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Biomedical subjects

N P Smirnova

Publications and source records attributed to N P Smirnova.

At least 19 recordsLinked to original sources
PubMed1995

[The role of macrophage suppressor activity in the mechanism of metastasis after tumor resection].

The rates of spontaneous metastasis to the lung (SML) and lymph nodes, cytotoxic and antimetastatic activity (AA) of macrophages in the course of and after resection of transplantable mammary adenocarcinoma MMTI as well as cloned tumor MMTv4 were studied in C3Hf mice. Murine macrophages showed AA in adoptive test in the course of MMTv4 growth and specific cytotoxic activity in tests in vitro. Macrophages from bearers of MMTv4 revealed non-specific cytotoxicity only. After tumor resection, a sharp increase in SML and metastasizing into lymph nodes was matched by a lack of AA and cytotoxic activity on the part of macrophages in mice operated on. In tumor cell recipients, they were found to stimulate metastasis formation. Only 60% of operated mice survived and macrophages obtained from them did not reveal any metastasis-stimulating activity. This activity was further curbed due to injections of indomethacin--an inhibitor of prostaglandin E2 synthesis--or as a result of indomethacin pretreatment of macrophages in vitro. The above data implicate suppressor activity in the explosion of metastatic formation observed after tumor resection. The role of macrophage suppressors and that of of prostaglandin E2 in postsurgical stimulation of metastasis spreading are discussed.

Adenocarcinoma↗
PubMed1979

[Effect of corazole in intensifying changes in the electrical activity of the brain in a constant magnetic field].

Corazol effects on the background and evoked biopotentials of the cerebral cortex, hypothalamus, and the cerebellar cortex were studied in rats exposed to a constant magnetic field (500, 1000, 4000 Oe). After the corazol pretreatement with subconvulsive doses there were sharp changes in the background rhythms; evoked potentials of the amplitude rose markedly, and there was also an increase of additional phases in its structure. Intensification of the constant magnetic field effect against the background of analeptic corazol action pointed to the importance of the central nervous system activation level in the response to the magnetic field action.

Animals↗
PubMed1976

[Change in the evoked potentials of the brain exposed to a constant magnetic field].

The influence of the constant magnetic field (CMF) upon the cerebral and cerebellar cortex potentials evoked by the sciatic stimulation was studied in rats. During the exposure to the CMF there occurred an increase of the evoked potentials in amplitude and the appearance of additional waves in their structure. The effect was enhanced with increase in the intensity of magnetic field within the range of 500-4000 oe.

Animals↗
PubMedDate not supplied

[Autonomic reactions in rabbits exposed to a constant magnetic field].

Chronic experiments on rabbits have shown that their exposure to a constant magnetic field of 4500 oersted for 3 hours causes a transient hypotension, a decrease in the respiratory rate and a trend for bradycardia. Immediately after the exposure the pressor reaction and bradycardia level decrease and by the end of the first day they increase. At this time the respiratory rate increases in response to the administration of epinephrine, acethylcholine or stimulation of the midbrain reticular formation. The exposure does not decrease the compensatory possibilities of the cardiovascular and respiratory systems. This follows from their reactions to accelerations of 6 and 10 g.

Acceleration↗
PubMedDate not supplied

[The character of changes in the background and superimposed rhythmics of cerebral biopotentials in rabbits exposed to a steady magnetic field of high intensity].

During a total action of a static magnetic field (SMF) of 1000--4000 Oe, high-amplitude synchronized discharges appear in the electrograms of the cortical and subcortical parts of the rabbit brain. An automatic frequency analysis exhibits increased bioelectrical activity in the range of 8 to 30 c/s with no substantial changes in slower rhythms. The effect increases as the field becomes stronger. A SMF of 1000 Oe tends to facilitate the photic driving which persists as an after-effect. In SMF of 3000 Oe the driving reaction is weakened; it is rapidly restored after cessation of the SMF action.

Animals↗
PubMedDate not supplied

[Electrical resistance of the brain tissue of rats exposed to a permanent magnetic field].

The cortical impedance of the large hemispheres of nembutal-anesthetized rats exposed to a constant magnetic field of 0.1, 0.4 and 1.6 T was investigated. During 20 min. exposure the impedance decreased (at the expense of a decrease in both of its components--capacity and active resistance). The impedance decrease was more pronounced (up to 93%) and statistically significant in a field of 1.6 T. After exposure the impedance decrease persisted for 10 min.

Animals↗
PubMedDate not supplied

[Cerebral evoked potential recovery cycles following exposure to a constant magnetic field in rats].

The recovery cycles of somatosensory evoked potentials (EP) in the cerebral cortex, hypothalamus and cerebellar cortex were studied in experiments on rats. During the action of constant magnetic field (CMF) with an intensity, subthreshold for the changes in biopotentials, as well as after intensive magnetic influence, the recovery of the response to test stimulation of the nerve was more rapid and more complete, the duration of areactivity and subnormality periods was reduced and phenomenon of facilitation was observed. The obtained data testify to a rise in the level of excitability of the studied brain structures under the effect of CMF. Paired stimulation of sciatic nerve with definite interstimuli intervals may also lead to the intensification or provocation of the "magnetic effect"--the appearance in the EP structure of additional phases under the effect of the subthreshold field.

Animals↗