Review of water bugs of the genus Micronecta Kirk. (Heteroptera,Corixidae) of the fauna of the Northwestern Caucasus

A review of the species of the genus Micronecta from the Northwestern Caucasus with a key is provided. The regional distribution of Micronecta griseola Horváth, M. poweri (Douglas et Scott), and M. pusilla (Horváth) is clarified. Micronecta anatolica anatolica Lindberg is recorded from Russia for the first time.     

Investigation of the functional characteristics of reticulo-spinal fibers of the ventral funiculus

Functional characteristics of single reticulo-spinal fibers of the ventral funiculi were studied at the level of the 10th thoracic segment of the spinal cord in anesthetized (with chloralose and pentobarbital) and decerebrate cats after removal of the cerebellum. The reticulospinal tract of the ventral funiculus consists of a broad spectrum of rhythmically active and "silent" fibers, divided into three groups: fibers with a high (65–110 m/sec), medium (45–60 m/sec), and low (20–40 m/sec) conduction velocity. Spontaneous rhythmic activity is more characteristic of the fibers of the last two groups. The quantitative ratio between rhythmically active and silent fibers was about twice as high in the decerebrate as in the anesthetized animals. Depending on the character of distribution of interspike intervals the spontaneous activity of the reticulo-spinal fibers of the animals of both groups could be classified in three types: I) with a uniform distribution of interval; II) with a tendency toward grouping of spikes into volleys; III) with marked grouping of the intervals. Fibers with low and medium conduction velocities more often had spontaneous activity of types I and II, while fibers with a high conduction velocity more often had activity of types II and III. The possible functional significance of the reticulo-spinal fibers of the ventral funiculi with different conduction velocities and types of spontaneous activity is discussed.     

Reticulospinal and vestibulospinal synaptic effects on the lumbar motor neurons of the monkey

It was established in experiments on rhesus monkeys by intracellular recording and computer averaging that fast-conducting reticulo- and vestibulospinal fibers form monosynaptic excitatory links with lumbar alpha-motor neurons. The monosynaptic bulbospinal effects are retained after sectioning of the pyramids or after chronic destruction of the motor cortex. The mean amplitude of the reticulomotor neuronal EPSP is less than that of the corticomotor neuronal EPSP, however, the mean amplitudes of the EPSP of individual motor neurons can reach similar values. In contrast to the corticomotor neuronal projections, the bulbomotor neuronal projections are directed primarily toward the motor neurons of the proximal muscles. In addition to monosynaptic EPSP, reticulo- and vestibulospinal impulses evoke disynaptic EPSP and IPSP in the lumbar motor neurons of monkeys which are very similar to the disynaptic effects found in subprimates.I. M. Sechenov Institute of Evolutionary Physiology and Biochemistry, Academy of Sciences of the USSR, Leningrad. Translated from Neirofiziologiya, Vol. 3, No. 4, pp. 408–417, July–August, 1971.     

Pyramidal and extrapyramidal synaptic effects upon chronically deafferented motoneurons of the spinal cord of a cat

By means of intracellular recording technique, studies have been made of the electrical activity of -motoneurons of the seventh lumbar segment in cats with chronic rhizotomy of the dorsal root fibers (L₄-S₂). Postsynaptic potentials of the reticular formation of the midbrain, medulla, and ventral columns of the spinal cord were compared with the reactions recorded from nonoperated animals; these potentials were evoked by stimulation of the motor cortex, red nucleus, and Deuters' nuclei. Deafferentiation did not cause statistically reliable variations in the amplitude of the descending monosynaptic E PSPs. Extrapyramidal short-latent disynaptic E PSPs and IPSPs remained also practically unchanged, while the responses of deafferented motoneurons to cortico-spinal impulses were considerably facilitated; this effect was retained in pyramidal cats. Deafferentation was not accompanied by variations in the dependence of the discharge frequency on the depolarizing current strength or by the variation in the threshold and input resistance of the motoneuron membranes. This suggests that intensification of the pyramidal synaptic action upon deafferented motoneurons was caused by the variation on the intermediate neuronal level.I. M. Sechenov Institute of Evolutionary Physiology and Biochemistry, Academy of Sciences of the USSR, Leningrad. Translated from Neirofiziologiya, Vol. 1, No. 1, pp. 35–46, July–August, 1969.     

Targeting radioresistant osteosarcoma cells with parthenolide

Osteosarcoma is a devastating tumor of bone, primarily affecting adolescents. Osteosarcoma tumors are notoriously radioresistant. Radioresistant cancers, including osteosarcoma, typically exhibit a considerable potential for relapse and development of metastases following treatment. Relapse and metastatic potential can, in part, be due to a specific radioresistant subpopulation of cells with stem-like characteristics, cancer stem cells, which maintain the capacity to regenerate entire tumors. In the current study, we have investigated whether in vitro treatments with parthenolide, a naturally occurring small molecule that interferes with NF-κB signaling and has various other effects, will re-sensitize cancer stem cells and the entire cell population to radiotherapy in osteosarcoma. Our results indicate that parthenolide and ionizing radiation synergistically induce cell death in LM7 osteosarcoma cells. Importantly, the combination treatment results in a significant reduction in the viability of both the overall population of osteosarcoma cells and the cancer stem cell subpopulation. This effect is dependent on the ability of parthenolide to induce oxidative stress. Therefore, as a supplement to current multimodal therapy, parthenolide may sensitize osteosarcoma tumors to radiation and greatly reduce the prevalence of relapse and metastatic progression.     

Investigation of synaptic connections between primary afferents and motoneurons in the frog spinal cord by intracellular injection of horseradish peroxidase

Parallel recordings of potentials from primary afferent fibers and motoneurons connected monosynaptically with them were obtained in experiments on the isolated, perfused frog spinal cord and this was followed by intra-axonal and intracellular injection of horseradish peroxidase. Terminals of the primary afferent fibers were shown to reach the motor nuclei of the ventral horn, and one fiber could form contacts with several motoneurons. Synapses formed by afferent terminals were found not only on distal, but also on proximal segments of dendrites and also on motoneuron bodies. Synapses were most numerous on the proximal segments of the dendrites and branches of the second-third orders. Recurrent axon collaterals of motoneurons forming synapses with dendrites were found.I. M. Sechenov Institute of Evolutionary Physiology and Biochemistry, Academy of Sciences of the USSR, Leningrad. Translated from Neirofiziologiya, Vol. 14, No. 1, pp. 60–68, January–February, 1982.     

Random fluctuations in readings of measurement devices: cosmophysic effects?

Fluctuations of "computer time" provided by the PC quartz generator were studied. It was shown that variations in the yearly course of the quartz generator frequency occur with periodicities of 13-15 days and 28-30 days. Regular fluctuations with periods of 0.5 and 1.0 min are typical of the short-term spectral component. Impulses of sharp and intense deceleration of "computer time" are often observed against the background of these regular fluctuations. The conclusion is made that fluctuations of "computer time" are of cosmophysical origin.