(HealthDay News) -- Gastroesophageal reflux disease (GERD) occurs when what's inside your stomach backs up into the esophagus. This may trigger an unpleasant taste in the mouth and a burning sensation in the chest or throat, commonly called heartburn.

MONDAY, June 21 (HealthDay News) -- It has long been known that chimpanzees sometimes kill their neighboring primates, and now new research suggests that they are apparently motivated to do so by a desire to gain territory.

MONDAY, June 21 (HealthDay News) -- As women increasingly compete in marathons and triathlons, experts warn that inexperienced female endurance athletes can damage their health.

SUNDAY, June 20 (HealthDay News) -- Among older men, having a high testosterone level is associated with a raised risk of heart disease or a heart attack, new research suggests.

MONDAY, June 21 (HealthDay News) -- Despite its endorsement last year by the American Diabetes Association as an effective way to diagnose type 2 diabetes, new research out of Singapore suggests that the hemoglobin A1c blood test may not accurately identify the disease among elderly Asians.

(HealthDay News) -- People with arthritis can take steps to lessen pain, increase movement and improve their mobility.

SUNDAY, June 20 (HealthDay News) -- Children exposed early in life to polychlorinated biphenyls (PCBs) may have a reduced immune response to tetanus and diphtheria vaccines, a new study indicates.

MONDAY, June 21 (HealthDay News) -- Exposure to flame-retardant chemicals may reduce a pregnant woman's levels of certain thyroid hormones that play a critical role in fetal brain development, a new study shows.

MONDAY, June 21 (HealthDay News) -- Although diabetes raises the chances of developing heat illness, many people with the condition don't know how to reduce their risk, a new Mayo Clinic survey reveals.

MONDAY, June 21 (HealthDay News) -- Popular cartoon characters are influencing the taste preferences of very young children, and not in a positive way, a new study suggests.

SATURDAY, June 19 (HealthDay News) -- For a small number of obese people, those extra pounds do not condemn them to heart disease or diabetes, Dutch researchers report.

MONDAY, June 21 (HealthDay News) -- Scientists who sequenced the genome of human body lice say their research will help improve understanding about the blood-sucking parasite's biology and evolution, and potentially lead to better control methods.

MONDAY, June 21 (HealthDay News) -- Using ear tubes to treat infections is safe for children who later receive cochlear implants, a new study finds.

MONDAY, June 21 (HealthDay News) -- Tumors of skin appendages, such as sweat glands, mammary glands, hair and nails, appear to be increasing in the United States, says a new study.

MONDAY, June 21 (HealthDay News) -- Breast-feeding seems to provide an immune system boost to infants, helping to prevent respiratory and gastrointestinal illnesses in babies, according to new research.

SUNDAY, June 20 (HealthDay News) -- New research suggests that the ubiquitous sugar known as fructose may cause certain fat cells in children to multiply faster, which might play a key role in childhood and adult obesity.

MONDAY, June 21 (HealthDay News) -- You're not the only one who can't always tell if your child has a viral illness or a bacterial infection that calls for antibiotics: Pediatricians say this is the most common diagnostic error they make, a new study shows.

MONDAY, June 21 (HealthDay News) -- Babies who are born vaginally pick up different bacteria than those who are delivered by cesarean section, potentially affecting how their immune systems develop, a new study suggests.

MONDAY, June 21 (HealthDay News) -- People using MP3 players are leaving themselves open to temporary changes in hearing, which over time might result in permanent hearing loss, Belgian researchers suggest.

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

MONDAY, June 21 (HealthDay News) -- Abbott's Architect HIV Ag/Ab Combo assay has been approved by the U.S. Food and Drug Administration.

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

MONDAY, June 21 (HealthDay News) -- Although the landscape is changing, many doctors do not have a problem with taking gifts or participating in corporate marketing, a new study shows.

MONDAY, June 21 (HealthDay News) -- There may be more troubling news about the ubiquitous plastics chemical bisphenol A (BPA): Women with polycystic ovary syndrome have higher levels of the chemical in their bloodstream, a study finds.