Tuesday, June 9, 2015

Cobalt speeds us up and slows us down

Cobalt is a relatively hard and brittle metal used to make fancy magnets and typically found along with copper and nickel in the Earth's crust. It's silver-white in appearance, but when combined with aluminum and oxygen it forms pretty blue compounds such as cobalt blue. Owing to its various effects on the human body, our lives can intersect with cobalt in many ways. One of the things the metal or molecules that contain it tend to do is alter our mobility, speeding us up or slowing us down.

Blood doping

Cobalt salts such as cobalt chloride can apparently be used to boost athletic performance. When dissolved into our body liquids, cobalt ions activate a molecular pathway that is otherwise turned on when our tissues aren't getting enough oxygen (i.e. hypoxia). This pathway leads to increased production of the protein erythropoietin (EPO), which in turn acts to increase the number of red blood cells available to move oxygen around our bodies (erythropoiesis). So cobalt essentially tricks our body into making more red blood cells. While cobalt salts have been explored as a means of treating anemia (not having enough red blood cells), it appears that some athletes and horse trainers are using it to try and gain an advantage. The deliberate enhancement of red blood cell numbers for purposes other than healing is known as blood doping. This can facilitate things like running really fast or far by ensuring there is more oxygen to support the involved muscles. As it hasn't been well studied, it's not clear exactly how much of an impact cobalt has on athletic performance. Nevertheless, cobalt salts are cheap, easy to acquire, and don't need to be injected, so their non-medical use is expected to continue.

Eclipse, an 18th century racehorse who hopefully wasn't fed cobalt (Source)

Vitamin B12

Vitamin B12 actually refers to a group of similar molecules that contain a central cobalt atom within a structure that can only be synthesized by microorganisms. Consequently, we are dependent on certain foods (animal-derived or fermented) as a source of this vitamin. In the event that we don’t eat enough of these foods and/or our gastrointestinal tract gets messed up and can’t absorb the vitamin efficiently from the food we eat, a deficiency can result. One of the important things that vitamin B12 does is enable a component of DNA synthesis, which is necessary for cell replication. A deficiency in the cobalt-bearing vitamin can result in adverse effects including extreme fatigue due to anemia and weakness due to peripheral neuropathy, both of which can slow a person down.

Herpes

Doxovir is a cobalt-containing antiviral drug currently being evaluated as a means of treating infection with the herpes simplex virus 1, the main cause of cold sores. The cobalt core of the drug molecule is thought to be able to interact with proteins used by the virus to get into cells, disrupting this process. While painful mouth ulcers don't exactly limit mobility, I'm guessing they might curtail your desire to talk. Maybe treating the ulcers with a cobalt-containing drug could speed up someone's speech?

Hip implants

One of the options for treating someone with a damaged hip joint that is slowing them down is to replace it with artificial parts. This often involves taking out the upper part of the femur (thigh bone) as well as the section of the pelvis (hip bone) it fits into, and then installing replacements. Various material types are used to make the replacement parts, one of which is metal alloys that consist of cobalt, chromium, and molybdenum. Metal implants are favoured because of their resistance to corrosion and wear. However, if both parts of the joint are made of metal, wear over time can result in small bits breaking off as the metal parts rub against each other. This can lead to toxicity due to increased dissolved metal concentrations in the body.

Thigh bone connected to the hip bone (Source)

Radiotherapy

One of the radioactive isotopes of cobalt, Co-60, is really good at producing gamma rays. This ability has been harnessed in the treatment of cancer by radiotherapy (zapping cancer cells with radiation to kill them). One of the common symptoms associated with this therapy is fatigue, so it's another way that cobalt can slow folks down. Cobalt-60 is manufactured by exposing stable cobalt-59 (the most common isotope of the metal) to neutrons in a nuclear reactor. It rose to prominence in the 1950s, as its high activity meant that treatment times were reduced from hours to minutes. Since then, use of cobalt-60 in radiotherapy has declined due to its limited lifespan, the fact that it's still pretty darn radioactive past the point at which it can be used, and its tendency to produce a fine dust that is challenging to provide protection against. It has largely been replaced by linear accelerators that generate super high energy x-rays.

Heart damage

In 1965, a brewery in Quebec City decided to add a cobalt salt to their beer. This was done to ensure the beer would foam nicely when it was poured, which had become an issue for breweries at the time due to the foam-killing effects of new detergents used to wash bottles. Unfortunately, the concentration of cobalt in the beer was sufficiently high that heavy drinkers ended up dosing themselves with enough of the metal to cause damage to their hearts. Within the year after the cobalt addition was made, 48 people in Quebec City were found to have serious heart damage, which in many cases resulted in congestive heart failure. The most common symptom was shortness of breath, which of course slows a person down. Similar epidemics of heart toxicity related to cobalt-spiked beer consumption were reported in Belgium, Minnesota, and Nebraska.


References

Alexander CS. 1972. Cobalt-beer cardiomyopathy. A clinical and pathologic study of twenty-eight cases. American Journal of Medicine 53(4):395-417.

Bernier J, Hall EJ, Giaccia A. 2004. Radiation oncology: a century of achievements. Nature Reviews Cancer 4(9):737-747.

Health Quality Ontario. 2006. Metal-on-metal total hip resurfacing arthroplasty: An evidence-based analysis. Ontario Health Technology Assessment Series 6(4):1-57. [Full text]

Heffern MC, Yamamoto N, Holbrook RJ, Eckermann AL, Meade TJ. 2013. Cobalt derivatives as promising therapeutic agents. Current Opinion in Chemical Biology 17(2):189-196. [Full text]

Ho EN, Chan GH, Wan TS, Curl P, Riggs CM, Hurley MJ, Sykes D. 2015. Controlling the misuse of cobalt in horses. Drug Testing and Analysis 7(1):21-30.

Hofman M, Ryan JL, Figueroa-Moseley CD, Jean-Pierre P, Morrow GR. 2007. Cancer-related fatigue: the scale of the problem. Oncologist 12(Suppl 1):4-10. [Full text]

Liao Y, Hoffman E, Wimmer M, Fischer A, Jacobs J, Marks L. 2013. CoCrMo metal-on-metal hip replacements. Physical Chemistry Chemical Physics 15(3):746-756. [Full text]

Lippi G, Franchini M, Guidi GC. 2006. Blood doping by cobalt. Should we measure cobalt in athletes? Journal of Occupational Medicine and Toxicology 1:18. [Full text]

Morin Y, Têtu A, Mercier G. 1969. Québec beer-drinkers' cardiomyopathy: Clinical and hemodynamic aspects. Annals of the New York Academy of Sciences 156(1):566-576.

Oh R, Brown DL. 2003. Vitamin B12 deficiency. American Family Physician 67(5):979-986. [Full text]

Samelko L, Caicedo MS, Lim SJ, Della-Valle C, Jacobs J, Hallab NJ. 2013. Cobalt-alloy implant debris induce HIF-1α hypoxia associated responses: a mechanism for metal-specific orthopedic implant failure. PLoS One 8(6):e67127. [Full text]

No comments:

Post a Comment