Podoplanin immunopositive lymphatic vessels at the implant interface in a rat model of osteoporotic fractures

Insertion of bone substitution materials accelerates healing of osteoporotic fractures. Biodegradable materials are preferred for application in osteoporotic patients to avoid a second surgery for implant replacement. Degraded implant fragments are often absorbed by macrophages that are removed from the fracture side via passage through veins or lymphatic vessels. We investigated if lymphatic vessels occur in osteoporotic bone defects and whether they are regulated by the use of different materials. To address this issue osteoporosis was induced in rats using the classical method of bilateral ovariectomy and additional calcium and vitamin deficient diet. In addition, wedge-shaped defects of 3, 4, or 5 mm were generated in the distal metaphyseal area of femur via osteotomy. The 4 mm defects were subsequently used for implantation studies where bone substitution materials of calcium phosphate cement, composites of collagen and silica, and iron foams with interconnecting pores were inserted. Different materials were partly additionally functionalized by strontium or bisphosphonate whose positive effects in osteoporosis treatment are well known. The lymphatic vessels were identified by immunohistochemistry using an antibody against podoplanin. Podoplanin immunopositive lymphatic vessels were detected in the granulation tissue filling the fracture gap, surrounding the implant and growing into the iron foam through its interconnected pores. Significant more lymphatic capillaries were counted at the implant interface of composite, strontium and bisphosphonate functionalized iron foam. A significant increase was also observed in the number of lymphatics situated in the pores of strontium coated iron foam. In conclusion, our results indicate the occurrence of lymphatic vessels in osteoporotic bone. Our results show that lymphatic vessels are localized at the implant interface and in the fracture gap where they might be involved in the removal of lymphocytes, macrophages, debris and the implants degradation products. Therefore the lymphatic vessels are involved in implant integration and fracture healing

Uncoupled excitons in semiconductor microcavities detected in resonant Raman scattering

We present an outgoing resonant Raman-scattering study of a GaAs/AlGaAs based microcavity embedded in a p-i-n junction. The p-i-n junction allows the vertical electric field to be varied, permitting control of exciton-photon detuning and quenching of photoluminescence which otherwise obscures the inelastic light scattering signals. Peaks corresponding to the upper and lower polariton branches are observed in the resonant Raman cross sections, along with a third peak at the energy of uncoupled excitons. This third peak, attributed to disorder activated Raman scattering, provides clear evidence for the existence of uncoupled exciton reservoir states in microcavities in the strong-coupling regime

Spintronics: Fundamentals and applications

Spintronics, or spin electronics, involves the study of active control and manipulation of spin degrees of freedom in solid-state systems. This article reviews the current status of this subject, including both recent advances and well-established results. The primary focus is on the basic physical principles underlying the generation of carrier spin polarization, spin dynamics, and spin-polarized transport in semiconductors and metals. Spin transport differs from charge transport in that spin is a nonconserved quantity in solids due to spin-orbit and hyperfine coupling. The authors discuss in detail spin decoherence mechanisms in metals and semiconductors. Various theories of spin injection and spin-polarized transport are applied to hybrid structures relevant to spin-based devices and fundamental studies of materials properties. Experimental work is reviewed with the emphasis on projected applications, in which external electric and magnetic fields and illumination by light will be used to control spin and charge dynamics to create new functionalities not feasible or ineffective with conventional electronics.Comment: invited review, 36 figures, 900+ references; minor stylistic changes from the published versio

The lexicon in narratives – an investigation of lexical skills during story-telling in children with and without language impairment

<p>Background: After the acquisition of basic grammatical skills, narrative competence gradually develops in preschool and primary school age, including the subsequent elaboration of syntactic complexity and the use cohesive elements. In addition, the adequate use of lexical means is an important component of story-telling. Previous research has shown children with language impairment have substantial difficulty when telling stories. Their deficits affect both the microstructural and the macrostructural level. Since lexical competence is relevant for narrative competence and lexical problems are often part of language impairment, the present study investigates the quantity, diversity, and composition of the lexicon in oral narratives.</p> <p>Method: The first, cross-sectional study includes 100 monolingual, typically developing (TD), German-speaking children at age 3;0-6;0. The children narrated three picture stories. The number of types, tokens, types-token ratio, mean length of utterance (MLU) and lexical composition were analysed. Results demonstrate that vocabulary size, as well as lexical composition, did not change over time, while lexical diversity and MLU increased with age. In study 2, a comparison of 34 children with language impairment (LI) and 34 age-matched TD children from study 1 shows a limited lexical diversity and a significantly lower MLU for children with LI. Children with LI used more nouns and more personal-social words, but fewer pronouns.</p> <p>Discussion: Vocabulary size and the use of word categories in children with LI are broadly similar to that of TD children. However, oral narratives of children with LI are characterized by a limited lexical diversity and shorter utterances. In addition, subtle differences with respect to the use of word categories were found, which are more typical for earlier phases of language development.</p

Pharmacological inhibition of Eph receptors enhances glucose-stimulated insulin secretion from mouse and human pancreatic islets.

Type 2 diabetes is characterised by impaired glucose-stimulated insulin secretion (GSIS) from pancreatic islets. Since erythropoietin-producing hepatoma (Eph)-ephrin bidirectional signalling fine-tunes GSIS from pancreatic beta cells, we investigated Eph receptor tyrosine kinases (RTK) as potential drug targets for selectively increasing GSIS