scholarly journals The relationship of brain-tissue loss volume and lesion location to cognitive deficit

1986 ◽  
Vol 6 (2) ◽  
pp. 301-307 ◽  
Author(s):  
J Grafman ◽  
A Salazar ◽  
H Weingartner ◽  
S Vance ◽  
D Amin
2021 ◽  
Author(s):  
Vitor Matias Grah ◽  
Guilherme Sampaio Silva ◽  
Karla Viana Rezende ◽  
Ayrton Senna do Brasil Amaral Alves ◽  
Maria Inês Vaz de Oliveira ◽  
...  

Background: Alzheimer disease(AD) is a progressive neurodegenerative dysfunction with a cognitive deficit and amyloid-β(Aβ) accumulation. That said, the apolipoprotein E (ApoE) has 4 variants, with E4 being linked to decreased cerebral blood flow and fragile blood-brain barrier (BBB). In this way, the BBB has an important role in removing substances that are toxic to the brain such as βA protein. Objective: Demonstrate the relationship of ApoE4 and BBB dysfunction in the pathophysiology of AD. Methods: Bibliographic review using the CAPES journals portal, in the last 5 years. Results: After analyzing the studies, it is inferred that in cases of homozygosity for ApoE4 in relation to ApoE3 there is a 15 fold increased chance of developing AD and 3 fold heterozygosity. It is concluded that the mechanism that probably explain is related to the secretion of ApoE by the pericytes that lining brain vessels in the BBB, whilst the subtype E4 exacerbates cyclophilinA, which promotes the activation of metalloproteinase-9, causing junctions rupture between adjacent endothelial cells, promoting the loss of βA homeostasis. Conclusion: It can be inferred, that ApoE has great importance in the regulation of the integrity of BBB’s integrity, is undeniable that such protein has a significant contribution in the pathophysiology of AD, hereupon, it’s urgent that these studies need to be continued to develop new therapies in individuals who express ApoE4.


Paleobiology ◽  
1980 ◽  
Vol 6 (02) ◽  
pp. 146-160 ◽  
Author(s):  
William A. Oliver

The Mesozoic-Cenozoic coral Order Scleractinia has been suggested to have originated or evolved (1) by direct descent from the Paleozoic Order Rugosa or (2) by the development of a skeleton in members of one of the anemone groups that probably have existed throughout Phanerozoic time. In spite of much work on the subject, advocates of the direct descent hypothesis have failed to find convincing evidence of this relationship. Critical points are:(1) Rugosan septal insertion is serial; Scleractinian insertion is cyclic; no intermediate stages have been demonstrated. Apparent intermediates are Scleractinia having bilateral cyclic insertion or teratological Rugosa.(2) There is convincing evidence that the skeletons of many Rugosa were calcitic and none are known to be or to have been aragonitic. In contrast, the skeletons of all living Scleractinia are aragonitic and there is evidence that fossil Scleractinia were aragonitic also. The mineralogic difference is almost certainly due to intrinsic biologic factors.(3) No early Triassic corals of either group are known. This fact is not compelling (by itself) but is important in connection with points 1 and 2, because, given direct descent, both changes took place during this only stage in the history of the two groups in which there are no known corals.


Author(s):  
D. F. Blake ◽  
L. F. Allard ◽  
D. R. Peacor

Echinodermata is a phylum of marine invertebrates which has been extant since Cambrian time (c.a. 500 m.y. before the present). Modern examples of echinoderms include sea urchins, sea stars, and sea lilies (crinoids). The endoskeletons of echinoderms are composed of plates or ossicles (Fig. 1) which are with few exceptions, porous, single crystals of high-magnesian calcite. Despite their single crystal nature, fracture surfaces do not exhibit the near-perfect {10.4} cleavage characteristic of inorganic calcite. This paradoxical mix of biogenic and inorganic features has prompted much recent work on echinoderm skeletal crystallography. Furthermore, fossil echinoderm hard parts comprise a volumetrically significant portion of some marine limestones sequences. The ultrastructural and microchemical characterization of modern skeletal material should lend insight into: 1). The nature of the biogenic processes involved, for example, the relationship of Mg heterogeneity to morphological and structural features in modern echinoderm material, and 2). The nature of the diagenetic changes undergone by their ancient, fossilized counterparts. In this study, high resolution TEM (HRTEM), high voltage TEM (HVTEM), and STEM microanalysis are used to characterize tha ultrastructural and microchemical composition of skeletal elements of the modern crinoid Neocrinus blakei.


Author(s):  
Leon Dmochowski

Electron microscopy has proved to be an invaluable discipline in studies on the relationship of viruses to the origin of leukemia, sarcoma, and other types of tumors in animals and man. The successful cell-free transmission of leukemia and sarcoma in mice, rats, hamsters, and cats, interpreted as due to a virus or viruses, was proved to be due to a virus on the basis of electron microscope studies. These studies demonstrated that all the types of neoplasia in animals of the species examined are produced by a virus of certain characteristic morphological properties similar, if not identical, in the mode of development in all types of neoplasia in animals, as shown in Fig. 1.


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