Dataset Information

Enzymatic dissolution of calcium and struvite crystals: in vitro evaluation of biochemical requirements.

ABSTRACT: To evaluate the factors that affect the enzymatic dissolution rate of calcium oxalate monohydrate (COM), calcium phosphate (brushite), and magnesium ammonium phosphate (struvite) crystals as enzymatic digestion of kidney stones could enhance lithotripsy or provide alternatives to surgical removal.At pH 4.2, pelleted COM crystals were combined with oxalate decarboxylase (ODC from Bacillus subtilis), oxalate oxidase (from Hordeum vulgare), or control. Crystal dissolution was followed by measuring increases in solution calcium ion concentration. For phosphate-based crystals, the rates of phosphorolysis by the enzyme purine nucleoside phosphorylase (PNP, assay form) were compared to the control solution using spectrophotometry.The addition of ODC to COM crystals resulted in production of highly soluble calcium formate and a 15-fold increase in COM solubility. By adding a formate-catabolizing enzyme (formate dehydrogenase), dissolution increased 47-fold compared with controls with nearly one half of the mineral dissolved. Oxalate oxidase showed much lower activity than ODC in COM dissolution. Using inorganic phosphate as a substrate, PNP was able to dissolve both brushite and struvite minerals in water at concentrations near saturation. Measuring dissolution by adding more PNP was not possible because of equilibrium and assay detection restraints.Stone dissolution using enzymes appears to be viable, particularly for oxalate-based minerals. In a closed system, product inhibition by calcium formate appeared to limit the extent of COM crystal dissolution using ODC. Although phosphate-containing minerals appear to be suitable phosphate sources for PNP, the reversibility of the reaction limits the use of this enzyme.

SUBMITTER: Thalji NK

PROVIDER: S-EPMC3166441 | biostudies-literature | 2011 Sep

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

Enzymatic dissolution of calcium and struvite crystals: in vitro evaluation of biochemical requirements.

Thalji Nabil K NK Richards Nigel G NG Peck Ammon B AB Canales Benjamin K BK

Urology 20110713 3

<h4>Objective</h4>To evaluate the factors that affect the enzymatic dissolution rate of calcium oxalate monohydrate (COM), calcium phosphate (brushite), and magnesium ammonium phosphate (struvite) crystals as enzymatic digestion of kidney stones could enhance lithotripsy or provide alternatives to surgical removal.<h4>Methods</h4>At pH 4.2, pelleted COM crystals were combined with oxalate decarboxylase (ODC from Bacillus subtilis), oxalate oxidase (from Hordeum vulgare), or control. Crystal diss ...[more]

PMID: 21741690

Similar Datasets

Project description:INTRODUCTION: Calcium-containing (CaC) crystals, including basic calcium phosphate (BCP) and calcium pyrophosphate dihydrate (CPP), are associated with destructive forms of osteoarthritis (OA). We assessed their distribution and biochemical and morphologic features in human knee OA cartilage. METHODS: We prospectively included 20 patients who underwent total knee replacement (TKR) for primary OA. CaC crystal characterization and identification involved Fourier-transform infra-red spectrometry and scanning electron microscopy of 8 to 10 cartilage zones of each knee, including medial and lateral femoral condyles and tibial plateaux and the intercondyle zone. Differential expression of genes involved in the mineralization process between cartilage with and without calcification was assessed in samples from 8 different patients by RT-PCR. Immunohistochemistry and histology studies were performed in 6 different patients. RESULTS: Mean (SEM) age and body mass index of patients at the time of TKR was 74.6 (1.7) years and 28.1 (1.6) kg/m², respectively. Preoperative X-rays showed joint calcifications (chondrocalcinosis) in 4 cases only. The medial femoro-tibial compartment was the most severely affected in all cases, and mean (SEM) Kellgren-Lawrence score was 3.8 (0.1). All 20 OA cartilages showed CaC crystals. The mineral content represented 7.7% (8.1%) of the cartilage weight. All patients showed BCP crystals, which were associated with CPP crystals for 8 joints. CaC crystals were present in all knee joint compartments and in a mean of 4.6 (1.7) of the 8 studied areas. Crystal content was similar between superficial and deep layers and between medial and femoral compartments. BCP samples showed spherical structures, typical of biological apatite, and CPP samples showed rod-shaped or cubic structures. The expression of several genes involved in mineralization, including human homolog of progressive ankylosis, plasma-cell-membrane glycoprotein 1 and tissue-nonspecific alkaline phosphatase, was upregulated in OA chondrocytes isolated from CaC crystal-containing cartilages. CONCLUSIONS: CaC crystal deposition is a widespread phenomenon in human OA articular cartilage involving the entire knee cartilage including macroscopically normal and less weight-bearing zones. Cartilage calcification is associated with altered expression of genes involved in the mineralisation process.

Project description:Magnetotactic bacteria (MTB) represent a group of microorganisms that are widespread in aquatic habitats and thrive at oxic-anoxic interfaces. They are able to scavenge high concentrations of iron thanks to the biomineralization of magnetic crystals in their unique organelles, the so-called magnetosome chains. Although their biodiversity has been intensively studied, their ecology and impact on iron cycling remain largely unexplored. Predation by protozoa was suggested as one of the ecological processes that could be involved in the release of iron back into the ecosystem. Magnetic protozoa were previously observed in aquatic environments, but their diversity and the fate of particulate iron during grazing are poorly documented. In this study, we report the morphological and molecular characterizations of a magnetically responsive MTB-grazing protozoan able to ingest high quantities of MTB. This protozoan is tentatively identified as Uronema marinum, a ciliate known to be a predator of bacteria. Using light and electron microscopy, we investigated in detail the vacuoles in which the lysis of phagocytized prokaryotes occurs. We carried out high-resolution observations of aligned magnetosome chains and ongoing dissolution of crystals. Particulate iron in the ciliate represented approximately 0.01% of its total volume. We show the ubiquity of this interaction in other types of environments and describe different grazing strategies. These data contribute to the mounting evidence that the interactions between MTB and protozoa might play a significant role in iron turnover in microaerophilic habitats.IMPORTANCE Identifying participants of each biogeochemical cycle is a prerequisite to our understanding of ecosystem functioning. Magnetotactic bacteria (MTB) participate in iron cycling by concentrating large amounts of biomineralized iron minerals in their cells, which impacts their chemical environment at, or below, the oxic-anoxic transition zone in aquatic habitats. It was shown that some protozoa inhabiting this niche could become magnetic by the ingestion of magnetic crystals biomineralized by grazed MTB. In this study, we show that magnetic MTB grazers are commonly observed in marine and freshwater sediments and can sometimes accumulate very large amounts of particulate iron. We describe here different phagocytosis strategies, determined using magnetic particles from MTB as tracers after their ingestion by the protozoa. This study paves the way for potential scientific or medical applications using MTB grazers as magnetosome hyperaccumulators.

Dataset Information

Enzymatic dissolution of calcium and struvite crystals: in vitro evaluation of biochemical requirements.

Publications

Enzymatic dissolution of calcium and struvite crystals: in vitro evaluation of biochemical requirements.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets