The inorganic part of hard tissues (bones and teeth) of mammals consists of calcium phosphate, mainly of apatitic structure. Similarly, most undesired calcifications (i.e. those appearing as a result of various diseases) of mammals also contain calcium phosphate. For example, atherosclerosis results in blood-vessel blockage caused by a solid composite of cholesterol with calcium phosphate. Dental caries result in a replacement of less soluble and hard apatite by more soluble and softer calcium hydrogenphosphates. Osteoporosis is a demineralization of bone. Therefore, from a chemical point of view, processes of normal (bone and teeth formation and growth) and pathological (atherosclerosis and dental calculus) calcifications are just an in vivo crystallization of calcium phosphate. Similarly, dental caries and osteoporosis can be considered to be in vivo dissolution of calcium phosphates. On the other hand, because of the chemical similarity with biological calcified tissues, all calcium phosphates are remarkably biocompatible. This property is widely used in medicine for biomaterials that are either entirely made of or coated with calcium phosphate. For example, self-setting bone cements made of calcium phosphates are helpful in bone repair and titanium substitutes covered with a surface layer of calcium phosphates are used for hip-joint endoprostheses and tooth substitutes, to facilitate the growth of bone and thereby raise the mechanical stability. Calcium phosphates have a great biological and medical significance and in this review we give an overview of the current knowledge in this subject.

/pdf/biological-and-medical-significance-of-calcium-phosphates-4zx1s7sv8d.pdf

Biological and medical significance of calcium phosphates.

Gout

The present overview is intended to point the readers’ attention to the important subject of calcium orthophosphates. These materials are of the special significance because they represent the inorganic part of major normal (bones, teeth and dear antlers) and pathological ( i.e. those appearing due to various diseases) calcified tissues of mammals. Due to a great chemical similarity with the biological calcified tissues, many calcium orthophosphates possess remarkable biocompatibility and bioactivity. Materials scientists use this property extensively to construct artificial bone grafts that are either entirely made of or only surface-coated with the biologically relevant calcium ortho-phosphates. For example, self-setting hydraulic cements made of calcium orthophosphates are helpful in bone repair, while titanium substitutes covered by a surface layer of calcium orthophosphates are used for hip joint endoprostheses and as tooth substitutes. Porous scaffolds made of calcium orthophosphates are very promising tools for tissue engineering applications. In addition, technical grade calcium orthophosphates are very popular mineral fertilizers. Thus ere calcium orthophosphates are of great significance for humankind and, in this paper, an overview on the current knowledge on this subject is provided.

https://www.mdpi.com/1996-1944/2/2/399/pdf

Calcium Orthophosphates in Nature, Biology and Medicine

The present overview is intended to point the readers' attention to the important subject of calcium orthophosphates. This type of materials is of special significance for human beings, because they represent the inorganic part of major normal (bones, teeth and antlers) and pathological (i.e., those appearing due to various diseases) calcified tissues of mammals. For example, atherosclerosis results in blood vessel blockage caused by a solid composite of cholesterol with calcium orthophosphates, while dental caries and osteoporosis mean a partial decalcification of teeth and bones, respectively, that results in replacement of a less soluble and harder biological apatite by more soluble and softer calcium hydrogenphosphates. Therefore, the processes of both normal and pathological calcifications are just an in vivo crystallization of calcium orthophosphates. Similarly, dental caries and osteoporosis might be considered an in vivo dissolution of calcium orthophosphates. Thus, calcium orthophosphates hold a great significance for humankind, and in this paper, an overview on the current knowledge on this subject is provided.

https://www.tandfonline.com/doi/pdf/10.4161/biom.18790

Calcium orthophosphates: Occurrence, properties, biomineralization, pathological calcification and biomimetic applications

This retrospective study of 100 patients who had surgical treatment for their carpal tunnel syndrome was performed to determine what factors.were associated with long-term success or failure. One hundred thirty hands were treated surgically with an average follow-up of 4 years (range, 2 to 6 years). All patients were given a course of conservative treatment that included steroid injection(s) and splinting until the patients were refractory to such therapy. Over 250 injections were given (117 wrists), with the average benefit time of 27 weeks (range 0 to 330). Most patients received two to three injections (maximum of nine). Variables associated with a failure to have long-term benefit after operation included weakness or atrophy of the abductor pollicis brevis muscle, presence of a predisposing condition, and failure to benefit from the initial steroid injection. Conversely, all 51 hands that had relief from median nerve paresthesia for more than 6 months by conservative therapy alone received long-term relief after surgery. Steroids were least effective in hands that had muscle involvement. Fifteen of the 40 hands with muscle involvement regained their muscle mass by the time of the final examination.

Long-term analysis of patients having surgical treatment for carpal tunnel syndrome.

Calcific deposits in the menisci of the knees of 215 cadavera were characterized roentgenographically and crystallographically as part of a study of the pathological basis of calcium pyrophosphate dihydrate crystal deposition disease. Deposits of a primary type were found in multiple cartilages in 5.6 per cent of cadavera: in 3.3 per cent the deposits were composed of calcium pyrophosphate dihydrate (Ca2P2 O7-2H2O) and in 2.3 per cent, of dicalcium phosphate dihydrate (CaHPO4-2H2O). Solitary deposits of the secondary type, composed of hydroxyapatite, were found in 1.4 per cent of cadavera.
The implications of these findings are discussed as they affect (1) the possible prevalence of calcium pyrophosphate dihydrate crystal deposition disease, (2) the traditional classification of pathological calcification of cartilage, and (3) the roentgenographic interpretation of meniscal calcification. The crystalline compounds of the three-component system CaO—P2O5—H2O that persist in soil as fertilizer are the same as the compounds identified in the meniseal deposits. Appropriate data from the soil chemistry literature are cited briefly as they provide background for speculation and future work on the mechanisms and significance of pathological calcifications in cartilage.

Studies on Pathological Calcifications in Human Cartilage: I. Prevalence And Types Of Crystal Deposits In The Menisci Of Two Hundred Fifteen Cadavera

Injection of commercially available microcrystalline adrenocorticosteroid esters into normal canine joints was ac-companied by a leukocyte-rich exudative response, roughly proportional to the dose injected. No tenderness or evidence of pain was noted. Injection of these preparations into normal human joints often induced similar reactions which were sometimes painful. The response varied with the preparation employed and in the case of hydrocortisone acetate, with the manufacturer of the drug. The possible injurious effects of this relatively painless inflammatory response are discussed.

https://onlinelibrary.wiley.com/doi/pdf/10.1002/art.1780070402

Inflammatory reaction after intrasynovial injection of microcrystalline adrenocorticosteroid esters.

This exhibit is intended to portray the central role that crystals play in two common "metabolic" arthritides, classic gout and chondrocalcinosis articularis1(pseudogout syndrome2). In this discussion we will reverse the usual order of presentation and cover the clinical features last. Diagnosis by Crystal Identification The differential diagnosis of arthritis is greatly aided by the gross and microscopic examination of synovial fluid (synovianalysis3). Crystals of sodium urate and calcium pyrophosphate are best seen in "wet" preparations of freshly aspirated synovial fluid. A drop of fluid is applied to a clean glass slide and overlaidimmediatelywith a clean coverslip, the edges of which are sealedimmediatelywith clear fingernail polish. Dried smears of fluid are difficult to inspect; centrifugation of the fluid before examination isnotrecommended. Compensated polarized light and phase contrast microscopy (magnification × 1,250) are simultaneously used in our laboratory; sodium urate crystals show

Joseph M. Hogan

Papers

Studies on Pathological Calcifications in Human Cartilage: I. Prevalence And Types Of Crystal Deposits In The Menisci Of Two Hundred Fifteen Cadavera

Inflammatory reaction after intrasynovial injection of microcrystalline adrenocorticosteroid esters.

Crystal Deposition Diseases: Sodium Urate (Gout) and Calcium Pyrophosphate (Chondrocalcinosis, Pseudogout)