Epigenetics: A New Vision for Treating Disease

The 19^th and 20^th century saw some huge milestones in our understanding of genes and inheritance, including evolutionary theory, Mendelian genetics, the discovery of DNA and the sequencing of the human genome. These are undeniably huge advancements that have transformed our view of how organisms work and have paved the way to many new treatments of genetic diseases.

But now, a new, rapidly expanding field is turning heads in the scientific community. Because it turns out that the mere sequence of bases (A, C, T and G) in our DNA isn’t the whole story. Epigenetics is the study of how chemical changes to our DNA can alter the expression of genes and, ultimately, have drastic effects on our phenotypes[1]. In some cases, these epigenetic changes can even be passed on from parent to offspring[2], going against the former strong belief that acquired characteristics cannot be inherited. An understanding of epigenetics could be crucial to treating diseases such as cancer and schizophrenia. As such, it is in society’s interests that scientific attention and funding be directed towards the field of epigenetics.

Let’s first consider the epigenetic basis of schizophrenia. Schizophrenia has a high concordance rate of around 53% among identical twins[1,3] as opposed to around 17% among fraternal twins[1], showing that genetics plays an influential role in its development. However, since the figure falls rather short of 100%, there must be other factors at work than merely a person’s DNA sequence – for identical twins are, at the genetic  level, exactly what they say on the tin: identical! This led scientists to believe that environmental factors must be at work as well[4]. Studies have shown that there are indeed environmental risk factors linked to schizophrenia. These include maternal nutritional deficiency during pregnancy[5], psychosocial stress[4,6] and cannabis use[4].

Hold up – how could a mother’s diet during pregnancy affect the risk of her child suffering from a terrible psychotic illness later in life? The answer lies in epigenetics. Epigenetic changes associated with schizophrenia have been linked to chemical changes to two genes in particular: RELN, which encodes a protein called reelin[3,5,7], thought to be involved in memory formation and brain plasticity[7]; and GAD1, which codes for an enzyme that produces an important neurotransmitter called γ-aminobutyric acid[8] (GABA). The chemical changes include the addition of methyl groups to promoter regions on the genes[1], and the removal of acetyl groups from histones[7], special proteins which associate with DNA and make it more compact[9]. These changes affect gene expression by effectively getting in the way of the molecular machinery that transcribes the genes, and hence cause a decrease in the levels of reelin and GABA in the brain, associated with the awful symptoms of schizophrenia.

Epigenetics is also implicated in many incidences of cancer. Whilst irreversible gene mutations (in which the DNA sequence itself is changed) are often responsible for the loss of control that leads to rapid cell division, scientists are becoming increasingly aware that epigenetic changes can also be the culprit[10]. Certain genes, called tumour suppressor genes, regulate the cell cycle and prevent cells from dividing too rapidly. Some tumour suppressor genes are like police officers that stand guard over the genome: if they detect any suspicious activity that could lead to the growth of a tumour, they will “arrest” the cell to stop it from dividing any further[11]. The cell will then effectively commit suicide (a process called apoptosis[9]).

Tumour suppressor genes may be inactivated by the mechanisms described earlier: the addition of methyl groups to DNA, and modifications to the histone proteins associated with DNA[1,12]. If these genes are no longer expressed, the cell has a massively increased risk of becoming cancerous[11]. Substances that inhibit the enzymes which carry out these epigenetic modifications could therefore lead to new cancer drugs! For example, the compound 5-azacytidine, which blocks the activity of DNA methyltransferases (the enzymes which add methyl groups to DNA), has been shown to treat haematological cancers such as leukaemia[13].

One of the major problems with trying to find cures for cancer is that every cancer case is unique. A treatment that works wonders for one patient could do nothing but worsen matters for another. Developing, trialling and mass-producing new drugs is also an incredibly costly process[1]. However, a better understanding of the epigenetic basis of cancer will undoubtedly open doors to previously unimaginable methods of diagnosis and treatment in the future[12,13].

As illustrated by these cases, epigenetics is clearly an area in which continued research could really accelerate medical progress in the coming decades. I hope to see many novel treatments for diseases such as schizophrenia and cancer arise as a result of research into epigenetics in my own lifetime.

REFERENCES

1. Carey, N. The Epigenetics Revolution: How Modern Biology is Rewriting Our Understanding of Genetics, Disease and Inheritance. 2012, Icon Books Ltd. ISBN: 978-184831-347-7

2. University of Utah: Epigenetics and Inheritance. Learn. Genetics: http://learn.genetics.utah.edu/content/epigenetics/inheritance/

3. Alonzi, A. The Epigenetics of Schizophrenia. 08/12/2014, What is Epigenetics: http://www.whatisepigenetics.com/the-epigenetics-of-schizophrenia/

4.  Svrakic, D.M.; Zorumski, C.F.; Svrakic, N.M; Zwir, I; Cloninger, C.R. Risk architecture of schizophrenia: the role of epigenetics. 0951-7367 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins

5. Kirkbride, J.B.; Susser, E.; Kundakovic, M.; Kresovich, J.K.; Smith, G.D.; Relton, C.L. Prenatal nutrition, epigenetics and schizophrenia risk: can we test causal effects? Epigenomics. 2012 Jun; 4(3): 303–315

6. Horan, W.P. ; Blanchard, J.J. Emotional responses to psychosocial stress in schizophrenia: the role of individual differences in affective traits and coping. Schizophr Res. 2003 Apr 1;60(2-3):271-83.

7. Gavin, D.P.; Sharma, R.P. Histone modifications, DNA methylation, and schizophrenia. Neurosci Biobehav Rev. 2010 May; 34(6): 882–888.

8. Wassef, A.; Baker, J.; Kochan, L.D. GABA and schizophrenia: a review of basic science and clinical studies. J Clin Psychopharmacol. 2003 Dec;23(6):601-40.

9. Purves, W.K.; Sadava, D.; Orians, G.H.; and Heller, H.C. Life, the Science of Biology 7^th edition 2004: Sinauer Associates, Inc., Massachusetts. ISBN: 0-7167-9856-5

10. Verma, M.; Srivastava, S. Epigenetics in cancer: implications for early detection and prevention. Lancet Oncol. 2002 Dec;3(12):755-63.

11. Wolpert, L. How We Live and Why We Die: The Secret Lives of Cells. 01/04/2010. ISBN: 978-0571239122

12. Boumber, Y.; Issa, J.P. Epigenetics in cancer: what’s the future? Oncology (Williston Park). 2011 Mar;25(3):220-6, 228.

13. Lamb, R.  How Epigenetics Works.  13/10/2008: HowStuffWorks.com: http://science.howstuffworks.com/life/genetic/epigenetics.htm

Motility Symbiosis - A Clue to Cellular Evolution?

Swimming inside the gut of the drywood termite Cryptotermes cavifrons is a remarkable microorganism called Caduceia versatilis¹. C. cavifrons and C. versatilis share a symbiotic relationship – that is, a partnership between two species from which both parties benefit in some way. The tiny protists inside the intestines of the termite help it to digest wood², allowing it to absorb the products it needs, whilst it provides a food source and habitat for the protists³.

What is so special about C. versatilis? The answer lies in the way in which it moves through the gut of the drywood termite. Looking through a microscope, it would appear at first that the microbe propels itself forward by the wavelike motion of tail-like structures called flagella, as is the case in many species of bacteria⁴.

In fact, the surface of the protist cell is lined with thousands of even tinier rod-shaped bacteria called spirochetes. These bacteria possess their own flagella, which rotate in perfect synchrony to create a wave of movement that propels C. versatilis forward. In other words, the protist is involved in another symbiotic relationship – the rod-like bacteria on its surface actually allow it to move through the gut of C. Cavifrons⁴. This type of symbiosis, ­­in which bacteria confer the ability to move onto their partners, is called motility symbiosis⁵.

Motility symbiosis is a rarely documented phenomenon; another of the few known examples of it is in a protist called Mixotricha paradoxa¹. Yet, believe it or not, it could hold a clue to a question upon which biologists today are still not agreed. Let’s take a look at the cells of eukaryotes (animals, plants, fungi and protists).

Many eukaryotic cells have their own flagellum-like tails, sometimes referred to as undulipodia as they differ somewhat in structure from the flagella found on bacteria⁶. Undulipodia also include cilia, small hair-like organelles which are found, for instance, in the windpipe of humans where they beat back and forth to keep our airways clear of dirt and mucus⁷. The whipping motion is driven by the action of special proteins inside undulipodia called motor proteins⁸.

The question, then, is: how did undulipodia arise in the first place? Most biologists believe that they evolved gradually from the flagella of prokaryotic cells, their structures changing as they became more specialised and adapted to the needs of eukaryotes. For example, undulipodia are considerably thicker than bacterial flagella and move in a whipping fashion rather than a rotating one⁶, which may be evolutionary adaptations to the bulkier size of eukaryotic cells: undulipodia which propel cells forward, such as the ones found on sperm cells, must be able to create a larger driving force in order to move a heavier cell.

This idea, known as autogeny⁶, is just one hypothesis, and in 1970 a biologist called Lynn Margulis proposed a more radical one: that somehow, undulipodia could have evolved from the symbiotic relationship of an immotile cell with a type of flagellum-possessing bacterium called a spirochete. This is where we come back to the idea of motility symbiosis: from the examples we have discussed above, we already know that it is possible for a symbiotic relationship to exist in which a bacterium confers motility onto another organism by effectively lodging on the membrane and rotating its own flagella to drive both cells forward. Margulis proposes that, at some point in evolutionary history, a spirochete and a eukaryote somehow fused together to form a single cell with the first undulipodium. This eukaryote, now having a competitive advantage over its peers in that in can move independently, would have been favoured by natural selection and hence undulipodia became widespread in eukaryotes.

This idea of endosymbiosis is vastly different to autogeny, which proposes gradual evolutionary changes, but Margulis argues her case strongly, claiming that undulipodia are more closely related in structure to spirochetes than to ordinary flagella⁶. Most biologists are sceptical about the origin of undulipodia by endosymbiosis due to a lack of supporting evidence – for example, if undulipodia were once free-living bacteria, why do they not contain their own DNA? – but Margulis’ hypothesis has not been rejected completely. Her appeal to existing cases of motility symbiosis in today’s biosphere, such as that in C. Versatilis, as evidence for endosymbiosis is perhaps a strong one – but, on the other hand, it could be a mere coincidence. The origin of undulipodia could be one of those great mysterious questions in science which will never be answered for definite.

References

1 Biology of Termites: a Modern Synthesis – D. E. Bignell, Y. Roisin, N. Lo (2011) – 15.7.3: Motility Symbiosis

2 Featured Creatures: Cryptotermes cavifron – A. S. Brammer, R. H. Scheffrahn, University of Florida (2002)
4 The Motility Symbiont of the Termite Gut Flagellate Caduceia versatilis Is a Member of the “Synergistes” Group – Y. Hongoh, T. Sato, M. F. Dolan, S. Noda, S. Ui, T. Kudo, M. Ohkuma (2007)

3 Termite Gut Symbionts – W. v Egmond (2004)

5 A Dictionary of Genetics – R. C. King, W. D. Stanfield, P. K. Mulligan (2007) – Motility Symbiosis

6 Doing Biology – J. Hagen, D. Allchin, F. Singer (1996) – Chapter 3: Lynn Margulis and the Question of How Cells Evolved

7 Structure and Function of Cilia – Ciliopathy Alliance

8 Life: The Science of Biology – B. Purves, D. Sadava, G. Orians, C. Heller (2004) – Chapter 5: Cells: The Basic Units of Life

Review: How We Live and Why We Die: The Secret Lives of Cells by Lewis Wolpert

The jaw-dropping complexity and sheer cleverness of cells is beyond the imagination of anyone who has not specialised in the rapidly growing field of cell biology, and the pace and tone of Lewis Wolpert’s book How We Live and Why We Die: The Secret Lives of Cells reflect this. As a reader one cannot fail to be immediately awestruck by the sense of scale conveyed by Wolpert’s writing style, and the passion he has for the subject is apparent throughout the book.

The volume has fourteen chapters, each of which address a different aspect of how the workings of cells give rise to the phenomenon of life. Some rather advanced concepts such as development and cell signalling are discussed in a light-hearted, accessible manner. Wolpert often uses a humorous, anecdotal style, such as when recounting the bizarre etymology of the gene Sonic hedgehog: the biologist who named the gene did so after one of his son’s computer games due to the fact that a mutation in the gene causes fly larvae to have “a hedgehoggy appearance”. Analogies are also used in places – for example, positional values are explained with reference to the French flag.

Chapters towards the end of the book focus on the causes of cancer and other diseases on the cellular level, and are highly informative on these more sensitive topics. There is finally a chapter on the evolution of the very first cells, that is to say, the origin of life on Earth, and describes several theories to address this ultimate question, including the Miller-Urey experiment and the RNA World hypothesis.

As an introduction to the exciting area of cell biology, this book more than fits the bill: I found it to be a highly enjoyable read as well as packing a lot of information and presenting it in a fashion which allows the book to be read by those with little previous knowledge of biology. 

The Science of Allergies

In my last post, which was about how and why the cells within our bodies communicate amongst each other, I used the example of our immune system. This incredible network of white blood cells guards our bodies against disease-causing microorganisms with a variety of defensive mechanisms; the importance of our immune system is reflected in the disastrous consequences of deficiency diseases such as AIDS. Without an immune system, a common cold would kill you. The whole system relies on the fact that our white blood cells recognise pathogens as foreign, and thus set off an alarm signal which triggers the whole response – including the familiar symptoms of coughing, fevers and inflammation. As amazing as it is, the immune system is not infallible, and often can be set off by harmless substances which happen to find their way into our bodies – resulting in an allergic reaction.

When an allergen enters your body (which may be from eating it, breathing it in, or via the bloodstream, e.g. insect bites), it will bind to specific receptors on white blood cells – this happens because of their complementary shape. These cells will then send out signals which trigger the production of a type of antibody called Immunoglobulin E, or IgE¹. IgE then goes and attaches to another type of white blood cell called mast cells². The next time that allergen comes along, it will bind to the IgE antibodies, which once again have a specific shape which allows them to recognise the invading substance³.  The binding of the allergen causes IgE to change shape, kicking into an action a signal transduction pathway which causes the mast cells to release chemicals such as histamine⁴.

The effect of these chemicals is to induce the well-known allergy symptoms: in nasal allergies (collectively known as allergic rhinitis⁵), such as hay fever, histamine causes inflammation, sneezing, running nose, etc. but some allergic reactions have more serious effects. Anaphylaxis, for example, can be brought on by an allergy to nuts or insect venom; characterised by symptoms such as rapid swelling and hives, anaphylaxis can be fatal if not treated⁶.

So essentially, your immune system does a great job of protecting you from nasty bacteria, viruses and fungi, but every so often it gets it wrong, going into overdrive at the first sign of something harmless like pollen or pet hair. In a sense, it’s the price that must be paid for having a really good immune system; so while hay fever can be a real nuisance and many allergies can be very harmful, it’s a lot better than not having a working immune system at all!

References

1 http://www.scientificamerican.com/article/what-function-does-immuno/

2 http://www.worldallergy.org/professional/allergic_diseases_center/ige/

3 http://health.howstuffworks.com/diseases-conditions/allergies/allergy-basics/allergy2.htm

4 http://www.mastcellaware.com/about.html

5 http://www.webmd.com/allergies/tc/allergic-rhinitis-overview

6 http://www.medicinenet.com/anaphylaxis/article.htm

The conversations of cells

Imagine fifty people trying to build a house, only none of them can speak to each other or converse in any other way. The fifty people are all working towards a common purpose, but without any communication, their endeavour is bound to fail!

Instead, the workforce must cooperate in a highly organised manner. Firstly, they should be divided into groups, each with a particular purpose: laying the bricks, making the measurements, collecting and transporting the necessary resources, and so on. Yet even between these groups there must be communication: the brick-laying team could run out of cement, and would need to call on the resource-collecting group to obtain or make some more. With a clearly defined organisational system, it can now be hoped that the task in hand will be completed.

The very same is true of the cells in our bodies. Our cells are accumulated into tissues; several types of tissue make up one organ; and multiple organs that work together to ensure one aspect of the body’s functioning make up an organ system. Organ systems include the circulatory system, the nervous system and the digestive system.

Like the workers in the house analogy, cells must converse all the time, and they do so in a language consisting largely of proteins and lipids. These chemical “words” must be picked up and recognised without fail, and they must specify a particular response – though this response may be different in different cell types. Our cells have a very impressive vocabulary and, between them, can understand and respond to many thousands of chemical messengers. How does it work?

The entire process is based on two simple but absolutely fundamental principles in biology. The first is that two molecules will only piece together if their shapes allow one to fit into another, like a key into a lock. The second is that proteins, enormous molecules which regulate pretty much every process in our bodies, are very flexible in structure and the binding or unbinding of one substance will cause it to change its shape.

Take, for example, what is known as a protein kinase cascade. A messenger from one cell may fit perfectly into a receptor on another. The receptor, a protein, will then change shape, allowing it to bind other proteins and add a chemical group to them, so that these proteins in turn will change shape, and so on and so on. An important feature of this cascade is that the message is amplified at every stage, in the sense that every protein, once activated, will activate many more. It is like when a rumour is spread – one person tells several people, each of whom tells several more, and before long, everyone knows!

The message takes its effect when a final activated protein binds to DNA in the cell, thus altering the way the cell behaves in some way. For instance, the message could cause the cell to divide rapidly, creating many clones of the same cell. This is often the case when our immune system responds to an infection: the bacteria or viruses which cause the illness carry particular proteins which may enter our own cells, and hence be recognised by white blood cells because of their specific shape. The white blood cells divide, kill the bacteria or viruses, and send out signals which are recognised by other types of white blood cells. This second class of white blood cells, once activated, divide into many copies and begin making antibodies, which fit perfectly into the proteins on the bacteria or viruses and hence allow them to be destroyed.

The field of cell signalling is concerned with understanding exactly how cells make sense of the multitude of chemical messengers around them, and exactly how these chemicals cause the specific responses they are intended to trigger. It is an expanding field and one which I find fascinating. I hope you will also be interested and eager to learn more!

References:

Life: the Science of Biology – Purves, W.K; Sadava, J; Orians, G.H; Heller, H.C

The Biochemistry of Cell Signalling – Helmreich, E.J.M.

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1782684/

Industrial enzymes

Why enzyme biotechnology is increasingly important for modern industries

Many people may be vague about the actual definition of “molecular bioscience” and what it does for the community. A prime example of biomolecules being used in our day-to-day lives – both on a domestic and an industrial scale – is enzymes.

What are enzymes?

Enzymes are biological catalysts: proteins, made in the cells, which speed up all the chemical reactions inside all living organisms. They do this by binding to substrates (chemicals involved in a metabolic reaction) and lowering the activation energy needed either to build them up into larger molecules, or to break them down into smaller ones¹.An example of an enzyme-based reaction is the breakdown of starch into glucose by amylase enzymes in the saliva.

The part of an enzyme which binds to a substrate is called its active site. The active site is very specific in structure and will only bind to a particular substrate – a bit like a key fits into a lock (in fact, this is known as the “lock-and-key” model²). Because of this, living organisms need a vast number of different enzymes – one for every chemical reaction that takes place inside the body!

Why are enzymes used so much in industry?

The use of enzymes for manufacture goes back to about 8,000 years ago³ – when humans first used yeast to ferment grapes into alcohol. In the absence of oxygen, the yeast enzymes would break down glucose into ethanol and carbon dioxide. This batch process for the production of ethanol is still used today. At the time, of course, there was no understanding of enzymes and this was merely experimental. However in modern days, as our understanding of molecular biosciences and biotechnology has improved, we have been able to exploit the properties of enzymes to use them quite diversely.

Enzyme biotechnology really took off in the 1950s. Examples of enzymes used in industrial processes include:

·         Sucrase enzymes in soft-centred chocolates

·         Proteases and lipases in baby food to start pre-digestion

·         Biological washing powders to break down stains into soluble amino acids/fatty acids

·         Pectinase in fruit juice to increase yield and make the juice clear

·         Yeast enzymes in the fermentation of sugar

·         Rennin used to coagulate cheese

·         In the textiles industry to enhance the preparation of cotton⁴

·         Esterase enzymes to remove adhesives for the recycling of paper

The list really does go on. Enzymes as a form of biotechnology are growing rapidly: Figure 1 shows the projected growth of the global industrial enzyme market up to 2015. Why are enzymes so attractive to industries?

Global industrial enzymes market, $ millions5	Estimated value in 2010	Predicted value in 2015	% increase
Technical enzymes	1000	1500	50
Food and beverage enzymes	975	1300	33

Figure 1: the global industrial enzymes market is expected to increase at a compound annual growth rate of 6%

The use of biological catalysts to speed up industrial reactions is often favoured over the use of metal catalysts for two main reasons.

Firstly, enzymes operate at fairly low temperatures and pressures, which keeps costs down. Typically the temperatures required by enzymes are about ten times lower than those required by inorganic catalysts! In addition, enzymes can be up to 10,000 times more efficient than ordinary chemical catalysts, so profit is maximised.

What are the drawbacks of enzyme biotechnology?

Figure 2: enzyme activity increases

 with temperature up until the 

optimum – then it denatures.⁶

Okay, so enzymes aren’t 100% ideal – there are drawbacks to using them. The main one is that the 3D structure of enzymes is so fragile and thus largely sensitive to changes in temperature and pH. Figure 2 shows a graph of enzyme activity against temperature. As with all chemical reactions, the rate of an enzyme-catalysed reaction increases with temperature – up to a point. The polypeptide chains in proteins are held together by weak intermolecular forces (known as van der Waals forces and hydrogen bonds). At a certain temperature – often around 42⁰C – these weak forces are overcome and the structure of the enzyme’s active site changes. This means that the substrate can no longer bind to the enzyme, which is now said to be denatured. Denaturation is an irreversible process, so industries must regulate temperature very carefully. Note from Figure 2 how the optimum temperature of an enzyme (the temperature at which it has the highest rate of activity) is just below the point where it denatures – about 37⁰C. There is a very fine balance to be struck, therefore, between increasing the rate of a reaction and not permanently denaturing the enzymes which are catalysing it.

Sharp changes in pH also cause the denaturation of enzymes because functional groups in the active sites can lose hydrogen ions in a solution which is too alkaline and gain them in a solution which is too acidic. This means that the substrate can no longer bind to the active site. Different enzymes have different optimum pHs and so this can be harder to control than temperature.

Other issues which arise are the cost of extracting enzymes and the difficulty in reusing them. Enzymes are usually extracted from micro-organisms which are grown economically in bulk fermenters⁷. However, this is not a cheap process, and because enzymes are combined with substrates in an aqueous solution it can be costly to separate and reuse them as well.

Since the 1960s⁸ industries have employed a technique which resolves all of the aforementioned problems: immobilisation. By this method, the enzymes themselves are trapped in an insoluble material such as fibrous polymer mesh, and packed into a column through which the substrate can be continually fed. There are numerous advantages to immobilising enzymes:

·         The enzymes are more stable, so they are less likely to be denatured. This also means that higher temperatures can be used, increasing the rate of reaction.

·         The enzymes can easily be recovered and reused, making immobilised enzymes a more cost-effective method.

·         The enzymes do not have to be removed from the product and do not contaminate it.

·         Since the products are separated from the enzymes, there is no “feedback inhibition” – where products bind to the active site and prevent more substrates from reacting.

However, another issue of the application of enzymes cannot be addressed by immobilisation. In the 1970s evidence arose that proteases used in biological detergents could break down keratin in the skin and lead to skin irritation⁹. Although this has not been scientifically proven many people claim to have skin sensitive to biological detergents.

Enzymes in the future?

Over time, the use and efficiency of enzymes in industry has increased rapidly and they are now used in a diverse range of industries, from textiles to tendering meat¹⁰. Of course, there is still room for development and as research continues into how the efficiency of enzymes can be improved, enzymes will be put to new uses and new ones will continue to be discovered¹⁰. A current area of research is into enzymes which can withstand greater extremes of temperature, which would be particularly desirable in laundry and industrial processes where high temperatures are needed.

Who knows what developments the future will bring; however, it can be said with reasonable certainty that the enzyme industry is one which will continue to grow and develop.

References

1.  Life Study: A Textbook of Biology by D. G. Mackean
2. A2 Level Chemistry: The Revision Guide (CGP)
3. http://www.absorblearning.com/chemistry/demo/units/LR1507.html
4. Enzyme Biotechnology in Everyday Life by Theresa Philips
5. http://www.bccresearch.com/report/enzymes-industrial-applications-bio030f.html
6. http://www.rsc.org/Education/Teachers/Resources/cfb/enzymes.htm
7. www.spolem.co.uk/worksheets/docs/industrial_enzymes.doc
8. Carrier-bound Immobilized Enzymes: Principles, Application and Design
9. New GCSE Biology by Gemma Young and Sarah Jinks
10. http://prof.dr.semih.otles.tripod.com/enzymesused/enzymesused.htm
11. 11. Semih Otles, Professor of Food Chemistry

What's new in biology? Nanoparticles allow carefully timed cancer drug delivery

A couple of months ago I wrote my first post on the topic of biomaterials, in which I touched on the use of nanoparticles in medicine. Now a recent piece of a research has caught my eye on IFLScience: http://www.iflscience.com/health-and-medicine/nanoparticles-give-tumors-one-two-punch-timing-drug-delivery

How cool is this?! Here we have two drugs which, when taken together, will attack tumour cells: erlotinib slows the growth of the cell, and doxorubicin damages the cell's DNA and prevents essential cell processes, leading to its death. The drugs have been shown to be more effective when delivered with a carefully measured time delay. And how do they discriminate between healthy cells and cancerous cells? Simple: the drugs are delivered by nanoparticles called liposomes which bind to folate receptors on cancer cells, causing the liposome to break down. The first drug is thus released into the cell, where it primes the cancer cell for the second drug, which is administered in the same way 4-24 hours later. Experiments on mice have shown that this time delay is significantly more effective than taking the two drugs at the same time.

This is a pretty big leap in cancer treatment and one of the great things is that the nanoparticles have such specificity that they can target tumour cells over healthy cells. Applications of nanotechnology are everywhere, really.