Subcellular optogenetic inhibition of G proteins generates signaling gradients and cell migration

Cells sense gradients of extracellular cues and generate polarized responses such as cell migration and neurite initiation. There is static information on the intracellular signaling molecules involved in these responses, but how they dynamically orchestrate polarized cell behaviors is not well understood. A limitation has been the lack of methods to exert spatial and temporal control over specific signaling molecules inside a living cell. Here we introduce optogenetic tools that act downstream of native G protein–coupled receptor (GPCRs) and provide direct control over the activity of endogenous heterotrimeric G protein subunits. Light-triggered recruitment of a truncated regulator of G protein signaling (RGS) protein or a Gβγ-sequestering domain to a selected region on the plasma membrane results in localized inhibition of G protein signaling. In immune cells exposed to spatially uniform chemoattractants, these optogenetic tools allow us to create reversible gradients of signaling activity. Migratory responses generated by this approach show that a gradient of active G protein αi and βγ subunits is sufficient to generate directed cell migration. They also provide the most direct evidence so for a global inhibition pathway triggered by Gi signaling in directional sensing and adaptation. These optogenetic tools can be applied to interrogate the mechanistic basis of other GPCR-modulated cellular functions

The importance of hemosiderin deposition in the infant brain: an autopsy study

Background/aim: Iron is an essential element involved in many metabolic processes. Presence and accumulation of iron in various body systems can result in different outcomes. Its accumulation in the central nervous system (CNS) cannot be detected routinely by application of hematoxylin-eosin staining. Detection of the presence of hemosiderin in the brain and cerebellum by application of Perls' dye is of importance in cases of infant deaths. Material and Methods: In this study, brain and cerebellar specimens obtained from 52 eligible infants (aged 0-1 years) autopsied in our institute between the years 2010 and 2013, independent of the cause of death, were analyzed in order to detect possible presence of hemosiderin. Perls' dye was used to detect histopathological staining intensity and distribution of hemosiderin in the brain and cerebellum. Results: Cases did not differ significantly as for the patients' age and gender (p = 0.473), type of the culprit trauma (p = 0.414), death/crime scene (p = 0.587), and diagnosis groups (p = 0.550). In this autopsy study blue colored hemosiderin granulations, stained with Perls' dye were detected in the brain (n: 39, 75%), and cerebellum (n: 35, 67.3%). A weakly negative, but significant correlation was detected between the postmortem interval and intensity values of cerebellar hemosiderin (Spearman's correlation coefficient: -0.381, p = 0.024). A statistically significant difference was found between the distribution scores of cerebral hemosiderin in cases with and without trauma history (p = 0.03). Median cerebral hemosiderin distribution scores were 2.5 and 2, respectively. Conclusions: The detection of a correlation between the presence of cerebral and cerebellar hemosiderin, and post-mortem interval in the age group of 0-1 years, should be interpreted as an important finding in the analysis of cerebral iron. The presence of hemosiderin in the CNS may be a significant finding in the elucidation of infant deaths and this procedure should be carried out on a routine basis

Corticotropin Releasing Factor-Induced CREB Activation in Striatal Neurons Occurs via a Novel Gβγ Signaling Pathway

The peptide corticotropin-releasing factor (CRF) was initially identified as a critical component of the stress response. CRF exerts its cellular effects by binding to one of two cognate G-protein coupled receptors (GPCRs), CRF receptor 1 (CRFR1) or 2 (CRFR2). While these GPCRs were originally characterized as being coupled to Gαs, leading to downstream activation of adenylyl cyclase (AC) and subsequent increases in cAMP, it has since become clear that CRFRs couple to and activate numerous other downstream signaling cascades. In addition, CRF signaling influences the activity of many diverse brain regions, affecting a variety of behaviors. One of these regions is the striatum, including the nucleus accumbens (NAc). CRF exerts profound effects on striatal-dependent behaviors such as drug addiction, pair-bonding, and natural reward. Recent data indicate that at least some of these behaviors regulated by CRF are mediated through CRF activation of the transcription factor CREB. Thus, we aimed to elucidate the signaling pathway by which CRF activates CREB in striatal neurons. Here we describe a novel neuronal signaling pathway whereby CRF leads to a rapid Gβγ- and MEK-dependent increase in CREB phosphorylation. These data are the first descriptions of CRF leading to activation of a Gβγ-dependent signaling pathway in neurons, as well as the first description of Gβγ activation leading to downstream CREB phosphorylation in any cellular system. Additionally, these data provide additional insight into the mechanisms by which CRF can regulate neuronal function

Resultados de la rehabilitacion despues de sufrir un traumatismo craneoencefálico

Entre los objetivos de la rehabilitación después de un traumatismo craneoencefálico está la mejoría de la función cerebral el aumento del grado de independencia la prevención de complicaciones y la obtención de un ambiente acceptable para el paciente. Durante el período de la rehabilitación pueden producirse varias complicaciones que conducen a discapacidades físicas, cognitivas y otras neurológicas que causan un importante retraso en la mejoría funcional. Este estudio ha sido diseñado para investigar las complicaciones observadas en los pacientes que se incluyeron en un programa de rehabilitación en fase aguda, sus relaciones con el estado funcional y los factores que tienen impacto en los resultados de la rehabilitación. Se incluyen en el estudio treinta pacientes con traumatismo craneoencefálico admitidos en la Unidad de Cuidados Intensivos de la Escuela de Medicina de la Universidad de Uludag. El programa de rehabilitación consistió en rehabilitación postural, una serie de ejercicios de movimiento, y ejercicios respiratorios. Se registraron las complicaciones que se encontraron durante el programa de rehabilitación de cuidados intensivos. Todos los pacientes fueron evaluados por una Medida de Independencia Funcional, por el grado de invalidez y mediante los niveles de función cognitiva de la Escala Rancho Los Amigos tras la admisión, y en el momento del alta. La mejoria se observó en los pacientes en términos de resultados funcionales y niveles de invalidez. Las complicaciones más frecuentes fueron la neumonía, atelectasia, anemia y meningitis. Se observó una disminución en los niveles de los resultados funcionales y de invalidez a medida que aumentó el número de complicaciones. En conclusión, la rehabilitación tiene un papel principal en la recuperación de pacientes con traumatismo craneoencefálico. La reducción de la incidencia de complicaciones y la mejora de los niveles de los resultados funcionales y de invalidez se pueden lograr con programas de rehabilitación. Estudios controlados a largo plazo con un gran número de pacientes son necesarios para obtener datos exactos sobre los factores asociados a los resultados de la rehabilitación

Autocrine motility factor receptor expression implies an unfavourable prognosis in resected stage I pulmonary adenocarcinomas

18th Annual Meeting of the European-Association-for-Cardiothoracic-Surgery/12th Annual Meeting of the European-Society-of-Thoracic-Surgeons -- SEP 12-15, 2004 -- Leipzig, GERMANYWOS: 000231906000010PubMed: 16184720Background : Pulmonary adenocarcinomas constitute a different histological subtype among the histological subtypes of non small cell lung carcinomas by showing comparably unfavourable rates of prognosis and different immunobiological features. Autonomous motility of tumour cells plays an important role in the regulation of local invasion and distant metastasis of tumour lesions which have great impact on overall survival. AMF (Autocrine motility factor) is a tumour secreted cytokine that stimulates motility during invasion and metastasis via its receptor, AMFR. We conducted an immunohistochemical study to investigate AMFR expression in pulmonary adenocarcinomas and its effect on survival. Material and methods: We assessed AMFR expression using a monoclonal antibody (3F3A) in a total of 32 surgical specimens with stage I pulmonary adenocarcinomas that underwent curative resection. We analyzed AMFR expression as a possible prognostic factor on survival and its correlations with clinicopathological features. Results: A total of 19 (59.3%) specimens showed AMFR expression. The 3-year survival rates of AMFR positive and AMFR negative patients were 47.3% and 84.6%, respectively, which was a significant difference (P = 0.0197). The univariate predictors of surgical outcome were AMFR expression (P = 0.032) and perineural invasion (P = 0.038). However, multivariate analysis revealed AMFR expression (P = 0.045) as the only independent prognostic factor. Conclusions : AMFR expression predicts an unfavourable surgical outcome in patients with stage I pulmonary adenocarcinomas.European Assoc Cardiothorac Surg, European Soc Thorac Sur

On the non-linear dynamics of torus-shaped and cylindrical shell structures

In this study, the non-linear dynamic analysis of torus-shaped and cylindrical shell-like structures has been studied. The applied material is assumed as the functionally graded material (FGM). The structures are considered to be used for important machines such as wind turbines. The effects of some environmental factors on the analysis like temperature and humidity have been considered. The strain field has been calculated in general form and in continue the dynamic governing equations of torus structure have been derived based on the first-order shear deformation theory. The rotation around two independent axes in the torus coordinate system is considered and time-dependent equations are solved using SAPM semi-analytical method. The stresses and deformations generated in the torus and cylindrical shaped structures are plotted. The rotation of structures has been attended due to some transportation purposes. The effect of internal pressures as well as rotational speed at torus and cylindrical structures has been investigated in several numerical diagrams. The results are presented in the form of graphs that consider the rotational effects, loading, thermal and humid (hygro-thermal) environments, and size of the structures. This research can provide scientific perspectives to researchers who will examine the dynamic analysis of torus and cylindrical shaped structures

On the generalized model of shell structures with functional cross-sections

In the present study, a single general formulation has been presented for the analysis of various shell-shaped structures. The proposed model is comprehensive and a variety of theories can be used based on it. The cross-section of the shell structure can be arbitrarily analyzed with the presented equations. In other words, various types of shell structures, including cylindrical, conical, spherical, elliptical, hyperbolic, parabolic, and any non-geometric structure with functional cross-section, can be modeled mechanically with only one partial differential equation system. The obtained equations have been solved by applying SAPM semi-analytical solution method. In order to present a comprehensive research, dynamic nonlinear analysis is considered. The variation of material properties through the thickness has been assumed as functionally graded and its effect on the strength of the shell structure with the functional cross-section has been investigated. The numerical results have been compared with available papers and also with FEM results for some structures that there is no paper available for validation. Different types of shell structures have been studied in terms of cross-sectional shape and properties. Finally, the effects of some important factors on the results such as boundary conditions, nonlinear analysis, dynamic analysis, and rotation of the structure around its central axis have been conducted thoroughly. This study and its original governing equations can be considered as a comprehensive reference for mechanical analysis of various shell structures with functional cross-sectional shape

Mechanical simulation of artificial gravity in torus-shaped and cylindrical spacecraft

Large deformations and stress analyses in two types of space structures that are intended for people to live in space have been studied in this research. The structure under analysis is assumed to rotate around the central axis to create artificial gravitational acceleration equal to the gravity on the Earth's surface. The analysis is fully dynamic, which is formulated based on the energy method by using the first-order shear deformation shell theory in two systems, cylindrical and torus. Also, the nonlinear von Kármán strain field has been assumed. The obtained set of partial differential equations has been solved using the semi-analytical polynomial solution method (SAPM). The main purpose of this paper is to study the effects of unusual conditions in the space outside the Earth's atmosphere (which is a complete vacuum environment without pressure) on the strength of the analyzed structure. The numerical results of the governing equations have been evaluated using those of other studies and the simulation efficiency performed in this research has been proven. Finally, the effect of important parameters on the numerical results, including the angular velocity of the structure (which causes artificial gravity), the amount of imposed mechanical and hygro-thermal loads, the structure size and material specifications have been investigated in more detail