scholarly journals The effect of the signalling scheme on the robustness of pattern formation in development

2012 ◽  
Vol 2 (4) ◽  
pp. 465-486 ◽  
Author(s):  
Hye-Won Kang ◽  
Likun Zheng ◽  
Hans G. Othmer
Keyword(s):  
Pattern Formation ◽  
Reaction Diffusion ◽  
Threshold Value ◽  
Cell Types ◽  
State Variable ◽  
Complex Process ◽  
Spatially Distributed ◽  
Stochastic Reaction ◽  
Different Cell Types ◽  
Parameter Values

Pattern formation in development is a complex process which involves spatially distributed signals called morphogens that influence gene expression and thus the phenotypic identity of cells. Usually different cell types are spatially segregated, and the boundary between them may be determined by a threshold value of some state variable. The question arises as to how sensitive the location of such a boundary is to variations in properties, such as parameter values, that characterize the system. Here, we analyse both deterministic and stochastic reaction-diffusion models of pattern formation with a view towards understanding how the signalling scheme used for patterning affects the variability of boundary determination between cell types in a developing tissue.

scholarly journals Electroretinography in dogs: a review 

2014 ◽  
Vol 59 (No. 11) ◽  
pp. 515-526 ◽  
Author(s):  
M. Drazek ◽  
M. Lew ◽  
S. Lew ◽  
A. Pomianowski
Keyword(s):  
Small Animal ◽  
Cell Types ◽  
Time Varying ◽  
Outer Retina ◽  
Light Stimulation ◽  
Full Field ◽  
Retinal Disorders ◽  
Spatially Distributed ◽  
Different Cell Types ◽  
Stimulation Of

Electroretinography (ERG) in the form of full-field, flash ERG is the most commonly used technique in veterinary ophthalmology for diagnosing the functioning of the outer retina. Under light stimulation spatially distributed different cell types within the retina produce time-varying electric responses. These are recorded in the form of ERG traces consisting of a series of positive and negative wavelets. The possibility of selective stimulation of individual types of retinal cells and the analysis of constituent components of ERGs are the basis for determining the source of abnormalities and diagnosis of various types of dysfunction. In many cases, the ERG allows diagnosis of hereditary retinal disorders in dogs before the appearance of behavioural and ophthalmoscopic symptoms. This review is an introduction to the electrophysiology of vision, intended for small animal practitioners, and aimed at presenting the benefits of ERG for early ophthalmic diagnostics in dogs.

Wound healing and local neuroendocrine regulation in the injured liver

2008 ◽  
Vol 10 ◽  
Author(s):  
Mohammad R. Ebrahimkhani ◽  
Ahmed M. Elsharkawy ◽  
Derek A. Mann
Keyword(s):  
Wound Healing ◽  
Molecular Mechanisms ◽  
Cell Types ◽  
Neuroendocrine System ◽  
Therapeutic Interventions ◽  
Antifibrotic Therapy ◽  
Complex Process ◽  
Wound Healing Response ◽  
Fibrotic Scar ◽  
Different Cell Types

The hepatic wound-healing response is a complex process involving many different cell types and factors. It leads to the formation of excessive matrix and a fibrotic scar, which ultimately disrupts proper functioning of the liver and establishes cirrhosis. Activated hepatic myofibroblasts, which are derived from cells such as hepatic stellate cells (HSCs), play a key role in this process. Upon chronic liver injury, there is an upregulation in the local neuroendocrine system and it has recently been demonstrated that activated HSCs express specific receptors and respond to different components of this system. Neuroendocrine factors and their receptors participate in a complex network that modulates liver inflammation and wound healing, and controls the development and progression of liver fibrosis. The first part of this review provides an overview of the molecular mechanisms governing hepatic wound healing. In the second section, we explore important components of the hepatic neuroendocrine system and their recently highlighted roles in HSC biology and hepatic fibrogenesis. We discuss the therapeutic interventions that are being developed for use in antifibrotic therapy.

scholarly journals Vascular Calcification in Chronic Kidney Disease: Diversity in the Vessel Wall

Biomedicines ◽  
2021 ◽  
Vol 9 (4) ◽  
pp. 404
Author(s):  
Prabhatchandra Dube ◽  
Armelle DeRiso ◽  
Mitra Patel ◽  
Dhanushya Battepati ◽  
Bella Khatib-Shahidi ◽  
...  
Keyword(s):  
Chronic Kidney Disease ◽  
Kidney Disease ◽  
Vascular Calcification ◽  
Molecular Mechanisms ◽  
Cell Types ◽  
Complex Process ◽  
Cardiovascular Morbidity And Mortality ◽  
Depth Analysis ◽  
Multiple Cell ◽  
Different Cell Types

Vascular calcification (VC) is one of the major causes of cardiovascular morbidity and mortality in patients with chronic kidney disease (CKD). VC is a complex process expressing similarity to bone metabolism in onset and progression. VC in CKD is promoted by various factors not limited to hyperphosphatemia, Ca/Pi imbalance, uremic toxins, chronic inflammation, oxidative stress, and activation of multiple signaling pathways in different cell types, including vascular smooth muscle cells (VSMCs), macrophages, and endothelial cells. In the current review, we provide an in-depth analysis of the various kinds of VC, the clinical significance and available therapies, significant contributions from multiple cell types, and the associated cellular and molecular mechanisms for the VC process in the setting of CKD. Thus, we seek to highlight the key factors and cell types driving the pathology of VC in CKD in order to assist in the identification of preventative, diagnostic, and therapeutic strategies for patients burdened with this disease.

A CELLULAR AUTOMATON TO MODEL THE DEVELOPMENT OF PRIMARY SHOOT MERISTEMS OF ARABIDOPSIS THALIANA

2007 ◽  
Vol 05 (02b) ◽  
pp. 641-650 ◽  
Author(s):  
ILYA R. AKBERDIN ◽  
EVGENIY A. OZONOV ◽  
VICTORIA V. MIRONOVA ◽  
NADEZDA A. OMELYANCHUK ◽  
VITALY A. LIKHOSHVAI ◽  
...  
Keyword(s):  
Arabidopsis Thaliana ◽  
Cellular Automaton ◽  
Gene Networks ◽  
Cell Types ◽  
Shoot Meristem ◽  
Regulatory Mechanisms ◽  
Developmental Gene ◽  
Complex Process ◽  
Different Cell Types ◽  
Shoot Meristems

Development of organisms is a very complex process in which a lot of gene networks of different cell types are integrated. Development of a cellular automaton (Ermentrout and Edelshtein-Keshet, J Theor Biol160:97–133, 1993) that models the morphodynamics of different cell types is the first step in understanding and analysis of the regulatory mechanisms underlying the functioning of developmental gene networks. A model of a cellular automaton has been developed, which simulates the embryonic development of shoot meristem in Arabidopsis thaliana. The model adequately describes the basic stages in development of this organ in wild and mutant types.

scholarly journals Emerging concepts in biliary repair and fibrosis

2017 ◽  
Vol 313 (2) ◽  
pp. G102-G116 ◽  
Author(s):  
Luca Fabris ◽  
Carlo Spirli ◽  
Massimiliano Cadamuro ◽  
Romina Fiorotto ◽  
Mario Strazzabosco
Keyword(s):  
Biliary Tree ◽  
Alagille Syndrome ◽  
Cell Types ◽  
Current Debate ◽  
Joint Control ◽  
New Concepts ◽  
Complex Process ◽  
Reparative Process ◽  
Mixed Origin ◽  
Different Cell Types

Chronic diseases of the biliary tree (cholangiopathies) represent one of the major unmet needs in clinical hepatology and a significant knowledge gap in liver pathophysiology. The common theme in cholangiopathies is that the target of the disease is the biliary tree. After damage to the biliary epithelium, inflammatory changes stimulate a reparative response with proliferation of cholangiocytes and restoration of the biliary architecture, owing to the reactivation of a variety of morphogenetic signals. Chronic damage and inflammation will ultimately result in pathological repair with generation of biliary fibrosis and clinical progression of the disease. The hallmark of pathological biliary repair is the appearance of reactive ductular cells, a population of cholangiocyte-like epithelial cells of unclear and likely mixed origin that are able to orchestrate a complex process that involves a number of different cell types, under joint control of inflammatory and morphogenetic signals. Several questions remain open concerning the histogenesis of reactive ductular cells, their role in liver repair, their mechanism of activation, and the signals exchanged with the other cellular elements cooperating in the reparative process. This review contributes to the current debate by highlighting a number of new concepts derived from the study of the pathophysiology of chronic cholangiopathies, such as congenital hepatic fibrosis, biliary atresia, and Alagille syndrome.

scholarly journals Turing Bifurcation and Pattern Formation of Stochastic Reaction-Diffusion System

2017 ◽  
Vol 2017 ◽  
pp. 1-9 ◽  
Author(s):  
Qianiqian Zheng ◽  
Zhijie Wang ◽  
Jianwei Shen ◽  
Hussain Muhammad Ather Iqbal
Keyword(s):  
Pattern Formation ◽  
Local Equilibrium ◽  
Reaction Diffusion ◽  
Taylor Series Expansion ◽  
Reaction Diffusion System ◽  
Diffusion System ◽  
Turing Bifurcation ◽  
Noise Function ◽  
Pattern Formations ◽  
Stochastic Reaction

Noise is ubiquitous in a system and can induce some spontaneous pattern formations on a spatially homogeneous domain. In comparison to the Reaction-Diffusion System (RDS), Stochastic Reaction-Diffusion System (SRDS) is more complex and it is very difficult to deal with the noise function. In this paper, we have presented a method to solve it and obtained the conditions of how the Turing bifurcation and Hopf bifurcation arise through linear stability analysis of local equilibrium. In addition, we have developed the amplitude equation with a pair of wave vector by using Taylor series expansion, multiscaling, and further expansion in powers of small parameter. Our analysis facilitates finding regions of bifurcations and understanding the pattern formation mechanism of SRDS. Finally, the simulation shows that the analytical results agree with numerical simulation.

scholarly journals Genetic regulation and pattern formation: A study of the yellow locus in Drosophila melanogaster

1974 ◽  
Vol 24 (1) ◽  
pp. 19-26 ◽  
Author(s):  
William G. Nash ◽  
Rhoda J. Yarkin
Keyword(s):  
Drosophila Melanogaster ◽  
Pattern Formation ◽  
Genetic Regulation ◽  
Phenotypic Expression ◽  
Type A ◽  
Cell Types ◽  
Wild Type ◽  
Unique Pattern ◽  
Distinct Cell ◽  
Different Cell Types

SUMMARYMany of the yellow alleles found in Drosophila melanogaster result in a unique pattern of phenotypic expression. These patterns follow the morphologically distinct cell types of the cuticle, so that for one allele all the bristles of the head and thorax might be mutant, while most of the fly appears wild type. A comparison of many different y mutants demonstrates that the yellow phenotype is expressed independently in most if not all the different cell types which form the cuticle. Control of this expression appears to reside at the yellow locus itself.

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