Platelet Fibrinogen Receptors in Migraine Patients

SYNOPSIS
In order to determine the platelet characteristics responsible for aggregation, the number and apparent dissociation constant (K D aPP ) of fibrinogen receptors were determined in 12 women with common migraine. The studies were performed by the use of 125 -fibrinogen. The patients were assessed in headache-fee intervals. The mean number of platelet fibrinogen receptors exposed in migraine patients was significantly higher than those obtained in healthy controls (p<0.05). The (K D aPP ) in migraineurs was about three times lower than in the controls (p<0.02). The results indicate that both the number and affinity of fibrinogen receptors or platelets are increased in migraine patients. The authors conclude that this phenomenon may be responsible for the increased number of circulating platelet aggregates in migraine patients and for the prevalence of various kinds of strokes during migraine attacks.     

Pachydermoperiostosis–critical analysis with report of five unusual cases

Pachydermoperiostosis (idiopathic hypertrophic arthropathy) {MIM 167100} is an uncommon disease characterized by unique phenotype (digital clubbing and pachydermia) and distinctive radiographic appearances (periostosis). Two families are reported that, in additional to the typical phenotype and radiographic characteristics of pachydermoperiostosis, show some rare and/or unusual, not yet reported, clinical findings. In the first family, distinctive features were severe progressive arthritis with villonodular involvement of the knees. The clinical course of the disease was much more severe than usually reported. The older brother was disabled at the age of 29 years. In the second family, the clinical history was exceptional, with unique early appearance of clinical signs. Pachydermoperiostosis is usually inherited as a dominant trait, but probable autosomal recessive inheritance has been reported. Also in the present families, autosomal recessive inheritance is likely, possibly explaining the severe clinical course of the disease. Differential diagnosis and the confusing nomenclature of pachydermoperiostosis are discussed. A. Latos-Bielenska and I. Marik are equal contributors.     

Dependence of InGaN Quantum Well Thickness on the Nature of Optical Transitions in LEDs

The design of the active region is one of the most crucial problems to address in light emitting devices (LEDs) based on III-nitride, due to the spatial separation of carriers by the built-in polarization. Here, we studied radiative transitions in InGaN-based LEDs with various quantum well (QW) thicknesses—2.6, 6.5, 7.8, 12, and 15 nm. In the case of the thinnest QW, we observed a typical effect of screening of the built-in field manifested with a blue shift of the electroluminescence spectrum at high current densities, whereas the LEDs with 6.5 and 7.8 nm QWs exhibited extremely high blue shift at low current densities accompanied by complex spectrum with multiple optical transitions. On the other hand, LEDs with the thickest QWs showed a stable, single-peak emission throughout the whole current density range. In order to obtain insight into the physical mechanisms behind this complex behavior, we performed self-consistent Schrodinger–Poisson simulations. We show that variation in the emission spectra between the samples is related to changes in the carrier density and differences in the magnitude of screening of the built-in field inside QWs. Moreover, we show that the excited states play a major role in carrier recombination for all QWs, apart from the thinnest one.     

Role of Metallic Adlayer in Limiting Ge Incorporation into GaN

Atomically thin metal adlayers are used as surfactants in semiconductor crystal growth. The role of the adlayer in the incorporation of dopants in GaN is completely unexplored, probably because n-type doping of GaN with Si is relatively straightforward and can be scaled up with available Si atomic flux in a wide range of dopant concentrations. However, a surprisingly different behavior of the Ge dopant is observed, and the presence of atomically thin gallium or an indium layer dramatically affects Ge incorporation, hindering the fabrication of GaN:Ge structures with abrupt doping profiles. Here, we show an experimental study presenting a striking improvement in sharpness of the Ge doping profile obtained for indium as compared to the gallium surfactant layer during GaN-plasma-assisted molecular beam epitaxy. We show that the atomically thin indium surfactant layer promotes the incorporation of Ge in contrast to the gallium surfactant layer, which promotes segregation of Ge to the surface and Ge crystallite formation. Understanding the role of the surfactant is essential to control GaN doping and to obtain extremely high n-type doped III-nitride layers using Ge, because doping levels >10²⁰ cm⁻³ are not easily available with Si.     

Lumican inhibits angiogenesis by interfering with α2β1 receptor activity and downregulating MMP-14 expression

Introduction

Previous studies showed that lumican, a small leucine-rich proteoglycan that binds to α2 integrin I domain, is an efficient inhibitor of cell adhesion and migration. In this report, we tested its effect on angiogenesis in vitro and in vivo.

Materials and methods

Effect of lumican on angiogenesis was evaluated by in vitro capillary tube formation test performed between Fibrin II Gels or in Matrigel™ and in vivo by Matrigel^™ plug assay in BALB/c mice. Changes in matrix metalloproteinases expression caused by lumican were analyzed in endothelial cells by real-time PCR, Western immunoblotting and gelatin zymography.

Results

In unchallenged endothelial cells, Matrigel™ induced robust capillary morphogenesis. In contrast, tube formation was dramatically reduced by lumican, and by siRNA to β1 integrin subunit mRNA but not by control siRNA. Similarly, lumican effectively inhibited neovascularization in vivo in assays using Matrigel™ plugs formed in BALB/c mice. Interestingly, lumican significantly reduced expression of matrix metalloproteinases, particularly MMP-14 that is known to activate other MMPs in close vicinity of endothelial cell membranes.

Conclusions

Our results provide strong evidence that lumican affects angiogenesis both by interfering with α2β1 receptor activity and downregulating proteolytic activity associated with surface membranes of endothelial cells.     

Are all prognostic factors in parotid gland carcinoma well recognized?

The aim of his study was to assess the treatment results and prognostic factors in patients with parotid gland carcinoma. The material consisted of 109 patients treated surgically, with or without complementary radiotherapy, between 1978 and 2008 (follow-up at least 5-years). 5-year overall and disease-specific survival were observed in 57.0% of the patients and 5-year disease-free survival was achieved in 50.0%. Univariate analysis including ten clinical and pathological features to assess their prognostic value was done. Parapharyngeal space invasion, facial nerve palsy, and high grade of tumor malignancy were the factors with the highest influence on the treatment results, because their presence decreased the chance for recovery 9.8, 9.7, and 8.2 times, respectively. Histologically positive cervical lymph nodes and extraparenchymal extension were the other factors connected with poor prognosis (prognosis worse 6.7 and 5.4 times, respectively). Clinically positive cervical lymph nodes, positive/uncertain microscopic margin, involvement of the deep lobe, or the whole gland increased the risk of treatment failure 3.4, 3.1, and 2.8, respectively. The age ≥60 years and male gender were statistically significant factors, correlated with poor prognosis and decreased chance for recovery 2.4 and 2.6 times. T-status and clinical stage had important influence on 5-year disease-free survival rate because there were significant differences in the treatment results between individual stages. Multivariate analysis proved that the independent prognostic value, among anatomic structures involved by the neoplasm, had mandible, facial nerve, and skin infiltration. Among tumor-related factors, T-stage and grade had the statistically significant influence on treatment results, and stage and lymph nodes metastases among clinical and pathological features. These results confirm the value of actually used TNM classification (2002). Although the parapharyngeal space invasion is a factor, which seems to have a significant, poor prognostic value, it was not included in this classification.     

VEGF-A stimulates lymphangiogenesis and hemangiogenesis in inflammatory neovascularization via macrophage recruitment

Lymphangiogenesis, an important initial step in tumor metastasis and transplant sensitization, is mediated by the action of VEGF-C and -D on VEGFR3. In contrast, VEGF-A binds VEGFR1 and VEGFR2 and is an essential hemangiogenic factor. We re-evaluated the potential role of VEGF-A in lymphangiogenesis using a novel model in which both lymphangiogenesis and hemangiogenesis are induced in the normally avascular cornea. Administration of VEGF Trap, a receptor-based fusion protein that binds and neutralizes VEGF-A but not VEGF-C or -D, completely inhibited both hemangiogenesis and the outgrowth of LYVE-1(+) lymphatic vessels following injury. Furthermore, both lymphangiogenesis and hemangiogenesis were significantly reduced in mice transgenic for VEGF-A(164/164) or VEGF-A(188/188) (each of which expresses only one of the three principle VEGF-A isoforms). Because VEGF-A is chemotactic for macrophages and we demonstrate here that macrophages in inflamed corneas release lymphangiogenic VEGF-C/VEGF-D, we evaluated the possibility that macrophage recruitment plays a role in VEGF-A-mediated lymphangiogenesis. Either systemic depletion of all bone marrow-derived cells (by irradiation) or local depletion of macrophages in the cornea (using clodronate liposomes) prior to injury significantly inhibited both hemangiogenesis and lymphangiogenesis. We conclude that VEGF-A recruitment of monocytes/macrophages plays a crucial role in inducing inflammatory neovascularization by supplying/amplifying signals essential for pathological hemangiogenesis and lymphangiogenesis.     

Modelling of Effective Thermal Conductivity of Composites Filled with Core-Shell Fillers

An effective model to calculate thermal conductivity of polymer composites using core-shell fillers is presented, wherein a core material of filler grains is covered by a layer of a high-thermal-conductivity (HTC) material. Such fillers can provide a significant increase of the composite thermal conductivity by an addition of a small amount of the HTC material. The model employs the Lewis-Nielsen formula describing filled systems. The effective thermal conductivity of the core-shell filler grains is calculated using the Russel model for porous materials. Modelling results are compared with recent measurements made on composites filled with cellulose microbeads coated with hexagonal boron nitride (h-BN) platelets and good agreement is demonstrated. Comparison with measurements made on epoxy composites, using silver-coated glass spheres as a filler, is also provided. It is demonstrated how the modelling procedure can improve understanding of properties of materials and structures used and mechanisms of thermal conduction within the composite.