Michael Yancey - Dr. Ting Cong - Week 5

Regarding the femoral head impaction grafting project, we are finished with physical testing and data analysis. Dr. Cong and I have begun writing a manuscript about the project. I specifically am responsible for writing methods and results for the mechanical testing and 3D analysis performed. Much of what I discuss in these sections has been covered in my previous posts, but in summary, I am reporting the following:

  • Defect volumes of the femoral head after simulated failure, repair, and compression of the repaired site.
    • The primary result is that the defect volume after compressing a repaired defect site is approximately 25% of the defect volume after compressing the same site before repair.
  • Linear displacement of the defect site following compression after simulated failure and compression following repair.
    • The primary result is that displacement after compressing a repaired defect site is approximately 50% of the displacement after compressing the same site before repair.
  • Modulus of elasticity of the defect site for 10-100N and 600-800N ranges both after simulated failure and compression following repair.
    • One interesting result is that the modulus in the 600-800N range, the linear stress-strain region of the femoral head defect site, is the same for both repaired and unrepaired defect sites.
    • This modulus is significantly less than previously reported moduli for femoral head cancellous bone. This may be due a combination of osteoporosis in the cadaveric femurs and the morcellation process of bone in the defect site.
    • However, modulus in the "toe region", defined for our purposes as the stress-strain slope in the 10-100N range, is four times greater, on average, in the repaired sites compared to unrepaired defect sites. 
    • I theorize this is because impaction grafting chain-milled bone into the defect site fills previously empty space, preventing much of the low force displacement that occurs due to gaps between morselized bone. However, beyond that initial displacement, stiffness/moduli is still limited by the morselized bone stiffness in the defect area.
---------------------------------------

For the Khormaee lab and the alginate gel project, I primarily worked image analysis methodology for widefield images of stained mesenchymal stem cells in alginate gels on a titanium substrate. 

One of the major challenges for this methodology was how to properly threshold what regions of the image were cells or just gel. This was a particular challenge for these images because the image's color changes dramatically, becoming darker closer to the titanium substrate. Depending on the chosen threshold, you essentially either include false positives by considering lighter portions of the alginate gel to be cells so that you capture all cells, or false negatives by excluding cells in the darker portion of the image. To solve this problem, I first perform a localized contrast filter, which emphasizes regions where image intensity changes dramatically. This normalizes the color of the image regardless of distance from the titanium substrate and, after smoothing filters, allows for easily thresholding cell areas for the purposes of cell counting.

--------------------------------------

There were no additional clinical experiences this week. However, Dr. Cong and I have coordinated attending multiple surgeries with Dr. Joseph Lane over the coming weeks before the immersion term is complete.

Comments

Post a Comment

Popular posts from this blog

India Dykes - Dr. Spector - Weeks 7 & 8

Image
 For the last two weeks of immersion I wrapped up the bioprinter conversion project and spent some time in Dr. Spector's clinic for office hours. In the clinic, we observed an eyelid lift consultation and a liposuction patient follow-up. We also saw a patient who had a large abdominal hernia that had been increasing in size over the past 4 years that needed to be repaired. Dr. Spector showed us the MRI of the hernia that showed the intestines extending beyond the abdominal wall. In the lab I successfully completed the bioprinter hardware build which included customizing several iterations of prototypes before finalizing the design and flashing the custom bioprinter firmware onto the Prusa board. In the future the bioprinter will be used in Dr. Spector's lab for 3D printing custom collagen breast cancer models and vascularized adipose tissue platforms.
Read more

Cory Knox - Dr. Liston - Wk8

My final week at immersion consisted of wrapping up surgeries with Shane, analyzing the data collected from the pilot Novelty Induced Hypophagia study, presenting my work amongst my peers and the immersion administration, and going to some of my final NYC bucket list locations.  The surgeries all went well and I was able to help Shane set up for his last few behavioral studies needed for the supplementary figures in his upcoming publication. We found that our pilot study was only effective on male mice, so 15 more males had to undergo fiber optic implantation to generate a well powered assay for later on. I am very thankful to Shane for teaching me so much this summer. The presentation also went well. It was interesting to see what my peers were doing this summer and I was excited to share the experiments that Shane and I had been working on.  I was also able to use the final week as a chance to visit some places in NYC that I had put off. It was very fun going to the Bronx zo...
Read more

Harry Zou Week 8

My last week was a busy week, both on the clinical side and also on the research side. I shadowed in the clinic and also in the hospital. On Wednesday, I shadowed a pulmonologist, Dr. Meredith Turetz in her practice. In her practice, Dr. Turetz mostly sees patients with bronchiectasis as well as asthma. The first patient came in as a follow up for severe asthma exacerbations and Dr. Turetz prescribed Symbicort, a medicine that she liked since it had both a fast acting component in a steroid as well as a long acting component in the bronchodilator. In between patients, we also had an interesting conversation on the changing landscape of asthma medication with more biologics being approved now. She also saw a patient who had bronchiestasis as well as a previous non-tuberculosis mycobacteria (NTM) infection. It was interesting to me to learn that even though the airways look dilated in bronchiestasis, the flimsy nature of the airways causes them to collapse resulting in restricted breathi...
Read more