scholarly journals Contraction and stress-dependent growth shape the forebrain of the early chicken embryo

Author(s):  
Kara E. Garcia ◽  
Ruth J. Okamoto ◽  
Philip V. Bayly ◽  
Larry A. Taber
1985 ◽  
Vol 52 (3) ◽  
pp. 593-600 ◽  
Author(s):  
L. Seaman ◽  
D. R. Curran ◽  
W. J. Murri

A continuum model for dynamic tensile cleavage fracture and fragmentation has been developed for detailed simulation of brittle fracture processes in elastoplastic materials. The model includes processes for nucleation of microcracks, stress-dependent growth, coalescence and fragmentation, and stress relaxation caused by the developing damage. Fracturing is characterized by a crack density with a distribution of sizes at each material point. The model extends previous work by treating more completely full material separation and stress-free volume growth, as well as multiple loadings, unloadings, and recompaction, and by describing the damage in greater microscopic detail.


Author(s):  
A. M. Watrach

During a study of the development of infectious laryngotracheitis (LT) virus in tissue culture cells, unusual tubular formations were found in the cytoplasm of a small proportion of the affected cells. It is the purpose of this report to describe the morphologic characteristics of the tubules and to discuss their possible association with the development of virus.The source and maintenance of the strain of LT virus have been described. Prior to this study, the virus was passed several times in chicken embryo kidney (CEK) tissue culture cells.


2017 ◽  
Vol 13 ◽  
pp. 8-24
Author(s):  
Zbigniew Zioło

The processes of technological  progress create new opportunities for economic, social and cultural growth, shape new relations between economic  entities and their environment,  and influence changes in the determinants  of entrepreneurship development.  These processes vary significantly in certain geographic locations, characterised by an enormous  diversity of natural, social, economic and cultural structures. As a consequence, this creates different opportunities  and different conditions for the development of entrepreneurship in certain spatial scales, from the continental scale, through national and regional to local scales. The article presents complex conditions  for the development of entrepreneurship, highlights its limitations resulting from institutional  barriers, and the importance of knowing the mechanisms of mutual relations between spatial systems and the influence of control instruments. The quality of central and local government authorities is of particular significance here, which do not always properly use the mechanisms of rational business support. A serious barrier to the development of entrepreneurship is the low quality of social capital, manifested in a lack of trust in institutional authorities and reluctance to engage in entrepreneurship and business development. The conclusions point out that further research should be developed that will take into account changing business conditions, with a defined strategic goal of raising the quality and standard of living, international competitiveness of the country and products in different market categories.


2020 ◽  
Vol 27 (11) ◽  
pp. 1744-1763 ◽  
Author(s):  
Stefano Menini ◽  
Carla Iacobini ◽  
Claudia Blasetti Fantauzzi ◽  
Giuseppe Pugliese

Vascular complications are among the most serious manifestations of diabetes. Atherosclerosis is the main cause of reduced life quality and expectancy in diabetics, whereas diabetic nephropathy and retinopathy are the most common causes of end-stage renal disease and blindness. An effective therapeutic approach to prevent vascular complications should counteract the mechanisms of injury. Among them, the toxic effects of Advanced Glycation (AGEs) and Lipoxidation (ALEs) end-products are well-recognized contributors to these sequelae. L-carnosine (β-alanyl-Lhistidine) acts as a quencher of the AGE/ALE precursors Reactive Carbonyl Species (RCS), which are highly reactive aldehydes derived from oxidative and non-oxidative modifications of sugars and lipids. Consistently, L-carnosine was found to be effective in several disease models in which glyco/lipoxidation plays a central pathogenic role. Unfortunately, in humans, L-carnosine is rapidly inactivated by serum carnosinase. Therefore, the search for carnosinase-resistant derivatives of Lcarnosine represents a suitable strategy against carbonyl stress-dependent disorders, particularly diabetic vascular complications. In this review, we present and discuss available data on the efficacy of L-carnosine and its derivatives in preventing vascular complications in rodent models of diabetes and metabolic syndrome. We also discuss genetic findings providing evidence for the involvement of the carnosinase/L-carnosine system in the risk of developing diabetic nephropathy and for preferring the use of carnosinase-resistant compounds in human disease. The availability of therapeutic strategies capable to prevent both long-term glucose toxicity, resulting from insufficient glucoselowering therapy, and lipotoxicity may help reduce the clinical and economic burden of vascular complications of diabetes and related metabolic disorders.


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