Category: Evolution

Categories
Biology Evolution human body

Osteoporosis and Menopause

Osteoporosis is a disease that weakens bones, increasing the risk of sudden and unexpected fractures. Literally meaning “porous bone,” osteoporosis results in an increased loss of bone mass and strength. The disease often progresses without any symptoms or pain.

Many times, osteoporosis is not discovered until weakened bones cause painful fractures usually in the back or hips. Unfortunately, once you have a broken bone due to osteoporosis, you are at high risk of having another. And these fractures can be debilitating. Fortunately, there are steps you can take to help prevent osteoporosis from ever occurring. And treatments can slow the rate of bone loss if you already have osteoporosis.

What Causes Osteoporosis?

Though we do not know the exact 

of osteoporosis, we do know how the disease develops. Your bones are made of living, growing tissue. An outer shell of cortical or dense bone encases trabecular bone, a sponge-like bone. When a bone is weakened by osteoporosis, the “holes” in the “sponge” grow larger and more numerous, weakening the internal structure of the bone.

Until about age 30, people normally build more bone than they lose. During the aging process, bone breakdown begins to outpace bone buildup, resulting in a gradual loss of bone mass. Once this loss of bone reaches a certain point, a person has osteoporosis.

How Is Osteoporosis Related to Menopause?

There is a direct relationship between the lack of estrogen during perimenopause and menopause and the development of osteoporosis. Early menopause (before age 45) and any prolonged periods in which hormone levels are low and menstrual periods are absent or infrequent can cause loss of bone mass.

Until about age 30, people normally build more bone than they lose. During the aging process, bone breakdown begins to outpace bone buildup, resulting in a gradual loss of bone mass. Once this loss of bone reaches a certain point, a person has osteoporosis.

What Are the Symptoms of Osteoporosis?

Osteoporosis is often called a “silent disease” because initially bone loss occurs without symptoms. People may not know that they have osteoporosis until their bones become so weak that a sudden strain, bump, or fall causes a fracture or a vertebra to collapse. Collapsed vertebrae may initially be felt or seen in the form of severe back pain, loss of height, or spinal deformities such as stooped posture.

Who Gets Osteoporosis?

Important risk factors for osteoporosis include:

  • Age. After maximum bone density and strength is reached (generally around age 30), bone mass begins to naturally decline with age.
  • Gender. Women over the age of 50 have the greatest risk of developing osteoporosis. In fact, women are four times more likely than men to develop osteoporosis. Women’s lighter, thinner bones and longer life spans account for some of the reasons why they are at a higher risk for osteoporosis.
  • Ethnicity. Research has shown that Caucasian and Asian women are more likely to develop osteoporosis. Additionally, hip fractures are twice as likely to occur in Caucasian women as in African-American women. However, women of color who fracture their hips have a higher mortality.
  • Bone structure and body weight. Petite and thin women have a greater risk of developing osteoporosis in part because they have less bone to lose than women with more body weight and larger frames. Similarly, small-boned, thin men are at greater risk than men with larger frames and more body weight.
  • Family history. Heredity is one of the most important risk factors for osteoporosis. If your parents or grandparents have had any signs of osteoporosis, such as a fractured hip after a minor fall, you may be at greater risk of developing the disease.
  • Prior history of fracture/bone breakage.
  • Certain medications. The use of some medications, such as the long term use of steroids (like prednisone) can also increase your risk of developing osteoporosis.
  • Some medical conditions: Some diseases including cancer and stroke may increase your risk for osteoporosis.

How Do I Know if I Have Osteoporosis?

A painless and accurate test can provide information about bone health and osteoporosis before problems begin. Bone mineral density (BMD) tests, or bone measurements, are X-rays that use very small amounts of radiation to determine bone strength.

A bone mineral density test is indicated for:

  • Women age 65 and older.
  • Women with numerous risk factors.
  • Menopausal women who have had fractures

How Is Osteoporosis Treated?

Treatments for established osteoporosis (meaning, you already have osteoporosis) include:

  • Medications such as alendronate (Binosto, Fosamax), ibandronate (Boniva), raloxifene (Evista), risedronate (Actonel, Atevia), and zoledronic acid (Reclast, Zometa)
  • Calcium and vitamin D supplements.
  • Weight-bearing exercises (which make your muscles work against gravity)
  • Injectable abaloparatide (Tymlos), teriparatide (Forteo) or PTH to rebuild bone
  • Injectable denosumab (Prolia, Xgeva) for women at high risk of fracture when other drugs don’t work
  • Hormone therapy

Is There a Safe Alternative to Hormone Therapy?

Alternatives to hormone therapy include:

  • Bisphosphonates. This group of medications includes the drugs alendronate (Binosto, Fosamax), risedronate (Actonel, Atelvia), ibandronate (Boniva) and zoledronic acid (Reclast, Zometa). Bisphosphonates are used to prevent and/or treat osteoporosis. All can help prevent spine fractures. Binosto, Fosamax,  Actonel, Atelvia, Reclast and Zometa can also reduce the risk of hip and other non-spine fractures.
  • Raloxifene (Evista). This drug is a selective estrogen receptor modulator (SERM) that has many estrogen-like properties. It is approved for prevention and treatment of osteoporosis and can prevent bone loss at the spine, hip, and other areas of the body. Studies have shown that it can decrease the rate of vertebral fractures by 30%-50%. It may increase the risk of blood clots.
  • Teriparatide (Forteo) and abaloparatide (Tymlos), are a type of hormone used to treat osteoporosis. They help rebuild bone and increase bone mineral density. They are given by injection and are used as a treatment for osteoporosis.
  • Denosumab (Prolia, Xgeva) is a so-called monoclonal antibody — a fully human, lab-produced antibody that inactivates the body’s bone-breakdown mechanism. It is used to treat women at high risk of fracture when other osteoporosis drugs have not worked.

How Can I Prevent Osteoporosis?

There are multiple ways you can help protect yourself against osteoporosis, including:

  • Exercise. Establish a regular exercise program. Exercise makes bones and muscles stronger and helps prevent bone loss. It also helps you stay active and mobile. Weight-bearing exercises, done at least three to four times a week, are best for preventing osteoporosis. Walking, jogging, playing tennis, and dancing are all good weight-bearing exercises. In addition, strength and balance exercises may help you avoid falls, decreasing your chance of breaking a bone.
  • Eat foods high in calcium. Getting enough calcium throughout your life helps to build and keep strong bones. The U.S. recommended daily allowance (RDA) of calcium for adults with a low-to-average risk of developing osteoporosis is 1,000 mg (milligrams) each day. For those at high risk of developing osteoporosis, such as postmenopausal women and men, the RDA increases up to 1,200 mg each day. Excellent sources of calcium are milk and dairy products (low-fat versions are recommended), canned fish with bones like salmon and sardines, dark green leafy vegetables, such as kale, collards and broccoli, calcium-fortified orange juice, and breads made with calcium-fortified flour.
  • Supplements. If you think you need to take a supplement to get enough calcium, check with your doctor first. Calcium carbonate and calcium citrate are good forms of calcium supplements. Be careful not to get more than 2,000 mg of calcium a day if you are 51 or older. Younger adults may be able to tolerate up to 2500 mg a day but check with your doctor. Too much can increase the chance of developing kidney stones.
  • Vitamin D. Your body uses vitamin D to absorb calcium. Being out in the sun for a total of 20 minutes every day helps most people’s bodies make enough vitamin D. You can also get vitamin D from eggs, fatty fish like salmon, cereal and milk fortified with vitamin D, as well as from supplements. People aged 51 to 70 should have 600 IU daily. More than 4,000 IU of vitamin D each day is not recommended. Talk to your doctor to see how much is right for you because it may harm your kidneys and even lower bone mass.
  • Medications. Most of the bisphosphonates that are taken by mouth as well as raloxifene (Evista) can be given to help prevent osteoporosis in people who are at high risk for fractures.
  • Estrogen. Estrogen, a hormone produced by the ovaries, helps protect against bone loss. It can be used as treatment for the prevention of osteoporosis. Replacing estrogen lost after menopause (when the ovaries stop most of their production of estrogen) slows bone loss and improves the body’s absorption and retention of calcium. But, because estrogen therapy carries risks, it is only recommended for women at high risk for osteoporosis and/or severe menopausal symptoms. To learn more, talk to your doctor about the pros and cons of estrogen therapy.
  • Know the high risk medications. Steroids, some breast cancer treatments (such as aromatase inhibitors), drugs used to treat seizures (anticonvulsants), blood thinners (anticoagulants), and thyroid medications can increase the rate of bone loss. If you are taking any of these drugs, speak with your doctor about how to reduce your risk of bone loss through diet, lifestyle changes and, possibly, additional medication.
  • Other preventive steps. Limit alcohol consumption and do not smoke. Smoking causes your body to make less estrogen, which protects the bones. Too much alcohol can damage your bones and increase the risk of falling and breaking a bone.
Categories
environment Evolution human body

Environmental Effects of the Atomic Bomb

When an atomic or nuclear bomb detonates, the 1 megaton blast kills or poisons everything within a two-mile radius. The accident at the Chernobyl power plant in 1986 and the bombs dropped on Hiroshima and Nagasaki in 1945 provide insight into the short and long-term effects of radiation and thermonuclear detonation on the environment. If enough nuclear weapons were exploded in a large-scale nuclear war, vast areas of the earth would become uninhabitable.

Immediate Environmental Effects

When an atomic bomb explodes, plutonium in the device undergoes fission, releasing enormous quantities of energy. The initial blast creates a blinding flash, followed by temperatures in the area of the explosion reaching upwards of 10 million degrees Celsius. Electromagnetic radiation leads to the formation of a fireball. A crushing wind caused by the initial blast destroys buildings and trees in its path. A single 15 kiloton bomb detonated over the center of Hiroshima near the end of World War II, destroying everything within a 1-mile radius of the city. The effect on the immediate environment is one of total devastation. The extreme heat of thermal radiation burns everything in its path, including animals, trees, buildings and people. Many of those who did not die from radiation or burns later developed cancers from the radiation.

Explosive Fallout

The detonation of an atomic bomb creates radioactive dust that falls out of the sky into the area around the site of the explosion. Wind and water currents carry the dust across a much larger radius than the initial explosion, where it contaminates the ground, water supply and the food chain. Initially, little was known about radioactive fallout. In the 1950s, scientists in the United States discovered from nuclear weapons testing that the particles in this dust were comprised of split atoms that were highly radioactive and dangerous. Radioactive particles from nuclear fallout also can contaminate both wild and domesticated animals, as well as agricultural plants.

Radiation Effects

The release of radiation from the Chernobyl power plant gives scientists an idea of what the effects would be on the environment in a small nuclear war. The amount of radiation released at Chernobyl is equivalent to the detonation of about a dozen atomic bombs at an altitude that would cause maximum blast damage. At Chernobyl, large amounts of radioactive particles called iodine-131 and cesium 137 were released into the environment during a fire that burned for 10 days. These isotopes are particularly dangerous to living organisms.

Water and Forest Contamination

Radioactive particles can travel from the site of an atomic bomb explosion and contaminate bodies of water, including aquatic life like fish. In addition, the fallout from the detonation of numerous atomic bombs would result in the contamination of berries and other plant life found in the surrounding areas and forests. Genetic mutations and disease in the generations of animals and humans following contamination would also occur. Animals in Chernobyl’s forests, for example, have high levels of radioactive cesium. Scientists expect the contamination to remain that way for decades.

Categories
Biology Evolution human body

New microevolutinary change :Median artery in the human forearm

The median artery is the main vessel that supplies blood to the forearm and hand, when first formed in the mother’s womb, but it disappears once two arteries seen in adults develop.

The radial and ulnar arteries usually replace the median artery during developmental stages in the womb, so most adults obviously don’t have a median artery, but increasing numbers of cases retain it, so a person can have all three arteries.

The median artery is now present in about 35% of people and researchers predict that people born 80 years from now will all carry a median artery if the trend continues.

“The median artery offers benefits because it increases overall blood supply and can be used as a replacement in surgical procedures in other parts of the human body,” said senior author Professor Maciej Henneberg, a researcher in the Biological Anthropology and Comparative Anatomy Research Unit at the University of Adelaide and the Institute of Evolutionary Medicine at the University of Zurich.

“This is microevolution in modern humans and the median artery is a perfect example of how we’re still evolving because people born more recently have a higher prevalence of this artery when compared to humans from previous generations.”

In the study, Professor Henneberg and colleagues aimed to investigate the prevalence of persistent median arteries in postnatal humans over the last 250 years and to test the hypothesis that a secular trend of increase in its prevalence has occurred.

They found a total of 26 median arteries in 78 upper limbs (a prevalence rate of 33.3%) obtained from Australians aged 51 to 101 years.

“Our study into the prevalence of the artery over generations shows that modern humans are evolving at a faster rate than at any point in the past 250 years,” said lead author Dr. Teghan Lucas, a researcher in the Department of Archaeology at Flinders University and the School of Medical Sciences at the University of New South Wales.

“Since the 18th century, anatomists have been studying the prevalence of this artery in adults and our study shows it’s clearly increasing.”

“The prevalence was around 10% in people born in the mid-1880s compared to 30% in those born in the late 20th century, so that’s a significant increase in a fairly short period of time, when it comes to evolution.”

“This increase could have resulted from mutations of genes involved in median artery development or health problems in mothers during pregnancy, or both actually,” he added.

“If this trend continues, a majority of people will have median artery of the forearm by 2100.”

“When the median artery prevalence reaches 50% or more, it should not be considered as a variant, but as a normal human structure,” the authors said.

Lucas.et al. find that the prevalence of the persistent median artery in postnatal life approximately tripled over the last 125 years.

Categories
Biology Evolution

New insight into the evolution of complex life on Earth

A novel connection between primordial organisms and complex life has been discovered, as new evidence sheds light on the evolutionary origins of the cell division process that is fundamental to complex life on Earth.

The discovery was made by a cross-disciplinary team of scientists led by Professor Buzz Baum of University College London and Dr Nick Robinson of Lancaster University.

Their research, published in Science, sheds light on the cell division of the microbe Sulfolobus acidocaldarius, which thrives in acidic hot springs at temperatures of around 75?C. This microbe is classed among the unicellular organisms called archaea that evolved 3.5 billion years ago together with bacteria.

Eukaryotes evolved about 1 billion years later — likely arising from an endosymbiotic event in which an archaeal and bacterial cell merged. The resulting complex cells became a new division of life that now includes the protozoa, fungi, plants and animals.

Now a common regulatory mechanism has been discovered in the cell division of both archaea and eukaryotes after the researchers demonstrated for the first time that the proteasome — sometimes referred to as the waste disposal system of the cell — regulates the cell division in Sulfolobus acidocaldarius by selectively breaking down a specific set of proteins.

The authors report: “This is important because the proteasome has not previously been shown to control the cell division process of archaea.”

The proteasome is evolutionarily conserved in both archaea and eukaryotes and it is already well established that selective proteasome-mediated protein degradation plays a key role in the cell cycle regulation of eukaryotes.

These findings therefore shed new light on the evolutionary history of the eukaryotes.

The authors summarise: “It has become increasingly apparent that the complex eukaryotic cells arose following an endosymbiotic event between an ancestral archaeal cell and an alpha-proteobacterium, which subsequently became the mitochondria within the resulting eukaryotic cell. Our study suggests that the vital role of the proteasome in the cell cycle of all eukaryotic life today has its evolutionary origins in archaea.”

Categories
Biology Evolution

Should evolution be equated with ‘progress’???

Evolution should neither be equated with progress nor with the elimination of older, less efficient species. Continuation of old species depends upon the environment. The new species may or may not be better. Formation of new species depends upon the occurrence of physical or reproductive barriers, genetic drift and natural selection that leads to the formation of new population or species which is unable to interbreed with the original population.

In fact, there is no real ‘progress’ in the idea of evolution. Evolution is ‘simply the generation of diversity and the shaping of the diversity by environmental selection’. The only progressive trend in evolution seems to be that more and more complex body designs have emerged over time. However, again, it is not as if the older designs are inefficient. Many of the older and simpler designs still survive. In fact, one of the simplest life forms – bacteria – in-habitat the most inhospitable habitats like hot springs, deep – sea thermal vents and the ice in Antarctica. In other words, human beings are not the pinnacle of evolution, but simply yet another species in the teeming spectrum of evolving life.

Thus, there is no such thing as ladder of progress but there are branches from the family tree of species.

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