In order to gain insight into the mechanisms underlying the dynamic changes in bone metabolism and bone quality after parathyroidectomy (PTX) in secondary hyperparathyroid patients with high levels of parathyroid hormone (PTH), we performed bone histomorphometric analysis with tetracycline labeling in iliac bone biopsy specimens taken before and after PTX, with special attention paid to osteocytes. At 2 to 4 weeks after PTX, PTH concentrations decreased markedly with evident reductions in bone turnover markers. Histomorphometry revealed that at 2 to 4 weeks following PTX, the osteoclast surface decreased to nearly 0%, with a substantial increase in osteoid volume and a reduction in fibrosis volume. Labeling with tetracycline was observed not only at the mineralization front on the bone surface but also around the osteocyte lacunar walls and canaliculi within both the basic multicellular units (BMUs) and bone structural units (BSUs), suggesting that mineralization was taking place along the lacunocanalicular system after PTX. The tetracyclinelabeled area was much greater in the BSUs than in the BMUs and at the mineralization front, and the tetracycline labeling in the BSUs was markedly increased after PTX compared with that in the low-and high-PTH control groups without PTX. The osteocyte number was decreased significantly after PTX, concomitant with an increase in the number of empty lacunae and a reduction of lacunar volume. Thus the increased osteocyte death and mineralization around the lacunocanalicular system in association with a rapid decline in PTH may underlie the changes in bone metabolism and quality that occur following PTX. ß

A profusion of phospholes: Diacenaphtho[1,2-b:1',2'-d]phospholes, a new class of arene-fused phosphole π-systems, were synthesized and their structural and electrochemical properties studied. The P-sulfide derivative has a high electron-transporting ability (μ(E) =2.4×10(-3) cm(2) V(-1) s(-1)) in a vacuum-deposited film.

Bone formation using the process known as minimodeling forms only lamellar bone in the absence of prior bone resorption even in uremic patients. In patients undergoing parathyroidectomy for secondary hyperparathyroidism, we compared the contribution of minimodeling to remodeling during the change in bone volume. Iliac bone biopsies were used to measure parameters related to minimodeling and remodeling before, at 3 to 4 weeks and 10 to 12 weeks after parathyroidectomy. Osteoblast surface due to minimodeling was greater than the entire bone osteoblast surface before and at 10 to 12 weeks after parathyroidectomy, but not 3 to 4 weeks after surgery. Minimodeling significantly increased osteoid volume 3 to 4 weeks after parathyroidectomy. The rate of change of osteoid volume by minimodeling was greater than that of osteoid volume during the first 3 to 4 weeks after surgery, indicating osteoid formation was more active at the minimodeling surface than at the entire bone surface. Furthermore, higher mineral apposition rates at the minimodeling sites than at remodeling sites yielded increased minimodeling bone volume at 10 to 12 weeks after surgery. Our results show that bone formation by minimodeling is more active than by remodeling and accounts, in part, for the increase of bone volume following parathyroidectomy.

Epoxy resins (bisphenol A type epoxy resins/2‐ethyl‐4‐methylimidazole) consisting of oligomers with different molecular weights were foamed using a temperature‐quench physical foaming method with CO2. The resulting cell morphologies could be classified into four types: non‐foamed structure, cracked structure, star‐shaped structure, and sphere‐shaped structure. The effects of the gel fraction and molecular weight between crosslinks (MC) on the cell morphology were investigated for the preparation of microcellular epoxy foams. MC was calculated by measuring the plateau rubber modulus of the rheological properties and the weight uptake of acetone. By varying the molecular weight of the epoxy oligomers and the cure time, the MC of the epoxy was controlled to modulate the cell morphology. The experiments elucidated the threshold MC value that permits CO2‐bubble nucleation: CO2‐bubble nucleation in the epoxy resin could be induced when the distance between the crosslinking points exceeded the critical size of bubble nucleus. Based on this information, the microcellular epoxy foam was prepared by maintaining MC above 104g mol−1 and the complex modulus above 6 × 108 Pa. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40407.

Macrocyclization due to the m‐phenylene tether is responsible for the stabilization of the azacyclophane‐based dication 12+. EPR (see picture) and quantum‐chemical studies indicate that 12+, which can be regarded as two m‐phenylenediamines linked by two p‐phenylenes, is a triplet diradical. Its properties differ from those of the open‐chain version 22+.

No abstract

From the viewpoint of para-meta topological bridging effect on the electronic coupling in organic mixed-valence( MV) systems, the optically induceda nd thermally assisted intramolecular charge/spin transfer (ICT/IST) processesh ave been investigated for three bis(triarylamine)( BTA) radical cations as missing key compounds in very basic BTAM Vs ystems. In contrast to the case of p-a nd m-dinitrobenzene radicala nions, the difference in the strength of electronic coupling (V)w as not so large for the present BTAM Vr adicalc ations,a lthough they still fall within the paradigm of strong V for para-linkage and weak V for meta-linkage. Unexpectedly,i th as been found that meta-phenylenediamine radical cation has an electronic coupling comparable to those in the para-conjugated BTA-based MV species, and the ICT/IST rate exceeds the ESR time-scale. This finding is very encouraging considering that sufficient electronic communication can be ensured even when the redox-active centers are linked directly by the meta-phenylene bridge, thus broadening the selection of p-bridging units for moleculebased optoelectronics.Recent progress in organic mixed-valence( MV) chemistry has conduced aw ealth of understanding of basic electron-and/or charge-transfer (ET/CT) phenomena. [1] In particular, bis(triarylamine) (BTA) radicalc ations are considered as versatile model systemsf or probing into variousa spects of electronic coupling between the neutral and chargedr edox-activec enterst hrough av ariety of p-bridging units (Scheme 1a). [1,6, 7] The strength of electronic coupling (V)i sm ainly determined by the type of aromatic bridge and the substitution pattern:i nt he case of unsubstituted phenylene bridge, para-phenylene ensures a Scheme1.(a) Schematic drawing of BTA-based MV compound, (b) para-and meta-dinitrobenzene radicalanions, and (c) the key BTA-based MV compounds.[a] Dr.M.U ebe,

The purpose of this study was to use histomorphometry to compare the microstructure of trabecular and cortical bone in patients with primary hyperparathyroidism (PH) with that seen in osteoporosis. Histomorphometric and node-strut analyses of iliac bones were performed on 11 female patients with PH (61.3 +/- 8.0 years old) and 61 age-matched female patients with involutional osteoporosis (OP) (63.6 +/- 5.6 years old). Cancellous bone volume (BV/TV), trabecular thickness (Tb.Th), trabecular number (Tb.N), trabecular separation (Tb.Sp), and wall thickness (W.Th) were not significantly different in these two groups. The bone formation rate (BFR) tended to be higher in the PH group than in the OP group. The number of nodes (N.Nd/TV) and node-to-node strut length (Nd.Nd/TV) were significantly higher in the PH group than in the OP group. The number of termini (N.Tm/TV) and terminus-to-terminus strut length/total strut length (Tm.Tm/TSL) were significantly lower in the PH group; cortical porosity was significantly higher in the PH group than in the OP group. No correlation was found between age and N.Nd in the PH group, but there was a negative correlation between age and N.Nd in the OP group. Our results show that trabecular connectivity was maintained while cortical porosity deteriorated in patients with PH compared with OP. These results suggest that there are microstructural differences between PH and OP in cancellous and cortical bone that result from the bone remodeling sequence in humans.