No door? No problem. T. cruzi uses the window to cause Chagas Disease

For invasive pathogens the only way to survive, and consequently make you sick, is to get inside your cells. This is a rough exercise as you have an immune system working everywhere in the body to prevent this and the cell to be invaded is none too happy with the idea either so invasive pathogens must use tricks.

After evading or surviving the immune system, another post for another day, some exploit a mechanism called receptor mediated endocytosis (RME), in which the pathogen binds to a receptor on the cell triggering the cell to alter its shape to internalise the pathogen. RME is used by cells to recycle extracellular components but it a pathogen can make itself fit the receptor instead it can trick the cell into giving it free access to its insides.

Another mechanism, commonly employed by membrane bound viruses, is membrane fusion. Given that membrane bound viruses contain a secondary structure called the nucleocapsid, which houses the genome, they can fuse their own membranes with the host cell which results in the nucleocapsid's release into the cytoplasm.

(a) HIV entry by fusion and (b) receptor mediated endocytosis of light blue dots ((a) modified from credit and (b) modified from credit

Treating the Bends

Last week I wrote about the Bends, a medical problem based in an understanding of physics that results in bubbles of (primarily) nitrogen in your blood if you move from one atmospheric pressure to another to quickly, typically surfacing from depth while diving too fast.

Of course I meant to point out that decompression occurs when the external atmospheric pressure drops quickly. Most commonly this occurs in divers but also happens in astronauts. I’d never really thought about that before.

Anyway I got as far as explaining how it occurs last time. This time we are interested in how you fix it.

Physics + Medicine = The Bends

About a fortnight ago I was in the unusual position of teaching human biology to medical physicists and physics to medical students. Interestingly, during this overlapping week a disease came up in both tutes, a physics based medical condition.

Zombies Pt 2 (or how I distracted my students)

Last week I mentioned how my students sidetracked me in a tute regarding introductions to the origins of life and in particular the acronym HOMR standing for Homeostasis, Organisation, Metabolism and Replication by initiating a discussion of whether or not zombies technically were alive. Well, the following week they had a test that occupied half the allocated tutorial time so instead of letting them out early I extended the discussion to real world zombies.

Zombies Pt. 1 (or how my students distracted me)

As I mentioned a little while ago I have been made an associate lecturer for first year biology at the University I have been doing my PhD at. Most of my job is taking tutorial classes and the other week during one of these classes I got totally distracted by a very interesting discussion.

(Merry) Christmas Disease

So I was feeling a little lazy and thought I should find a disease related to Christmas, that way it’d be topical and I’d look like a genius. Well maybe not a genius, as all I did was type “Christmas” and “disease” into google and it returned “Christmas disease”. Don’t worry though, the disease itself is pretty cool!

Contrary to popular belief Christmas disease is not limited to public drunkenness

Sickles, blood disease and the Greek god Priapus

I saw the Carnal Carnival was coming up and this month’s theme is Blood. Blood disease, that shouldn’t be too hard I thought.

So I started thinking about blood diseases and remembered a disease I learnt about in undergraduate genetics classes called Sickle Cell Anaemia.