Loud, startling noises may increase the risk of knee injury, says a study published online in the Scandinavian Journal of Medicine & Science in Sports.

Honking horns, sirens and other sudden noises can disrupt circuits in the brain controlling muscles and ligaments that stabilize the knee, causing people to trip and fall, researchers suggest. Buzzers and shouting during sports competitions could affect athletes who normally have good balance and muscular control, they said.

An estimated 250,000 sprains and tears to the anterior cruciate ligament, which is essential for normal knee function, are reported every year in the U.S., according to the Centers for Disease Control and Prevention. Researchers suggest some ACL injuries are likely due to a noise-induced startle response in the central nervous system that results in coordination errors.

The study involved 18 men and 18 women in their early 20s from the University of Delaware. The subjects were seated in a motorized chair designed to move either leg at a controlled speed. Their dominant leg was strapped at the ankle while a special arm attached to the chair raised the knee at a 30-degree angle. Electrodes recorded thigh-muscle activity as the arm slowly forced the knee to bend a further 40 degrees during six trials. Participants were instructed to resist knee bending as fast and as hard as possible in all six trials. During three trials, subjects heard a brief, high-pitched beep, about as loud as a motorcycle, through earphones just before the knee began to bend.

The beep induced a startle response that significantly increased muscle stiffness during the first four degrees of bending compared with no-beep trials. As the startle response subsided, muscle activity and joint stiffness were significantly reduced as the knee continued to bend to the full 70 degrees. The higher initial stiffness followed by markedly reduced stiffness likely reflects a disturbance in neuromuscular control that can lead to abnormal stresses on the joint and unintentional injury, the researchers said.

Caveat: The beep used in the study may not compare with loud sounds heard during athletic competitions, researchers said. Fluctuating estrogen levels may affect joint looseness and neuromuscular control in women, they said.

Title: An acoustic startle alters knee joint stiffness and neuromuscular control

Vitamin D and cancer: Adding a synthetic form of vitamin D to standard chemotherapy drugs may prolong the lives of patients with pancreatic cancer, one of the most aggressive and deadliest cancers, says a study in the current issue of Cell. The combination treatment significantly reduced tumor growth in mice and increased their survival by 57% compared with chemotherapy alone.

The vitamin D-like compound, a drug called calcipotriol normally used to treat psoriasis, appears to reprogram pancreatic cells that become highly activated by the cancer and form a barrier around tumors, blocking chemotherapy drugs, researchers said. Calcipotriol helps to restore normal cell activity and weaken the barrier.

An estimated 46,000 people are diagnosed with pancreatic cancer in the U.S. every year and 40,000 die from the disease, according to the National Institutes of Health. Low levels of vitamin D are associated with a higher risk of pancreatic cancer.

The study, led by the Salk Institute for Biological Studies in La Jolla, Calif., tested the vitamin D compound in experiments on three groups of mice with pancreatic tumors. One group was treated with the chemotherapy drug gemcitabine, one received calcipotriol and a third received both.

After nine days, tumors were significantly reduced in 70% of combination-treated mice compared with only chemotherapy, but calcipotriol by itself had no effect. The combination therapy improved tumor circulation, allowing chemo drugs to reach deeper into the tumor. Mice on the combination therapy survived about 22 days, compared with 14 days for chemo-only mice. About 29% of combination-treated mice survived an average of 52.8 days and were considered long-term survivors.

Vitamin D was also effective in treating mice with chronic pancreatitis, a risk factor for pancreatic cancer.

A compound similar to calcipotriol is being tested on patients at two sites in the U.S.

Caveat: The study was in mice and tested only one form of vitamin D.

Title: Vitamin D Receptor-Mediated Stromal Reprogramming Suppresses Pancreatitis and Enhances Pancreatic Cancer Therapy

Melanoma moles: Counting arm moles may be a quick and easy screening tool to identify people under age 50 at high risk of aggressive melanoma skin cancers, says a study in the European Journal of Cancer Prevention.

Most skin cancers can be detected early with regular skin exams performed by a doctor or self-exams, according to the American Cancer Society. But doctors are often too busy to perform skin checks and few people take the time to examine themselves, researchers said.

The study suggests the presence of 20 or more moles, called melanocytic nevi, on both arms is indicative of a higher number of body moles and greater risk of melanoma, according to the researchers. The 20-mole rule can only be applied to younger patients as moles tend to disappear as people age, they said.

From February to May 2012, researchers counted arm and body moles on 2,175 patients from five dermatology clinics in Italy, Germany, Greece and Serbia. Freckles and so-called liver spots were excluded.

On average, patients with fewer than 10 arm moles had fewer than 51 body moles while those with 20 or more moles had 50 or more body moles. Of subjects under 50 years old, 21.8% had 20 or more arm moles and 26.3% had 50 or more body moles. In contrast, 6.8% of patients over age 50 had 20 or more arm moles and 12.8% had 50 or more body moles.

Caveat: As subjects were dermatology patients, they may have had more moles and a higher prevalence of melanoma than the general population, researchers said.

Title: Twenty nevi on the arms: a simple rule to identify patients younger than 50 years of age at higher risk for melanoma

Diet-induced anxiety: Consuming a single high-fat meal can disrupt chemicals in the brain that regulate mood and anxiety, says a study in the journal Metabolism. The study found mice displayed anxiety-like behavior after one large dose of a saturated fatty acid called palmitic acid, which is present in most high-fat diets. The dose was comparable to the amount of palmitic acid that would be consumed from bingeing on junk food or a high-fat meal, researchers said.

Palmitic acid appears to decrease levels of serotonin, a neurotransmitter, or chemical messenger, that regulates mood and other complex processes in the brain. Decreases in serotonin are associated with anxiety and depression.

The study, at the University of Illinois at Urbana-Champaign, follows a 2013 study that showed a week of high-fat feeding caused anxiety-like behavior in mice. The latest study delivered just one dose of palmitic acid by injection to genetically normal mice and mice lacking inflammatory genes and proteins. Controls weren't treated. Mice were videotaped during behavior tests administered after two and 24 hours.

Palmitic-treated mice were significantly less active after two hours compared with controls. But activity levels were similar in normal and genetically altered mice, suggesting altered locomotion wasn't due to inflammation, despite its association with dietary fat, researchers said.

Food intake also decreased in palmitic-treated mice but both appetite and motor activity were similar to controls after 24 hours. At that time, palmitic-treated mice began displaying anxiety-like behavior, spending less time exploring new objects and exposed open spaces—a delayed reaction similar to anxiety patterns in humans, researchers said. Levels of a key marker of serotonin breakdown increased by 33% in the amygdala, the brain's emotional-processing center, of the palmitic-treated mice after 24 hours.

Caveat: The research hasn't been proven in human subjects.

Title: The saturated fatty acid, palmitic acid, induces anxiety-like behavior in mice

Measles reality: Adults and children who caught the measles were off work or school for an average of two weeks, and more than a third spent at least one night in the hospital, a study in PLoS One found. Measles can be significantly more disruptive to daily life than other infectious diseases, such as flu and chickenpox, according to the report, which assessed the burden of measles on the quality of life.

Measles is a highly contagious respiratory disease that typically causes a high fever, skin rash, raspy cough and inflamed eyes or conjunctivitis. Close to 600 cases of measles have been confirmed in 18 U.S. outbreaks so far this year, more than double the cases recorded in 2013, according to the CDC. The disease is a leading cause of death in unvaccinated young children, according to the World Health Organization.

The study involved 203 people in the U.K. who contracted measles from 2012 to 2013. About half of the subjects were age 13 and older and half were younger than 13. Measles' impact on normal daily activities at the start of the illness, the worst day of infection and after three weeks was reported on questionnaires. (Parents responded on behalf of young children.)

Of the 203 patients, 93% hadn't been vaccinated against measles and just under half were under age 13. About 96% couldn't carrying out normal daily activities during the illness and close to 40% reported being unable to care for themselves. The fifth day of the illness was considered the worst by patients of all ages.

More than 90% of patients suffered pain and discomfort related to measles and 64% experienced anxiety and depression.

Caveat: Individuals were unlikely to complete the questionnaires for the worst day of their illness on that day, researchers said. Symptoms were self-reported.

Title: The Effect of Measles on Health-Related Quality of Life: A Patient-Based Survey