THURSDAY, Dec. 16 (HealthDay News) -- People have been using herbal supplements for centuries to cure all manner of ills and improve their health. But for all the folk wisdom promoting the use of such plants as St. John's wort and black cohosh, much about their effect on human health remains unknown.

(HealthDay News) -- When certain substances in the urine crystallize to form a solid mass in the kidney or ureter, a kidney stone is born.

(HealthDay News) -- Oral health problems, such as gum disease or mouth sores, can be related to other health issues.

THURSDAY, Dec. 16 (HealthDay News) -- Naturally occurring high hemoglobin levels don't pose a threat to chronic kidney disease (CKD) patients on dialysis, and there is no need to lower these levels, a new study suggests.

THURSDAY, Dec. 16 (HealthDay News) -- People with acute abdominal pain who go to a hospital emergency department feel more confident about their diagnosis when they have a CT scan, a new study finds.

THURSDAY, Dec. 16 (HealthDay News) -- A new study suggests that managers might fail to appreciate the value that overqualified workers can bring to their companies.

WEDNESDAY, Dec. 15 (HealthDay News) -- U.S. Food and Drug Administration advisers urged the agency to take a new look at data that may indicate potential safety problems with dental fillings that include mercury.

THURSDAY, Dec. 16 (HealthDay News) -- U.S. scientists have unraveled the genetic code for the most common type of brain cancer in children.

THURSDAY, Dec. 16 (HealthDay News) -- Asthma and chronic obstructive pulmonary disease (COPD) patients who are treated with inhaled corticosteroids may face a significantly higher relative risk for both the development and progression of diabetes, new Canadian research suggests.

THURSDAY, Dec. 16 (HealthDay News) -- A new U.S. study finds that 75 percent of children consume caffeine daily, largely through sodas. And the more caffeine they consumed, the less they slept.

THURSDAY, Dec. 16 (HealthDay News) -- Researchers who have studied a woman with a missing amygdala -- the part of the brain believed to generate fear -- report that their findings may help improve treatment for post-traumatic stress disorder (PTSD) and other anxiety disorders.

THURSDAY, Dec. 16 (HealthDay News) -- A federal judge in Florida will start hearing arguments Thursday in the latest legal challenge to the constitutionality of a key provision of the nation's new health-care reform law -- that nearly all Americans must carry health insurance or face a financial penalty.

Here are some of the latest health and medical news developments, compiled by the editors of HealthDay:

THURSDAY, Dec. 16 (HealthDay News) -- Within a year of having a stroke, almost two-thirds of Medicare patients die or wind up back in the hospital, a new study reports.

(HealthDay News) -- Here are the latest clinical trials, courtesy of ClinicalConnection.com:

THURSDAY, Dec. 16 (HealthDay News) -- Federal health officials on Thursday recommended revoking approval of the drug Avastin to fight breast cancer, citing the medication's poor performance in follow-up studies and its potential for serious side effects.

THURSDAY, Dec. 16 (HealthDay News) -- Almost 60 percent of American adults say they had difficult childhoods featuring abusive or troubled family members or parents who were absent due to separation or divorce, federal health officials report.