Strong Hydrogels for Osteochondral Regeneration

This article deals with polymer hydrogels developed for biomedical engineering applications, especially cartilage and osteochondral interface regeneration. The hydrogels were reinforced by a strong fibers of an epoxy-amine, createdin a matrix using three dimensional printing. A resultant gel was made in the fiber matrix, and physical properties tested to compare to that of natural cartilage. With this approached, modulus values for the gel did meet the values for natural cartilage, which is a very markedly important factor, as many unreinforced hydrogels can not meet these standards.

I originally read the article from a different source, which required a membership and I only have the original paper in a pdf form, which I cannot figure out how to add here, but if you wish to read it please contact me and I will get it to you. Below is a link to a more concise overview. The article I read also went into some very interesting physiological mechanisms that can be accomplished by varying the chemistry of the gel, including improved cartilage regeneration.

This is very interesting to me as I am currently doing research regarding regeneration of the osteochondral interface, and see the need for a real solution for the many many thousands of individuals that suffer joint damage and arthritic symptoms.

http://ieeexplore.ieee.org/xpl/articleDetails.jsp?arnumber=5778724

The Family and Functions of Nebulin

In myofibrils, there are many proteins which combine and work together en masse to contract muscles, e.g. actin, myosin, and tropomyosin. One such protein is nebulin, which constitutes a family of proteins of a common characteristic (a series of repeating 35 amino acids) with a variety of functions.

Nebulin, nearly four times the size of the next contender in its family, is the most commonly known. It has been labeled for decades as a molecular ruler which determines the length of the associated actin filaments. However, recent studies suggest that nebulin does not specify a certain length that the actin must adhere to; rather, the nebulin acts as a regulator and stabilizer of the actin filament’s length. Its loss has contributed to larger Z-disc widths and decreased force production from the affected muscles.

N-RAP, or Nebulin-Related Anchoring Protein, is the next-longest but not as interesting. It is found in striated muscle and plays its major role in assembly of myofibrils and actin filaments in the sarcomeres.

Nebulette is about a sixth of nebulin’s length but is found only in cardiac muscle. At first, nebulette was thought to be the “functional counterpart of nebulin in heart muscle.” Despite its comparatively small size and localization to the Z-disc, nebulette does function to stabilize the actin filament like its brother. Its superiority to nebulin in cardiac muscle has been attributed by the paper to tropomyosin’s dependence on nebulette for stability of the thin filament. In fact, mutations of nebulette’s gene have correlated with DCM (dilated cardiomyopathy) in both mice and humans, those in mice leading to severe heart failure.

The two final family members, LASP-1 and LASP-2 are similar in domain structure, but have different effects on the cell. Unlike LASP-1, LASP-2 may localize to different parts of the cell, including the Z-discs and adhesion between cells. “It has been speculated that LASP-2 acts as a molecular scaffold that is important for actin filament and focal adhesion stabilization and organization.” LASP-1 has had different roles throughout different studies, its loss contributing both to decreased rates of cell migration and proliferation as well as increased rates of cell migration and concentration. The discrepancy is explained by the authors as “reconciled by the fact that the LASP-1 depletion studies represent transient, incomplete reduction of LASP-1, whereas the LASP-1 knockout mouse is a chronic, complete loss of LASP-1.” A lack of LASP-1 has been suggested to increase the cell migration and number of tumors in breast, ovarian, and liver cancers, contributing to its role in cell signaling, whatever it may precisely be.

Nebulin and its family members are important constituents of muscles and contribute heavily to our homeostasis. They are an interesting topic chiefly for their impact on the material that will be on the next test, but also because of the specifics of their functions that are not so widely known.  

Citing URL source: http://www.sciencedirect.com.lib-ezproxy.tamu.edu:2048/science/article/pii/S0962892410001996

A Cellular Memory Mechanism Aids Overload Hypertrophy in Muscle Long After an Episodic Exposure to Anabolic Steroids

This article goes in depth about the biological mechanism in which muscle fibers respond to some sort of strength training or steroid use. Researchers have found that having a previous history of anabolic steroid use has lead to a greater increase in muscle mass after periods of inactivity. They contribute this to the idea of "muscle memory", essentially giving cells a head start on a process they are already familiar with. An explanation that they have proposed is based on the fact that muscle fibers have multiple nuclei, these myonuclei increase in number with the enlargement of muscle mass. When going through periods of inactivity, muscle mass decreases, but the number of myonuclei remain the same. The increased number of myonuclei contributes to the cells muscle memory when undergoing subsequent muscle hypertrophy.

These experiments were run by implanting a testosterone pellet in the skin of the neck of female mice. 14 days after implantation, the number of myonuclei increased by 66%, increasing the muscle fiber cross sectional area by a whooping 77%. The mice strictly subjected to vigorous exercise only saw an increase in myonuclei by 51% and a 48% rise in cross sectional area. Less than a week after removal of the testosterone pellet, the level of testosterone in the blood was nearly undetectable. 3 weeks after removal, the muscles were analyzed. The muscles showed a 41% retention rate of the myonuclei. During subsequent overload exercise, the previously exposed testosterone group showed a 27% greater increase in muscle mass in comparison to the control group.

This article is appealing to me because I enjoy learning about health and fitness related topics. I also want to encourage people to get out there and be active! These are your prime years, might as well take advantage of that. Hope anyone who reads this thought it was as interesting as I did.

Here's the link to the article:
http://jp.physoc.org/content/early/2013/10/28/jphysiol.2013.264457.full.pdf+html

Study: Light enhances brain activity during cognitive task even in blind people

Researchers at the University of Montreal have discovered that light will stimulate brain activity even in patients who are completely blind. According to one of the researchers "Light doesn't just allow us to see, it tells the brain whether it's night or day which in -turn ensures that our physiology, metabolism and behavior are synchronized with environmental time". Brains can “see” light via a photoreceptor in the ganglion layer of the retina that is different from rods and cones. These specialized photoreceptors contribute to visual function in the brain even when other receptors have lost their ability to function properly. Tests were performed on blind patients involving blue lights that were adjusted between an on and off functions. Every time the patients had the ability to recognize that the light was on. After these physical tests were performed, a series of electrical tests were used to assess brain activation in accordance to light. The results were the same; the brain reacted to a stimulus of light. Further research is still underway but theory may explain why the brain's performance is improved when light is present during tasks. I found this article somewhat applicable because my aunt is completely blind but whenever she went outside she would always comment on how bright the day was outside causing me to be somewhat confused, because how could she possibly know if it was brighter or dimmer outside? Now of course, the research has not gone into enough depth to recognize if a blind person can recognize brighter lights compare to others but it was interesting to find out that blind people can in fact recognize daylight and their body will respond to it.