Functional Characteristics Of Cells Research Articles

Effects of nitrous oxide on the functional characteristics of cells in the extrastriate cortex of the cat.

The directional preferences, receptive field areas, peristimulus-time (PST) histograms and spontaneous activities of 112 feline visual cortical (area 18) cells were studied before, during, and after the administration of nitrous oxide. These cellular characteristics were altered by nitrous oxide inhalation; some quite substantially. The data indicate that the functional characteristics of cortical visual cells, such as the receptive field and the directional preference, are variable; and, among other factors, depend also on the anaesthetic administered to the animal.

Long-term modifications of unit activity in area 7 of the cat neocortex after unilateral division of the optic radiation

Changes in functional characteristics of cells in area 7 of the cat parietal cortex at different times after unilateral division of the optic radiation were studied in semichronic experiments. Neuronal responses were studied in the affected and intact hemispheres to adequate stimuli of different modalities and to direct electrical stimulation of the primary neocortical projection zones. In area 7 on the side of the operation neuronal sensitivity to stimuli of different sensory modalities were restored. In area 7 of the intact hemisphere the number of cells with local receptive fields gradually increased after the operation and the average size of the receptive fields also increased. It is concluded that mechanisms of plasticity of the partietal association cortex are based on the ability of cells of this zone to receive impulses, via the system of intracortical association fibers, from other sensory or nonspecific brain systems, and also their ability to reorganize their firing pattern depending on changing internal and external environmental conditions.

Some morphological and functional characteristics of cells of the porcine theca interna in tissue culture.

Theca interna cells were collected from large porcine follicles in the follicular phase of the cycle. The theca interna layer was manually separated from the theca externa, washed thoroughly, occasionally treated with hyaluronidase solution and trypsinized. The resulting cell suspension consisted of approximately 70% theca interna cells, 8% granulosa cells, and 23% nonsteroidogenic cells. In one experiment, cells collected from the granulosa layer and the theca interna of the same follicles were compared. Specific cell types were identified by: 1) staining with Oil Red 0 (ORO) to visualize lipid droplets in the cytoplasm, 2) measuring activity of the Δ 36-hydroxysteroid dehydrogenase (Δ 36-OH SH) enzyme, and 3) quantitating estrogen production by the cultured cells.

Some morphological and functional characteristics of cells of the porcine theca interna in tissue culture.

Theca interna cells were collected from large porcine follicles in the follicular phase of the cycle. The theca interna layer was manually separated from the theca externa, washed thoroughly, occasionally treated with hyaluronidase solution and trypsinized. The resulting cell suspension consisted of approximately 70% theca interna cells, 8% granulosa cells, and 23% nonsteroidogenic cells. In one experiment, cells collected from the granulosa layer and the theca interna of the same follicles were compared. Specific cell types were identified by: 1) staining with Oil Red 0 (ORO) to visualize lipid droplets in the cytoplasm, 2) measuring activity of the Δ 36-hydroxysteroid dehydrogenase (Δ 36-OH SH) enzyme, and 3) quantitating estrogen production by the cultured cells.

Studies on normal human bone marrow cultures in controlled environment thin-film culture systems.

Two thin film culture systems, the controlled environment steady state system (SS) and the rocker tube configuration of that system (RT), were used to identify some of the conditions that appear to maintain morphologic and functional characteristics of cells of human bone marrow explants in vitro. The systems configuration assured continual gassing, control and easy monitoring of the cultures. Cytocentrifuge preparations of media of specimens cultured in RT disclosed, though in decreasing numbers, various hematopoietic cells for periods exceeding one month. Hematopoietic cells shed from specimens cultured in the SS system were retained in the culture tubes; cells of the myelocytic series predominated for the first two weeks while an increasing number of monocytes and macrophages appeared in the media of of older cultures. Histologic examination of cultured explants disclosed preservation of the marrow architecture and the persistence of hematopoietic cells. Specimens cultured in RT tubes tended to be less cellular than similar cultures placed in dialysis bags or as cultured in the SS system. Immunoglobulins (Ig) were released into the culture media at a constant rate throughout the period of culture. Specimens that were cultured at a controlled pH of 7.4 released 2 to more than 4 times as much Ig as similar specimens maintained at a pH level of 7.1. There were no definitive differences in Ig levels in the cultures maintained at comparable pH levels and overlaid with various CO2 concentrations, i.e. 2%, 5%, 10% similarly, no differences in Ig levels were found in specimens cultured in media containing fetal bovine sera as opposed to horse sera.

Defense Mechanisms in Infectious and Related Diseases

Both non-specific and specific mechanisms play a part in the defense against infectious disease. The former are concerned with the varying structural and functional characteristics of cells and tissues and the latter with the formation of specific antibodies and the altered reactivity of tissues. Because of limitations of space, emphasis in this review will be on general mechanisms, and prob­ · lems of specific diseases will be considered only as they are related to those of infectious disease as a whole. It is obvious, also, that many important contributions cannot be discussed in detail; only those will be cited which appertain to functional aspects of im­ munology. It would be impossible, otherwise, to survey even slightly the large number of papers published in the year 1938 alone.