Responses of Neurons of the Extrastriate Area 21b of the Cat Brain Cortex to Changes in Orientation of Moving Visual Stimuli

We studied the responses of neurons of the extrastriate cortical area 21b of the cat to changes in orientation of the movements of visual stimuli within the receptive field (RF) of the neuron under study. Our experiments demonstrated that 24 of 108 cells (22%) responded differentially to a certain extent to orientation of the movements of visual stimuli. As a whole, neurons of the area 21b did not demonstrate fine tuning on the optimum angle of orientation. In many cases, neuronal responses to different orientations of the movement of visual stimulus depended significantly on specific parameters of this stimulus (its shape, dimensions, and contrast). Some directionally sensitive neurons responded to a change in orientation of the movement of visual stimuli by modification of the index of directionality. We also studied spatial organization of the RF of neurons with the presentation of stationary visual stimuli. Comparison of the neuronal responses to a change in orientation of the movements of stimuli and to presentation of stationary stimuli showed that the correlation between the orientation sensitivity of the neuron under study and the stationary functional organization of its RF was insignificant. We hypothesize that inhibitory processes and subthreshold influences from a space surrounding the RF play a special role in the formation of the neuronal responses generated in the associative visual cortical regions to visual stimulation.     

Modifications of Visual Evoked Potentials in Patients with Glaucoma

We compared the visual evoked EEG potentials (VEP) elicited by presentation of a reversal chess pattern in patients with glaucoma and in the control group. Amplitudes, peak latencies of the main VEP components (N75, P100, and N145), interpeak intervals, and interpeak magnitudes were measured, and a spectral analysis of the averaged VEP was performed. In patients suffering from glaucoma, the latencies of the N75 and P100 components were greater, while the interpeak intervals P100-N145 and N75-N145 were shorter, than those in the control group. Glaucoma-related changes in the VEP spectral characteristics, in particular a drop in the spectral power of oscillations corresponding to the alpha rhythm, were observed.     

Consumption of a high-fat-high-sucrose diet partly diminishes mechanical and structural adaptations of cardiac muscle following resistance training

[Purpose]The purpose of this study was to investigate the effects of a high-fat high-sucrose (HFHS) diet on previously reported adaptations of cardiac morphological and contractile properties to resistance training.[Methods]Twelve-week-old rats participated in 12-weeks of resistance exercise training and consumed an HFHS diet. Echocardiography and skinned cardiac muscle fiber bundle testing were performed to determine the structural and mechanical adaptations.[Results]Compared to chow-fed sedentary animals, both HFHS- and chow-fed resistance-trained animals had thicker left ventricular walls. Isolated trabecular fiber bundles from chow-fed resistance-trained animals had greater force output, shortening velocities, and calcium sensitivities than those of chow-fed sedentary controls. However, trabeculae from the HFHS resistance-trained animals had greater force output but no change in unloaded shortening velocity or calcium sensitivity than those of the chow-fed sedentary group animals.[Conclusion]Resistance exercise training led to positive structural and mechanical adaptations of the heart, which were partly offset by the HFHS diet.     

Light energy supply in plate-type and light diffusing optical fiber bioreactors

The light distribution profiles of plate-type photobioreactors were investigated. Light reaching individual channels of a plate module is dependent on the orientation of the module to the sun, the position of the channel within a plate and the position of the plate. The highest incident radiation was measured at the south oriented side of the first channel of the front plate. The light intensity decreased from top to ground channels. Different types of light diffusing optical fibers (LDOF) were characterized with respect to their applicability in photobioreactor systems.     

Unloading of the soleus in tail-suspended rats increases the number of intrafusal fibers in muscle spindles

Transmission electron microscopy was used to study the ultrastructure of muscle spindles (encapsulated stretch receptors) in m. soleus of adult Wistar rats after repeated hindlimb unloading. It was shown that the unloaded soleus contained not only spindles with a typical number of intrafusal fibers (four) but also spindles with five or six fibers. The increase in the number of intrafusal fibers in muscle spindles of the unloaded animals is likely to be caused by the proliferation of their satellite cells (myoblasts).     

Release of N-Acetylaspartylglutamate from Slices of Rat Cerebellum, Striatum, and Spinal Cord, and the Effect of Climbing Fiber Deprivation

Abstract: The release of endogenous N -acetylaspartylglutamate (NAAG) from slices of rat cerebellum, striatum, and spinal cord upon depolarization with 50 m M K⁺ was investigated. NAAG in superfusates was prepurified using an ion exchanger, esterified, and then quantified by gas chromatography-mass spectrometry. Deuterated NAAG was used as internal standard. A depolarization-induced release of NAAG was found in all three regions. The release was Ca²⁺ dependent to over 85% in cerebellum and striatum, but only to approximately 70% in spinal cord. In addition, the effect of lesions of the olivocerebellar pathway on the K⁺-induced release of NAAG was studied: Treatment of the animals with 3-acetylpyridine reduced the release of NAAG from cerebellar hemispheres significantly, by about 40% compared with controls. These results suggest that part of the NAAG released from cerebellar slices on depolarization is related to climbing fibers. Implications of these findings concerning possible physiological roles of NAAG in the three CNS regions are discussed.     

Superelastic Hybrid CNT/Graphene Fibers for Wearable Energy Storage

The demands for wearable technologies continue to grow and novel approaches for powering these devices are being enabled by the advent of new electromaterials and novel fabrication strategies. Herein, a novel approach is reported to develop superelastic wet‐spun hybrid carbon nanotube graphene fibers followed by electrodeposition of polyaniline to achieve a high‐performance fiber‐based supercapacitor. It is found that the specific capacitance of hybrid carbon nanotube (CNT)/graphene fiber is enhanced up to ≈39% using a graphene to CNT fiber ratio of 1:3. Fabrication of spring‐like coiled fiber coated with an elastic polymer shows an extraordinary elasticity capable of 800% strain while affording a specific capacitance of ≈138 F g^?1. The elastic rubber coating enables extreme stretchability and enabling cycles with up to 500% strain for thousands of cycles with no significant change in its performance. Multiple supercapacitors can be easily assembled in series or parallel to meet specific energy and power needs.     

Detection of early ischemic damage by analysis of mitochondrial function in skinned fibers

The skinned fibers technique was applied for studies of the effects of global acute ischemia (1 h at 37°C) and long time (15 h) hypothermic (4°C) preservation of isolated rat hearts under different conditions (immersion or low-flow perfusion) on mitochondrial function in the cells in vivo. Skinned fibers were obtained by using saponin for permeabilization of the sarcolemma in separated fiber bundles cut from left ventricle. The experimental protocol of the respiration rate determination included a cytochrome c test to check the intactness of the outer mitochondrial membrane. The apparent K_m for ADP and the effect of creatine on the mitochondrial activity were also evaluated in these permeabilized fibers, taken from different groups of hearts. The preservation of low-flow perfused hearts resulted only in a slight decrease of creatine (20 mM) stimulated respiration at 0.1 mM ADP. The fibers from ischemic hearts or from hearts preserved by immersion showed a decrease of the apparent K_m for ADP, and a complete loss of the stimulatory effect of creatine. In these fibers, we could observe that the outer mitochondrial membrane was damaged. In conclusion, the results of this study show that assessment of mitochondrial parameters sensitive to organelles swelling – intactness of outer membrane and functionally coupled creatine kinase reaction – are the most sensitive indicators of early hypoxic or ischemic damage to mitochondria. Their determination in biopsy samples could be used for evaluation of the efficiency of the cardiac protection in heart surgery. (Mol Cell Biochem 174: 79–85, 1997)     

Adhesion, orientation, and movement of cells cultured on ultrathin fibronectin fibers

Summary This study examined the behavior of rat tendon fibroblasts, baby hamster kidney fibroblasts, macrophage-like P388D1 cells, and neurons from rat dorsal root ganglia, cultured on fibronectin strands 0.2–5 μm in diameter. We investigated cell spreading, orientation, formation of focal contacts, the speed of cell movement, and the speed of neurite outgrowth in cells cultured on fibronectin strands, glass covered with fibronectin, and plain, nontreated glass. Fibronectin strands significantly promoted cell spreading and caused a marked alignment of all kinds of cells to the direction of the fiber. The fibers caused the alignment of actin filaments in fibroblasts and focal contacts in fibroblasts and macrophages and increased polymerization of F-actin in cells. Fibronectin fibers also increased the speed and persistence of cell movement and the rate of neurite outgrowth. Macrophages grown on fibronectin fibers produced numerous actin-rich microspikes and adopted a polarized, migratory phenotype. These findings indicate that fibronectin strands, resembling natural components of the extracellular matrix, are more effective in activating various types of cells than two-dimensional, fibronectin-covered substrata. The results also confirm the suitability of the three-dimensionally oriented fibronectin form for use in clinical practice.