Central nervous system cellular organization

O The acute leukemias are diseases of bone marrow resulting from aberrant proliferation of hematopoietic precursors. The hallmark of these malignancies is the leukemic blast cell, a visibly immature and abnormal cell in the peripheral blood that often replaces the bone marrow and interferes with normal hematopoiesis. These blast cells proliferate in the marrow and inhibit normal cellular elements, resulting in anemia, neutropenia, and thrombocytopenia. Leukemia also may infiltrate other organs, including the liver, spleen, bone, skin, lymph nodes, and central nervous system (CNS). Virtually anywhere there is blood flow, the potential for extramedullary (outside the bone marrow) leukemia exists. 

NO has complex roles in immunological host responses against viruses, and especially against HIV-1 infection. In HIV-1 infection, NO cannot be rigidly classified as an anti-inflammatory or proinflammatory molecule, but it can be deemed a true inflammatory mediator. Many studies support a proviral effect of NO in HIV-1 infection, mainly based on stimulation of viral replication, and on toxic effects on various cells, including central nervous system cells, via oxidative injury that may cause cellular and organ dysfunction, and immunosuppression and immunopathology, especially in the central nervous system. 

Anatomically, the chemosensory cells of these animals share a unifying set of characteristics they are bipolar neurons with ciliated dendrites closely apposed to the environment and axons that project into the central nervous system from a peripherally located cell body. This is a cellular bodyplan that is characteristic of chemosensory cells from a broad range of metazoan phyla, so much that has been learned by the study of crustacean chemosensory neurophysiology has been of heuristic value to the understanding of chemoreception in other organisms. 

Although inhalant abuse is now recognized as a worldwide problem, organic solvents are currently the least studied drugs of abuse. For example, relatively little is known about the underlying cellular mechanisms of action through which these substances produce their effects in the central nervous system."... 

Cannabinoids are able to cause different effects at the level of various systems and/or organs the most important effects occur on the central nervous system and on the cardiovascular system. In fact, they are able to affect mood, memory, motor coordination and cognition, and they increase heart rate and variate the systemic arterial pressure. Furthermore, it is well known the capability of cannabinoids to reduce intraocular pressure and to affect the respiratory and endocrine systems (L. E. Hollister, Health Aspects of Cannabis, Pharmacological Reviews, 38,1-20,1986). More recently, it was found that they suppress the cellular and humoral immune response and have antiinflammatory properties (A. W. Wirth et al.. Antiinflammatory Properties of Cannabichromene, Life Science, 26,1991-1995,1980). 

The mechanism by which 1,1,1-trichloroethane and other organic solvents depress the central nervous system is poorly understood, but is thought to involve interactions of the parent compound with lipids and/or proteinaceous components of neural membranes (Evans and Balster 1991). No known methods specifically counteract the central nervous system effects of 1,1,1-trichloroethane. Because the specific cellular or biochemical nature of central nervous system depression is poorly understood, it is difficult to propose any method to interfere with this effect of 1,1,1 -trichloroethane, other than to prevent further exposure to the compound so that it can be cleared from the body. 

Electric fields can modulate neuronal activity in the central nervous system. They influence a variety of cellular events, such as membrane differentiation, neurite growth during both development and structural regeneration, organization of local neuronal circuits, and even receptor localization (Faber and Korn, 1989). When synaptic activity is blocked in hippocampal slices by removing extracellular Ca, recurrent spontaneous paroxysms, termed seizure-like events, occur in the CAl region. CAl neurons discharge in synchrony and result in massive neuronal excitation (Konnerth et al., 1986). 

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