Phosphate Deposits Research Articles

A review on calcinosis cutis

Calcinosis, marked by hydroxyapatite, calcium, and phosphate deposits in skin and subcutaneous tissues, is common in individuals with various physiological conditions, soft tissue ailments, and autoimmune disorders. Researchers categorize and analyze these occurrences, shedding light on their pathophysiology. They also review scientific evidence regarding non- pharmacologic and pharmacodynamic treatments. Calcinosis cutis involves the accumulation of insoluble calcium ions in the epidermis and subcutaneous tissue, classified into dystrophic, metastatic, idiopathic, iatrogenic, and calciphylaxis subgroups. Dysplastic deposits result from cellular damage, while metastatic calcification stems from irregular potassium and phosphorous metabolism. Undiagnosed calcification occurs independently of tissue destruction or underlying disease. Autoimmune syndrome-induced epidermal calcification is a rare therapy-related effect. Calciphylaxis, primarily affecting the vascular system, is introduced, with disturbances in calcium and phosphorus biotransformation and congenital hypothyroidism as contributing factors.

Phosphate δ13Corg chemostratigraphy from the Gantour basin, Morocco: A proof of concept from the K–Pg transition to mid-Thanetian

The Late Cretaceous–early Paleogene interval is globally associated with transient to long-term changes in the stable carbon isotopic composition of marine carbonates (δ13Ccarb). Based on biostratigraphic reconstruction, this critical period of Earth's history is thought to coincide with the deposition of world heritage Paleocene phosphate deposits (phosphorites) in northwestern Morocco. However, the detailed stratigraphy of the Gantour basin, one of the most important Moroccan phosphate deposits, has not yet been constrained. For instance, the former “Montian” Stage has been used to tentatively approximate the Danian, whereas the succeeding Selandian Stage remains to be identified. Here, we develop a detailed organic carbon isotopic (δ13Corg) curve from phosphorus-rich horizons of the western Gantour sedimentary sequence in an attempt to constrain their stratigraphic placement and depositional age model. Upsection, these strata host long-term negative and positive δ13Corg trends that tend to correlate with global δ13Ccarb records of the Cretaceous–Paleogene and mid-Thanetian transitional boundaries. The data support the presence of Danian and Selandian rocks in the Gantour basin, which are succeeded by strata containing characteristic signatures of the well-known Cenozoic δ13C maximum at 58–57.5 Ma (the Paleocene Carbon Isotope Maximum). Our results shift the previously proposed Cretaceous–Paleogene transition in the Gantour basin further down into the older sediment C2M layer without interfering with recorded massive biological turnover in faunal diversity and abundance. Moreover, the refined stratigraphy suggests that the deposition of the Gantour phosphorites spanned ∼8.5 Myr. Our results confirm the utility of δ13Corg chemostratigraphy for dating and correlating phosphate-bearing deposits of the Tethyan province. They have important implications for deciphering Paleocene phosphogenesis, the co-evolution of associated vertebrate groups, and for prospecting phosphorus-rich mineral deposits.

New Insights from Geophysical, Hydrogeological and Borehole Data into the Deep Structure of the Louta Phosphatic Deposit (Gantour Basin, Morocco): Mining Implications

The Gantour Phosphatic Basin (GPB) is formed by a sedimentary series of Maastrichtian to the Eocene age, which consists of alternating phosphate layers and sterile levels. This series outcrops in the northern part of the basin, where it is exploited in open-pit mines. The exploration methodology employed by the Office Chérifien des Phosphates (OCP) group to investigate the GPB is based on direct recognition with boreholes drilled on a 500 × 500 m grid. This research is concerned with the compilation and analysis of data collected during several drilling campaigns conducted on the central segment of the GPB, namely the Louta deposit. This research also includes acquiring, processing, and interpreting new geophysical and hydrogeological data. Its main objective is to provide a better understanding of the deep structure of the phosphatic series. Therefore, the present study was carried out according to a multidisciplinary approach that comprises three parts. (i) The first one involves geological modeling of the exploration borehole data using Datamine Studio RM software (version 1.4), developed by Datamine Corporate Ltd., (Bristol, United Kingdom). It results in establishing a series of geological cross-sections that display a detailed view of the deep structure of the phosphatic series and its lateral variations. (ii) The second part is related to the hydrogeological study, whose purpose was to elaborate on an accurate and updated piezometric map of the study area. The new map helps understand the groundwater flow in the Louta deposit. Furthermore, the superimposition of the piezometric level with the geological sections throws light on the flooded volume of phosphate in this deposit. (iii) The third part of the study focuses on implementing the Electrical Resistivity Tomography (ERT) method. The interpretation of the recorded geoelectrical data not only highlights the main features controlling the mode and the proportion of the phosphate series deepening under the Plio-Quaternary cover but also confirms the evolution of the overall structure of the studied area. The obtained 2D ERT models generally corroborate the cross-sections produced by geological modeling. They also correlate with the information provided by the hydrogeological study. Such information will help guide future hydrogeological and mining extraction planning in the studied area.

Tri-Component Hydrogel as Template for Nanocrystalline Hydroxyapatite Deposition Using Alternate Soaking Method for Bone Tissue Engineering Applications.

Composite hydrogels containing apatite-like particles can act as scaffolds for osteoblast proliferation, with applications in bone tissue engineering. In this respect, porous biocompatible hydrogels were obtained from chitosan, oxidized pullulan, and PVA in different ratios. The stability of the hydrogels was ensured both by covalent bonds between aldehyde groups of oxidized pullulan and free amino groups of chitosan, and by physical bonds formed during freeze-thaw cycles and lyophilization. The deposition of calcium phosphates was performed by alternate soaking of the porous hydrogels into solutions with calcium and phosphate ions, assuring a basic pH required for hydroxyapatite formation. The mineralized hydrogels were characterized using FTIR spectroscopy, scanning electron microscopy, X-ray diffraction, and thermogravimetric analysis, showing that inorganic particles containing between 80 and 92% hydroxyapatite were deposited in a high amount on the pore walls of the polymeric matrix. The composition of the organic matrix influenced the crystallization of calcium phosphates and the mechanical properties of the composite hydrogels. In vitro biological tests showed that mineralized hydrogels support the proliferation of MG-63 osteoblast-like cells to a greater extent compared to pristine hydrogels.

Фосфатное минеральное сырьё: запасы, производство и горнорудные проекты

The paper presents the results of analyzing the reserves of phosphate mineral raw materials, their involvement in mining and processing activities both globally and in the Russian Federation. It is demonstrated that the reserves available for high-margin development have currently declined, the volumes of mining and processing of phosphate minerals have decreased, and the mining conditions have become more complicated with a corresponding deterioration in extracted ore grades. The issues with fertilizer production predefined the transformation of geopolitical conditions and manifestations of the pre-crisis food situation in the world. We have made forecast calculations of the countries' supply of phosphate mineral reserves based on the current mining and processing volumes. We reviewed the global experience of implementing large-scale mining projects to draw new phosphate mineral deposits into economic activities. It is already required to identify potentially investment-attractive phosphate deposits using various methods of their investment assessment in order to meet the needs of rural households both in the world and in the Russian Federation. Therefore, the purpose of this study was to develop methodological approaches to investment analysis of prospective phosphate mineral reserves in the Russian Federation based on the identified specific features of phosphate mining and production in the context of pre-crisis global food situation. A methodological approach to expert scoring of phosphate mineral deposits is proposed. An investment analysis of the prospective apatite ore deposits has been made, the results of which were used as the basis for selecting the most investment-attractive ones.

Advances for Improving Phosphorus Use Efficiency in Agriculture

An impending crisis is the continuous availability of phosphate fertilizers, which underlie global food production. The rock phosphate deposits on which the world depends are not only finite but many are polluted and many are located in geopolitically unstable locations, implying that significant changes will be required to maintain food supply for an increasing global population. There is no single solution, but a combination of phosphorus management measures is required not just to extend the life of the remaining non-renewable rock phosphate sources, but also to result in a more efficient, sustainable phosphorus cycle. Improving the effectiveness of fertilizer applications to agricultural land, as well as a better understanding of phosphorus cycling in soil-plant systems and the interplay between soil physics, chemistry and biology in conjunction with plant characteristics are among the solutions. The finite nature of rock phosphate supply and the development of other sources of phosphorus fertilizers is unavoidable. There are clear prospects and it is now critical to prioritize a concerted effort to increase phosphorus usage efficiency.

A Clean, Rapid, and Controllable Approach for Establishing Bioactive Surfaces on Zirconia Implants

AbstractZirconia implants have great application prospects due to their favorable biocompatibility and esthetic properties. However, the percentage of osseointegration of zirconia implants is lower than that of titanium implants. This study, structures bioactive surfaces on zirconia using a femtosecond laser combined with hydroxyapatite (HA) crystals and evaluates the surface morphology, functional groups, crystal phase, mechanical performance, and cell response. The results revealed that calcium phosphate deposition coincided with the establishment of micro‐grooves on the zirconia surface. The crystal composition and flexural strength of zirconia showed no significant changes after the surface treatment. Furthermore, the modified surface promoted cell adhesion and proliferation through adjustments in cell morphology. The findings suggest that the combination of femtosecond laser and HA crystals offers a clean, rapid, and controllable approach to preparing bioactive surfaces for zirconia implants.

Ti3C2Tx MXene/delignified wood supported flame-retardant phase-change composites with superior solar-thermal conversion efficiency and highly electromagnetic interference shielding for efficient thermal management

The development of form-stable phase-change material (PCM) with solar-thermal harvest, electromagnetic interference (EMI) shielding, and flame-retardancy is crucial for efficient building energy management and conservation. Herein, novel Ti3C2Tx MXene/delignified wood supported form-stable phase-change composites (PMPCMs) with superior solar-thermal conversion efficiency, highly EMI shielding effects, and excellent flame-retardancy were fabricated by alkaline boiling delignification, ammonium dihydrogen phosphate (ADP) and MXene deposition, and melted n-octadecane impregnation. Benefiting from the powerful surface tension and capillary force of the wood-based support materials, PMPCMs can effectively encapsulate the melted n-alkane molecules and inhibit their leakage. The differential scanning calorimetry results showed that PMPCMs possessed superior n-octadecane encapsulation yield and high thermal energy storage density (166.9–191.6 J/g). Decorating delignified wood by MXene significantly improved the solar-thermal storage efficiency (up to 88.4 %) and EMI shielding performance of PMPCMs. The average EMI shielding effectiveness of PMPCM-10 was enhanced to 34.12 dB in X-band frequency range of 8.2–12.4 GHz. Moreover, with the introduction of the flame-retardant ADP, the peak heat release rate (pHRR) and total heat release (THR) of PMPCMs decreased noticeably, demonstrating the enhanced flame retardancy of delignified wood supported phase-change composites. In summary, PMPCMs exhibited superior application prospects in building energy management and electromagnetic shielding fields.

Remote Outcomes with Poly-ε-Caprolactone Aortic Grafts in Rats.

Poly-ε-caprolactone ((1,7)-polyoxepan-2-one; PCL) is a biodegradable polymer widely used in various fields of bioengineering, but its behavior in long-term studies appears to depend on many conditions, such as application specificity, chemical structure, in vivo test systems, and even environmental conditions in which the construction is exploited in. In this study, we offer an observation of the remote outcomes of PCL tubular grafts for abdominal aorta replacement in an in vivo experiment on a rat model. Adult Wistar rats were implanted with PCL vascular matrices and observed for 180 days. The results of ultrasound diagnostics and X-ray tomography (CBCT) show that the grafts maintained patency for the entire follow-up period without thrombosis, leakage, or interruptions, but different types of tissue reactions were found at this time point. By the day of examination, all the implants revealed a confluent endothelial monolayer covering layers of hyperplastic neointima formed on the luminal surface of the grafts. Foreign body reactions were found in several explants including those without signs of stenosis. Most of the scaffolds showed a pronounced infiltration with fibroblastic cells. All the samples revealed subintimal calcium phosphate deposits. A correlation between chondroid metaplasia in profound cells of neointima and the process of mineralization was supported by immunohistochemical (IHC) staining for S100 proteins and EDS mapping. Microscopy showed that the scaffolds with an intensive inflammatory response or formed fibrotic capsules retain their fibrillar structure even on day 180 after implantation, but matrices infiltrated with viable cells partially save the original fibrillary network. This research highlights the advantages of PCL vascular scaffolds, such as graft permeability, revitalization, and good surgical outcomes. The disadvantages are low biodegradation rates and exceptionally high risks of mineralization and intimal hyperplasia.

Mineral resource assessment through geostatistical analysis in a phosphate deposit

Purpose. The selection of an appropriate variographic model is crucial in geostatistics to obtain accurate estimates of mineral reserves. The aim of this work is to develop a reserve estimation tool using a geostatistical approach. Methodology. The geostatistical approach is based on selecting the most representative variographic models for the studied variables. The model selection is done by applying a cross-validation procedure leave-one-out (LOOCV). LOOCV is a resampling technique used in statistical analysis and machine learning to estimate the generalization error of a model and compare the performance of different models. The studied variables are then estimated using ordinary kriging. Findings. The application of the proposed approach has resulted in satisfactory results in terms of dispersion of grades and thicknesses of mineralized layers in a phosphate deposit. To evaluate the quality of the adjustment models obtained, efficiency factors such as Nash-Sutcliffe, and RMSE (Root Mean Square Error), were employed. These factors provide quantitative measures of the agreement between the observed and predicted values. The NSE (Nash-Sutcliffe efficiency) and RMSE (root mean square error) values of 0.572 and 6.599, respectively, indicate a better fit and greater accuracy of the adjustment models. The accuracy and efficiency criteria of the studied variables have acceptable values, with a mean square error (MSE) of 1.54 · 10-7. Originality. The combination of the least squares and LOOCV methods in the geostatistical analysis leads to improved estimation precision, greater reliability in representing the spatial variability of the parameters, and enhanced confidence in the validity of the adjustment models. Practical value. The development of a computer code for this geostatistical approach provides a practical tool for decision-makers to use in the management and exploitation of mining sites. Overall, this study has contributed to the advancement of geostatistical techniques and their application in the mining industry.

Mineral chemistry in apatite from heavy mineral concentrate samples as a prospecting tool for carbonatites in the Angico dos Dias region, BA/PI border, Brazil

Apatite is one of the most common minerals found in a wide variety of rocks. It has variations of minor and trace elements in its composition that allow the recognition of its host lithotype. In this study, apatite grains identified in rock samples and grains recovered from heavy mineral concentrates in the Angico dos Dias Carbonatite Complex region, located on the border between the State of Bahia and the south of the State of Piauí, Brazil, were analyzed using an electron probe microanalyzer. These concentrates come from alluvial sediments downstream of the carbonatitic body from drainage channels. Sampling was guided by regional geochemical analytical results for the chemical elements of apatite. Grains were detected in alluvial covers for up to 9.5 km downstream in all fraction including coarse sand (1.0 mm) in proximal samples and up to medium sand fractions (0.50 mm) in distal samples. The 96 analytical results on 48 apatite grains show that most have chemical signatures characteristic of metacarbonatitic lithotypes (SrO 0.88–1.7 wt%) and that some host lithotypes were affected by the substituition processes (Si + LREE (Ce+La+Nd) 0.15–0.59 apfu), which may be an alternative to metasomatic fenitization. Statistical analysis by principal component analysis (PCA) helped the visualization and interpretation of the data by constructing clusters of the different compositions of apatite. The apatite fields of carbonatitic and silicate source rocks were separated and associated with the results obtained for alluvial apatite grains, resulting in carbonatitic derivation. The results of using this prospecting tool were satisfactory. Thus, it was possible to classify and detect the sources of alluvial apatite grains relating them to the Angico dos Dias carbonatite body, in addition to proposing a new potential area for the occurrence of carbonatitic bodies northeast of the Angico dos Dias phosphate deposit.

Guttapercha Improves In Vitro Bioactivity and Dentin Remineralization Ability of a Bioglass Containing Polydimethylsiloxane-Based Root Canal Sealer.

Guttapercha (GP, trans-1,4-polyisoprene) is the most used tooth root filling material, and it must be used with an appropriate cement (typically a polydimethylsiloxane (PDMS)-based sealer) to ensure an adequate canal obturation. This study aimed to assess the bioactivity and dentin remineralization ability of a bioglass containing PDMS commercial endodontic sealer, BG-PDMS (GuttaFlow Bioseal), and to evaluate the possible influence of a GP cone (Roeko GP point) on the mineralization process. To this end, BG-PDMS disks were aged alone or in the presence of a GP cone in Hank's Balanced Salt Solution (28 d, 37 °C). Dentin remineralization experiments were carried out under the same conditions. Micro-Raman and IR analyses demonstrated that BG-PDMS is bioactive, thanks to the formation of a silica-rich layer with nucleation sites for B-type carbonated apatite deposition. This phase was thicker when BG-PDMS was aged in the presence of GP. The two materials influenced each other because GP, which alone did not show any bioactivity, nucleated a calcium phosphate phase under these conditions. Analogously, dentin remineralization experiments showed that BG-PDMS is able to remineralize dentin, especially in the presence of GP. Under the experimental conditions, GP acted as a templating agent for calcium phosphate deposition.

Calcium Pyrophosphate and Basic Calcium Phosphate Deposition Diseases: The Year in Review 2022

Calcium-containing crystal deposition diseases are a common cause of pain and disability but remain relatively under-investigated. No drug has been identified that can prevent deposition or effect dissolution of either calcium pyrophosphate (CPP) or basic calcium phosphate (BCP) crystals. In comparison to the field of gout and urate biology, published research in relation to calcium crystal deposition diseases in 2022 was relatively modest in quantity. In CPP deposition (CPPD) disease, progress was made mainly in epidemiology, imaging, surgical management and Gitelman’s syndrome. In relation to BCP crystals, the effect on tenocytes in vitro was explored and results indicate that BCP crystals likely reduce tendon matrix integrity via their interaction with tenocytes. The involvement of calcification in the progression of osteoarthritis (OA) was elegantly demonstrated contributing to further discovery of the process of OA progression. There was a paucity of mechanistic and genetic studies in calcium crystal deposition diseases published in 2022, nor any breakthrough in therapy, showing that there is abundant scope for investigation under these themes in the future.

Allografts for partial meniscus repair: an in vitro and ex vivo meniscus culture study.

The purpose of this study was to evaluate the treatment potential of a human-derived demineralized scaffold, Spongioflex® (SPX), in partial meniscal lesions by employing in vitro models. In the first step, the differentiation potential of human meniscal cells (MCs) was investigated. In the next step, the ability of SPX to accommodate and support the adherence and/or growth of MCs while maintaining their fibroblastic/chondrocytic properties was studied. Control scaffolds, including bovine collagen meniscus implant (CMI) and human meniscus allograft (M-Allo), were used for comparison purposes. In addition, the migration tendency of MCs from fresh donor meniscal tissue into SPX was investigated in an ex vivo model. The results showed that MCs cultured in osteogenic medium did not differentiate into osteogenic cells or form significant calcium phosphate deposits, although AP activity was relatively increased in these cells. Culturing cells on the scaffolds revealed increased viability on SPX compared to the other scaffold materials. Collagen I synthesis, assessed by ELISA, was similar in cells cultured in 2D and on SPX. MCs on micro-porous SPX (weight >0.5g/cm3) exhibited increased osteogenic differentiation indicated by upregulated expression of ALP and RUNX2, while also showing upregulated expression of the chondrogen-specific SOX9 and ACAN genes. Ingrowth of cells on SPX was observed after 28days of cultivation. Overall, the results suggest that SPX could be a promising biocompatible scaffold for meniscal regeneration.

Study on filling mining technology for gently inclined thin to medium thick phosphorus deposits

This study is grounded in research conducted at the Kunyang Phosphate Mine No. 2, a Chinese open-pit phosphate mining enterprise owned by the Yunnan Phosphate Group Co., Ltd. Due to the small inclination angle and the presence of weak interlayers in the middle of the gently inclined thin to medium thick phosphate ore layer, mining such ore bodies cannot rely on self weight migration, making roof management difficult and mining costs high technical challenges. The methods utilized on-site research, engineering comparisons, and theoretical analysis experiments to address the gently inclined phosphorus deposits. Based on the actual technical and economic conditions of current phosphorus mines, the advantages, disadvantages, and practical conditions of upward horizontal layered filling mining method, upward horizontal layered drift filling mining method, and pseudo inclined segmented strip filling mining method are compared. Priority should be given to using the pseudo inclined segmented strip method as the main method for mining, supplemented by the upward horizontal layered filling method in the panel area. And theoretical calculation methods were applied to obtain various numerical values of the filling capacity of the 2 million t/a mine filling test section, providing technical support for the mining design and equipment selection of the filling test system. The relevant research results can provide guidance for the selection of mining methods for gently inclined thin to medium thick phosphate deposits with an average inclination angle of 15°. The theoretical calculation method used can provide technical guidance for the filling system and filling equipment.

Rhinolith in a 19-Year-Old Girl: A Case Report of a Rare Condition

Rhinolith means formation of stone in the nasal cavity which is an uncommon cause of nasal obstruction. It occurs due to mineralization of an endogenous or exogenous nidus with deposition of mineral salts, calcium and magnesium phosphates. Patients usually present with foul smelling/ purulent nasal discharge, nasal bleeding, nasal obstruction, halitosis, tooth ache or palatal perforation. Endoscopic removal of rhinolith leads to less morbidity which the treatment of choice. We report a case of 19-year-old female with rhinolith on the right nasal cavity which was removed endoscopically.

Geology and mineralization of Nb, P, Fe and light rare earth elements of the Araxá alkaline-carbonatite complex, Minas Gerais state, Brazil

New 40Sr/39Ar dating revealed that the magnetite phlogopitite at the center of the Araxá complex reached the surface at 98 Ma, and generated volcanoes with mineralized volcanic tuffs and crater lakes. At the bottom of the crater lakes, micro-graywacke deposited. Based on the mineral composition, hydrothermal structures, and δ18O and δD values, a hydrothermal episode occurred between ∼98 and 86 Ma Ma. The δ18O of phlogopites of phlogopities vary between 4.8‰ and 5.7‰, and those of magnetitites are 4.3‰ and 6.8‰. The δ18O of the water in equilibrium with phlogopites of the phlogopitites vary between 2.3‰ and 3.2‰, and those with magnetitite are 4.3‰ and 1.8‰. The δD of phlogopites of phlogopitites vary between −86.5‰ and −95.2‰, and those of magnetitite are −84.9‰, and −85.8‰. The δD of the water in equilibrium with phlogopites of the phlogopitites vary between −26.8‰ and −35.5‰, and with magnetitite are −25.6‰, and −26.26‰. During the hydrothermal event, magnetite phlogopitites were hydrothermally altered into phlogopite magnetitite, magnetite apatitite (epifoskorites), and mineralized with pyrochlore. At 84 Ma, the phlogopitic core was permeated by veins and micro-veins of Sr-rich norsethite carbonatites. At 83.5 Ma, calcitic carbonatites and micro-phlogopitites originating from the same mantle source as the magnetite phlogopitite intruded, which resulted in the formation of a carbonatite ring around the core and the assimilation of part of the phlogopitic core. This magmatism generated a new hydrothermal event of limited coverage that mineralized phlogopitites and carbonatites with monazite and massive pyrite ± chalcopyrite. The magmatism ended at 77 Ma, when phosphorous-saturated calcitic carbonatite surrounded the core. The saturation of phosphorous favored the crystallization of apatite, which generated phosphate deposits.

Losing vigilance in diagnosing pulmonary alveolar microlithiasis: A report on four cases

Pulmonary alveolar microlithiasis (PAM) is a rare chronic lung disease characterized by calcium and phosphate deposition in the alveolar lumen throughout the parenchyma of both lungs, with predominance in the middle and lower lung fields. It is caused by mutations in the recessive gene, SLC34A2, on the autosomal chromosome. In this article, we characterize four cases of PAM and analyze the loss of diagnostic vigilance in two of them. Patients came to medical facilities with clinical manifestations such as cough, shortness of breath, chest pain, and fatigue. The initial diagnosis was unclear in two cases because the X-ray film’s quality was not good enough and the medical staff had little experience in clinical and chest X-ray interpretations for PAM. The definitive diagnosis was based on a combination of high-resolution computed tomography (CT) and bronchoalveolar lavage fluid testing. In addition, chest X-ray and high-resolution CT enable the assessment of the stage, progression, and severity of the disease. There is currently no specific treatment for PAM other than lung transplantation.

Intra-Cranial Arterial Calcifications in Hemodialysis Patients.

Background and objectives: Vascular calcification is an integral part of atherosclerosis and has been reported to be an independent risk factor for cardiovascular diSsease. Intra Cranial Arterial Calcifications (ICAC) in maintenance hemodialysis (MHD) is highly prevalent. Materials and Methods: The aim of this retrospective study was to assess the predictors and outcomes of ICAC in MHD patients compared to a control group without kidney disease. A blinded neuroradiologist graded ICAC in brain imaging (computerized tomography) of MHD patients. Age- and sex-matched patients with normal kidney function served as the control group. Results: A total of 280 patients were included in the cohort; 140 of them were MHD patients with a mean ICAC score of 2.3 ± 0.2 versus a mean ICAC score of 1.4 ± 0.2 in the control group (p < 0.01). More than 90% of hemodialysis patients in our study had some degree of ICAC. Lower albumin and higher phosphorus and CRP levels were associated with increased ICACs. The multivariate analysis model for predictors of 1-year mortality demonstrated an increased odds ratio for mortality as the ICAC score increased. Conclusions: ICAC is very prevalent among MHD patients and results not simply from passive deposition of calcium and phosphate but rather from complex and active processes involving inflammation and structural changes in blood vessels. ICAC independently predicted all-cause mortality and may help with risk stratification of this high-risk population.

Comparative study of calcium phosphate deposition on nanotubular and sandblasted large grit acid-etched titanium substrates

Titanium and its alloys are widely used in biomedical applications due to their excellent properties such as biocompatibility, good corrosion resistance, low density, and high elastic modulus. However, their bioinert behavior often results in prolonged osseointegration periods. Therefore, surface modification techniques have been investigated to improve the bioactivity of titanium. In this study, the morphological and chemical properties of sandblasted, large grit, acid-etched (SLA), and nanotubular (NT) surfaces were investigated before and after the deposition of calcium phosphate (CaP) compounds by a chemical conversion method. Various techniques were used to characterize these surface modifications applied to titanium, including microhardness tests, atomic force microscopy, water contact angle measurements, scanning electron microscopy, grazing angle X-ray diffraction, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy. The results showed that the SLA surface was rougher than the NT surface, and the hydrophilic behavior of both samples was enhanced after immersion in NaOH and chemical conversion. The higher concentration of Ca, P, and phosphate functional groups on the NT surface indicates that a greater amount of CaP was deposited on this surface. The CaP-modified NT surface exhibited a favorable surface topography and chemical composition, which may be advantageous for use in titanium dental implants. In addition, in vitro assays showed that the samples prepared here are promising candidates for biomedical use, as they exhibited high cell viability, non-toxicity, and osteogenic properties.