Specific Binding and Mineralization of Calcified Surfaces by Small Peptides

Several small (<25aa) peptides have been designed based on the sequence of the dentin phosphoprotein, one of the major noncollagenous proteins thought to be involved in the mineralization of the dentin extracellular matrix during tooth development. These peptides, consisting of multiple repeats of the tripeptide aspartate-serine-serine (DSS), bind with high affinity to calcium phosphate compounds and, when immobilized, can recruit calcium phosphate to peptide-derivatized polystyrene beads or to demineralized human dentin surfaces. The affinity of binding to hydroxyapatite surfaces increases with the number of (DSS)n repeats, and though similar repeated sequences—(NTT)n, (DTT)n, (ETT)n, (NSS)n, (ESS)n, (DAA)n, (ASS)n, and (NAA)n—also showed HA binding activity, it was generally not at the same level as the natural sequence. Binding of the (DSS)n peptides to sectioned human teeth was shown to be tissue-specific, with high levels of binding to the mantle dentin, lower levels of binding to the circumpulpal dentin, and little or no binding to healthy enamel. Phosphorylation of the serines of these peptides was found to affect the avidity, but not the affinity, of binding. The potential utility of these peptides in the detection of carious lesions, the delivery of therapeutic compounds to mineralized tissues, and the modulation of remineralization is discussed

Microscopic polyangiitis complicated by the development of prostate cancer and utamide-induced hepatitis

We report a case of a 65-year-old man with microscopic polyangiitis who developed prostate cancer and gastric adenocarcinoma after prolonged oral use of cyclophosphamide. Acute hepatitis with jaundice and marked increase in aminotranferases occurred after 6 months of flutamide treatment for metastatic prostate carcinoma. It is suggested that patients with vasculitis or other autoimmune disorders should avoid prolonged use of cyclophosphamide and other cytotoxic drugs in order to minimize long-term adverse effects, of which the risk of cancer is by far the most important. In patients on flutamide treatment, careful monitoring of flutamide administration with repeated liver function tests should be undertaken, and the drug must be immediately discontinued in patients with abnormal results to avoid progression of liver injury

pH-responsive polymeric nanoassemblies encapsulated into alginate beads: morphological characterization and swelling studies

The aim of this study is to design and develop novel hybrid pH-responsive hydrogels. For this purpose, new copolymers with different molecular weights and different content of the hydrophobic part are synthesized. The self-assembly behavior of PSMA-co-PDMAEMA copolymerswasstudiedin two different dispersion media (simulated gastric fluid-SGF, pH = 1.2 and simulated intestinal fluid-SIF, pH = 6.8) and in different concentrations. The physicochemical characteristics of the nano-assemblies were found to be dependent on the composition of the copolymer and the aqueous environment. Having a complete knowledge of the self-assembly behavior of the copolymers in aqueous media, the encapsulation of the PSMA-co-PDMAEMA 1/2 nano-assemblies into Alginate beads was achieved by following the protocol of the preparation of hydrogels. The Calcium:Alginate hydrogels were used as reference systems for comparison reasons. The size and the morphology of pure and mixed beads were found to be dependent on the composition of the block copolymer, as revealed from SEM images. The behavior of the mixed hydrogels was the same during the swelling studies, but the rate of the swelling and the amount of weight change were found to be additionally dependent on the composition of the polymeric guest. The hydration state of the polymeric chains plays a key role inthe swelling behavior of the mixed hydrogels. In conclusion, pH-responsive hybrid hydrogels were developed and their behavior and morphology are strongly dependent on the molecular characteristics of the polymeric guest. © 2018, Springer Science+Business Media B.V., part of Springer Nature