Nav: Home

Researchers propose new treatment to prevent kidney stones

August 08, 2016

Researchers have found evidence that a natural fruit extract is capable of dissolving calcium oxalate crystals, the most common component of human kidney stones. This finding could lead to the first advance in the treatment of calcium oxalate stones in 30 years.

Jeffrey Rimer, associate professor of chemical engineering at the University of Houston, was lead author of the study, published Aug. 8 in the online edition of Nature. The work offers the first evidence that the compound hydroxycitrate (HCA) is an effective inhibitor of calcium oxalate crystal growth that, under certain conditions, is actually able to dissolve these crystals. Researchers also explain how it works.

The findings are the result of a combination of experimental studies, computational studies and human studies, Rimer said.

Kidney stones are small, hard mineral deposits that form inside the kidneys, affecting up to 12 percent of men and seven percent of women. High blood pressure, diabetes and obesity can increase the risk, and the reported incidence is on the rise.

Preventive treatment has not changed much over the last three decades. Doctors tell patients who are at risk of developing stones to drink lots of water and avoid foods rich in oxalate, such as rhubarb, okra, spinach and almonds. They often recommend taking citrate (CA), in the form of potassium citrate, a supplement that can slow crystal growth, but some people are unable to tolerate the side effects.

The project grew out of preliminary work done by collaborator John Asplin, a nephrologist at Litholink Corporation, who suggested HCA as a possible treatment. HCA is chemically similar to CA and is also available as a dietary supplement.

"HCA shows promise as a potential therapy to prevent kidney stones," the researchers wrote. "HCA may be preferred as a therapy over CA (potassium citrate)."

In addition to Rimer and Asplin, authors on the paper include Giannis Mpourmpakis and his graduate student, Michael G. Taylor, of the University of Pittsburgh; Ignacio Granja of Litholink Corporation, and Jihae Chung, a UH graduate student working in Rimer's lab.

The head-to-head studies of CA and HCA determined that while both compounds inhibit the growth of calcium oxalate crystals, HCA was more potent and displayed unique qualities that are advantageous for the development of new therapies.

The team of researchers then used atomic force microscopy, or AFM, to study interactions between the crystals, CA and HCA under realistic growth conditions. According to Rimer, the technique allowed them to record crystal growth in real time with near-molecular resolution.

Chung noted that the AFM images recorded the crystal actually shrinking when exposed to specific concentrations of HCA. Rimer suspected the initial finding was an abnormality, as it is rare to see a crystal actually dissolve in highly supersaturated growth solutions. The most effective inhibitors reported in the literature simply stop the crystal from growing.

It turned out that Chung's initial finding was correct. Once they confirmed it is possible to dissolve crystals in supersaturated solutions, researchers then looked at reasons to explain why that happened.

Mpourmpakis and Taylor applied density functional theory (DFT) - a highly accurate computational method used to study the structure and properties of materials - to address how HCA and CA bind to calcium and to calcium oxalate crystals. They discovered HCA formed a stronger bond with crystal surfaces, inducing a strain that is seemingly relieved by the release of calcium and oxalate, leading to crystal dissolution.

HCA was also tested in human subjects, as seven people took the supplement for three days, allowing researchers to determine that HCA is excreted through urine, a requirement for the supplement to work as a treatment.

While Rimer said the research established the groundwork to design an effective drug, questions remain. Long-term safety, dosage and additional human trials are needed, he said.

"But our initial findings are very promising," he said. "If it works in vivo, similar to our trials in the laboratory, HCA has the potential to reduce the incidence rate of people with chronic kidney stone disease."
-end-


University of Houston

Related Calcium Articles:

A docking site per calcium channel cluster
In our brain, information is passed from one neuron to the next at a structure called synapse.
Astrophysicists discovered a star polluted by calcium
An international team of astrophysicists led by a scientist from the Sternberg Astronomical Institute of the Lomonosov Moscow State University reported the discovery of a binary solar-type star inside the supernova remnant RCW 86.
Daily reminders to increase calcium intake are effective
Mary Jung, an assistant professor of health and exercise sciences at UBC's Okanagan campus, recently completed a nationwide study with more than 730 Canadians who were not meeting Canada's recommended dietary intake for calcium.
New guideline on calcium and vitamin D supplementation
A new evidence-based clinical guideline from the National Osteoporosis Foundation and the American Society for Preventive Cardiology says that calcium with or without vitamin D intake from food or supplements that does not exceed the tolerable upper level of intake should be considered safe from a cardiovascular standpoint.
Calcium induces chronic lung infections
The bacterium Pseudomonas aeruginosa is a life-threatening pathogen in hospitals.
Calcium supplements may damage the heart
After analyzing 10 years of medical tests on more than 2,700 people in a federally funded heart disease study, researchers at Johns Hopkins Medicine and elsewhere conclude that taking calcium in the form of supplements may raise the risk of plaque buildup in arteries and heart damage, although a diet high in calcium-rich foods appears be protective.
Physics researchers question calcium-52's magic
After a multi-institution team's work computing the calcium-48 nucleus, researchers moved on to a larger, heavier, and more complex isotope -- calcium-52 -- and the results surprised them once again.
Study paves way for new therapies in fight against calcium disorders
A study led by researchers at Georgia State University provides new insights into the molecular basis of human diseases resulting from mutations in the calcium-sensing receptor, a protein found in cell membranes.
Calcium channels team up to activate excitable cells
Voltage-gated calcium channels open in unison, rather than independently, to allow calcium ions into and activate excitable cells such as neurons and muscle cells, researchers with UC Davis Health System and the University of Washington have found.
A calcium pump caught in the act
Researchers at Aarhus University have described one of the cell's key enzymes, the calcium pump, in its decisive moment -- a so-called transition state.

Related Calcium Reading:

Vitamin K2 and the Calcium Paradox: How a Little-Known Vitamin Could Save Your Life
by Kate Rheaume-Bleue (Author)

The Calcium Lie II: What Your Doctor Still Doesn't Know: How Mineral Imbalances Are Damaging Your Health
by Robert Thompson MD (Author), Kathleen Barnes (Author)

The Calcium Factor: The Scientific Secret of Health and Youth
by Robert R. Barefoot (Author), Carl M. Reich (Author)

The Calcium Bomb: The Nanobacteria Link to Heart Disease & Cancer
by Douglas Mulhall (Author), Katja Hansen (Author)

Death By Calcium (New, First Edition)
by Thomas E., MD, JD Levy (Author)

Calcium Bentonite Clay: Nature’s Pathway to Healing Balance, Detox, Stimulate, Alkalize
by Perry A~ (Author)

Calcium Chloride Recovery in Soda Ash Production by Solvay's Process
by Temesgen Atnafu (Author), Seid Yimer (Author)

Excess Calcium Disease: What you should know about high blood calcium, parathyroid hormone and hyperparathyroidism
by Peter A. Galbraith

User's Guide to Calcium & Magnesium: Learn What You Need to Know about How These Nutrients Build Strong Bones
by Nan Kathryn Fuchs (Author)

Calcium Signaling (Protein Biochemistry, Synthesis, Structure and Cellular Functions)
by Masayoshi Yamaguchi (Editor)

Best Science Podcasts 2018

We have hand picked the best science podcasts for 2018. Sit back and enjoy new science podcasts updated daily from your favorite science news services and scientists.
Now Playing: TED Radio Hour

Dying Well
Is there a way to talk about death candidly, without fear ... and even with humor? How can we best prepare for it with those we love? This hour, TED speakers explore the beauty of life ... and death. Guests include lawyer Jason Rosenthal, humorist Emily Levine, banker and travel blogger Michelle Knox, mortician Caitlin Doughty, and entrepreneur Lux Narayan.
Now Playing: Science for the People

#492 Flint Water Crisis
This week we dig into the Flint water crisis: what happened, how it got so bad, what turned the tide, what's still left to do, and the mix of science, politics, and activism that are still needed to finish pulling Flint out of the crisis. We spend the hour with Dr Mona Hanna-Attisha, a physician, scientist, activist, the founder and director of the Pediatric Public Health Initiative, and author of the book "What the Eyes Don't See: A Story of Crisis, Resistance, and Hope in an American City".