Posts Tagged ‘Immune System’

The needle free vaccine, how Nanopatch works

// April 22nd, 2010 // 4 Comments » // How Things Work, Recent Research

Nanopatches

Researchers from Queensland University have discovered a new way to administer vaccines, a Nanopatch. Smaller than a postage stamp, the patch puts the vaccine through your skin. No need for an injection.

So how does it work?

The Nanopatch is full of micro-nanoprojections containing antigen – part of the bacteria or virus you are immunising against. These nanoprojections puncture the skin and deliver the antigen into your epidermis. The puncture is a breadth of a hair deep.

In your epidermis are Langerhans cells, members of the immune system. Their role is to pick up antigens from infecting nasties, or in this case the Nanopatch. Once they have collected something, they physically move from the skin to your lymph nodes. Lymph nodes are the hub of the immune system. Once there, the Langerhans cells mature and display the antigen to passing naïve T-cells.

T-cells are specialised cells which specifically recognise one type of antigen. It’s like a policeman with a picture of just one criminal. A naïve T-cell doesn’t have a picture yet. It collects one from a Langerhans cell and other cells in the lymph nodes. With that the T-cell matures, looking out for the antigen. Next time it sees it, it will be armed and ready.

T-cells, along with B-cells, protect you from getting the same disease twice. T-cells in particular are needed to clear infections like HIV and malaria, and needle vaccines don’t stimulate them enough. The nanopatch focuses on T-cells specifically. It gives them their first look at the disease, without the pesky side-effect of getting traumatically ill.

According to Queensland University, the latest research shows that the Nanopatch can provide a similar level of protection to a needle delivery, but uses 100 times less vaccine. The Nanopatch is still being trialed on mice.

No more screaming kids on injection day isn’t the only benefit. The Nanopatch will be cheaper to produce than normal vaccines and doesn’t need to be refrigerated or administered by a trained nurse. Lead researcher Mark Kendall said “it is easy to imagine a situation in which a government might provide vaccinations for a pandemic such as swine flu to be collected from a chemist or sent in the mail.” It would be perfect for developing countries, where administering needle vaccines can be difficult and expensive.

ResearchBlogging.orgCrichton, M., Ansaldo, A., Chen, X., Prow, T., Fernando, G., & Kendall, M. (2010). The effect of strain rate on the precision of penetration of short densely-packed microprojection array patches coated with vaccine Biomaterials, 31 (16), 4562-4572 DOI: 10.1016/j.biomaterials.2010.02.022

Catching cancer part two – HPV infection versus the face of Tasmanian Devils

// January 2nd, 2010 // 5 Comments » // How Things Work, Sex and Reproduction

Following on from yesterday’s post about the Tasmanian Devils, this is all about HPV – a highly infectious virus that can cause cancer (well, sort of. Read on.)

The Human Papillomavirus is crazy infectious – around three out of four women will have it at some time in their lives. That’s a LOT of people considering it’s transmitted sexually – ‘specially when you consider people who get married before sex and nuns and what not. It’s spread by skin to skin contact in the genital region, so a condom won’t completely protect you. Cling wrap all around the nether regions is what you need to stop this ninja virus. The stealthy, sneaky sonbich could be anywhere, including in your cells right now.

HPV infects the epidermis and can cause nothing, warts, or cancer. Most HPV just loiters around and is eventually cast out by your hard-core immune system, making you a lucky carrier! Some forms of HPV cause genital warts, an unpleasant and unattractive affliction which is nevertheless treatable. Other types are associated with cervical (and anal, vaginal and penile) cancers. Cervical cancer is the second most frequent cancer in women worldwide. 🙁

How does a virus cause cancer? Well, to put it simply, it messes with the cell cycle. Before your cell divides, it checks that things are okay – it checks the DNA for any mistakes (p53 is a protein involved in this) and it makes sure it has enough proteins to go ahead without making more mistakes (pRB is the man for this.) The virus produces two proteins – E6 and E7 that bind to p53 and pRB respectively, and inactivates them. This means your cell can replicate without the proper checks (good for the virus), leading to more cancerous changes. p53 in particular is a famous tumor suppressant, and messing with it can lead to out of control replication and chromosomal instability. In some cases, the virus DNA can insert itself into your normal DNA – then there’s no getting rid of it.

The journey to cancer takes around 10 years and a number of other cell mutations. Very different to the Tasmanian Devil face tumors in which the cancer is directly infectious. When I say “HPV causes cancer” I actually mean certain types of HPV can cause pre-cancerous changes in a cell which could one day lead to cancer. Think of it as the first mutation…

Freaked out? Well good news! There is a vaccine! Two actually, Cervarix and Gardasil protect against HPV types 16 and 18, which cause 70% of cervical cancers. Gardasil also protects against most genital warts by coinkidink. That doesn’t mean you can stop getting pap smears ladies. Still gotta do that. Sucks to be us.

This is a very cool vaccine though – in one generation of women (in the developed world they immunised at the age of 12, hope it’s available to developing countries as well), we could eliminate 70% of cervical cancer cases. That’s freaking fantastic! Oh, and HPV isn’t the only virus that can lead to cancer. Hepatitis can cause liver cancer, and Epstein-Barr Virus, lymphoma. We’ve got vaccines against Hepatitis viruses too!

A parting tip, swanky statistics available from WHO. And don’t type HPV into google images. Not cool guys… not cool.

Chemistry of Kissing

// July 18th, 2009 // 9 Comments » // How Things Work, Sex and Reproduction

In the words of Henry Finck, “is not a kiss the very autograph of love?” Well, some kisses are better than others Frinck, and it can be hard to tell who’s gonna be good and who’s not. The one who seems perfect on paper can be absolutely shocking in the lips department, while the bad-for-you going-nowhere person can make you weak at the knees after a mere second of lip action. Why the difference?

If you think about it in terms of biological selection, a kiss is a pretty important thing. It’s a selection factor, ‘cos you probably wouldn’t stay with someone who was a crap kisser, and I bet you wouldn’t either. Now, within my friendship group there’s been quite a bit of cross-dating (or whatever the term is) over the years, and I can tell you that the people I think kiss great do not always get the same ruling from my friends. Some couples have chemistry, and some just don’t.

WHY? What are we tasting on their lips? What in a kiss is so important that it is given a make-or-break status in choosing a mate?

The best theory around is that a kiss gives you information (though taste and smell) about the other persons immune system on a genetic level, in particular the MHC complex. Let me tell you the story.

In the dark and murky depths of chromosome six lies a section of some four million nucleotides, genetic material that encode for MHC’s – major histocompatibility complexes. Histocompatibility being a historical term, as it was first identified as determining which blood type you have – A, B, AB or O. The section of DNA on chromosome six encodes for a whole bunch of different MHC molecules, and the alleles are codominantly expressed – meaning you make both the maternal and paternal products.

mhc-1-1

Behold MHC molecules, there be the peptide binding cleft and there the transmembrane region that acts like an anchor, yarr!

MHC Class 1 molecules are expressed constitutively in all nucleated cells, while Class 2 molecules are expressed only in special antigen-presenting cells of the immune system, like dendritic cell, macrophages and B cells.

mhc-1-2

mhc-1-3

Your body can be a bad neighborhood, so police natural killer cells and other members of the immune system drive by frequently to check the ID of your cells, to see if they are terrorists infected or cancerous. If an MHC protein is visible and is only expressing self-proteins, the cell can live another day.

mch-2-1

Now let’s say a cell gets infected by a virus, which pokes in some genes of its own so it can hijack our replicative machinery, much like a pirate commandeers a ship to make booty.

mch-2-2

Virus oh noes ensue.

mhc-2-3

mhc-3-1

Caught red-handed holding non-self proteins, the cell is told to kill itself quietly (apoptosis), or is ruthlessly killed by the immune system in a dramatic action sequence worthy of Schwarzenegger.

Of course, it’s a little more complicated than this. Instead of just two MHC’s on your surface, you have heaps (it took too long to draw!) The MHC region of the genome is extremely polymorphic, and the goal is to have as many different versions of MHC possible, both in your own DNA and across the species. The more variety there is, the more likely someone out there will have what they need to survive HIV or H1N1 or any of the other freaky viruses that get us worried now and then.

So what would happen if your parents ignored the signs given to them by the almighty kiss, and you don’t have much variety in your MHC’s.

mhc-3-2

mhc-3-3

The virus slips past the immune system like a ninja, will replicate and spread, and you’ll get sicklier.

So when we kiss someone, we’re really just saying “Hey, how’s your MHC compared to mine? Ooh… you taste different… MAN our kids will have kick-ass immune systems!” Opposites certainly attract in this case.

How was the discovery made? They got men to work out, and then asked women to smell their sweaty shirts and pick which one smelled better, and then they ran genetic tests. Women were more likely to dig the stink of a guy whose MHC was very different to her own.

It’s interesting to note that women on the pill are more likely to choose the WRONG PERSON in these tests, possibly because their body thinks it’s pregnant and it’s a bit late to go choosing a mate based on genetics. This could be a contributing factor to divorce – people hook up when the woman is on the pill, they get married, she stops taking it to become pregnant, and suddenly they lose their chemistry. Something to keep in mind.

So go out there and kiss! Sample the MHC molecules around you, and run your own genetic screening! Albert Einstein himself said “any man who can drive safely while kissing a pretty girl is simply not giving the kiss the attention it deserves.”






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