Delivery of siRNAs Against Selective Ion Channels and Transporter Genes Using Hyaluronic Acid-coupled Carbonate Apatite Nanoparticles Synergistically Inhibits Growth and Survival of Breast Cancer Cells.

Introduction: Dysregulated calcium homeostasis and consequentially aberrant Ca2+ signalling could enhance survival, proliferation and metastasis in various cancers. Despite rapid development in exploring the ion channel functions in relation to cancer, most of the mechanisms accounting for the impact of ion channel modulators have yet to be fully clarified. Although harnessing small interfering RNA (siRNA) to specifically silence gene expression has the potential to be a pivotal approach, its success in therapeutic intervention is dependent on an efficient delivery system. Nanoparticles have the capacity to strongly bind siRNAs. They remain in the circulation and eventually deliver the siRNA payload to the target organ. Afterward, they interact with the cell surface and enter the cell via endocytosis. Finally, they help escape the endo-lysosomal degradation system prior to unload the siRNAs into cytosol. Carbonate apatite (CA) nanocrystals primarily is composed of Ca2+, carbonate and phosphate. CA possesses both anion and cation binding domains to target negatively charged siRNA molecules. Methods: Hybrid CA was synthesized by complexing CA NPs with a hydrophilic polysaccharide - hyaluronic acid (HA). The average diameter of the composite particles was determined using Zetasizer and FE-SEM and their zeta potential values were also measured. Results and Discussion: The stronger binding affinity and cellular uptake of a fluorescent siRNA were observed for HA-CA NPs as compared to plain CA NPs. Hybrid CA was electrostatically bound individually and combined with three different siRNAs to silence expression of calcium ion channel and transporter genes, TRPC6, TRPM8 and SLC41A1 in a human breast cancer cell line (MCF-7) and evaluate their potential for treating breast cancer. Hybrid NPs carrying TRPC6, TRPM8 and SLC41A1 siRNAs could significantly enhance cytotoxicity both in vitro and in vivo. The resultant composite CA influenced biodistribution of the delivered siRNA, facilitating reduced off target distribution and enhanced breast tumor targetability.

Dentinal Tubule Occluding Efficacy Of Er: YAG Laser And Universal Adhesive Loaded With Nano-Carbonated Apatite.

ER:YAG laser and experimental resin-based dental adhesive loaded with functionalized carbonated apatite filler were used in this study to evaluate the dentin interaction in terms of penetration and occlusion of the dentinal tubules aiding in the control of dentin hypersensitivity (DH). Spheroidal Carbonated apatite nanoparticles (N-CAP), with an average size of 20±5 nm diameter, were synthesized, characterized, and incorporated in a universal adhesive "All Bond Universal, Bisco, USA", in (2% weight) concentration. Er:YAG laser "Lightwalker, FOTONA, EU" was adjusted to an energy output of 40mJ/ pulse and pulse repetition of 10 Hz for 10 seconds. Dentin specimens were prepared from the buccal surface of 75 extracted sound human molars. The specimens were randomly divided into five groups (n=15) according to the surface treatment: Group (L): Laser only; Group (LB): Laser in combination with adhesive; Group (LBN): Laser in combination with adhesive loaded with N-CAP; Group (B): adhesive only; and Group (BN): adhesive loaded with N-CAP. Depth of penetration and occlusion of the dentinal tubules were assessed using Environmental Scanning Electron Microscope Examination (ESEM). One-way ANOVA was used to compare groups, followed by a pairwise test for multiple comparisons (α=0.05). Groups (LB), and (LBN) showed the highest mean of dentinal tubules' penetration, with a non-significant difference between them. In contrast, the specimens treated with laser only (L) showed the most minor penetration. The employment of ER-YAG laser irradiation with the adhesive loaded with N-CAP was evaluated to be effective in penetrating and occluding the opened dentinal tubules.

Tuning Mg Doping and Features of Bone-like Apatite Nanoparticles Obtained via Hydrothermal Synthesis.

Nanocrystalline apatites have been intensively studied for decades, not only for their well-known mimesis of bone apatite but also for applicative purposes, whether as biomaterials for skeletal repair or more recently for a variety of nanomedical applications enabled by their peculiar surface characteristics. Particularly, ion-doped apatites are of great interest because the incorporation of foreign ions in the composition of apatite (nano)crystals alters the bulk and surface properties, modifying their ability to interact with the external environment. This is clearly seen in the physiology of bone tissue, whose mineral phase, a low crystallinity apatitic phase, can dynamically exchange ions with cells, thus driving bone metabolism. Taking bone mineral as a model, the present work describes the development of Mg-doped hydroxyapatite nanoparticles, exploiting hydrothermal synthesis to achieve extents of Mg2+ doping hardly achieved before and using citrate to develop stable apatite colloidal dispersions. Morphological and physicochemical analyses, associated with in-depth investigation of ions populating the apatitic lattice and the nonapatitic surface layer, concurred to demonstrate the cooperative presence of Mg2+ and citrate ions, affecting the dynamic ion retention/release mechanisms. Achieving high Mg2+ doping rates and understanding how Mg doping translates into surface activation of apatite-based nanoparticles is expected to foster the design of novel smart and tunable devices, to adsorb and release ionic species and cargo molecules, with potential innovations in the biomedical field or even beyond, as in catalysis or for environmental remediation.

In Situ Evolution of Ionic Sites at Clay Mineral Interfaces Facilitates Fluoride and Phosphorus Mineralization.

Soil minerals influence the biogeochemical cycles of fluoride (F) and phosphorus (P), impacting soil quality and bioavailability to plants. However, the cooperative mechanisms of soil minerals in governing F and P in the soil environment remain a grand challenge. Here, we reveal the essential role of a typical soil mineral, montmorillonite (Mt), in the cycling and fate of F and P. The results show that the enrichment of metal sites on the Mt surface promotes the mineralization of F to the fluorapatite (FAP) phase, thereby remaining stable in the environment, simultaneously promoting P release. This differential behavior leads to a reduction in the level of F pollution and an enhancement of P availability. Moreover, solid-state NMR and HRTEM observations confirm the existence of metastable F-Ca-F intermediates, emphasizing the pivotal role of Mt surface sites in regulating crystallization pathways and crystal growth of FAP. Furthermore, the in situ atomic force microscopy and theoretical calculations reveal molecular fractionation mechanisms and adsorption processes. It is observed that a competitive relationship exists between F and P at the Mt interface, highlighting the thermodynamically advantageous pathway of forming metastable intermediates, thereby governing the activity of F and P in the soil environment at a molecular level. This work paves the way to reveal the important role of clay minerals as a mineralization matrix for soil quality management and offers new strategies for modulating F and P dynamics in soil ecosystems.

Increasing control over biomineralization in conodont evolution.

Vertebrates use the phosphate mineral apatite in their skeletons, which allowed them to develop tissues such as enamel, characterized by an outstanding combination of hardness and elasticity. It has been hypothesized that the evolution of the earliest vertebrate skeletal tissues, found in the teeth of the extinct group of conodonts, was driven by adaptation to dental function. We test this hypothesis quantitatively and demonstrate that the crystallographic order increased throughout the early evolution of conodont teeth in parallel with morphological adaptation to food processing. With the c-axes of apatite crystals oriented perpendicular to the functional feeding surfaces, the strongest resistance to uniaxial compressional stress is conferred along the long axes of denticles. Our results support increasing control over biomineralization in the first skeletonized vertebrates and allow us to test models of functional morphology and material properties across conodont dental diversity.

Efficacy of sintered Zinc-doped fluorapatite scaffold as an antimicrobial regenerative bone filler for dental applications.

OBJECTIVES: The objective of this study was to assess whether zinc-doped fluorapatite (ZnFA) could serve as an effective antimicrobial dental bone filler for bone regeneration compared to autografts. METHODS: FA and 2 % zinc-doped FA (2ZnFA) were synthesized and characterized in-house. Compressed and sintered FA and 2ZnFA disks were incubated with bacteria to assess antimicrobial properties. Adipose-derived stem cells were cultured on these discs to evaluate the surfaces' ability to support cell growth and promote osteogenic differentiation. Surfaces exhibiting the highest expressions of the bone markers osteopontin and osteocalcin were selected for an in vivo study in a rat mandibular defect model. Twenty rats were divided into 5 groups, equally, and a 5 mm surgical defect of the jaw was left untreated or filled with 2ZnFA, FA, autograft, or demineralized bone matrix (DBM). At 12 weeks, the defects and surrounding tissues were harvested and subjected to microCT and histological evaluations. RESULTS: Standard techniques such as FTIR, ICP-MS, fluoride probe, and XRD revealed the sintered FA and ZnFA's chemical compositions and structures. Bacterial studies revealed no significant differences in surface bacterial adhesion properties between FA and 2ZnFA, but significantly fewer bacterial loads than control titanium discs (p < 0.05). Cell culture data confirmed that both surfaces could support cell growth and promote the osteogenic differentiation of stem cells. MicroCT analysis confirmed statistical similarities in bone regeneration within FA, 2ZnFA, and autograft groups. CONCLUSION: The data suggests that both FA and 2ZnFA could serve as alternatives to autograft materials, which are the current gold standard. Moreover, these bone fillers outperformed DBM, an allograft material commonly used as a dental bone void filler. CLINICAL SIGNIFICANCE: The use of FA or 2ZnFA for treating mandibular defects led to bone regeneration statistically similar to autograft repair and significantly outperformed the widely used dental bone filler, DBM. Additional translational research may confirm FA-based materials as superior substitutes for existing synthetic bone fillers, ultimately enhancing patient outcomes.

Nanoscale osseointegration of zirconia evaluated from the interfacial structure between ceria-stabilized tetragonal zirconia and cell-induced hydroxyapatite.

BACKGROUND: The osseointegration of zirconia implants has been evaluated based on their implant fixture bonding with the alveolar bone at the optical microscopic level. Achieving nano-level bonding between zirconia and bone apatite is crucial for superior osseointegration; however, only a few studies have investigated nanoscale bonding. This review outlines zirconia osseointegration, including surface modification, and presents an evaluation of nanoscale zirconia-apatite bonding and its structure. HIGHLIGHT: Assuming osseointegration, the cells produced calcium salts on a ceria-stabilized zirconia substrate. We analyzed the interface between calcium salts and zirconia substrates using transmission electron microscopy and found that 1) the cell-induced calcium salts were bone-like apatite and 2) direct nanoscale bonding was observed between the bone-like apatite and zirconia crystals without any special modifications of the zirconia surface. CONCLUSION: Structural affinity exists between bone apatite and zirconia crystals. Apatite formation can be induced by the zirconia surface. Zirconia bonds directly with apatite, indicating superior osseointegration in vivo.

Novel Synthetic Carbonate Apatite as a Bone Substitute in Implant Treatments: Case Reports.

Bone graft materials are often used in implant treatment to optimize functional and esthetic outcomes. The requirements for bone grafting materials are the ability to maintain space for bone regeneration to occur and the capability of being resorbed by osteoclasts and replaced with new bone tissue occurring in passive chemolysis and bone remodeling. Carbonate apatite (CO3Ap) granules (Cytrans Granules, GC) are a chemically synthetic bone graft material similar to autogenous bone minerals and more biocompatible than allografts and xenografts. The aim of this report is to evaluate the efficacy of CO3Ap granules in implant treatments when used alone or in combination with autogenous bone. The clinical findings and the radiographic and histologic assessments in three cases of immediate implant placement and lateral and vertical guided bone regeneration are reported. Despite the short-term follow-ups, histologic findings showed that CO3Ap granules were efficiently resorbed and replaced bone in clinical use. Furthermore, the clinical findings showed that CO3Ap granules maintained their morphology around the implant. This limited short-term case report suggests that this bone substitute is effective. However, further clinical studies and long-term reports of this new biomaterial are needed.

Enzymatic phosphatization of fish scales-a pathway for fish fossilization.

Phosphatized fish fossils occur in various locations worldwide. Although these fossils have been intensively studied over the past decades they remain a matter of ongoing research. The mechanism of the permineralization reaction itself remains still debated in the community. The mineralization in apatite of a whole fish requires a substantial amount of phosphate which is scarce in seawater, so the origin of the excess is unknown. Previous research has shown that alkaline phosphatase, a ubiquitous enzyme, can increase the phosphate content in vitro in a medium to the degree of saturation concerning apatite. We applied this principle to an experimental setup where fish scales were exposed to commercial bovine alkaline phosphatase. We analyzed the samples with SEM and TEM and found that apatite crystals had formed on the remaining soft tissue. A comparison of these newly formed apatite crystals with fish fossils from the Solnhofen and Santana fossil deposits showed striking similarities. Both are made up of almost identically sized and shaped nano-apatites. This suggests a common formation process: the spontaneous precipitation from an oversaturated solution. The excess activity of alkaline phosphatase could explain that effect. Therefore, our findings could provide insight into the formation of well-preserved fossils.

Evaluation of toothpastes for treating root carious lesions - a laboratory-based pilot study.

BACKGROUND: Root caries is preventable and can be arrested at any stage of disease development. The aim of this study was to investigate the potential mineral exchange and fluorapatite formation within artificial root carious lesions (ARCLs) using different toothpastes containing 5,000 ppm F, 1,450 ppm F or bioactive glass (BG) with 540 ppm F. MATERIALS AND METHODS: The crowns of each extracted sound tooth were removed. The remaining roots were divided into four parts (n = 12). Each sample was randomly allocated into one of four groups: Group 1 (Deionised water); Group 2 (BG with 540 ppm F); Group 3 (1,450 ppm F) and Group 4 (5,000 ppm F). ARCLs were developed using demineralisation solution (pH 4.8). The samples were then pH-cycled in 13 days using demineralisation solution (6 h) and remineralisation solution (pH 7) (16 h). Standard tooth brushing was carried out twice a day with the assigned toothpaste. X-ray Microtomography (XMT) was performed for each sample at baseline, following ARCL formation and after 13-day pH-cycling. Scanning Electron Microscope (SEM) and 19F Magic angle spinning nuclear magnetic resonance (19F-MAS-NMR) were also performed. RESULTS: XMT results showed that the highest mineral content increase (mean ± SD) was Group 4 (0.09 ± 0.05), whilst the mineral content decreased in Group 1 (-0.08 ± 0.06) after 13-day pH-cycling, however there was evidence of mineral loss within the subsurface for Groups 1, 3 and 4 (p < 0.05). SEM scans showed that mineral contents within the surface of dentine tubules were high in comparison to the subsurface in all toothpaste groups. There was evidence of dentine tubules being either partially or completely occluded in toothpaste groups. 19F-MAS-NMR showed peaks between - 103 and - 104ppm corresponding to fluorapatite formation in Groups 3 and 4. CONCLUSION: Within the limitation of this laboratory-based study, all toothpastes were potentially effective to increase the mineral density of artificial root caries on the surface, however there was evidence of mineral loss within the subsurface for Groups 1, 3 and 4.

Stratified control of chemical crystallization in a pellet fluidized bed for pH-Adjusted fluoride and phosphate reduction: An experimental study.

Chemical crystallization granulation in a fluidized bed offers an environmentally friendly technology with significant promise for fluoride removal. This study investigates the impact of stratified pH control in a crystallization granulation fluidized bed for the removal of fluoride and phosphate on a pilot scale. The results indicate that using dolomite as a seed crystal, employing sodium dihydrogen phosphate (SDP) and calcium chloride as crystallizing agents, and controlling the molar ratio n(F):n(P):n(Ca) = 1:5:10 with an upflow velocity of 7.52 m/h, effectively removes fluoride and phosphate. Stratified pH control-maintaining weakly acidic conditions (pH = 6-7) at the bottom and weakly alkaline conditions (pH = 7-8) at the top-facilitates the induction of fluoroapatite (FAP) and calcium phosphate crystallization. This approach reduces groundwater fluoride levels from 9.5 mg/L to 0.2-0.6 mg/L and phosphate levels to 0.1-0.2 mg/L. Particle size analysis, scanning electron microscopy-energy-dispersive X-ray spectroscopy, and X-ray diffraction physical characterizations reveal significant differences in crystal morphology between the top and bottom layers, with the lower layer primarily generating high-purity FAP crystals. Further analysis shows that dolomite-induced FAP crystallization offers distinct advantages. SDP not only dissolves on the dolomite surface to provide active sites for crystallization but also, under weakly acidic conditions, renders both dolomite and FAP surfaces negatively charged. This allows for the effective adsorption of PO43-, HPO42-, and F- anions onto the crystal surfaces. This study provides supporting data for the removal of fluoride from groundwater through induced FAP crystallization in a chemical crystallization pellet fluidized bed.

Preventive dental erosion with silver diamine fluoride: An in vitro study.

OBJECTIVES: To evaluate the erosion preventive effect of 38 % silver diamine fluoride (SDF) solution in enamel and dentin of human permanent teeth. METHODS: Ninety enamel and ninety dentin blocks were prepared from permanent molars and allocated into three groups. Gp-SDF received a one-off application of 38 % SDF solution. Gp-SNF received a one-off application of a solution containing 800 ppm stannous chloride and 500 ppm fluoride. Gp-DW received a one-off application of deionized water. The blocks were submitted to acid challenge at pH 3.2, 2 min, 5 times/day for 7 days. All blocks were immersed in human saliva between cycles for one hour. The crystal characteristics, percentage of surface microhardness loss (%SMHL), surface loss, and elemental analysis and surface morphology were examined by X-ray diffraction (XRD), microhardness test, non-contact profilometry, and energy-dispersive X-ray spectroscopy (EDS) and scanning electron microscopy (SEM), respectively. Data of%SMHL and surface loss were analyzed by one-way ANOVA. RESULTS: XRD spectra revealed that fluorapatite and silver compounds formed in Gp-SDF, while fluorapatite and stannous compounds formed in Gp-SNF. Gp-DW presented only hydroxyapatite. The median (interquartile range) of%SMHL in Gp-SDF, Gp-SNF and Gp-DW were 27.86(3.66), 43.41(2.45), and 46.40(3.54) in enamel (p< 0.001), and 14.21(1.57), 27.99(1.95), and 33.18(1.73) in dentin, respectively (p < 0.001). The mean (standard deviation, µm) of surface loss of Gp-SDF, Gp-SNF, and Gp-DW were 2.81(0.59), 4.28(0.67), and 4.63(0.64) in enamel (p < 0.001) and 4.13(0.69), 6.04(0.61), and 7.72(0.66) in dentin, respectively (p < 0.001). SEM images exhibited less enamel corruption and more dentinal tubular occlusion in Gp-SDF compared to Gp-SNF and Gp-DW. EDS analysis showed silver was detected in Gp-SDF while stannous was detected in the dentin block of Gp-SNF. CONCLUSION: 38 % SDF yielded superior results in protecting enamel and dentin blocks from dental erosion compared to SNF and DW. CLINICAL SIGNIFICANCE: Topical application of 38 % SDF is effective in preventing dental erosion in human enamel and dentin.

Early Colonial Diet in El Japón, Xochimilco, Mexico: Examining dietary continuity through stable isotope analysis of bone collagen and bioapatite.

OBJECTIVES: Early colonial documents from central Mesoamerica detail raising and planting of European livestock and crops alongside native ones. The extent to which Indigenous people, especially of the rural commoner class, consumed newly introduced foods is less known. This gap in knowledge is addressed through stable isotope analysis and comparison to published archaeological botanical, human, and faunal data. MATERIALS AND METHODS: Stable isotope analysis of bone collagen and bioapatite is applied to 74 skeletal samples of Indigenous human remains representing Colonial period individuals from El Japón-a farming hamlet in the Xochimilco area-to provide insight into long-term individual dietary practices in the context of a rapidly transforming Mesoamerican world. RESULTS: Carbon isotope ratios in collagen (δ13Ccollagen) average -8.10/00 VPDB (SD 0.55), while δ15N averages 8.90/00 AIR (SD 0.50). δ13Cbioapatite averages -2.90/00 VPDB (SD 0.60). Modest increase in carbon isotopic diversity is observed among more recent males from El Japón when compared to earlier males and females. DISCUSSION: Based on the isotopic results, it is estimated that the individuals of El Japón consumed maize or other C4 plants as a central source of carbohydrates. Dietary protein was largely supplied through domestic maize-fed fauna but potentially supplemented by wild terrestrial and aquatic fauna and fowl. Similarity in skeletal isotopic composition between precontact Mesoamericans from other sites and El Japón individuals of both earlier and later stratigraphy is interpreted as continuity in local diets and foodways despite potentially available European alternatives. Colonial taxation demands on preexisting agricultural regimes may have incentivized maize production, thus indirectly contributing to the maize-centered aspect of local foodways.

OBJETIVOS: Los textos de la época colonial temprana del centro de México documentan la producción de cultivos y ganado europeo a la par de los productos agropecuarios nativos. La magnitud a la cuál las comunidades indígenas consumieron estos productos se conoce con menos certeza en especial dentro de los asentamientos rurales. En este trabajo, se analiza la variabilidad de datos de isótopos estables en el sitio El Japón, Xochimilco y los resultados se comparan con respecto al sexo biológico y la cronología; así como también con datos publicados de muestras humanas y faunísticas. MATERIALES Y MÉTODOS: Se aplican los estudios de isotopos estables en colágeno y bioapatita a 74 muestras esqueléticas de El Japón de la época colonial temprana, una aldea agrícola del área de Xochimilco, con tal de abordar las practicas dietéticas en el contexto de un mundo Mesoamericano en transformación tras el contacto europeo. RESULTADOS: Los isótopos estables de carbono en colágeno (δ13Ccollagen) producen un promedio de −8.10/00 VPDB (DE 0.55), mientras tanto los isótopos estables de nitrógeno en el mismo tejido producen un promedio de 8.90/00 AIR (DE 0.50). Los isótopos estables de carbono en la bioapatita (δ13Cbioapatite) producen un promedio de −2.90/00 VPDB (DE 0.60). Se observa un incremento mínimo en la diversidad isotópica entre los individuos de sexo masculino en comparación a los individuos de sexo femenino de la etapa temprana y tardía del sitio. DISCUSIÓN: Con base en los resultados isotópicos, y con base en comparación a muestras humanas de contextos arqueológicos europeos y norteamericanos se estima que los individuos de El Japón consumieron maíz u otros cultivos tipo C4 como fuentes principales de carbohidratos. Las fuentes de proteína dietética posiblemente fueron fauna alimentada con maíz, pero también se pudieron haber suplementado con alimentos silvestres incluyendo aves silvestres, y fauna terrestre o acuática. La similitud en variación isotópica entre sitios mesoamericanos que preceden el contacto europeo y El Japón de ambas etapas (temprana y tardía) se interpretan como persistencia en fuentes de alimentación y tradiciones culinarias a pesar de las posibles alternativas europeas. Las demandas tributarias coloniales sobre la producción agrícola chinampera pudiesen haber contribuido indirectamente a la continuidad del maíz como fuente alimenticia principal.

Porous Mg-Zn-Ca scaffolds for bone repair: a study on microstructure, mechanical properties and in vitro degradation behavior.

Biodegradable porous Mg scaffolds are a promising approach to bone repair. In this work, 3D-spherical porous Mg-1.5Zn-0.2Ca (wt.%) scaffolds were prepared by vacuum infiltration casting technology, and MgF2 and fluorapatite coatings were designed to control the degradation behavior of Mg-based scaffolds. The results showed that the pores in Mg-based scaffolds were composed of the main spherical pores (450-600 µm) and interconnected pores (150-200 µm), and the porosity was up to 74.97%. Mg-based porous scaffolds exhibited sufficient mechanical properties with a compressive yield strength of about 4.04 MPa and elastic modulus of appropriately 0.23 GPa. Besides, both MgF2 coating and fluorapatite coating could effectively improve the corrosion resistance of porous Mg-based scaffolds. In conclusion, this research would provide data support and theoretical guidance for the application of biodegradable porous Mg-based scaffolds in bone tissue engineering.

Crystal induced arthropathies-a comparative study of 40 patients with apatite rheumatism, chondrocalcinosis and primary synovial chondromatosis.

Introduction: Apatite rheumatism (AR), chondrocalcinosis (Ch-C), and primary synovial chondromatosis (prSynCh) are regarded as distinct clinical entities. The introduction of the non-staining technique by Bély and Apáthy (2013) opened a new era in the microscopic diagnosis of crystal induced diseases, allowing the analysis of MSU (monosodium urate monohydrate) HA (calcium hydroxyapatite), CPPD (calcium pyrophosphate dihydrate) crystals, cholesterol, crystalline liquid lipid droplets, and other crystals in unstained sections of conventionally proceeded (aqueous formaldehyde fixed, paraffin-embedded) tissue samples. The aim of this study was to describe the characteristic histology of crystal deposits in AR, Ch-C, and prSynCh with traditional stains and histochemical reactions comparing with unstained tissue sections according to Bély and Apáthy (2013). Patients and methods: Tissue samples of 4 with apatite rheumatism (Milwaukee syndrome), 16 with chondrocalcinosis, and 20 with clinically diagnosed primary synovial chondromatosis were analyzed. Results and conclusion: Apatite rheumatism, chondrocalcinosis, and primary synovial chondromatosis are related metabolic disorders with HA and CPPD depositions. The authors assume that AR and Ch-C are different stages of the same metabolic disorder, which differ from prSynCh in amorphous mineral production, furthermore in the production of chondroid, osteoid and/or bone. prSynCh is a defective variant of HA and CPPD induced metabolic disorders with reduced mineralization capabilities, where the deficient mineralization is replaced by chondroid and/or bone formation. The non-staining technique of Bély and Apáthy proved to be a much more effective method for the demonstration of crystals in metabolic diseases than conventional stains and histochemical reactions.

Nephrolithiasis Associated with Nephrocalcinosis Is Primarily Composed of Carbonate Apatite.

INTRODUCTION: This study was designed to determine the mineral composition of calculi in nephrocalcinosis with nephrolithiasis, diagnose the underlying disease, and monitor the course of renal function in patients with nephrocalcinosis-nephrolithiasis. METHODS: Renal calculi extruded in a series of 8 patients with nephrocalcinosis were analysed using Fourier transmission infrared spectrometry. In 4 patients, next-generation sequencing using a nephrocalcinosis-nephrolithiasis panel was performed to determine the nature of the underlying disease. In addition, longitudinal analysis of renal function was performed in all patients. RESULTS: Seven patients revealed carbonate apatite as the sole constituent of renal calculi. One patient showed a mixed composition of dicalcium phosphate dihydrate/carbonate apatite at first analysis yet in subsequent episodes also had calculi composed of pure carbonate apatite. Further molecular analysis displayed distal renal tubular acidosis in 2 of 4 patients who consented to sequencing. No known genetic defect could be found in the other two cases. In line with prior reports, decline of renal function was dependent on underlying disease. Distal renal tubular acidosis revealed a progressive course of renal failure, whereas other causes showed stable renal function in long term analysis. CONCLUSION: Nephrocalcinosis with nephrolithiasis is a rare condition with heterogeneous aetiology. Yet mineral composition of renal calculi predominantly consisted of pure carbonate apatite. This uniform finding is similar to subcutaneous calcifications of various origins and might propose a general principle of tissue calcification. Progressive decline of renal function was found in distal renal tubular acidosis, whereas other conditions remained stable over time.

Injectable macroporous naturally-derived apatite bone cement as a potential trabecular bone substitute.

In this study, we have formulated a novel apatite bone cements derived from natural sources (i.e. eggshell and fishbone) with improved qualities that is, porosity, resorbability, biological activity, and so forth. The naturally-derived apatite bone cement (i.e. FBDEAp) was prepared by mixing hydroxyapatite (synthesized from fishbone) and tricalcium phosphate (synthesized from eggshell) as a solid phase with a liquid phase (a dilute acidic blend of cement binding accelerator and biopolymers like gelatin and chitosan) with polysorbate (as liquid porogen) to get a desired bone cement paste. The prepared cement paste sets within the clinically acceptable setting time (≤20 min), easily injectable (>85%) through hands and exhibits physiological pH stability (7.3-7.4). The pure apatite phased bone cement was confirmed by x-ray diffraction and Fourier transform infrared spectroscopy analyses. The FBDEAp bone cement possesses acceptable compressive strength (i.e. 5-7 MPa) within trabecular bone range and is resorbable up to 28% in simulated body fluid solution within 12 weeks of incubation at physiological conditions. The FBDEAp is macroporous in nature (average pore size ~50-400 µm) with interconnected pores verified by SEM and micro-CT analyses. The FBDEAp showed significantly increased MG63 cell viability (>125% after 72 h), cell adhesion, proliferation, and key osteogenic genes expression levels (up to 5-13 folds) compared to the synthetically derived, synthetic and eggshell derived as well as synthetic and fishbone derived bone cements. Thus, we strongly believe that our prepared FBDEAp bone cement can be used as potential trabecular bone substitute in orthopedics.

Metal leakage from orthodontic appliances chemically alters enamel surface during experimental in vitro simulated treatment.

Human enamel is composed mainly of apatite. This mineral of sorption properties is susceptible to chemical changes, which in turn affect its resistance to dissolution. This study aimed to investigate whether metal leakage from orthodontic appliances chemically alters the enamel surface during an in vitro simulated orthodontic treatment. Totally 107 human enamel samples were subjected to the simulation involving metal appliances and cyclic pH fluctuations over a period of 12 months in four complimentary experiments. The average concentrations and distribution of Fe, Cr, Ni, Ti and Cu within the enamel before and after the experiments were examined using ICP‒MS and LA‒ICP‒MS techniques. The samples exposed to the interaction with metal appliances exhibited a significant increase in average Fe, Cr and Ni (Kruskal-Wallis, p < 0.002) content in comparison to the control group. The outer layer, narrow fissures and points of contact with the metal components showed increased concentrations of Fe, Ti, Ni and Cr after simulated treatment, conversely to the enamel sealed with an adhesive system. It has been concluded that metal leakage from orthodontic appliances chemically alters enamel surface and microlesions during experimental in vitro simulated treatment.

In vivo assessment of marine vs bovine origin collagen-based composite scaffolds promoting bone regeneration in a New Zealand rabbit model.

The ability of human tissues to self-repair is limited, which motivates the scientific community to explore new and better therapeutic approaches to tissue regeneration. The present manuscript provides a comparative study between a marine-based composite biomaterial, and another composed of well-established counterparts for bone tissue regeneration. Blue shark skin collagen was combined with bioapatite obtained from blue shark's teeth (mColl:BAp), while bovine collagen was combined with synthetic hydroxyapatite (bColl:Ap) to produce 3D composite scaffolds by freeze-drying. Collagens showed similar profiles, while apatite particles differed in their composition, being the marine bioapatite a fluoride-enriched ceramic. The marine-sourced biomaterials presented higher porosities, improved mechanical properties, and slower degradation rates when compared to synthetic apatite-reinforced bovine collagen. The in vivo performance regarding bone tissue regeneration was evaluated in defects created in femoral condyles in New Zealand rabbits twelve weeks post-surgery. Micro-CT results showed that mColl:BAp implanted condyles had a slower degradation and an higher tissue formation (17.9 ± 6.9 %) when compared with bColl:Ap implanted ones (12.9 ± 7.6 %). The histomorphometry analysis provided supporting evidence, confirming the observed trend by quantifying 13.1 ± 7.9 % of new tissue formation for mColl:BAp composites and 10.4 ± 3.2 % for bColl:Ap composites, suggesting the potential use of marine biomaterials for bone regeneration.