Week 6 and 7

Druing week 6 and 7, I was able to see most interesting and longest surgeries one of which took about 16 hours. The most interesting case was glossectomy which is removing a tongue tumor from a patient's mouth. A patient was 66 year old male who was heavy smoker. Smoking can cause not only lung cancer but also tongue, oral, and trachea cancers. To eradicate the tumor, formerly radiation was treated to the tongue of the patient. However, due to the radiation treatment tongue was seriously swollen so the patient could not move tongue properly, which means swallowing and speech was partially impaired. As the first surgery, mandible and lower jawbone was completely opened and neck was also dissected to remove tongue with tumor. In this case, entire tongue was excised since tumor was internally located at the bottom of the tongue where main blood supply flows through. Even if partial tongue tissues can be saved from tongue tumor, they will not be able to survive without main source of blood supply, the bottom part of the tongue. The picture on the right is a huge tongue specimen from the patient. After taking out tongue, the space on the bottom of the mouth is filled with a lower part of pectoral muscle and the upper part of the muscle with skin was used for neotongue. The first two pictures below indicate front part of pectoral muscle with skin and back side of muscle. The second picture below shows a neotongue made by the front part of muscle with skin.
This neotongue is mainly for aesthetic purpose and partially for functional purpose since the patient will not be able to chew, swallow and speak for a while. Once he gets physical therapy, his mobility of the pseudotonuge can be trained and partially recovered. Even if neotongue cannot move as much as normal tongue can, donor blood vessel and muscle of the neotongue will provide better blood supply to the defect site and better blood supply helps wound healing and protect tissues from potential damage from subsequent radiation. After surgery, I saw the patient during clinical round and his pseudotongue looked as great as original tongue even if still it need to be trained. I believe that both of two surgeries were really great examples to indicate how important blood supply is for tissue to survive and how broad spectrum is for plastic surgery to cover. Plastic surgery can reconstruct from a tiny nerve to the entire our body using either endogenous tissue or biosynthetic material. However, in terms of better blood supply, endogenous tissue still works better than engineered material so this is one of the engineer’s challenges to overcome.
In addition to clinical experience, I tried to finish up my project. As I discussed my project before, I had to find suitable biodegradable material for covering 3-D fluidic vascular network device based on melt-spun sugar fibers (cotton candy). As a simple trial, I tried to make device using a couple of material that I could easily get. For the first trial, I used RGD-modified alginate cross-linked with CaCl2 and made hydro-gel that could cover 3-D cotton candy capillary network. Lower concentration of RGD-modified alginate gel was too soft to keep its shape and let sugar based networking device dissolved away. Thus, I tried to make different stiffness of hydro-gels via changing concentration of RGD-modified alginate to let the shape of 3-D capillary network to stay as it is. While I was trying to make a device using hydro-gel I searched literature relevant to biodegradable material where cells can adhere. Also, I was given a new clinical project additionally which is investigating how successfully “vascularized muscle flap salvage” following bypass or femoral artery surgery were done so far. To pursue this project, I need to get patients' information first so it may take some time to figure out getting an access to patients' information such as patients' pre and post conditions after surgery. While my mentor finds a way to let me get the data, I will get some background information about vascularized muscle flap salvage after bypass or femoral artery surgery via literature search.
I can not imagine how fast time flied by and it is already the last week to get a clinical experience. I have had a great time and I am sure that all of what I have observed and acquired during this program will help me not only pursue my research more creatively and effectively but also make my life more valuable. Also, I hope how we have done in Weill medical college will help next year' Cornell BME Ph.D students to get much more valuable experiences. Lastly I really thank for Dr. Spector, Dr. Frayer, Dr. Wang, Belinda and last but not least Claudia Fischbach to help me to have a great opportunity in Weill Medical College. I really thank for everybody who supports this awsome program and I will never forget 2009 summer in Weill medical colloege.

Week 5

During week 5, most of surgeries were related with hernia which is a protrusion of tissue or part of an organ below the muscle tissue which cover them. Thus, abdominal hernia patients has bumpy intestinal wall, which makes their abdomen uneven. It can result from various reasons such as overweight, being too skinny, weak abdominal wall, and pregnancy. Even if the reasons are various, most reasons cause higher pressure to the abdominal tissues or organs and press them too much. Or weak abdominal wall is too weak to sustain the organs and tissues properly. That is why the tissue and organ are pressed down and transform to a bulky shape. Thus one of the common methods to correct hernia is covering the bumpy area with flattened mesh. Fascia which is connective tissue covering intestinal well is connected to the mesh and they fascia and mesh play role as a covering layer to the organs and tissues. Usually “Prolene mesh” is widely used and helps pressed-down organs and tissues keep stay and abdomen look flat. However, prolene mesh is synthetic polymer so cells and blood vessels cannot grow on the top. Even if this patient took antibiotics, the blood vessels could not go through the mesh and antibiotics also could not reach to the mesh. Thus, this caused infection. Infected mesh and intestinal well muscle were debrided and muscle or soft tissue graft has to be done. Through this, I re-realized that how important blood supply is for giving nutrients and oxygens for cells as well as deliverying drugs such as antibiotics to prevent infection. Also, blood supply is a key point to eradicate tumor as I am interested in tumor angiogenesis. Here is the point that I can interconnect this clinical experinece and my research. Soft tissue is usually used to replace the defect parts since soft tissue such as adipose tissue is well-known to help angiognesis. Also I have seen interplay of cancer cells and adipose tissue has a synergistic impact on tumor angiogenesis. It was a good time to interconnect my research and clinical experience.