FLORIDA - BACKGROUND: Close to 10 million Americans suffer from osteoporosis, a disease of the bones. Bones are living tissues that are constantly being absorbed and replaced. When the creation of new bone does not keep up with the removal of old bone, osteoporosis occurs. Bones then become very weak and can break even from a minor fall. About half of all women over 50 and one in four men will break a bone due to osteoporosis. Some people lose height and become shorter. It will affect posture and cause a person to hunch or stoop. This happens when bone in the spine break or collapse. Twenty percent of seniors who break a hip die within one year from problems related to the broken bone or from surgery to repair it. People who do survive require long-term nursing home care. Osteoporosis is responsible for millions of fractures and billions in costs. Experts predict that by 2025, $25.3 billion will be spent each year. (Source: www.nof.org).
NEW RESEARCH: While there are so many Americans affected by osteoporosis, the causes of it remain a mystery. New research is being conducted to address osteoporosis in a unique way. Postmenopausal women and aging men are not the only ones who have to worry about bone loss. Studies have found that on average, an astronaut will lose one to two percent of bone mass each month in space. Researchers believe that by solving the problem of why bone loss occurs in space, important clues will be revealed about what causes osteoporosis on Earth.
Astronauts usually experience bone loss in the lower halves of their bodies (lumbar vertebrae and legs). Also they experience a rise in calcium levels in the blood, which increases the risk of kidney stones. The suspected cause of bone loss in space is weightlessness. The pull of gravity 350 km above Earth’s surface is 90 percent as strong as it is on the ground. As a result, the acceleration they feel is as little as 0.0001% of the gravitational acceleration on Earth’s surface. Their bones no longer have to fight against Earth’s gravitational pull. Therefore, they experience less mechanical strain to the skeletal system. Scientists believe reduced stress on bones may be responsible for the progressive bone loss in long-term residents of space, mimicking what happens to those that are confined to beds due to illness or old age.
In prolonged weightlessness, bone mass decreases due to the lack of stress on the bones that slows the formation of new bone. Fewer bone-building cells, along with a constant level of bone-destroying activity, results in a net loss of bone mass. Why weightlessness inhibits the development of osteoblasts is currently being studied at Vanderbilt University. A chemical in the development of osteoblast cells from precursor cells is an enzyme called "creatine kinase-B." Scientists are trying to figure out which molecules in the body regulate the activity of this enzyme and how those chemicals are affected by low gravity, hoping that this knowledge will point to a way to boost osteoblast formation in space. Another study at the Medical College of Georgia is investigating a possible connection between eating and bone destruction. Ingesting food causes level of a certain hormone to increase in the blood stream. This hormone can stimulate production of insulin after a meal, triggering cells to absorb glucose from the blood. Bone cells are sensitive to this hormone. Researchers have found that when this hormone attaches to "receptor" molecules on bone cells, osteoclast (bone destroying) activity goes down and osteoblast (bone creating) activity goes up. Whether hormones like this can be given to astronauts as a supplement to prevent bone degradation is unknown to scientists so far. Another study led by Dr. Douglas Chang at the University of California, San Diego has found that the discs in astronauts are becoming weaker, faster. In zero gravity, they grow an average of two inches when their spines straighten out, resulting in more disc herniation’s. NASA research has already made some headway in their research. For example, their research led to the development of a fast and inexpensive tool to measure the extent of osteoporosis by analyzing the stiffness of bones. (Source: www.science.nasa.gov).