Medical Minutes
A pill to prevent hearing loss
It may soon be possible to take a pill to prevent hearing loss. Researchers have discovered that inhibiting an enzyme called cyclin-dependent kinase 2 (CDK2) may help protect against noise-induced or drug-induced hearing loss. In animal studies, investigators have found that CDK2 inhibitors prevent the death of inner ear cells.
According to the World Health Organization, 360 million people worldwide suffer from hearing loss caused by congenital defects or other factors. These factors include infectious disease, use of certain medicines, or exposure to excessive noise. Yet, there are currently no FDA-approved drugs to prevent or treat hearing loss.
A team of researchers at St. Jude Children’s Research Hospital screened more than 4,000 drugs for their ability to protect cochlear cells from the chemotherapy agent cisplatin. Cisplatin is used to treat a variety of cancers, but causes irreversible hearing loss in up to 70 percent of patients.
The researchers identified multiple compounds that protected cochlear cells from cisplatin, several of which are already approved to treat other conditions. Three of the 10 most effective compounds were inhibitors of an enzyme called CDK2. One of these CDK2 inhibitors, kenpaullone, was more effective than four other compounds that are currently in clinical trials for treating hearing loss.
Injecting kenpaullone into the middle ear protected both mice and rats from cisplatin-induced hearing loss. In addition, kenpaullone protected the hearing of mice to noise as loud as 100 dB. “Given that 100-dB noise is in the range of noise insults commonly experienced by people in our society, kenpaullone could have significant clinical application in treating noise-induced hearing loss,” said study investigator Dr. Jian Zuo, who is with St. Jude’s Research Hospital, Memphis, Tennessee.
Walking away from dementia
Women who have high physical fitness levels at middle age may have a significantly lower risk of developing dementia decades later compared to women who are moderately fit, according to a new study published in the journal Neurology.
The researchers found in their study that when the highly fit women developed dementia, they developed the disease an average of 11 years later (age 90) than women who were moderately fit (age 79).
“These findings are exciting because it’s possible that improving people’s cardiovascular fitness in middle age could delay or even prevent them from developing dementia,” said study author Helena Hörder, PhD, of the University of Gothenburg in Gothenburg, Sweden.
For the study, 191 women (average age of 50) took a bicycle exercise test until they were exhausted to measure their peak cardiovascular capacity. The average peak workload was measured at 103 watts. A total of 40 women met the criteria for a high fitness level, or 120 watts or higher. A total of 92 women were in the medium fitness category and 59 women were in the low fitness category.
Over the next 44 years, the women were tested for
dementia six times. During that time, 44 of the women developed dementia. However, only 5 percent of the highly fit women developed dementia, compared to 25 percent of moderately fit women and 32 percent of the women with low fitness. The highly fit women were 88 percent less likely to develop dementia than the moderately fit women.
Higher vitamin D levels may protect against cancer
High levels of vitamin D may be associated with a lower risk of developing cancer, including liver cancer. At least that is what Japanese researchers are now reporting. They conducted a study and found that higher levels of vitamin D are linked with an overall lower risk of cancer.
Vitamin D is made by the skin in response to sunlight. It helps to maintain calcium levels in the body to keep bones, teeth and muscles healthy. While the benefits of vitamin D on bone diseases are well known, there is growing evidence that vitamin D may benefit other chronic diseases, including some cancers.
Most studies have been carried out in European or American populations, and evidence from Asian populations is limited. As vitamin D concentrations and metabolism can vary by ethnicity, it is important to find out whether similar effects would be seen in non-Caucasian
populations. So, an international research team based in Japan set out to assess whether vitamin D was associated with the risk of total and site specific cancer.
They analyzed data from the Japan Public Health Center-based Prospective (JPHC) Study, involving 33,736 male and female participants aged between 40 to 69 years. Participants were then monitored for an average of 16 years, during which time 3,301 new cases of cancer were recorded. After adjusting for several known cancer risk factors, such as age, weight, physical activity levels, smoking, alcohol intake and dietary factors, the researchers found that a higher level of vitamin D was associated with a lower (around 20 percent) relative risk of overall cancer in both men and women.
Higher vitamin D levels were also associated with a lower (30 to 50 percent) relative risk of liver cancer, and the association was more evident in men than in women. The authors say their findings support the theory that vitamin D may protect against the risk of cancer, but that there may be a ceiling effect, which may suggest that there are no additional benefits beyond a certain level of vitamin D. The researchers write that further studies are warranted to clarify the optimal concentrations of vitamin D for cancer prevention.
John Schieszer is an award-winning national journalist and radio and podcast broadcaster of The Medical Minute. He can be reached at medicalminutes@gmail.com.
John Schieszer is an award-winning national journalist and radio and podcast broadcaster of The Medical Minute.
