Biochemical and Pharmacological Rationales in Radiotracer Design
Lelio G. Colombetti in Principles of Radiopharmacology, 2019
Bones are constantly in a dynamic state of formation and reabsorption of mineral constituents which reaches equilibrium in the adult.134 Major bone mineral constituents are calcium and phosphorus in the form of submicroscopic crystals called hydroxyapa-tite [3Ca3(PO4)2Ca(OH)2].135 Strontium and fluorine have been used as radiopharmaceuticals for skeletal imaging because of their chemical similarity to the abundant bone constituents of calcium and hydroxyl ion, respectively.136 In areas of active bone repair, growth, or tumor, there is an increased uptake of calcium and hydroxyl ions (or their radionuclide counterparts, strontium and fluorine).137 These isotopes have also been used to locate bone tumor metastases to soft tissues138 and soft tissue tumor metastases to bone.139
Endocrine Disorders, Contraception, and Hormone Therapy during Pregnancy
“Bert” Bertis Britt Little in Drugs and Pregnancy, 2022
Parathyroid glands (~4) are located along the posterior border of the thyroid gland. Their function is primarily in the regulation of bone mineral metabolism. Parathyroid hormone (PTH) maintains extracellular fluid calcium concentration. During pregnancy, calcium requirements increase to 3 to 4 times the non-pregnant daily requirement, especially during the latter half of gestation when most of the fetal bone mineral is deposited. Calcium and phosphorus are actively transported across the placenta, resulting in lower maternal serum calcium concentration, an increase in PTH secretion, and decreased calcitonin production (Schedewie and Fisher, 1980). During gestation, 1,25 dihydroxy vitamin D levels and intestinal absorption of calcium increase strikingly (Bouillon and Van Assche, 1982; Heany and Skillman, 1971; Kumar et al., 1979).
Nutrition for health and sports performance
Nick Draper, Helen Marshall in Exercise Physiology, 2014
While not providing a source of calorific energy, minerals serve three important functions within the body. They combine with other chemicals to synthesise the building blocks for tissues, are integral to the structure of enzymes and assist in the regulation of many physiological functions within the body. As can be seen from Table 2.10, calcium is the most abundant mineral and its role includes structural, metabolic, regulatory and enzymatic functions. Calcium is an essential element for healthy bones and teeth and a lack of calcium within the diet has been linked to osteoporosis which is a bone mineral deficiency. Weight-bearing exercise and a diet with the RDA for calcium can help to prevent the development of osteoporosis. Phosphorus, the second most plentiful mineral in the body, is also an essential structural component for healthy bones and teeth. Calcium, sodium and potassium, as will be discussed in the next chapter, have a particularly important role in nerve impulse transmission and muscle contraction.
Bone-friendly lifestyle and the role of calcium or vitamin D supplementation
Published in Climacteric, 2022
I. R. Reid
Calcium is one of the important building blocks of bone, along with the other bone mineral phosphate, and with an adequate protein supply to allow the osteoblasts to construct and maintain the type I collagen matrix that is the critical structural and architectural component of bone. In the 1950s and 1960s, the idea was introduced that calcium intake was important in determining bone mass and, thus, fracture risk. These concerns were substantially based on calcium balance studies carried out over periods of a few weeks, but are not supported by more recent work in which bone balance over periods of years has been shown to be unrelated to calcium intake in populations with intakes greater than about 400 mg/day (Figure 2) [39]. These findings are consistent with the fact that calcium intakes in most of Africa and Asia were, until recently, <300 mg/day, yet these populations had fracture rates generally lower than those in Western Europe and North America. Calcium intake can become critical to bone health at lower levels, and some African children with intakes of about 100 mg/day but normal vitamin D status do develop impairment of bone mineralization.
Pulsed radiofrequency energy device (PEAK plasmablade™) and CustomBone® Cranioplasty: an appealing surgical rendez-vous
Published in British Journal of Neurosurgery, 2023
F. Graziano, R. Maugeri, G. R. Giammalva, E. Lo Bue, G. Zabbia, D. G. Iacopino
Cranioplasty is a surgical procedure that aims to re-establish the skull integrity following a previous craniotomy due to the occurrence of traumas, tumors and/or congenital malformations. Ideally, cranioplasty procedures should provide restoration of the protective functions of the skull with maintenance of the original aesthetics and long-term mechanical performance. The ideal material for cranioplasty should be chemically inert, biocompatible, biomechanically reliable, easily manufactured, individually shaped, safe, and able to promote osteoblast migration. Hydroxyapatite (HA) has for decades been widely considered as the gold standard for bone scaffolds, as its composition is very close to that of bone mineral, thus exhibiting excellent biocompatibility, a low inflammatory reaction as well as good osteogenic ability and osteoconductivity (Figure 1).1–5
Osteoblast precursors and inflammatory cells arrive simultaneously to sites of a trabecular-bone injury
Published in Acta Orthopaedica, 2018
Magnus Bernhardsson, Per Aspenberg
The clodronate-treated tibiae were analyzed with micro-CT (Skyscan 1174, v. 2; Bruker, Aarteselaar, Belgium). In a 180° scan, a pixel size of 11.2 µm, aluminum filter 0.5 mm, rotation step of 0.4° and frame averaging of 3, and energy settings of 50 kV and 800 µA were used to acquire radiographic images. NRecon (Skyscan, v. 1.6.8.0; Aarteselaar, Belgium) was used to reconstruct the images and correct them for ring artifacts and beam hardening. Within the former drill holes, a volume of interest (VOI) was defined as a cylinder with a diameter of 1.2 mm and 1.5 mm in length into the bone marrow cavity, starting from the endosteal side. 2 hydroxyapatite standards of known density (0.25 and 0.75 g/cm3) were used to calibrate the bone mineral density. The total bone volume (BV/TV) of the VOIs was analyzed in CTAn (Skyscan, v. 1.10; Aarteselaar).