NEWSLETTER – FEBRUARY 2013
PREVENTIVE HEALTH – Screening for Osteoporosis
Osteoporosis is the term used to describe a condition in which bone density is reduced resulting in a weakening of the bone and a susceptibility to fractures
The growth and maintenance of bone requires that new material is constantly being replaced and old or damaged material is removed. This process is controlled by two types of cells, osteoclasts, which remove old or defective bone and reabsorb normal bone to release calcium, and osteoblasts which generate new bone. The balance between these two processes is critical in maintaining bone strength and integrity.
A number of factors can alter the rate of bone absorption and regeneration
Osteoporosis of spine weakens vertebrae causing distortion (kyphosis). Vertebrae are susceptible to compression fracture
Other factors which have been associated with increased risk for osteoporosis include family history, prolonged ingestion of corticosteroids, rheumatoid arthritis, hyperparathyroidism, low body weight, prolonged inactivity and excessive alcohol consumption.
There are two main types of bone, trabecular, the spongy bone that predominates in vertebrae and at the end of bones, and cortical bone which forms the hard outer layer. Trabecular bone is more actively involved in resorbtion and regeneration and therefore tends to more affected by osteoporosis. Common sites of fracture, the wrists, hips and spine, tend to have more trabecular bone.
Screening for osteoporosis is currently recommended for all women over 65 and women over 60 who have known risk factors. Routine screening of men over 70 may be beneficial, however all men with known risk factors such as prolonged use of corticosteroids, should be screened.
Screening for osteoporosis is a relatively simple and inexpensive procedure which involves measurement of bone density using dual-energy x-ray absorptiometry (DXA). This may be done on peripheral bones such as the heel, however whole body scans are recommended for more accurate assessment.
The onset of osteoporosis can be delayed or prevented by the use of calcium (60 mg /day) and vitamin D (1000 IU/day) supplements and regular exercise. Supplements are particularly important as there has been a dramatic reduction in the consumption of dairy products in an effort to reduce cholesterol levels. Dairy products were the main source of dietary calcium for much of the population.
For further information on the action of vitamin D and calcium see Newsletter Vol1 No3
DID YOU KNOW – bones are cell factories.
Apart from providing skeletal support for the body and protecting various organs, bones also churn out billions of replacement cells to maintain the viability and integrity of the bodies various organs and tissues
The trabecular or spongy bone that forms the end of long bones and the centre of other bones is the body’s cell factory. The trabeculae are needle like structures that create a meshwork of connecting spaces. The spaces contain a mixture of blood vessels and tissue commonly known as bone marrow. There are two main types of bone marrow
Red marrow contains stem cells, the progenitor cell that can grow into any type of specialised cell. These cells are responsible for replacing cells that reach the end of their lifespan or cells that have been damaged or destroyed by disease or accident.
There are two main types of stem cell in red marrow
The generation of multiple different cell types from bone marrow
Yellow marrow. This is composed mostly of fat and connective tissue. It can transform back into red marrow if the cell turnover in their body cannot be satisfied by the red marrow.
NEWS – ferroportin is a prognostic indicator in breast cancer
Ferroportin is a protein which controls the storage and release of iron from cells. Recent studies have shown that levels of this protein are a good indicator of how aggressive a particular breast tumour may be.
Researchers at the Wake Forest Baptist medical Center have shown that tissue culture cell lines derived from aggressive tumours had low levels of ferroportin which allowed increased levels of intracellular iron and increased growth rates. When ferroportin was added to the cell cultures, the rate of growth of the tumour cells decreased.
Iron is transported into cells by DMT-! And out of cells by ferroportin
Tumour cells with normal levels of ferroportin produced less aggressive tumours when injected into mice, compared with tumour cells with decreased ferroportin
A review of data from 800 cancer patients confirmed that ferroportin levels were a strong predictor for recurrence of breast tumours.
This is potentially a very important finding. It has been long recognised that many breast tumours present little or no risk to women if left untreated, however there is no accurate predictor of the future behaviour of a breast tumour and therefore most women elect to have radical surgery, chemotherapy or radiotherapy. If ferroportin can be shown to accurately separate aggressive from relatively benign tumours, many women will be spared unnecessary treatment.