Search results for "Movement"
showing 10 items of 2021 documents
Microcinematographic Studies of Mycoplasma hominis Cells
1973
Cells of two strains of Mycoplasma hominis growing in liquid medium on a glass surface were observed continuously, and cinematographic pictures were taken. Most of the observed structures showed reversible changes of their shape, suggesting the presence of contractile material in membrane or cytoplasma. The frequency and speed of such variations were measured. The deformations seem to be related to multiplication. The mechanisms of these phenomena are unknown.
A comparison of spreading and motility behaviour of 8701-BC breast carcinoma cells on type I, I-trimer and type V collagen substrata. Evidence for a …
1991
Ductal infiltrating carcinoma (d.i.c.) of human breast is a highly invasive neoplasm characterized by enhanced deposition of collagen. Paradoxically, enhanced collagen deposition is not correlated with inhibition of the migration of tumour cells into the host tissue. d.i.c. is characterized by the reappearance of ‘embryonic’ type I-trimer collagen and an increase in type V collagen content in the matrix. The effects of these two collagen types were compared with type I collagen as culture substrata on the spreading pattern, cytoskeletal organization and motile behaviour of 8701-BC breast carcinoma cells using rhodamine-phalloidin staining, a DNAase I-competition assay, scanning electron mic…
Photoreceptor vitality in organotypic cultures of mature vertebrate retinas validated by light-dependent molecular movements
2006
AbstractVertebrate photoreceptor cells are polarized neurons highly specialized for light absorption and visual signal transduction. Photoreceptor cells consist of the light sensitive outer segment and the biosynthetic active inner segment linked by a slender connecting cilium. The function of mature photoreceptor cells is strictly dependent on this compartmentalization which is maintained in the specialized retinal environment. To keep this fragile morphologic and functional composition for further cell biological studies and treatments we established organotypic retina cultures of mature mice and Xenopus laevis. The organotypic retina cultures of both model organisms are created as co-cul…
Effect of angular velocity on soleus and medial gastrocnemius H-reflex during maximal concentric and eccentric muscle contraction.
2009
At rest, the H-reflex is lower during lengthening than shortening actions. During passive lengthening, both soleus (SOL) and medial gastrocnemius (MG) H-reflex amplitudes decrease with increasing angular velocity. This study was designed to investigate whether H-reflex amplitude is affected by angular velocity during concentric and eccentric maximal voluntary contraction (MVC). Experiments were performed on nine healthy men. At a constant angular velocity of 60 degrees /s and 20 degrees /s, maximal H-reflex and M-wave potentials were evoked at rest (i.e., H(max) and M(max), respectively) and during concentric and eccentric MVC (i.e., H(sup) and M(sup), respectively). Regardless of the muscl…
Influence of gravity vector on eye movement elicited by linear acceleration.
1991
When the body/head motion is sensed by otolith organs, they respond not only to the resultant acceleration of the motion but also to the gravitational force. We investigated the influence of the gravity vector on the otolithic-ocular reflex caused by motion in normal subjects. The sled type linear accelerator, moving back and forth with a frequency of 0.25 Hz and an amplitude of 2 m, generated right-left linear acceleration with a maximum magnitude of 0.5 g. We tested every subject under seven different postures: 1) 135 degrees forward tilted (F.T.), 2) 90 degrees F.T., 3) 45 degrees F.T., 4) upright sitting, 5) 45 degrees backward tilted (B.T.), 6) 90 degrees B.T., and 7) 135 degrees B.T. …
Vertical ground reaction force measurements and video measurements provide comparable estimates of distance moved by mice during artificial light and…
2011
Video-based measures of spontaneous activity of rodents are of interest in studying, e.g. physiology. However, video-based tracking methods typically require light. The purpose of the present study was to develop a video based method for tracking movements of mice during a dark period. The method was applied in comparing the dark and light period activities of mice. Ten male mice were used in the present study. The activity of the animals was monitored simultaneously with video and ground reaction force (GRF) recordings during consecutive 12h periods of artificial light and dark. Texture based background subtraction method was used to track the mouse from the video recording, while the weig…
Synchronized rotation in swarms of magnetotactic bacteria.
2017
Self-organizing behavior has been widely reported in both natural and artificial systems, typically distinguishing between temporal organization (synchronization) and spatial organization (swarming). Swarming has been experimentally observed in systems of magnetotactic bacteria under the action of external magnetic fields. Here we present a model of ensembles of magnetotactic bacteria in which hydrodynamic interactions lead to temporal synchronization in addition to the swarming. After a period of stabilization during which the bacteria form a quasiregular hexagonal lattice structure, the entire swarm begins to rotate in a direction opposite to the direction of the rotation of the magnetic …
The elastic body model: a pedagogical approach integrating real time measurements and modelling activities
2007
In this paper, we describe a pedagogical approach to elastic body movement based on measurements of the contact times between a metallic rod and small bodies colliding with it and on modelling of the experimental results by using a microcomputer-based laboratory and simulation tools. The experiments and modelling activities have been built in the context of the laboratory of mechanical wave propagation of the two-year graduate teacher education programme of Palermo’s University. Some considerations about observed modifications in trainee teachers’ attitudes in utilizing experiments and modelling are discussed.
Mapping Brain Response to Social Stress in Rodents With c-fos Expression: A Review
2002
Social defeat is an important event in the life of many animals, and forms part of the process of social control. Adapting to social defeat is thus an intrinsic part of social "homeostasis", and mal-adaptation may have pathological sequelae. Experimental models of social defeat (e.g. inter-male aggression) have existed for many years. However, very few studies have investigated the changes in brain activity in male animals exposed to the social stress of being defeated by another conspecific male, and in all these studies the expression of the immediate-early gene c-fos has been used as the marker of neuronal activity. In general, the results obtained inform that many areas of the brain, es…
Eye movements when reading sentences with handwritten words.
2016
The examination of how we read handwritten words (i.e., the original form of writing) has typically been disregarded in the literature on reading. Previous research using word recognition tasks has shown that lexical effects (e.g., the word-frequency effect) are magnified when reading difficult handwritten words. To examine this issue in a more ecological scenario, we registered the participants’ eye movements when reading handwritten sentences that varied in the degree of legibility (i.e., sentences composed of words in easy vs. difficult handwritten style). For comparison purposes, we included a condition with printed sentences. Results showed a larger reading cost for sentences with dif…