Why are women more prone to knee injuries than men?

Researchers from The University of Texas Medical Branch at Galveston have found that women who take the birth control pill, which lessen and stabilize estrogen levels, were less likely to suffer serious knee injuries. The findings are currently available inMedicine & Science in Sports & Exercise, the official journal of the American College of Sports Medicine.

Female athletes are 1.5 to 2 times more likely than their male counterparts to injure their anterior cruciate ligament, or ACL. The ACL is a ligament that connects the top and bottom portions of the knee. Damage to this ligament is a serious athletic injury that can be career altering. Return-to-play rates after ACL injury are as low as 49 percent among soccer players. Also, this injury may lead to lifelong issues with knee instability, altered walking gait and early onset arthritis.

Using a national insurance claims and prescription database of 23,428 young women between 15 and 19, the study found that women with an ACL knee injury who were taking the birth control pill were less likely to need corrective surgery than women of the same age with ACL injuries who do not use the birth control pill.

Researchers have proposed that the female hormone estrogen makes women more vulnerable to ACL injury by weakening this ligament. A previous investigation found that more ACL injuries in women occur during the points of their menstrual cycle when estrogen levels are high.

"Birth control pills help maintain lower and more consistent levels of estrogen, which may prevent periodic ACL weakness," said lead author and M.D. -- Ph.D. student Aaron Gray. "With this in mind, we examined whether oral contraceptive use protected against ACL injuries that require surgery in women."

Women between15-19 y in need of ACL reconstructive surgery, the age group with the highest rates of ACL injuries by a wide margin, were 22 percent less likely to be using the birth control pill than non-injured women of the same age.

Gray said that puberty might explain the high number of ACL injury cases in young women of this age. During puberty, there is a sharp rise in estrogen levels as well as growth spurts in the legs. Following one of these growth spurts, it takes time for the adolescent to develop good coordination with their newly elongated limbs.

"Young athletes currently use birth control pills for various reasons including more predictable cycles and lighter periods," Gray said. "Injury risk reduction could potentially be added to that list with further, prospective investigations."

Story Source:

The above story is based on materials provided by University of Texas Medical Branch at Galveston. Note: Materials may be edited for content and length.

Journal Reference:

Aaron M Gray, Zbgniew Gugala, Jacques G Baillargeon. Effects of Oral Contraceptive Use on Anterior Cruciate Ligament Injury Epidemiology. Medicine & Science in Sports & Exercise, 2015; 1 DOI: 10.1249/MSS.0000000000000806

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Compound found to trigger innate immunity against viruses

A scientist's illustration of immunology research at UW Medicine's South Lake Union campus.

Credit: Dennis Wise

Research from UW Medicine and collaborators indicates that a drug-like molecule can activate innate immunity and induce genes to control infection in a range of RNA viruses, including West Nile, dengue, hepatitis C, influenza A, respiratory syncytial, Nipah, Lassa and Ebola.

The findings, published today in the Journal of Virology show promising evidence for creating a broad-spectrum antiviral.

"Our compound has an antiviral effect against all these viruses," said Michael Gale Jr., University of Washington professor of immunology and director of the UW Center for Innate Immunity and Immune Disease. The finding emerged from research by his lab in concert with scientists at Kineta Inc. and the University of Texas at Galveston.

Gale said he thinks the findings are the first to show that innate immunity can be triggered through a molecule present in all our cells, known as RIG-I.

RIG-I is a cellular protein known as a pathogen recognition receptor. These receptors detect viral RNA and signal an innate immune response inside the cell that is essential for limiting and controlling viral infections. The signal induces the expression of many innate immune and antiviral genes and the production of antiviral gene products, pro-inflammatory cytokines, chemokines and interferons.

"These products act in concert to suppress and control virus infection," the researchers wrote.

Such activation of the innate immune response to control viral infection has been tested successfully in cells and in mice. Next steps would be to test dosing and stability in animal models and then in humans, a process that could take two to five years, Gale said.

Currently, there are no known broad-spectrum antiviral drugs and few therapeutic options against infection by RNA viruses. RNA viruses pose a significant public health problem worldwide because their high mutation rate allows them to escape the immune response. They are a frequent cause of emerging and re-emerging viral infections. West Nile virus infections, for example, started in the United States in 2000 and remerged in 2012. The World Health Organization reports 50 million to 100 million new cases of dengue fever yearly and 22,000 deaths caused by the related dengue virus. Dengue is now present in the southern U.S.

Hepatitis C, which is transmitted through the blood, infects upward of 4 million people each year; 150 million people are chronically infected and at risk for developing cirrhosis or liver cancer, according to the paper. Direct-acting antivirals can control hepatitis C and show promise of long-term cure, but viral mutation to drug resistance is a concern with prolonged use of these drugs. Also the drugs' exorbitant costs make them unaffordable to many or most patients.

There is tremendous interest in triggering innate immunity, said Shawn Iadonato, chief scientific officer at Seattle biotech Kineta. Some viral infections, he pointed out, cannot be treated by traditional antivirals. Activating innate immunity also will make the viruses less likely to resist the drug actions because the therapy targets the cell, via gene action, rather than the virus itself.

"It's routine for us to think of broad-spectrum antibiotics, but the equivalent for virology doesn't exist," Iadonato said.

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Story Source:

The above post is reprinted from materials provided by University of Washington. The original item was written by Bobbi Nodell. Note: Materials may be edited for content and length.

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