Study: Kidney stones have distinct geological histories

A human kidney stone from the Mayo ClinicCREDIT: Mayandi Sivaguru, Bruce Fouke Lab's Jessica Saw, Carl R. Woese Institute of Genomic Biology, U. of I.

A geologist, a microscopist and a doctor enter a laboratory and, along with their colleagues from across the country, make a discovery that reverses centuries of thinking about the nature and composition of kidney stones. The key overview of the team, reported in the newspaper Scientific reports, is that kidney stones are built in calcium-rich layers that resemble other mineralizations in nature, such as those forming coral reefs or from hot springs, Roman aqueducts or underground oilfields .

More importantly for human health, the researchers found that kidney stones partially dissolve and grow back again and again as they form.

This contradicts the widely held notion that kidney stones are homogeneous rocks that never dissolve and are different from all other rocks in nature, said Bruce Fouke, professor of geology and microbiology at the University of California. Illinois. Mayo Clinic School of Medicine and Ph.D. student at I University; and Mayandi Sivaguru, Deputy Director of Carl Zeiss Laboratories @ Leasing at the Carl R. Woese Institute of Genomic Biology of the University of Indonesia.

"Contrary to what doctors learn in their medical training, we found that kidney stones were undergoing a dynamic process of growth, dissolution, growth and dissolution," Fouke said. "This means that one day we may be able to intervene to completely dissolve the stones in the patient's kidney, which most doctors would say is impossible today.

"Instead of being worthless crystalline masses, kidney stones are a minute record of the health and functioning of a person's kidney," he said.

Sivaguru, the lead author of the study who led the study on microscopy, concluded that the results were the result of further study of kidney stones and kidney stones. a wider range of optical and electronic microscopy techniques. Methods included light field microscopy, phase contrast, polarization, confocal, fluorescence and electron microscopy, with newly invented combinations of these tools and X-ray spectroscopy.

Many of these techniques are commonly used in geology and geobiology, but they have not been used to study mineralization in living organisms, such as kidney stones and gallstones that form in the human body. In particular, the use of ultraviolet light, which causes the fluorescence of certain minerals and proteins at different wavelengths, offered a vast treasure of information.

Recently developed technology, Airyscan super-resolution microscopy, allowed the team to visualize the samples at a resolution of 140 nanometers, a much higher magnification than is normally possible with light microscopy.

This effort led to colorful and dramatic images of the history of internal growth of kidney stones, revealing that they were formed by alternating thin layers of organic matter and crystals, interrupted in places with prominent interior crystals.

In the early stages of development of kidney stones, the researchers found that crystals of a hydrated form of calcium oxalate adhere to each other, forming a large, irregular bouquet. Layers of organic matter and crystals accumulate above this inner core, creating an outer shell. The stones continue to dissolve and develop. Being able to see the layers clearly for the first time has recreated this geological history, Fouke said.

"In geology, when you see diapers, it means something older is under something younger," he said. "A layer can be deposited on very short to very long periods."

But many layers were broken, revealing that some of the stones – usually the inner dihydrate crystals – had dissolved. New crystals of a dehydrated form of calcium oxalate had begun to grow again in these voids.

"Therefore, a single stone represents a series of events over time that are essential to decipher the history of kidney disease," said Mr. Fouke.

Researchers and doctors who study and treat kidney disease will now have to rethink their basic assumptions, Saw said.

"Before this study, it was thought that a kidney stone was only a crystal that was growing with time," she said. "What we see here is that it's dynamic.The stone grows and dissolves, grows and dissolves.It's very rich in components.It's very much alive. "

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