Metals in Artificial Joints

In my Inorganic Biomaterials class this semester we learn about different materials that have applications in medical devices and how they are used. I’ve learned about metals, ceramics, and composites and how they are processed to improve how they work in the body. We have learned a lot about metals because they are one of the most widely used materials in implants and we’ve recently been focusing on artificial hips. These artificial joints are usually made of a combination of materials with the stem constructed out of titanium or cobalt-chromium. For hip joints the round head is usually cobalt-chromium or ceramic, and the cup that it fits into is made of a polymer, although some are metal or ceramic.

Artificial Hip

The stem is made of metal in all artificial hips to make sure that it is strong enough to withstand the forces in the joint. The problem is that metals are too strong. The metal stem is stronger than the bone that it is implanted into, so it will tend to take on most of the forces that are applied to the joint. The problem is that bone is a living material and when it doesn’t feel the compression forces it normally would it begins to weaken. This can cause loosening as the implant separates from the bone. So, contrary to what you would think, we  actually want metal that is weaker so that it better matches the natural properties of bone.

Bone and MetalAnother problem is that metal and bone have very different structures. The smooth surface of metal is nothing like the porous structure inside our bones. Osteoblasts, the cells that make bone don’t attach well to the smooth surface of metal, so bone won’t grow around the implant to hold it in place. To change this people have developed different ways of added metal coatings to implants that look more like the structure of bone. The osteoblasts like this surface better than the normal smooth surface, so the bone is more likely to grow around the implant, holding it in place and making it more difficult to dislodge. The picture on the right shows bone (left) growing on Trabecular Metal (right) which has been engineered to mimic the natural structure of bone.

Basically, scientists are working to try and make the metal in artificial joints more like bone so that the body responds better to it.

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How Chemotherapy Drugs Work

In my Cell Biology class we recently had a discussion about a scientific paper called: Phosphorylation of Mcl-1 by CDK1–cyclin B1 initiates its Cdc20-dependent destruction during mitotic arrest. That’s quite a mouthful, and as a scientific paper it’s pretty complex and difficult for the average person, but it offers and explanation for how many chemotherapy drugs which are used to treat cancer are actually able to kill the cancer cells. That may sound pretty basic, but we have actually been using these drugs without really understanding how they kill cells. We have known that these drugs (including Taxol, Nocadazole, Vinblastine, and Vincristine) limit the normally dynamic nature of microtubules, which are usually constantly breaking down and rebuilding in different ways to allow changes in the cell, but didn’t know why this made cells die.

The rearrangement of microtubules, which act as a form of structural support within the cell, is most important and dynamic during mitosis (cellular replication) when the microtubules help ensure that the DNA is separated properly between the two new cells. The picture above shows how microtubules (green) have to rearrange in the different stages of cell division (going from a to f) to properly separate the DNA (blue). When dividing cells are treated with these chemo drugs, their microtubules aren’t able to rearrange and help the chromosomes align and separate properly and they get stuck in mitosis. Scientists knew that this happened, but not how that would cause the cells to die.

This paper identified a protein (Mcl-1) which acts as a timer during cell division, if the cell takes too long to divide the protein signals the cell to die. Mitosis was not thought of as a timed process, it continues for as long as it takes until the DNA is properly divided and the two new cells separate. This shows that when something goes wrong and the cell becomes stuck, like when treated with these types of chemo drugs, it will go through a controlled death process. Since cancer cells are dividing at a much higher rate than normal, healthy cells, mostly cancer cells are affected.

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Cell Video

Over the years I’ve taken a lot of different Biology courses and in many of them I’ve watched the same animated video of a cell. The first time was in my high school AP Biology class where we would ask the teacher to watch it at least every other week. When I got to Lehigh and started my first college Biology class the professor played the exact same video and a lot of my other bio classes since have also shown it or clips from it.The Inner Life of the Cell

It’s called “The Inner Life of the Cell” and was made by a company called XVIVO for Harvard University’s BioVisions. Basically its a really cool video, even if you don’t know whats going on in it, that shows different mechanisms inside the cell that allow a white blood cell to sense and respond to changes in its surroundings. It has cool animations with beautiful background music. In high school, that pretty much why we wanted to watch it, but as I’ve gone through more Biology classes I’ve learned more about what the video actually shows. We watched a clip recently in my Cell Biology class after we learned about how microtubules ( a protein structure inside the cell that helps support it and give it its shape) assemble. That’s this part:

Microtubules in The Inner Life of the CellLater, when I rewatched the video, I realized that I actually understand a lot about what’s going on in the video now. I can appreciate it for the science that it rather than just the interesting visuals and nice music.

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Founder’s Day

Since we just passed the midpoint of the semester I have been very busy, which is why its been a while since my last post. First we had pacing break and then I was busy with midterms and presentations, but now things are settling back down again. Last week was very busy for me with two tests along with my IPD (Integrated Product Development) midterm presentation all over the course of 3 days. So when I finally finished my presentation on Friday, I was excited to be done with everything and get to enjoy my weekend.

It also happened to be Founder’s Day, which is when Lehigh celebrates the founding of the University in 1865 by Asa Packer. I went to the ceremony which is in the Packer Memorial Church on campus. They honor student leaders, faculty, and donors along with Asa Packer. Afterwards everyone moves to the lawn in front of STEPS where the Marching 97  (our marching band) plays while you eat free food. You also get a free shirt for attending.

It was a nice way to start the weekend after a long week, but it was sad to realize that it would be my last Founder’s Day at Lehigh. I’m glad I got the chance to enjoy it.

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Bioengineering Labs

Each of the three different bioengineering tracks here at Lehigh has an upperclassmen lab requirement where you learn the different techniques relevant to that track. For the Biopharmaceutical track its the Integrated Biotechnology Lab (BIOE 343), the Bioelectronics/Biophotonics track has the Integrated Bioelectronics/Biophotonics Lab (BIOE 331), and for the Biomechanics and Biomaterials track we take the Integrated Biostructural Mechanics Lab (BIOE 357) which I took last semester.

That sounds really complicated, but in it we learned how to culture mammalian cells and some other basic techniques for testing and analyzing them. Its a three hour lab that you have twice a week up on Mountaintop campus, but it was one of my favorite classes because we got to do hands-on work. Since its a class of only about 10 people for 6 hours a week, we also got a chance to really get to know some of our fellow BioEs.

Immunofluorescence stained cell

This is one of the best pictures from that lab. We did a lot of immunofluorescence staining, that’s when you use an antibody that has a tag on it that glows when you hit it with a specific color of light. The antibody would bind to some specific molecule that we wanted to look at and glow, so we could see where that molecule was in the cell. The green are actin filaments, structures that provide structural support to the cell. The blue is the nucleus and the red are focal adhesions, where the cell attaches to the surface that its sitting on.

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S’mores and Aliens

Lehigh University Joshua Pepper

Joshua Pepper

On Tuesday night, the Gryphons (Lehigh’s version of RAs) for Campus Square (the on campus apartments I’m living in) hosted the Search for Extraterrestrial Life Under the Stars. An astronomy professor, Dr Joshua Pepper, came to talk to us about his work in looking for planets that could support life while we made s’mores. Every so often the Gryphons organize these kinds of events so that you get a chance to get together with the people living in your building and get more involved in the community. They also usually have free food.

It was interesting to learn about something completely different that’s going on at Lehigh that I probably never would have heard about otherwise. We talked about how they look for planets that are Earth-like and could therefore support life of the kind that we’re used to. These are planets that we won’t be able to reach in the foreseeable future, but with telescopes we can learn more about them and if life could exist there. It was a nice change of pace, especially during exam time.

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Celtic Classic

Believe it or not, Bethlehem is home to the largest free Celtic festival in North America. My parents came up this weekend for the third year in a row so we could go to Celtic Classic. It takes place around this time every year right on the other side of the river. The festival includes the US National Highland Games Championship, which is basically a bunch of very strong men in kilts throwing really heavy things. Its a lot of fun with Celtic music, dancing, and lots of kilts. My parents were even talking about how they’re planning on coming back next year even though I’ll have graduated.

We spent most of the weekend going between the 6 different stages to listen to music. I also watched some bagpipe bands in the opening ceremony, a few of the Highland Games competitions (throwing cabers, stones, and a bale of hay using a pitchfork), and the Border Collie herding demonstration. Over the course of the year there are a few different festivals in Bethlehem and it can be a nice break from homework and studying to spend a few hours enjoying the music and events.

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