The research identifies a transporter, encoded by the gene, as a potential target for drugs to boost oxalate secretion in the gut and help prevent kidney stones, said Peter Aronson, M.D., professor of internal medicine and physiology and senior author of the research.

The most common type of kidney stones are composed of calcium oxalate. The transporter, known as SLC26A6, normally secretes oxalate into the intestine and prevents absorption of too much of the oxalate from the diet.

"When this gene is knocked out in the mouse, more oxalate from the diet is absorbed, the plasma level of oxalate is increased, more oxalate is excreted in the urine by the kidney, and kidney stones are formed," Aronson said.

In addition to pinpointing a potential drug target, he said the research raises the possibility that abnormal expression or regulation of the anion transporter encoded by the gene could cause kidney stones in humans, although this has not yet been tested directly.

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Though the team originally estimated a higher 10-year risk for cardiac events in the surgical group at the start of the study due to their associated conditions, researchers found at follow-up that the patients had a much lower risk than the control group for having a heart complication (18.3 vs. 30 percent). Using the study parameters and risk models based on previously published data, the team estimated that for every 100 patients, the surgery would prevent 16.2 cardiovascular events and 4.1 overall deaths, as compared to the control group. However, should the number of deaths during surgery approach 4 percent, the protective effect is limited, as may be in the case in centers with very low volumes of weight loss surgeries.

In reviewing the cardiovascular risk factors calculated during the study, the team found that at follow-up, the percentage of the surgery population meeting criteria for diabetes was reduced from 30 percent (59 pts) to 11 percent (19 pts), and also showed reductions in blood pressure, LDL cholesterol and BMI.

"With an understanding of the very close link between obesity and cardiovascular risk, we feel confident that a procedure like bariatric surgery is an effective alternative to current therapies, which can have a considerable and lasting improvement in cardiac health," said John Batsis, M.D., of the Mayo Clinic, and lead author of the study. "For the patients who are eligible for surgery, this suggests a reduced risk of cardiac events or death."

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