BME 262 Biomaterials Yeditepe University Spring 2009 by pptfiles


									BME 262 Biomaterials Yeditepe University Spring 2009 Prof. Dr. A. Cüneyt Taş
Exam-1 results & answers

Collagen and Keratin are two of the most common biopolymers found in mammalians.
We have underlined these two biopolymers in classes starting from the very first day of this semester.

The definition of BIOACTIVITY was one of the questions of Homework-1.

The effect of a given agent, such as a vaccine, upon a living organism or on living tissue
The biomaterial itself must exert the above-mentioned effect on its surrounding tissues or surrounding organ. Bioactivity does not mean the growth of cells on the surface of the biomaterial. Cells could grow on numerous biomaterials which are not bioactive at all.

Osteoclasts ERODE the hard tissues.
Osteoblasts DEPOSIT new hard tissue exactly on the spots eroded by the osteoclasts. Bone remodeling is necessary to keep the bones fresh, healthy, and alive. The term “bone remodeling” implies the erosion of bones and deposition of new bone, continuously, on a daily basis. Bone remodeling is also named as “bone turnover.”

Bone remodeling is stimulated and initiated by biomechanical loading, again on a daily basis.

Bone graft materials obtained from cadaver are called ALLOGRAFTS. 1.) Infection, 2.) Bone tumors may be transplanted if the surgeon chooses to use bone grafts from cadaver. These are called the RISKS. This does NOT mean that every allograft could cause infection or the transfer of bone tumors from the cadaver to the patient. These are only risks involved in such practices.

Bioresorbability of a given biomaterial should be tested by using the osteoclast cells. These cells perform the in vivo resorption process. This was mentioned in class.

If a metallic biomaterial is causing severe inflammation upon implantation, one must first suspect its chemical composition.

If that metal contains known toxic elements, upon dissolution of those elements (following implantation) from the surface of the metallic implant, this may cause that inflammation.
To determine the chemical composition (i.e., weight percent of elements present in it) of a metal, the best way is to use ICP-AES (inductively-coupled plasma atomic emission spectroscopy) analysis. One can also use AAS (atomic absorption spectroscopy) analysis.

Aragonite, CaCO3 (nacre)
The below morphology is responsible from the observation of iridescence.

Aluminum alloys are metals, and bonding in such alloys is metallic bonding. However, in spider silk the bonding is covalent (just like the bonding in diamond).

Mineral of human bones and teeth:

Calcium hydroxyapatite

Three upper layers of teeth:

Dentin Pulp

Biomimetic interface (from Homework-4):

biomimetic and synthetic interfaces which intend to mimic cellular membranes

The main problem associated with the MR scans in USA:
Doctors are ordering their patients too much of poor quality MR scans, which are not able to clearly show the problematic spots On top of this; health insurance companies are readily paying the costs of such unnecessary MR scans Doctors in USA started to own their MR scan labs, since this became a very good business!! Source: The International Herald Tribune article in

Unit cells come together to form the crystal lattices

Silicone is a POLYMER

Silicon is a METAL

2nd World War times, (esp 1941-1944) shown are blood plasma sets used by British and American armed forces..

400 mL-capacity cans.. One contained distilled water and the other has the dried blood plasma. Upon mixing the two, in about 3 minutes, plasma would be ready to use.. Only until the end of the war, doctors realized that blood plasma would not differ from one race to another. During the first 4 years, injured soldiers were sacrificed while waiting for the blood plasma from their own “race....”

Segregated Blood Throughout WWII and afterwards the American Red Cross maintained a segregated blood supply. Not only was blood segregated by "White" and "Colored", but the "White" blood was further segregated into "Christian" and "Hebrew." President Eisenhower ordered that the national blood supply no longer be segregated. The Red Cross was one of the major forces opposing the merging of the blood supply. The head of the Red Cross told Eisenhower that the South did not want any mixed blood, producing Eisenhower's famous reply, "OK then the South won’t get any blood!”

Sources: 1.) Blanch Weisen Cook, C-SPAN 3 History, September 28, 2007

2.) M. G. Kenny, “A Question of Blood, Race and Politics,” J. History of Medicine and Allied Sciences, 61(4), 456-491 (2006).

The very first, well-documented blood transfusion was performed in 1492 on “Pope Innocent VIIII,” just before he would be embarking a new Holy War against the Turks. The blood of three ten-year-old boys (all sacrificed) was infused to the Pope, but he also died within a short while like those poor boys, perhaps due to the air bubbles introduced into his veins by his Jewish physician.

Source: G. A. Lindeboom, J. of the History of Medicine, 455459, October 1954.

Blood plasma essentially consists of water, inorganic electrolytes and blood proteins (such as, fibrinogen, globulin, serum albumin, etc.).

Plasma that is free from the clotting factors, such as fibrin, is called blood serum.

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