Hypophosphatasia: A Systemic Skeletal Disorder Caused by Alkaline Phosphatase Deficiency

Hypophosphatasia (HPP) is an inherited systemic bone disease caused by the deficiency of tissue-nonspecific alkaline phosphatase (TNAP). HPP is classified into six forms and the symptoms of HPP vary depending on the form. The pathophysiology of HPP is basically due to a defect of bone mineralization. TNAP is encoded by the ALPL gene, and the TNAP protein expressed in bone, kidney, liver, and neuronal cells and is linked to the cell membrane via a glycosylphosphatidylinositol anchor. TNAP is an ectoenzyme hydrolyzing phosphate compound such as inorganic pyrophosphate. TNAP plays an important role in mineralization of hard tissues. Defect of mineralization process causes hypomineralization of hard tissues, which leads to rickets or osteomalacia and dental manifestations. In addition, hypomineralization of the ribs results in respiratory failure in the severe forms, which is the main cause of death. Inheritance of HPP is autosomal recessive, but autosomal dominant cases have been reported in the milder forms. To date, a total of 335 mutations in the ALPL gene have been reported, and mutation sites are scattered throughout the gene. Recent development of enzyme replacement therapy has opened up a new vista on the treatment of this previously untreatable disease

Convergence of vitamin D and lysophosphatidic acid signaling in stimulating human osteoblast maturation

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A Primal-Dual Quasi-Newton Method for Constrained Optimization

One of the most important developments in nonlinear constrained optimization in recent years has been the recursive quadratic programming (RQP) method suggested by Wilson, Han, Powell and many other researchers. It is clear that the role of the auxiliary quadratic programming problem is to calculate (implicitly) the inverse Hessian of the dual objective function. We describe the Hessian of the Lagrangian and that of the dual objective function as the primal Hessian and the dual Hessian, respectively. In this paper, a new method for constrained optimization, called the primal-dual quasi-Newton method, is proposed. The main feature of this method is that it improves (explicitly) both the primal Hessian and the dual Hessian using quasi-Newton methods. Several variants of the primal-dual quasi-Newton method are possible: the properties of these methods are described and the computational results obtained for some test problems are given

First-principles study on the intermediate compounds of LiBH4_4

We report the results of the first-principles calculation on the intermediate compounds of LiBH$_4$. The stability of LiB$_3$H$_8$ and Li$_2$B$_n$H$_n (n=5-12)$ has been examined with the ultrasoft pseudopotential method based on the density functional theory. Theoretical prediction has suggested that monoclinic Li$_2$B$_{12}$H$_{12}$ is the most stable among the candidate materials. We propose the following hydriding/dehydriding process of LiBH$_4$ via this intermediate compound : LiBH$_4 \leftrightarrow {1/12}$Li$_{2}$B$_{12}$H$_{12} + {5/6}$ LiH $+ {13/12}$H$_2 \leftrightarrow$LiH $+$ B $+ {3/2}$H$_2$. The hydrogen content and enthalpy of the first reaction are estimated to be 10 mass% and 56 kJ/mol H$_2$, respectively, and those of the second reaction are 4 mass% and 125 kJ/mol H$_2$. They are in good agreement with experimental results of the thermal desorption spectra of LiBH$_4$. Our calculation has predicted that the bending modes for the $\Gamma$-phonon frequencies of monoclinic Li$_2$B$_{12}$H$_{12}$ are lower than that of LiBH$_4$, while stretching modes are higher. These results are very useful for the experimental search and identification of possible intermediate compounds.Comment: 7 pages, 5 figures, submitted to PR