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Biomedical subjects

E V Korneeva

Publications and source records attributed to E V Korneeva.

12 recordsLinked to original sources
PubMed2004

Half-life of leu-enkephalin in the serum of infants of the first year of life on different types of feeding: relationship with temperament.

The half-life of leu-enkephalin in the serum of infants aged under 1 year is significantly shorter than in adults. In girls leu-enkephalin half-life is significantly longer than in boys. The half-life of leu-enkephalin is different in infants on breast and formula feeding. Nine characteristics of temperament in infants of the first year of life were determined using EITQ and ITQ questionnaires. Serum leu-enkephalin half-life directly correlated with temperament characteristics (activity, perception, threshold), but not with the level psychomotor development.

Adult↗
PubMed1994

Hydrodynamic characteristics and equilibrium rigidity of pullulan molecules.

The hydrodynamic characteristics of the polysaccharide pullulan (polymaltotriose) in water have been investigated and its molecular characteristics have been determined. Experimental values varied over the following ranges: velocity sedimentation coefficient (S): 0.9 < S < 11.2, translational diffusion coefficient (10(7) cm2 s-1): 1.1 < D < 14.7 and intrinsic velocity (cm3 g-1): 6.7 < [eta] < 164, which corresponds to a change in molecular weight (x 10(3)) in the range 3.9 < MSD < 644. On the basis of analysis of the literature and our experimental data, excluded volume effects have been shown to have a prevailing influence on the chain length of these polysaccharides. The equilibrium rigidity and hydrodynamic chain diameter of pullulan were evaluated on the basis of the theory of hydrodynamic properties of a wormlike necklace, taking into account excluded volume effects. At low M (< 30 x 10(3)) the translation friction data (in contrast to viscometric data) cannot be described in the framework of the theory of linear molecules.

Chemical Phenomena↗
PubMedDate not supplied

Sensory information--the major factor of ontogeny.

On the basis of their own data authors postulate that the increase in sensory input during early ontogeny results in a delay in the development of the sensory systems formed earlier. In connection with this, the sensory basis of behavioral patterns becomes ineffective, causing their reorganization and the appearance of new forms of behavior. Limitation of sensory input during during the critical periods of development stimulates the accelerated manifestation of behavioral patterns. However, this acceleration also has long-lasting negative effects - alterations in the process of learning and memory in adult animals.

Aging↗
PubMedDate not supplied

[The morphogenesis of Wulst neurons in the pied flycatcher under conditions of limited afferent inflow].

Golgi preparations of the pied flycatcher Wulst region (the structure analogous to the mammalian visual cortex) were analyzed using the method of computerized morphometry, to study the influence of visual deprivation on the development of different types of neurons selected previously. Deprivation was accomplished by covering the young's eye with nontransparent caps. The experiments were carried out in 10-day-old nestlings (the onset of patterned vision) and 13-day-old nestlings (functioning patterned vision). In 10-day-old nestlings, the deprivation produced constructive changes in dendritic apparatus of projective stellate cells (among them, the most pronounced was more than three-fold increase in the number of foci of maximal branching) practically not affecting the small stellate-like cells. In 13-day-old nestlings, cells belonging to all selected cell types underwent destructive changes: their quantitative characteristics were decreased as compared to those in control nestlings. A large number of tree-like neurons were revealed in the Wulst in the deprived 10-day-old nestlings while in the control age-matched nestlings they were virtually never found. This phenomenon may be explained by the increased affinity to impregnation evoked by deprivation-induced biochemical changes in the tree-like neurons or to increase in their number. In the latter case, the phenomenon may be considered as compensatory, directed at the establishing of contacts with nonvisual afferents.

Afferent Pathways↗
PubMedDate not supplied

[Visual afferentation deficit during diffuse photosensitivity period in nestlings affects morphogenesis in Wulst neurons].

Golgi-stained preparations were processed with computerized morphometry to study the effect of the deprivation (eyes covered with nontransparent caps) on the development of neurons in the Wulst (the structure analogous to mammalian visual cortex) of pied flycatcher nestlings. Six-day-old nestlings that have only one form of the visual perception--diffuse photosensitivity--were studied. In the previous paper [Korneeva et al., 1994] in was shown that the Wulst of 6-day-old nestlings consisted of non-differentiated neurons and stellate-like cells at different stages of maturation; the latter group was subdivided into more- and less-mature cells. This work proved that even a 1.5-day-long deprivation (actual duration being counted off from the moment of appearance of the first retinal photoreceptors at the age of 4.5 days) resulted in significant changes in the geometry of stellate-like neurons. The changes in less-mature cells were predominantly destructive (decline of all quantitative indices of a cell, including the significant decrease in the total length of dendrites, maximal radius of the dendritic field and cell branching index), while the changes in more-mature cells were constructive (increase in all quantitative cell indices, including statistically significant increase in the soma section area, total length of dendrites, maximal radius of dendritic field and the number of foci of maximal branching). Different reactions of these cell types to the limitation of visual afferentation may be connected with differences in the afferent inflow to less- and more-mature cells or/and with different maturational stages of these neurons at the onset of deprivation.

Afferent Pathways↗
PubMedDate not supplied

[Increasing selectivity of defense behavior during development of pied flycatcher nestlings].

The development of defense reaction was studied in the wildlife and experimentally in 7 broods of altricial pied flycatcher (Ficedula hypoleuca) nestlings. Field studies demonstrated that passive-defense response first appeared on the 4th day of the nest life. It developed from the cessation of begging in young relatively satiated nestlings to characteristic freezing response independent of the level of feeding motivation in older nestlings. Older nestlings also acquire the defense reaction in response to novel visual stimuli. The efficiency of the natural stimulus for defense behavior (species-specific alarm call) nongradually changes during the nest life attaining the 100% level only on the 11th posthatching day. During the initial phase of defense behavior development, the reaction can be induced by different rhythmically organized stimuli. Later it becomes considerably more selective and other rhythmic and acoustic signals become much less effective than the alarm call.

Acoustic Stimulation↗
PubMedDate not supplied

[The role of visual afferentation in the development of early defense behavior of pied flycatcher nestlings].

The development of defense behavior in normal and visually deprived pied flycatcher nestlings was studied in the wild. It was demonstrated that the young deprived of the visual afferentation did not develop the freezing posture. In the majority of cases, specific alarm call suppressed begging in visually deprived nestlings less effectively than in the control ones. Visually deprived nestlings could not discriminate between the alarm call and other rhythmically organized acoustic signals even though the latter effectively suppressed begging.

Acoustic Stimulation↗
PubMedDate not supplied

[Age dynamics of visually guided behavior and visual evoked potentials of altricial nestlings].

Comparative study has been carried out of factors of organization of visually guided feeding behaviour (observation method) and the degree of maturity of the visual mechanisms by the criterion of Wulst EPs formation and of their recovery cycles in normally developing and visually deprived nestlings. In has been established that during the period following the opening of the eyes (5-9th day) the feeding behaviour is connected with diffuse photo-sensitivity of visual mechanisms. Diffuse photo-sensitivity fully provides for natural feeding behaviour at the corresponding stage of development of visual functions. Complete visual deprivation during the whole period of diffuse photo-sensitivity does not influence subsequent development of the visual system.

Age Factors↗
PubMedDate not supplied

[Sensory information--an important factor in ontogeny].

Ontogenetic process reveals a row of consecutive stages characterized by the gradual increase in complexity and by the changing specificity of sensory mechanisms basic for the adaptive behavior of the young. The study examines the mechanisms of interaction among different sensory systems during the formation of early behavioral patterns and analyzes why, at a certain stage of development, a particular sensory stimulus loses its efficacy in the organization of a given behavior and is substituted by another one, previously ineffective. A special attention is paid to formation of behavior based on sensory information within the limits of ontogenetically fixed developmental critical periods and to the role of the early sensory experience in learning in adult animals.

Aging↗
PubMedDate not supplied

[A quantitative morphological study of the effect of partial visual deprivation on the formation of 2 types of Wulst neurons in pied flycatcher nestlings].

Neurons of the Wulst area (analogous to mammalian visual cortex) were studied with the method of computerized morphometry (6 parameters) in frontal Golgi-stained sections of pied flycatcher nestlings which were binocularly deprived since the age of 1-1.5 days post-hatching. The current study was focused on two types of neurons: spiny stellate and small spineless stellate-like cells. It was found that the visual deprivation not only slowed down the morphogenesis of these neurons but also caused the constructive changes--increase in the number of foci of maximal dendrite branching--in spiny stellate neurons which we had earlier defined as projective cells. Changes in small spineless stellate-like neurons (earlier defined as intercalate cells) were of, mostly, opposite direction. In the latter neurons we observed a reduction of the number of dendrites and dendrite branches. Opposite changes in different cell groups caused by the limitation of sensory input may, on the one hand, point to a difference in functional connections of ascending afferent fibers with different types of neurons, and, on the other hand, indicate a different degree of the influence of visual experience on the development of these neurons.

Animals↗