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Query: UMLS:C0451641 (urolithiasis)
 3,973 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Struvite urolithiasis forms as a consequence of a urinary tract infection by urease-producing species of bacteria such as Proteus mirabilis. Ammonia, produced by the enzymatic hydrolysis of urea, elevates urine pH causing a supersaturation and precipitation of Mg++ as struvite (NH4MgPO4). Calcium often precipitates as well, forming the mineral carbonate-apatite (Ca10(PO4)6CO3). We have developed a procedure based on direct observation by light microscopy whereby struvite crystal growth can be quickly monitored in response to chemical changes in urine. As struvite crystals assume a characteristic shape or crystal habit based on their growth rate, the effect of urine chemistry and the action of various crystallization or urease inhibitors on struvite formation can be quickly shown. In addition preliminary effects of alkaline pH, or the presence of toxic compounds on bacteria can also be shown through their loss of motility.
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PMID:A simple technique for studying struvite crystal growth in vitro. 218 Jan 68

Ammonia is quantitatively the major buffer for hydrogen ion in the urine. Further, the excretion of ammonia can be varied by acid base status and is therefore of homeostatic importance. Acid base status exerts its effect on ammonia excretion both directly and also via an effect on renal ammonia production from glutamine. The mechanism of the effect of acid base status on glutamine deamidation and deamination is uncertain. Apart from its homeostatic role in health and disease alterations in renal ammonia production may assume pathological importance in potassium depletion and uric acid urolithiasis.
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PMID:Significance, mechanisms and control of renal ammoniagenesis. 694 3