiasis involves chemotherapy (Boutielle & Buguet, 2012), although patients are rarely completely free of the parasites (Tanowitz et al., 1992).
The drugs administered can be categorised into two groups; drugs that can cross the blood barrier (Nifurtimox and Melarsoprol) and drugs that cannot cross the blood barrier (Pentamidine isethionate, Suramin) (Wiser, 2011).
African trypanosomiasis, stage 1 treatment – before the parasite invades the CNS – involves injections of either Pentamidine or Suramin into the muscle tissue, depending on which sub-species of parasite the patient has been infected with (Boutielle & Buguet, 2012). Pentamidine is administered for T. gambiense infections (Wiser, 2011). The drug works by severing and damaging DNA in the trypanosomes’ kinetoplasts (Bacchi, 2009). As previously mentioned, the kinetoplast DNA contains the information for mitochondrial replication meaning the trypanosomes carry on replicating but produce cells that are much less aerobically efficient (Bacchi, 2009). Suramin is given to patients with the T. rhodesiense infection, because Pentamidine treatment is not sufficient enough to combat the T. rhodesiense infection (Wiser, 2011). Suramin binds to the body’s Low Dense Lipoproteins (LDLs), which trypanosomes desperately need for important, structural lipids such as cholesterol (Bacchi, 2009). When the trypanosomes bind to the LDLs Suramin is shown to inhibit their enzymes required for Glycolysis in aerobic respiration (Bacchi, 2009). Although this sounds like a very effective way of dealing with the parasite, tests have shown that the inhibition process is slow and only targets newly made enzymes in the cell (Bacchi, 2009). For both drugs, treatment failures are very uncommon (Boutielle & Buguet, 2012). This being said, harmful side effects are often reported (Tanowitz et al., 1992). Anaphylactic shock – a severe, and sometimes fatal allergic reaction - is a prime example (Boutielle & Buguet, 2012).
The second stage of African Trypanosomiasis is more aggressive than the first stage, so stronger drugs such as Melarsoprol and Eflornithine are administrated intravenously (Boutielle & Buguet, 2012). Melarsoprol inhibits the enzymes such as Pyruvate kinase, preventing energy (ATP) from being produced (Gutteridge, 1985). The drug is controversially acclaimed, because of its heavy-metal arsenic group. Diarrhoea, fever and even heart and kidney damage are common amongst patients, and several treatment courses of Melarsoprol have shown 5-10% mortality rates (Boutielle & Buguet, 2012). 
Eflornithine inhibits the enzyme Ornithine decarboxylase within trypanosomes, an enzyme critical to polyamine synthesis and cell replication (Pegg, 2006). Cure rates have been claimed to be as high as 99% in some regions, although only with patients with the T. gambiense infection (Wiser, 2011). Both Melarsoprol and Eflornithine treatments are very expensive due to cost of the drugs and the need for hospitalisation during treatment (Wiser, 2011).
The main drug used for American Trypanosomiasis is Nifurtimox. This drug targets the trypanosomes in the body’s cells – stage 1 of the disease. Usually, when T. cruzi invades a cell, macrophages produce oxides (e.g. Nitric oxide) which subject the organism to oxidative stress (López-Muñoz et. al., 2010). This is where more reactive, oxygen containing compounds called free radicals are produced. These compounds can cause a lot of damage to proteins and tissue (Betteridge, 2000), including the trypanosomes’ cell tissues. In the absence of the drug the amastigote trypanosomes overcome a lot of the oxidative stress through several methods, including activating cell mediators that inhibit oxygen-intermediate synthesising enzymes (López-Muñoz et. al., 2010). Following Nifurtimox treatment and working alongside macrophages more oxidising free radicals are produced to suppress trypanosomal replication inside the cell. Many patients develop side effects from the tissue-damaging treatment, which makes Nifurtimox less effective during the chronic phase (Wiser, 2011). Because there aren’t many new drugs under development to combat the disease, treatment is mostly focused on supportive care for patients (Wiser, 2011). Treatments for easing symptoms include pacemaker fittings, bed rest, hydration and anti-arrhythmic agents (Wiser, 2011).













References:

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Moore, A. (2013). Trypanosomiasis, African (Sleeping Sickness). Retrieved from http://wwwnc.cdc.gov/travel/yellowbook/2014/chapter-3-infectious-diseases-related-to-travel/trypanosomiasis-african-sleeping-sickness.

Martin, L. (2003). Human African Trypanosomiasis (HAT). Retrieved from http://legacy.earlham.edu/~martilu/trypanosomiasispathology.htm

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