Nanoreinforced Hydrogels for Tissue Engineering: Biomaterials that are Compatible with Load‐Bearing and Electroactive Tissues

Given their highly porous nature and excellent water retention, hydrogel‐based biomaterials can mimic critical properties of the native cellular environment. However, their potential to emulate the electromechanical milieu of native tissues or conform well with the curved topology of human organs needs to be further explored to address a broad range of physiological demands of the body. In this regard, the incorporation of nanomaterials within hydrogels has shown great promise, as a simple one‐step approach, to generate multifunctional scaffolds with previously unattainable biological, mechanical, and electrical properties. Here, recent advances in the fabrication and application of nanocomposite hydrogels in tissue engineering applications are described, with specific attention toward skeletal and electroactive tissues, such as cardiac, nerve, bone, cartilage, and skeletal muscle. Additionally, some potential uses of nanoreinforced hydrogels within the emerging disciplines of cyborganics, bionics, and soft biorobotics are highlighted.     

Molecular Pathogenesis and Treatment Perspectives for Hypereosinophilia and Hypereosinophilic Syndromes

Hypereosinophilia (HE) is a heterogeneous condition with a persistent elevated eosinophil count of >350/mm³, which is reported in various (inflammatory, allergic, infectious, or neoplastic) diseases with distinct pathophysiological pathways. HE may be associated with tissue or organ damage and, in this case, the disorder is classified as hypereosinophilic syndrome (HES). Different studies have allowed for the discovery of two major pathogenetic variants known as myeloid or lymphocytic HES. With the advent of molecular genetic analyses, such as T-cell receptor gene rearrangement assays and Next Generation Sequencing, it is possible to better characterize these syndromes and establish which patients will benefit from pharmacological targeted therapy. In this review, we highlight the molecular alterations that are involved in the pathogenesis of eosinophil disorders and revise possible therapeutic approaches, either implemented in clinical practice or currently under investigation in clinical trials.     

Particle phase acidity and oligomer formation in secondary organic aerosol

A series of controlled laboratory experiments are carried out in dual Teflon chambers to examine the presence of oligomers in secondary organic aerosols (SOA) from hydrocarbon ozonolysis as well as to explore the effect of particle phase acidity on SOA formation. In all seven hydrocarbon systems studied (i.e., alpha-pinene, cyclohexene, 1-methyl cyclopentene, cycloheptene, 1-methyl cyclohexene, cyclooctene, and terpinolene), oligomers with MW from 250 to 1600 are present in the SOA formed, both in the absence and presence of seed particles and regardless of the seed particle acidity. These oligomers are comparable to, and in some cases, exceed the low molecular weight species (MW < 250) in ion intensities in the ion trap mass spectra, suggesting they may comprise a substantial fraction of the total aerosol mass. It is possible that oligomers are widely present in atmospheric organic aerosols, formed through acid- or base-catalyzed heterogeneous reactions. In addition, as the seed particle acidity increases, larger oligomers are formed more abundantly in the SOA; consequently, the overall SOA yield also increases. This explicit effect of particle phase acidity on the composition and yield of SOA may have important climatic consequences and need to be considered in relevant models.     

Evaluation of the precision of dimensional measurements of the mandible on panoramic radiographs

The task of objective perimetry is to scan the visual field and find an answer about the function of the visual system. Flicker-burst stimulation--a physiological sensible combination of transient and steady-state stimulation--is used to generate deterministic sinusoidal responses or visually evoked potentials (VEP's) at the visual cortex, which are derived from the electroencephalogram by a suitable electrode array. In this paper we develop a new method for the detection of VEP's. Based on the periodogram of a time-series, we test the data for the presence of hidden periodic components, which correspond to steady-state VEP's. The method is applied successfully to real data.     

Targeted disruption of the Wnt2 gene results in placentation defects

Wnt genes have been implicated in a range of developmental processes in the mouse including the patterning of the central nervous system and limbs. Reported here for the first time is the expression of Wnt2 in the early heart field of 7.5-8.5 dpc (days post-coitum) mouse embryos, making Wnt2 a potentially useful gene marker for the early stages of heart development. Expression was also detected in the allantois from 8.0 dpc and at later stages in the placenta and umbilicus. Mice deficient in Wnt2, generated by gene targeting, displayed runting and approximately 50% died perinatally. Histological analysis revealed alterations in the size and structure of placentas from these mice from 14.5 dpc. The placental defects were associated primarily with the labyrinthine zone and included oedema and tissue disruption and accumulation of maternal blood in large pools. There was also an apparent decrease in the number of foetal capillaries and an increase in the amount of fibrinoid material in the Wnt2 mutant placentas. These results suggest that Wnt2 is required for the proper vascularisation of the mouse placenta and the placental defects in Wnt2-deficient mice result in a reduction in birthweight and perinatal lethality.     

Changes in cerebral vasomotor reactivity in relation to respiratory and metabolic stimuli: an analysis of its behavior in hypertensive and normotensive subjects

We know that increases in the arterial blood pressure determines changes in the behaviour of the cerebrovascular resistance and also the possible lack of vasomotor reactivity. In order to clarify the pathway of circulatory vasomotor reactivity in arterial hypertension, we carried out a study on a group of hypertensive subjects (20 patients) who were compared to a group of normotensive controls (18 patients). A transcranial doppler (TCD) study was performed with rebreathing tests (apnea and hyperventilation) and it was carried out in both groups of subjects. The TCD was repeated after an administration of sublingual pill of nitroglycerin. In both groups the hyperventilation caused a significant reduction in the velocity peak in the middle cerebral artery (norm.: 84.88 +/- 4.86 cm/sec 60 +/- 5.2 cm/sec; hyperten. 84.50 +/- 7.1 cm/sec 58.80 +/- 5.47 cm/sec) in contrast apnea induced a major increase in the velocities (norm.: 84.88 +/- 4.86 cm/sec 102.50 +/- 4.89 cm/sec; hyperten.: 84.50 +/- 7.1 cm/sec 101.59 +/- 10.6 cm/sec). We noticed a statistical significant difference between the velocities recorded in the different tests (Anova test p < 0.0001). The behaviour of the velocities in the rebreathing tests after nitroglycerin was similar when compared to the same test were performed without the drug. This study suggests that there is no difference in the behaviour of the cerebral reactivity between normotensives and the hypertensive subjects without vascular or cardiac compliance. Finally we would emphasize the role of TCD in the recording changes of cerebrovascular resistances due to pressure or metabolic causes.     

High-CMRR CMOS current output stage

A novel current-mode output stage is presented which achieves high CMRR owing to an auxiliary high-gain feedback loop. Compared to the traditional solution, an approximately doubled transconductance is also obtained. SPICE simulations using the model parameters of a 0.8 /spl mu/m CMOS process are found in remarkable agreement with expected results.