ANALYSIS OF THE GEOTROPIC ORIENTATION OF YOUNG RATS. V

Young rats bearing a mass of 1.06 gm. both at shoulder level on the back and posteriorly at the sacrum exhibit in their geotropic progression a relationship between angle θ of oriented path and inclination α of substratum which differs from those obtained with rats of the same race carrying the same total added load concentrated anteriorly or posteriorly. The distributed load affects more or less equally all the groups of receptor units concerned in tension excitation. It is shown that the variation of orientation is organically determined, quantitatively, by the intensity of tension excitation, regardless of the imposition of the added loads. The bearing of these facts upon the theory of the geotropic orientation is discussed.

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The importance of CREB phosphorylation by PKA, CaMK and MAPK for olfactory learning in young rats

Neuroscience Research ◽

10.1016/s0168-0102(00)81442-x ◽

2000 ◽

Vol 38 ◽

pp. S99

Author(s):

J Zhang

Keyword(s):

Olfactory Learning ◽

Creb Phosphorylation ◽

Young Rats

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On the Fibrinolytic System in Aged Rats, and Its Reactivity to Endotoxin and Cytokines

Thrombosis and Haemostasis ◽

10.1055/s-0038-1648525 ◽

1992 ◽

Vol 67 (06) ◽

pp. 697-701 ◽

Cited By ~ 6

Author(s):

J J Emeis ◽

A Brouwer ◽

R J Barelds ◽

M A Horan ◽

S K Durham ◽

...

Keyword(s):

Plasminogen Activator ◽

Fibrinolytic Activity ◽

Fibrinolytic System ◽

Tissue Type ◽

High Dose ◽

Base Line ◽

Aged Rats ◽

Tissue Type Plasminogen Activator ◽

Young Rats ◽

Type Plasminogen Activator

SummaryAged rats are more susceptible to endotoxin-induced effects, including microthrombosis and platelet aggregation, than are young rats. To investigate whether changes in the fibrinolytic system might be involved, we investigated the fibrinolytic activity in plasma euglobulin fractions and tissues (lung and heart) of young (6-months old) and aged (24-months old) rats under baseline conditions and after challenge with endotoxin. Aged rats had lower plasma levels of tissue-type plasminogen activator (t-PA) and of urokinase-type PA (u-PA) activity. PA inhibitor (PAI) activity was higher in the plasma of aged rats, as was t-PA activity in lung and heart.Rats were treated with either a low dose (1 μg/kg) or a high dose (10 mg/kg) of endotoxin. Both treatments induced a transient phase of increased blood fibrinolytic activity, as evidenced by higher levels of tissue-type plasminogen activator (t-PA) activity and decreased levels of PA inhibitor (PAI) activity. Over time, the fibrinolytic activity decreased, probably due to increased levels of PA inhibitor.Both the early increase in t-PA activity, and the subsequent increase in PAI activity, were more pronounced in the aged rats, as compared with the younger rats, after the high dose of endotoxin. The aged rats also responded to an injection of interleukin-1β or tumor necrosis factor-α with a larger increase of PAI activity than did the younger rats.Together the data suggest that, compared to young rats, aged rats have a decreased base-line plasma fibrinolytic activity, while their fibrinolytic system is more responsive to challenge by endotoxin and cytokines.

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DEFORMATION AND CRACKING OF THE PLATFORM JOINT OF THE PREFABRICATED-MONOLITHICRC BUILDING FRAME

Building and reconstruction ◽

10.33979/2073-7416-2020-90-4-38-47 ◽

2020 ◽

Vol 90 (4) ◽

pp. 38-47

Author(s):

VL.I. KOLCHUNOV ◽

◽

D.V. MARTYNENKO ◽

Keyword(s):

Reinforced Concrete ◽

Plane Stress State ◽

Hollow Core ◽

Finite Element Scheme ◽

Element Scheme ◽

Joint Structure ◽

Numerical Studies ◽

Distributed Load ◽

Different Types ◽

Design Characteristics

A computational model and the results of numerical studies of the structure of a platform joint in a reinforced concrete precast-monolithic frame of a building from panel-frame elements of industrial production are presented. Modeling of the plane stress state of the joint structure is carried out by a finite element scheme, using finite elements of different types and a nonlinear law of deformation to determine the design characteristics of reinforced concrete. The parameters of deformation of the platform joint structure at different loading levels, including stage-by-stage cracking and destruction, have been determined. The schemes of distribution and stress concentration zones in the characteristic sections of the platform joint are established when the distributed load is transferred from the frame of the panel-frame to the hollow-core floor panels and concrete for embedding the joint in the presence of a cavity in the frame frame for centering elements.

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