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Researchers at Karolinska Institute in Sweden can now explain how the body protects itself against urinary tract infections with an antibiotic produced by the body itself. The discovery, which has been published in Nature Medicine, is said to "revolutionize" understanding of how the body defends itself against bacterial attack in the urinary tract.
"Antibiotic-resistant bacteria are a growing problem," explains research leader Prof. Annelie Brauner of Karolinska's department of clinical microbiology. "As the development of resistance to the body's own antibiotic is very rare, it can be used as an alternative or a complement to conventional antibiotic medication." She will now followup her findings in collaboration with doctors at Sheba Medical Center at Tel Hashomer. The collaboration with Israel was initiated by the late Prof. Justen Passwell, a longtime pediatric immunologist and director of Sheba's Safra Children's Hospital who died in June. Brauner says that despite his tragic passing, the collaboration will continue in Passwell's memory, with Sheba's Dr. Benny Dekel in charge of the Israeli side.
Urinary tract infection is one of the most common reasons for outpatient visits. Up to 60 percent of all women develop such an infection in their life, and of these, 20% have recurrent problems. Children have urinary infections less often, but when the kidneys are involved up to 40% get scarring.
It was previously thought that the urinary tract was kept sterile by the flow of urine, which stops bacteria from lodging in the mucus membrane. However, the researchers have now shown that an endogenous peptide is of critical significance - a finding that paves the way for new forms of treatment.
The researchers measured levels of the antibacterial peptide LL-37 (cathelicidin) in the urine of healthy children and children with a urinary tract infection. They found that the levels were low in the former group but high in the latter. Using cultivated human kidney and urinary bladder cells, they were then able to identify which cells in the body produce LL-37.
"We were able to show that LL-37 is produced in the epithelial cells of the urinary tracts and the kidneys, and that its build-up and secretion occur within a few minutes of a bacterial attack," says Brauner. Experiments on mice showed that animals lacking the gene for an antimicrobial peptide almost identical to the human peptide LL-37 are more vulnerable to urinary tract infection. In such animals, the infection was often more serious and the kidneys more swollen.
"Urinary tract infection is not only painful for the patient, but also an economical burden to society," she continues. "Our findings point to a new way to prevent urinary tract infection by boosting the antibacterial peptide LL-37. For patients suffering from recurrent infection, attack would be the best form of defense." In the continued research with Sheba, children with recurrent infections will be studied, with the aim of increasing endogenous production of cathelicidin. "We hope and foresee that such a way of increasing endogenous cathelicidin levels will serve as an alternative or complement to traditional antibiotics," Brauner concludes.
EYES BIGGER THAN STOMACH
A new study of eating habits suggests that properly sized serving utensils may help dieters avoid overeating. Using willing colleagues, Cornell University researchers led by Food and Brand Lab director Brian Wansink threw an ice-cream party to test whether oversized bowls and extra-large scoops caused partygoers to dish up more dessert. The study will appear in the American Journal of Preventive Medicine.
"Just doubling the size of someone's bowl increased how much people took by 31%," says Wansink, a consumer researcher. "We also saw that giving people a scoop that was a little bit larger increased things by about 14.5%.
Eighty-five food and nutrition experts gathered at the ice-cream social to celebrate a colleague's achievement. The researchers randomly handed out either small or large bowls, and provided either small or large scoops.
Diet experts and nutritionists have already documented a string of environmental clues that influence consumption. They include the variety of food, music, temperature and whether we're with someone who's eating faster or slower than we are, Wansink says. The visual illusion caused by tableware may be another environmental clue, he said.
"Four ounces of ice cream in a small bowl may appear appropriate for a mid-afternoon snack, but in a larger bowl may seem too little, leading one to over-serve," the study said.
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