Definition of Osteoclast

Osteoclast: A cell that nibbles at and breaks down bone and is responsible for bone resorption.

Osteoclasts are large multinucleate cells (cells with more than one nucleus) that differentiate from another type of cell called a macrophage.

In normal bone, bone formation and bone resorption are closely coupled processes involved in the normal remodeling of bone. In osteoporosis, the net rate of bone resorption exceeds the rate of bone formation, resulting in a decrease in bone mass without a defect in bone mineralization. In women, osteoclast activity is increased because of decreased estrogen after the menopause. (Men with prematurely decreased testosterone may also have increased osteoclast activity.) These changes result in further net loss of bone. The amount of bone available for mechanical support of the skeleton eventually falls below the fracture threshold and one may suffer a fracture with little or no trauma.

The term "osteoclast" has a curious history. It was derived by putting osteo- (from the Greek osteon, bone) together with -clast (from the Greek klastos, broken). It was originally a surgical instrument used to fracture bones. The cell we call an osteoclast was then named an osotoclast to avoid confusing it with the surgical instrument. When the instrument became outmoded, the mantle of osteoclast fell upon the cell that resorbs bone.


http://www.medterms.com/script/main/art.asp?articlekey=11794

Boy, that's a long paper to decode. Can you help me out with some more specific questions or exact terms you need clarified?

"In my non-scientific way, I'm thinking that along with stimulating osteoclast activity, EPO may also stimulate osteoblast activity... :)"

Sorry, but that's not really something that can be taken directly from this study. The study did not go on long enough or look at the right things to be able to make that conclusion. Could have, but didn't. Bone resorption is directly linked to the control and release of inflammatory hormones: PEs. Unfortunately I don't know off the top of my head which hormonal mechanisms govern bone formation or how.

To determine whether or not GLAs aid bone formation, the researchers would need to do x-rays of the maxillary bones at various times through an extended orthodontic process, with appropriate controls, to measure actual bone formation/calcium deposition. Then you'd have enough data. Or, a much easier, and more appropriately applicable study to do would be to recruit human subjects with freshly broken bones, blind the study appropriately, and use GLA supplementation and frequent x-rays to determine rate of healing (bone reformation.) The larger the study the more reliable the results. And rats are not humans. Mammalian, yes, but unfortunately not all lab observations in rodents translate to human beings.

One of the important things to take from the study is that the rats were dosed with GLA BEFORE the orthodonics were put in place. 20 days before! The researchers knew ~ and stated in their paper ~ that organisms have pools of fatty acids, etc. that are slow to change and wanted to be sure there was an adequate amount of GLA enhancement before starting the procedure. This underscores the importance of regular, daily, ongoing supplementation/appropriate diet.

OK, I have to run and do the mom-taxi thing again. LMK what you need discussed or explained further.

Oh, one thing I CAN say, is higher levels of Calcium in your diet and in your blood WILL increase the rate of bone formation. Inevitably. So if you want to grow new bone, max out your Calcium intake.

Gotta run!