Studies of the Mechanism of Development of “Deprivation” Potentiation of Population Responses of Neurons in Field CA1 of Living Hippocampal Slices

Experiments on rat hippocampal slices were performed with testing of the synaptic connections of Schaffer collaterals and neurons in field CA1 to study the effects of interrupting low-frequency test stimulation (0.05 Hz) on the amplitude of population spikes. These studies demonstrated a correlation between the duration of pauses in stimulation (form 10 to 120 min) and increases in the amplitude of spikes (on average by 30–100% of baseline response magnitude). This deprivation potentiation was additive and could persist for long periods of time (testing was up to 1 h). Preliminary induction of long-term post-tetanic potentiation, which prevented the subsequent development of the late, but not the short-term phase, for 1–3 h, led to suppression of the development of deprivation potentiation after a 60-min pause in stimulation. Similar results were obtained in experiments using 20 M polymyxin B, which blocks protein kinase C and the PKC-dependent phase of long-term post-tetanic potentiation; this is evidence supporting the previously advanced hypothesis that the development of deprivation potentiation and the late, PKC-dependent phase of long-term post-tetanic potentiation share common mechanisms, associated with people phosphorylation.     

Mechanisms of recognition of the outlines of “vanishing” optotypes

The aim of the present work was to study the interaction between the optical properties of images of “ disappearing” optotypes and their recognition thresholds. The “disappearing” optotypes were figures with complex outlines and had a unique property-they were close to the threshold of recognition and observation, which increases the accuracy of measurement of visual acuity and the subjects’ attention to them. The recognition distances of “disappearing” optotypes were measured. A relationship was found between the recognition distance of “disappearing” optotypes and different optical density profiles on the one hand and the spatial and spatial frequency characteristics of the stimuli on the other. The decisive factor determining the threshold of recognition of optotypes in spatial frequency terms is its spatial frequency spectrum; that in spatial terms is the width of the black/white pair or black-white triad in the complex outline. Regardless of the shape of the optotype, one of the most important limiting factors was the concordance of this test with the scattering function of the subject’s eye optics. __________ Translated from Rossiiskii Fiziologicheskii Zhurnal imeni I. M. Sechenova, Vol. 91, No. 9, pp. 1080–1090, September, 2005.     

Effect of Cell–Cell Interactions on the Observable Strength of Adhesion of Sheets of Cells

Previous research in cellular adhesion has focused primarily on studying isolated cells under conditions where cells do not interact with each other. However, in vivo cells form sheets where both cell–substratum and cell–cell interactions contribute to the overall adhesive behavior. Our understanding of how cell–cell and cell–substratum interactions affect the overall process of cell adhesion in these situations is limited. To address this problem, we developed a systematic approach to evaluate how cell–cell and cell–substratum interactions affect the critical shear stress for detachment for semiconfluent and confluent sheets of cells. Our studies were based on subjecting cultures of adherent cells to a defined hydrodynamic flow in a radial-flow chamber with a gap height of 140 m. Using phase-contrast microscope imaging and analysis we measured shear-dependent patterns of detachment as a function of the extent of cell confluency. Our results show that the critical shear stress for detachment is maximum at intermediate extents of confluency of 10%–40%. These results have important implications for sodding vascular grafts and tissue engineering. © 1999 Biomedical Engineering Society. PAC99: 8718-h, 8719Rr     

Numerical Simulation of thePorous Structure of Biomaterials

Porous biomaterials are widely used as bone replacement materials because of thers high biocompatibility and osteoconductivity property. Understanding of their porous structure (i. e. geometrical and topological characteristic) and studying how to the body fluid flow through them are essential to investigate thed egradation behaviour at the surface-liquid interface. This research develops a numerical model to simulate the porous structure of biomaterials based on the stochastic approach in pore size distribution and interconnectivity.     

The Quantitative Stereologic Analysis of the Ultrastructure of Scirrhous Carcinoma of Breast

1.IntroductionInordertofindQutthebestwaytodiagnoseandtreatthecarcinomaofbreaSt,thestudyforpathology,andmorphometryorstereologyareverynecessary.ButthequantitativeanalysisoftheultrastructllreortheStere0l0gyaboutbreaStcarcinomahasnotyotbeenseenandnottobereported('x'x').Sowemeasured28morphologicalparametersofmit0chondrion,lysosome,roughendoplasmicreticulumandribosomeintencasesofscirrhouscarcinomaofbreastbystereologicmethods.Wehopedthatthisworkwouldpr0vides0mequantitativedaaforpathologyandearlydi…     

A case of prevailing deficit of nonliving categories or a case of prevailing sparing of living categories?

We describe a new case of semantic deficit in which nonliving categories are disproportionately impaired. PL, a woman affected by progressive degeneration of the left temporal lobe, was examined twice, at a distance of 1 year. The deficit was first apparent on naming and on a verbal semantic questionnaire, but a year later nonliving categories were disproportionately affected also on verbal comprehension (word/picture matching task). Body parts and musical instruments were also investigated: the former was the best preserved category, whereas the latter was the most severely affected. Considering all categories, functional and perceptual information was not differently affected, but there was a trend toward a worse score for nonliving category functional questions. Discussing the current hypotheses on the genesis of category dissociations, we conclude that nonliving categories might not be a true domain, and that their impairment could simply derive from the relative sparing of the domains of the living categories, for which separate cognitive and anatomical representations can be better postulated. Finally, we discuss the problems raised by published cases in an attempt to find a consistent anatomical substrate for category dissociations.     

Effects of Terahertz Radiation at Atmospheric Oxygen Frequency of 129?GHz on Blood Nitrite Concentrations under Conditions of Different Types of Stress against the Background of Administration of Nonselective Inhibitor of Constitutive NO-Synthases

We studied the effect of terahertz radiation at atmospheric oxygen frequency 129 GHz on blood nitrite concentration in different types of experimental stress against the background of administration of nonselective inhibitor of constitutive NO-synthases. Normalizing effects of radiation on blood nitrite dynamics in animals with acute stress was shown after 15-min exposure and in animals with chronic stress after 30-min exposure. No positive effect of terahertz radiation was observed on altered blood nitrite concentration in male rats after preliminary administration of nonselective constitutive NO-synthase isoform inhibitor L-NAME.     

Investigation of the “valency” of antibodies by means of azoproteins

Summary The valency of antibodies was studied by the method of exhaustion of antisera against mono-and diazoproteins, and subsequent cross reactions both with the antibodies left over in the supernatant fluid of the serum and with the precipitating and nonprecipitating antibodies isolated from the precipitate.It was proved that the antibodies interact with the antigens as multivalent compounds.The valency determined with regard to the azoproteins is dependent upon the number of groups introduced.Thus, bivalent antibodies correspond to monoazoproteins and trivalent ones to diazoproteins.The valency of antibodies is, evidently, determined by the structural similarity of the heterologous and the immunizing antigens as well as by the less complete specific conformity between the individual structural peculiarities of the antigen and its antibody.From the Tashkent Pharmaceutical Institute (Director-Docent M. A. Azizov)Presented by Active Member AMN SSSR N. N. Zhukov-Verezhnikov     

Biological Activity of Some Derivatives of β-Cyclodextrin

New compounds of β-cyclodextrin containing covalently bound (conjugated) residues of acetylsalicylic and 1-(4-isobutylphenyl)-propionic acids were synthesized in the reaction of chlorides of the corresponding acids with β-cyclodextrin. We studied antiplatelet and antiphlogistic properties of these substances. It was shown that new compounds are comparable and in some cases are superior to the reference drugs acetylsalicylic acid and ibuprofen by anti-inflammatory and antiaggregant activities.     

Universalization of health or of social security?

This article presents an analysis of the architecture of Mexico's health system based on the main economic problem, failing to achieve a GDP growth rate to increase real wages and give workers in formal employment coverage social security. This analysis describes the relationship between social security of the population and employment status of it (either formal or informal employment) and the impact that this situation poses to our health system. Also, it ends with a reform proposal that will give all workers the same social rights, ie to grant universal social security.     

Mechanisms of IFNγ regulation of autoimmune myocarditis

A protective effect of interferon-gamma (IFNγ) has been described in a number of models of autoimmune disease, including experimental autoimmune myocarditis (EAM). Some reports have suggested that regulation of apoptosis in autoreactive lymphocytes mediate these protective functions. We examined the potential of IFNγ to regulate apoptotic mechanisms in detail, both in vitro and in vivo in EAM. We observed multiple apoptotic defects in caspase activity, and the expression of TNF superfamily members on CD4⁺ T cells. In addition, we observed selective defects in CD4⁺ T cell activation in response to antigenic stimulation. These activation and apoptotic defects were CD4⁺ cell autonomous, independent of the genotype of APCs. Inhibition of nitric oxide production in vivo did not reproduce the severe form of EAM of IFNγ-deficient mice, indicating that this pathway does not mediate the protective effect of IFNγ. Crosswise adoptive transfer of wild type, IFNγ^−/−, and IFNγR^−/−EAM demonstrated that IFNγ signaling was critical in CD4⁺ cells, but that non-CD4⁺ sources of IFNγ production were also involved in the control of disease. Together, these data indicate multiple mechanisms of autonomous and non-autonomous CD4⁺ T cell regulation mediated by IFNγ in the control of autoimmune heart disease.     

Descartes' Passions of the soul--seeds of psychiatry?

Rene Descartes (1596-1650), often called the 'father of modern philosophy', aimed at rooting all knowledge in certainty so that our understanding of the world could progress without error. To achieve this, he needed at least one sure thing on which to build. Starting with the most basic knowledge, the fact of his own existence--cogito ergo sum (I think therefore I am), he systematically proceeded to explain the world. Such systematic understanding would be accessible to anyone who applied the Cartesian method, and in turn would lead to a good life. Descartes' Passions of the Soul was written according to his method of certainty and fits in with a meticulously refined worldview. It is one of the first systematic treatises to explain a wide array of emotions, both normal and abnormal. Based on the Cartesian dualistic model of mind and body, the work helps ground a long medical tradition of separating 'rational' consciousness from emotions. For Descartes, emotions arose from two sources, the intellect and the body (Passions of the Soul and Passions of the Body). The more subtle 'Passions of the Soul' were viewed as superior to coarser and often-troublesome emotions taking root in the body. It is interesting to note the absence of clarity, however, in Descartes' division of intellectual emotions from bodily emotions, perhaps revealing an enduring weakness in the dualistic model itself. The work grapples with the multi-causal nature of psychopathology and brings out complex interactions between temperament and life experience. While modern neuroscience makes ever-tighter associations between physiology and experience, many of the basic scientific challenges we face today are outlined in this 350-year-old book.     

Reflex regulation of the “spontaneous” activity of the chemoreceptors of the tongue

Summary The spontaneous activity of the chemoreceptors of the frog's tongue was studied during stimulation of the interoceptors of the stomach and of the sympathetic chain. It was found to be under the control of the nervous system, adapting the receptors to give improved perception, and it indicates the preparedness of these apparatuses to receive stimuli. Spontaneous activity may be fundamentally a partial principle of the functioning of receptor elements. Further electrophysiological investigations of this problem are proceeding.(Presented by Active Member AMN SSSR P. K. Anokhin) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 55, No. 8, pp. 7–11, August, 1963     

Mechanisms of toxic effect of streptozotocin on β-cells in the islets of langerhans

Administration of streptozotocin caused selective damage to endocrine β-cells in rat pancreatic islets, which was related to activation of apoptosis. The cytotoxic effect of streptozotocin was associated not only with DMA damage due to dysfunction of the antioxidant defense system, but also with activation of the caspase cascade and TNF-related apoptosis-inducing ligand.