If you are curious about Earth's periodic mass extinction events such as the sudden demise of the dinosaurs 65 million years ago, you might consider crashing asteroids and sky-darkening super volcanoes as culprits.
But a new study suggests that it is the ocean, and in particular the epic ebbs and flows of sea level and sediment over the course of geologic time, that is the primary cause of the world's periodic mass extinctions during the past 500 million years.
"The expansions and contractions of those environments have pretty profound effects on life on Earth," says Shanan Peters, a University of Wisconsin-Madison assistant professor of geology and geophysics and the author of the new Nature report.
Overweight men are not more likely to be infertile, as past research has shown to be true in obese women, according to a new study. The results will be presented at The Endocrine Society’s 90th Annual Meeting in San Francisco.
Findings of the study, performed in New York in nearly 300 very overweight men, were unexpected, said coauthor Nanette Santoro, MD, an Albert Einstein College of Medicine obstetrician-gynecologist who is trained in reproductive endocrinology.
Santoro and her colleagues studied 292 men who gave semen samples at fertility clinics. The men were ages 18 to 50 and, on average, had a body mass index (BMI) of 28, which is considered nearly obese. The authors found that greater body weight was not associated with worse sperm production or sperm motility. Impaired sperm production is the cause of infertility in 90 percent of infertile men, according to Santoro. About 6 percent of reproductive-age men are infertile, she said.
One of the nation’s leading joint specialists, Javad Parvizi, M.D., Ph.D., of the Rothman Institute at Thomas Jefferson University Hospital, says you should believe your grandmother, friend or co-worker when they tell you it’s going to rain — even if it’s simply because their aching knees, hips, hands or shoulders “say so.”
Dr. Parvizi, who is also director of clinical research at the Rothman Institute at Jefferson, and associate professor of Orthopaedic Surgery at Jefferson Medical College of Thomas Jefferson University in Philadelphia, explains that even though individuals can experience pain fluctuations with the slightest change in barometric pressure, most patients report significant increases in pain before and during severe changes in weather, like summer downpours and thunderstorms.
Why would humans evolve allergy problems? A team from the Randall Division of Cell & Molecular Biophysics, King's College London are working on a molecule vital to the chicken's immune system which represents the evolutionary ancestor of the human antibodies that cause allergic reactions.
Crucially, they have discovered that the chicken molecule behaves quite differently from its human counterpart, which throws light on the origin and cause of allergic reactions in humans and gives hope for new strategies for treatment.
The chicken molecule, an antibody called IgY, looks remarkably similar to the human antibody IgE. IgE is known to be involved in allergic reactions and humans also have a counterpart antibody called IgG that helps to destroy invading viruses and bacteria. Scientists know that both IgE and IgG were present in mammals around 160 million years ago because the corresponding genes are found in the recently published platypus genome. However, in chickens there is no equivalent to IgG and so IgY performs both functions.
Every year, about 500 million people worldwide are infected with the parasite that causes dysentery, a global medical burden that among infectious diseases is second only to malaria. In a new study appearing in the June 15 issue of Genes and Development, Johns Hopkins researchers may have found a way to ease this burden by discovering a new enzyme that may help the dysentery-causing amoeba evade the immune system.
"This is the first enzyme to be identified that looks like it could mediate immune system evasion," says Sin Urban, Ph.D., an assistant professor of molecular biology and genetics at Hopkins.
The EhROM1 enzyme, it turns out, is part of an ancient group of enzymes—they are found in every branch of life from bacteria to man—known as rhomboid enzymes. In most animals, rhomboid enzymes seem to play a role in cell-to-cell communication, but a couple of years ago Urban found that malaria parasites use rhomboid enzymes for a more sinister purpose: to enter host cells uninvited.
It's an urban legend we've all read - you meet some nice girl in Thailand and you black out and wake up in a bathtub without a kidney.
Kidneys, and other replaceable organs, have value because the wait list is long and someone has to die to donate them.
Arthur Matas, Professor of Surgery at the University of Minnesota, writing in this week's BMJ says a regulated system of compensation for living donors may be the solution to the growing shortage of kidneys for transplantation.
But Jeremy Chapman, from the Centre for Transplant and Renal Research in Sydney, argues that this could reduce the supply of all organs. He believes that the idea of the regulated market is a myth, which could have devastating consequences on the less easily regulated environments of Asia and Africa.