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Biomedical subjects

V N Alekseev

Publications and source records attributed to V N Alekseev.

14 recordsLinked to original sources
PubMed1989

[The expediency of peripheral iridectomy in the surgical treatment of open-angle glaucoma].

Results of surgical interventions in two groups of patients with open-angle glaucoma are analysed and compared. In group one (51 patients) antiglaucomatous operation was made without peripheral iridectomy and in group II (46 patients)--together with the latter. Immediate results after operations on occasion of open-angle glaucoma made without peripheral iridectomy have shown a good hypotensive effect, preservation and a certain improvement of visual functions in the majority of the cases, significant weakening of inflammatory reaction in the eye in early postoperative period as compared with results after operations made together with peripheral iridectomy.

Aged↗
PubMed1983

Space motion sickness: phenomenology, countermeasures, and mechanisms.

A summary of the incidence of Space Motion Sickness (SMS) in 27 Soviet cosmonauts who flew on missions varying from 2-185 d in the Salyut-6/Soyuz vehicle complex is presented. A questionnaire indicated that 88% (24) of the cosmonauts developed some type of "illusionary sensations" while 44% (12) presented some degree of SMS. The SMS countermeasures used in flight included an antihistaminic drug, pneumatic cuffs applied to the thigh region, application of lower body negative pressure, a head cap that restricted head movement while simultaneously providing force stimulus to the cervical antigravity muscles, and finally the use of an insole counterpressure device that added pressure to the sole of the foot.

Humans↗
PubMedDate not supplied

[Vestibular function and interanalyzer interaction following space flight].

This paper presents the results of pre- and post-flight vestibular examinations using single and combined vestibular, optokinetic, proprioceptive, postural tests and cerebellar coordination tests. After extended flights most crewmembers showed spontaneous, position and positional nystagmus that points to vestibular dysfunction. The methods developed by the authors helped differentiate mechanisms of post-flight vestibular dysfunctions: in Group 1 subjects spontaneous nystagmus parameters varied during all tests; in Group 2 subjects they varied only in response to active tilt tests; in Group 3 subjects they varied only in response to vestibular, optovestibular and proprioceptive stimulation; and in Group 4 subjects they varied only in response to proprioceptive optovestibular stimulation and cerebellar coordination tests. Individual patterns of the above changes are associated with different pathways of adaptation of the vestibular function that depend on the involvement of various structures and compartments of the central nervous system.

Eye Movements↗
PubMedDate not supplied

[Pattern of vestibular reactions and sensory interactions in weightlessness (data of the experiment "Optokinesis")].

This paper presents results of studying spontaneous and evoked optokinetic, opto-oculomotor and vestibulo-oculomotor reactions in microgravity. The examinations were performed during the 7-day Soviet-Indian and 237-day Salyut-7 missions. During an early stage of adaptation to microgravity the following changes occurred: enhanced spontaneous activity of the eyes, including spontaneous nystagmus in one of the crewmembers, decline of the efficiency of saccadic pursuit (disappearance of saccades in the course of pursuit of a moving stimulus, decrease of the saccadic amplitude, emergence of correction microsaccades in response to fixation events), and decrease of the threshold of the optokinetic nystagmus. The compensatory counter-rotation of the eyeballs during head side-to-side movements with open eyes in dark glasses did not disappear but slightly decreased, being slightly accompanied by low-amplitude nystagmus. When rocking the head with open eyes, one of the cosmonauts showed a complete eye destabilization and other cosmonauts displayed high-amplitude nystagmus. In response to head rotation with open eyes they developed clonic nystagmus. Vestibular stimulation in the form of active head movements helped to normalize the pattern of opto-ocular responses.

Adaptation, Physiological↗
PubMedDate not supplied

[Results of a study of vestibular function and space perception among members of the crew of the first and second "Sal'iut 6" space station expedition].

The results of studies of the vestibular function and spatial perception function in crewmembers of long-term (96- and 140-day) space missions aboard Salyut-6 are presented. Similar changes and individual variations are revealed. All the cosmonauts have shown the following changes: increased reactivity of the otolith organ, decreased sensitivity of the cupular system, asymmetry of most parameters studied, and illusory reactions inflight, individual reactions are as follows: level of changes, dynamics and time of recovery, development of vestibulo-vegetative symptomocomplex during early adaptation to zero-g, signs of decline in vestibulo-vegetative tolerance postflight, and changes in reciprocal relations between the otolith organ and semicircular canals.

Acoustic Maculae↗
PubMedDate not supplied

[Results of a study of vestibular function and space perception in cosmonauts].

The results of studying the vestibular function and the function of spatial perception in 26 cosmonauts before and after 30 space flights are discussed. The typical postflight changes in these functions were: an increase in the reactivity of the otolith organ, a decrease in the sensitivity of semicircular canals, a decline in the accuracy of perception of spatial coordinates, asymmetry of most parameters, development of illusionary reactions inflight. The cosmonauts also showed individual variations with respect to the degrees of the above responses, the dynamics and length of adaptation, the development of the motion sickness symptom-complex, etc. At R+O some cosmonauts exhibited a change in the direction of the eye counter-rotation, i. e., the negative otolith reflex or at turn towards the tilt direction. Possible mechanisms of these vestibular changes are discussed.

Adult↗