Novel Vanadium-Loaded Ordered Collagen Scaffold Promotes Osteochondral Differentiation of Bone Marrow Progenitor Cells.

Bone and cartilage regeneration can be improved by designing a functionalized biomaterial that includes bioactive drugs in a biocompatible and biodegradable scaffold. Based on our previous studies, we designed a vanadium-loaded collagen scaffold for osteochondral tissue engineering. Collagen-vanadium loaded scaffolds were characterized by SEM, FTIR, and permeability studies.

Ordered collagen membranes: production and characterization.

A collagen membrane with microscopic order is presented. The membranes were produced with acid-soluble collagen, using two different methods to obtain orientation. The product was characterized by mean of UV and IR spectra, scanning electronic microscopy, optical microscopy and laser diffractometry.

Evoked potentials in the rabbit visual cortex reflect changes in line orientation and intensity.

Changes in the amplitudes of evoked potentials in the visual cortex of conscious rabbits in response to substitution of flashing lines of different orientations (0-90 degrees ) but constant intensity were studied, along with interneurons of different intensities but constant orientation, and complex stimuli with simultaneous changes in flash orientation and intensity. Factor analysis of the results showed that analysis of the N85 peak of evoked potentials produced by substitution of stimuli with different orientations but constant intensity identified a two-dimensional sensory space for orientations. An achromatic sensory space was also detected using substitution of lines of different intensities but constant orientation.

[Visual evoked potentials in rabbit's visual cortex reflect variations in orientation and intensity of lines].

Amplitude variations of visual evoked potentials (VEP) in rabbit were studied using changes of three types of stimuli: lines with different orientations (0-90 degree) but constant in intensity, lines with different intensities but constant in orientation, and complex stimuli with different intensities and different orientations. Factor analysis of component N85 of VEP to stimuli with varying orientation and constant intensity revealed two-dimensional sensorial space of orientations. Also, the two-dimensional achromatic sensorial space was revealed for stimuli different only in intensities.

[Electrodynamics of interactions in electrolyte solutions and their biological significance].

Attention is drawn to the fact that the interaction of charges in aqueous solutions of electrolytes, such as media having physiological characteristics, depends not only on the distance between interacting charges but also on the frequency that determines their dynamics. This fact has significant consequences for some biological processes and their kinetics. The analysis of reasons for charge shielding, including the dynamic effects, shows that, even at distances exceeding the Debye length, electric interactions in systems similar to physiological are effective provided that charges move with frequencies higher than 250 MHz.

Collagen stability, hydration and native state.

Molecular dynamics simulations of a collagen-like peptide (Pro-Hyp-Gly)4-Pro-Hyp-Ala-(Pro-Hyp-Gly)5 have been done in order to study the contribution of the hydration structure on keeping the native structure of collagen. The simulation shows that the absence of water produces a distortion on the molecular conformation and an increase in the number of intra-molecular hydrogen bonds. This is in agreement with previous experimental results showing the stiffness of collagen under severe drying and its increase in the thermal stability.

[The perceptive color space of the rabbit].

Discrimination of colors was studied using instrumental learning paradigm in three rabbits (Oryctolagus cuniculus). The rabbits were able to discriminate all but red stimuli by their color. The red stimulus could not be discriminated from the black one.

[The discrimination by the rabbit of light intensities and the plotting of its achromatic space].

Elaboration of differential instrumental conditioned reflexes in rabbits showed that probabilities of responses to differential stimuli were inversely related to differences in intensity between conditioned and differential stimuli. Factor analysis of a response probability matrix revealed two orthogonal axes. They could be interpreted as the axes of brightness and darkness in achromatic space of a rabbit.

[Transcutaneous electrostimulation of the primary elements of the visual system in children after the extraction of a congenital cataract].

Courses of transcutaneous electrostimulation of the visual analyzer periphery according to E. B. Kompaneets were administered to 31 children (56 eyes) aged 4 to 12 because of low vision acuity after congenital cataract extraction.

[Effects of the intersensory action of sound on the performance of a simple motor reaction to light in the cat].

In 6 alert cats, placing responses to light and their latencies with added sound stimuli were investigated. The latency recovery cycles demonstrated that in cases of sound-light intervals 750-0 ms and light-sound intervals 0-75 ms the latencies to light were reduced, the maximum of this effect being at sound-light intervals 250-200 ms. Latency to light was enhanced at light-sound intervals 100-350 ms, the maximum being at 100-200 ms.

Effect of Triton X-100 on the physical properties of liposomes.

The interaction of the nonionic detergent Triton X-100 with phospholipid bilayers of liposomes made of egg yolk phosphatidylcholine was studied through the behavior of several physical properties. The dielectric permittivity spectra between 30 kHz and 13 MHz, the viscosity, the density, and the d.c.

Effect of additives on liposomes: an electric birefringence study.

Under the influence of an electric field, vesicles in suspension partially deform or orientate, rendering the medium optically birefringent. The amplitudes of the birefringence under fields of variable amplitude lead to evaluation of the anisotropy of the electrical delta alpha and optical delta G polarisabilities of the vesicles. By using pulsed fields, rates of establishment and decay of birefringence enable vesicle sizes d to be measured.

Electric birefringence as a means of studying the effect of anaesthetics on liposomes.

Birefringence can be induced in liposome suspensions using electric fields. The fields interact predominantly with anisotropic electrical polarisabilities which give rise to induced dipole moments. Using pulsed electric fields, the optical and electrical polarisabilities and the geometrical size of the liposomes can be measured simultaneously.

[The effects of electric stimulation of the visual cortex of the cat in a behavior model of placing reaction].

In 5 alert cats, the dependence of latency and probability of placing reaction on the parameters of electrical stimulation of visual cortex (the pulse duration and frequency in a series, number of pulses in a series) was studied. The values of current parameters were analogous to those that aroused human phosphens. The results revealed the conformity of the dependence of phosphens and cat's motor reaction on the current parameters.

[Characteristics of the response of rabbit visual cortex neurons to intracortical electric stimulation].

Responses of visual cortex neurons to single and rhythmical intracortical electrical stimulation were investigated in rabbits. Stimulating and recording electrodes were separated by 0.7-1.