Inadequate interaction between open- and closed-loop postural control in phobic postural vertigo.

Phobic postural vertigo (PPV) is characterized by a subjective dizziness and postural imbalance. Changes in postural control strategy may cause the disturbed postural performance in PPV. A better understanding of the mechanisms behind this change in strategy is required to improve the diagnostic tools and therapeutic options for this prevalent disorder. Here we apply stabilogram diffusion analysis (SDA) to examine the characteristics and modes of interaction of open- and closed-loop processes that make up the postural control scheme in PPV. Twenty patients with PPV and 20 age-matched healthy controls were recorded on a stabilometer platform with eyes open and with eyes closed. Spatio-temporal changes of the center of pressure (CoP) displacement were analyzed by means of SDA and complementary CoP amplitude measures. (1) Open-loop control mechanisms in PPV were disturbed because of a higher diffusion activity (p < 0.001). (2) The interaction of open- and closed-loop processes was altered in that the sensory feedback threshold of the system was lowered (p = 0.010). These two changes were comparable to those observed in healthy subjects during more demanding balance conditions such as standing with eyes closed. These data indicate that subjective imbalance in PPV is associated with characteristic changes in the coordination of open- and closed-loop mechanisms of postural control. Patients with PPV use sensory feedback inadequately during undisturbed stance, and this impairs postural performance. These changes are compatible with higher levels of anti-gravity muscle activity and co-contraction during the conscious concentration on control of postural stability.

[On mechanism of nonlinear laser cleavage of DNA]. / O mekhanizme nelineinogo lazernogo razrezaniia DNK.

Dependences of nonlinear laser cleavage of DNA on a concentration of the free-radical scavenger, beta-mercaptoethanol, have been measured. The obtained data rule out the free-radical mechanism of the nonlinear laser cleavage and agree with the mechanism based on two-quantum excitation energy transfer from a dye to DNA. A high concentration of beta-mercaptoethanol has been found to cause DNA hyperchromicity.

[Neutralizing morbillivirus antibodies in the population of the Baikal seal Phoca sibirica]. / Neitralizuiushchie morbillivirus antitela v populiatsii baikal'skikh nerp Phoca sibirica.

The antibodies neutralizing Baikal seal morbillivirus (BSMV) were studied in sera from 148 normal Baikal seals (Phoca sibirica). The virus-neutralizing antibodies were demonstrated in sera of 61.5% of the animals examined. A comparative analysis of antibodies in NT and cell-ELISA method is presented. The role of BSMV in morbidity and mortality of seals (Phoca sibirica) is discussed.

[Ebola virus reproduction in cell cultures]. / Reproduktsiia virusa Ebola v kletochnykh kul'turakh.

Ebola-Zaire virus production in Vero and BGM cells was studied. The CPE developed in both cell cultures. The cell monolayer destruction by 80-90% was seen at a low multiplicity of infection in 7-8 days after virus inoculation. An overlay composition was developed for virus titration using plaque assay. The plaque production was shown to be directly proportional to the virus dose. The curve of Ebola virus production in Vero cell culture fluid was determined. At a multiplicity of infection of 0.01 PFU/cell, the maximum virus titer of 10(6.4) PFU/ml was reached in 7 days postinfection. Specific antisera were generated by inoculation of guinea pigs. Indirect immunofluorescent assay was used for testing of virus-specific antigen and antibody.

[An experimental infection of the seal Phoca sibirica with the morbilli virus]. / Eksperimental'noe infitsirovanie nerpy Phoca sibirica morbillivirusom.

A Baikal seal (Phoca sibirica) was experimentally infected with Baikal seal morbillivirus (BSMV) isolated from Baikal seals during an epizootic in 1987-1988. The seal was infected with BSMV with an infectious titer of 10(7.0) TCD50/ml, and daily observations of the animal clinical condition were made. The virus-specific antibodies in the seal serum were determined by ELISA and virus neutralization test. The clinical picture showed a mild infection. The ELISA-active antibodies were detected 10 days postinfection and reached the maximum in 20 days. Virus-neutralizing antibodies were detected in 16 days after infection, reached the maximum titer of 1:640 in 20 days and remained at this level for 39 days (the observation period). These data indicate that BSMV can induce a disease in the natural host with production of virus-neutralizing antibodies. The results of this work and the earlier reports show that the epizootic in Baikal seals was induced by BSMV.

[The isolation and characteristics of continuous virus-producing lymphoid suspension cultures of African green monkey cells]. / Poluchenie i kharakteristika perevivaemykh virusprodutsiruiushchikh limfoidnykh suspenzionnykh kul'tur kletok afrikanskikh zelenykh martyshek.

Five continuous lymphoid suspension cell cultures were established by cultivation of lymphocytes from African green monkeys. The immunological typing revealed the mixed pattern of cultures consisting of B and T cell types. Two types of viruses: herpesvirus and retrovirus C-type were demonstrated by electron microscopy. Indirect immunofluorescence and molecular hybridization studies showed one of the viruses to be an EBV-related herpesvirus of green monkeys designated HVGM and the other to belong to H (S) TLV-1 group.

[Comparative analysis of genomes of oncogenic B-lymphotropic herpesviruses reproducing in cell lines obtained from different monkey species]. / Sravnitel'nyi analiz genomov onkogennykh B-limfotropnykh virusov gerpesa, reprodutsiruiushchikhsia v kletochnykh liniiakh, poluchennykh ot obez'ian razlichnykh vidov.

The aim of this work was to study genomes of B-lymphotropic oncogenic herpesviruses of Macaca arctoides (HVMA), Papio hamadryas (HVP) and Cercopithecus aethiops (HVGM). Blot-hybridization detected inter- and intraspecific genome heterogeneity of investigated viruses in restriction sites EcoR1, Pst1 and Hind111. Virus-specific sequences in two-cell lines obtained from HVMA-induced rabbit tumours can prove HVMA a role in malignant tumour induction in rabbits.

[Nonlinear laser photomodification of nucleic acids induced by intercalating dyes]. / Nelineinaia lazernaia fotomodifikatsiia nukleinovykh kislot, indutsirovannaia interkaliruiushchimi krasiteliami.

Results of a cycle of investigations of two-quantum affinity modification of nucleic acids (NA) are presented. The modification is induced by laser excitation of chromophoric molecules which are in intercalative complexes with NA. The following subjects are considered: theoretical basis of the two-quantum affinity modification: experimental investigation of nonlinear scission of DNA; theory and experiment on the light--induced diffusion of DNA. The latter is an effect which accompanies the scission and allows one to obtain information on it. The modification specificity and universality in a dye type are established experimentally. Influence of free radicals, oxygen, heating and hydrodynamical phenomena in bulk are excluded. The modification has been shown to be dependent on NA structure (secondary and tertiary) and to provide information on it. Total aggregate of the data obtained is in agreement with the suggested modification mechanism which is based on the radiationless transfer of two-quantum excitation energy from the chromophore to NA.