Significance of glycosidases and phosphatases in Cercopithecus and Macaca cells

When selected ratios of different glycosidases and phosphatases from primary monkey kidney cells or from monkey kidney cell lines are presented graphically, characteristic patterns do evolve. Three different subtypes of Vero cells show similar glycosidase patterns. The Vero subtypes tested show glycosidase patterns that are closely similar to those of primary cells of Cercopithecus aethiops. Glycosidase patterns of BS-C-1 and CV-1 cells are less similar to those of primary Cercopithecus cells than are those of Vero cells. Primary kidney cells from Macaca cynomolgus show significantly different glycosidase patterns compared with those of different Cercopithecus cells. The distinct glycosidase patterns can be used to classify the tested cell lines in relation to each other.     

Fine structure and functions of haemerythrocytes and leucocytes of Sipunculus nudus

The marine sipunculan worm, Sipunculus nudus Linné, possesses a voluminous coelomic cavity filled with a fluid containing different types of free cells. Most of them (more than 90%) are nucleated haemerythrocytes. They arise from free, small haemerythroblastic cells which are described in this report. Different kinds of leucocytes are also found in the coelomic fluid, particularly granulocytes which are phagocytic cells showing some similarities with vertebrate macrophages. These cells seem to arise from small hyalocytes, which are cells having morphological and physiological resemblances with vertebrate lymphocytes. It appears that the older granulocytes are progressively degranulated and give rise to large hyalocytes. Ciliary cells arising from small cells, very similar to small hyalocytes, have also been observed and it is supposed that they give rise to urn cells. Lastly, some of the biological functions of the free coelomic cells of the sipunculan worms are described.     

Differentiation mechanism and function of the cereal aleurone cells and hormone effects on them

The cereal aleurone cells differentiate from the endosperm epidermis with the exception of endosperm transfer cells. Aleurone cells contain proteins, lipids, and minerals, and are important for digesting the endosperm storage products to nurse the embryo under effects of several hormones during the seed germination. The differentiation of aleurone cells is related to location effect and special gene expression. Moreover, the differentiation of aleurone cells is probably affected by the cues from maternal tissues. In the paper, differentiation mechanism and function of aleurone cells and hormone effects on them are reviewed. Some speculations about the differentiation mechanism of aleurone cells are given here.     

Replicative activity of isolated chromatin from proliferating and quiescent early passage and aging cultured mouse cells

Replicative activity of isolated chromatin from late passage cultured mouse cells has been compared to the activities of chromatin preparaions from dividing and quiescent early passage cells. Rates of endogenous DNA synthesis are similar for chromatin from growing or resting cells but this activity is stimulated 2.5-fold in senescent cell chromatin. Chromatin from growing young cells copies exogenously added single stranded DNA at the highest efficiency. Chromatin of senescent cells copies this template at a lower rate and resting young cell chromatin replicates single stranded DNA at the lowest efficiency. Similar relative rates are obtained when activated DNA is copied by the various chromatin preparations. Total activity of DNA polymerase extracted by salt from chromatin is similar for dividing and quiescent young cells but the proportion of DNA polymerase beta is higher in the latter. Elevated activities of DNA polymerases are extracted from chromatin of old cells. It is concluded, therefore, that chromatin-directed replication is differently arrested in non-dividing senescent cells and in quiescent early passage cells. The possible regulatory mechanisms of DNA replication in quiescence and aging are discussed.     

Ontogeny of the vascular bundles and contiguous tissues in the maize leaf blade

The patterns of initiation and early development of the minor and major veins in the flat portion of the leaf blade of maize (Zea mays L.) follow similar patterns. The veins and their associated bundle sheath cells commonly arise from cell assemblages derived from a single cell lineage, or longitudinal file of cells, rather than from two “half vein units” derived from different cell lineages. In addition, apparently, none of the vascular cells derived from the procambium is directly related ontogenetically to a bundle sheath cell. In veins derived from larger cell assemblages, the lateral bundle sheath cells are more closely related ontogenetically to the mesophyll cells, which are derived from the ground meristem, than to the vascular cells, which are derived from procambium. The bundle sheath cells, accordingly, are interpreted as being ground meristem in origin.     

Isolation and Characterization of Tubules and Plasma Membranes from Cytophaga columnaris

Tubular structures are released from cells of Cytophaga columnaris after lysis of the cells. To determine the nature of these tubules, they were purified and their composition was determined. Tubules were isolated after treating cell lysates with 1.0% sodium dodecyl sulfate at pH 8.1, which solubilizes all structural components except tubules. Plasma membranes from the same organism were isolated by discontinuous sucrose gradient centrifugation of lysed cells. Both tubules and membranes are composed of lipids and proteins. Lipids extracted from tubules and plasma membranes produced similar patterns when examined by thin-layer chromatography. Proteins solubilized from membranes were separated into 14 bands by polyacrylamide gel electrophoresis, whereas those solubilized from tubules separated into only 5 bands. The presence of lipids in tubules from C. columnaris supports the idea that they are derived from membranes of intact cells. In this respect they are similar to tubules produced by cells of Clostridium botulinum and different from other tubular structures ("rhapidosomes") found in cells of Saprospira grandis.     

Vertical motion detectors and their synaptic relations in the third optic lobe of the fly

The synaptic relations of the giant vertical cells in the lobula plate of the fly were investigated using electron microscopical procedures and Lucifer yellow dye backfill and injection techniques. Histological features of the giant vertical cells are described. The giant vertical cells are exclusively postsynaptic in the lobula plate. They function to integrate input from dense arrays of chemical synapses and have a wide spatial input from the lobula plate. The giant vertical cells are postsynaptic to perpendicularly occurring cells. There are two classes of cells presynaptic to the vertical cells, one of which contains large dense-core vesicles. The giant vertical cells are not the only cells postsynaptic to these two classes of perpendicualr cells. A second group of smaller tangential cells, the twin vertical cells, were also found postsynaptic to many of the same cells that synapsed with the giant vertical cells. The twin vertical cells and the giant vertical cells are therefore integrating some of the same information in the lobula plate.     

The function and origin of follicular dendritic cells

Follicular dendritic cells (dendritic reticular cells) in germinal centres bind antigen-antibody complexes via C3 receptors and retain the complexes at their surface for long periods of time. The follicular dendritic cells (FDC) are distinct from macrophages and from dendritic cells found in T-dependent areas, and are not derived from bone marrow stem cells. On histological evidence it has been proposed that they are derived from reticulum cells. Complexes are probably transported to FDC by a subpopulation of B cells in the marginal zone. Binding of complexes to FDC causes germinal centre enlargement and is a very efficient, and possibly essential stimulus to the generation of B memory cells which recognize epitopes on antigen or antibody in the complexes. An hypothesis is discussed which draws together these observations and suggests that antigen on FDC plays a central role in control of humoral immunity.     

Phenotypic and functional differences between NKT cells colonizing splanchnic and peripheral lymph nodes

NKT cells are considered unconventional T cells. First, they are restricted by a nonclassical MHC class I molecule, CD1d, which presents glycolipids; second, their TCR repertoire is very limited. After stimulation by their TCR, NKT cells rapidly release large amounts of cytokines, such as IL-4 and IFN-gamma. Little is known about NKT cells present in lymph nodes. In the present report we show that NKT cells are differently distributed in various lymph nodes and are, for instance, abundant in pancreatic and mesenteric lymph nodes of C57BL/6 mice and nonobese diabetic mice. The high frequency of NKT cells in splanchnic lymph nodes is not simply a consequence of inflammatory signals, as draining lymph nodes still contain low frequencies of NKT cells after IFA or CFA injections. NKT cells from splanchnic lymph nodes harbor a Vbeta repertoire similar to that of splenic and liver NKT cells, in contrast to peripheral NKT cells that are not biased toward Vbeta8 segments. Analysis of cytokine production by NKT cells from splanchnic lymph nodes reveals that they produce at least as much IL-4 as IFN-gamma, in contrast to NKT cells from other organs (spleen, liver, and peripheral lymph nodes), which produce much more IFN-gamma than IL-4. These specific features of NKT cells from splanchnic lymph nodes might explain their protective action against the development of pathogenic Th1 cells in type 1 diabetes.     

Differentiation of monocytes into multinucleated giant bone-resorbing cells: two-step differentiation induced by nurse-like cells and cytokines

Bone resorption in the joints is the characteristic finding in patients with rheumatoid arthritis (RA). Osteoclast-like cells are present in the synovial tissues and invade the bone of patients with RA. The characteristics of these cells are not completely known. In the work reported here, we generated these cells from peripheral-blood monocytes from healthy individuals. The monocytes were co-cultured with nurse-like cells from synovial tissues of patients with RA (RA-NLCs). Within 5 weeks of culture, the monocytes were activated and differentiated into mononuclear cells positive for CD14 and tartrate-resistant acid phosphatase (TRAP). These mononuclear cells then differentiated into multinucleated giant bone-resorbing cells after stimulation with IL-3, IL-5, IL-7, and/or granulocyte-macrophage-colony-stimulating factor. TRAP-positive cells with similar characteristics were found in synovial fluid from patients with RA. These results indicate that multinucleated giant bone-resorbing cells are generated from monocytes in two steps: first, RA-NLCs induce monocytes to differentiate into TRAP-positive mononuclear cells, which are then induced by cytokines to differentiate into multinucleated giant bone-resorbing cells.     

Origins and selection of epidermal progenitors and stem cells: a challenge for tissue engineering

The use of epidermal stem cells and their progeny for tissue engineering and cell therapy represents a source of hope and major interest in view of applications such as replacing the loss of functionality in failing tissues or obtaining physiologic skin equivalents for skin grafting. The use of such cells necessitates the isolation and purification of rare populations of keratinocytes and then increasing their numbers by mass culture. This is not currently possible since part of the specific phenotype of these cells is lost once the cells are placed in culture. Furthermore, few techniques are available to unequivocally detect the presence of skin stem cells and/or their progeny in culture and thus quantify them. Two different sources of stem cells are currently being studied for skin research and clinical applications: skin progenitors either obtained from embryonic stem cells (ESC) or from selection from adult skin tissue. It has been shown that "keratinocyte-like" cells can be derived from ESC; however, the culturing processes must still be optimized to allow for the mass culture of homogeneous populations at a controlled stage of differentiation. The functional characterization of such populations must also be more thoroughly achieved. In order to use stem cells from adult tissues, improvements must be made in order to obtain a satisfactory degree of purification and characterization of this rare population. Distinguishing stem cells from progenitor cells at the molecular level also remains a challenge. Furthermore, stem cell research inevitably requires cultivating these cells outside their physiological environment or niche. It will thus be necessary to better understand the impact of this specific environmental niche on the preservation of the cellular phenotypes of interest.     

Stem cells and regenerative medicine: principles, prospects and problems

Stem cells have been used routinely for more than three decades to repair tissues and organs damaged by injury or disease, most notably haematopoietic stem cells taken from bone marrow, umbilical cord or, increasingly, from peripheral blood. Other examples, such as grafts of skin to treat severe burns, entail transplantation of stem cells within organized tissue rather than following isolation. The prospect of exploiting stem cells more widely in regenerative medicine was encouraged both by the development of human assisted conception and growing evidence that various adult cells retained greater versatility than had been suspected hitherto. The aim is to employ stem cells as a source of appropriately differentiated cells to replace those lost through physical, chemical or ischaemic injury, or as a result of degenerative disease. This may entail transplantation of just a single type of cell or, more challengingly, require a complex of several different types of cells possessing a defined architecture. Cardiomyocytes, hepatocytes or neuronal cells producing specific transmitters offer promising examples of the former, although how transplanted healthy cells will function in a perturbed tissue environment remains to be established. Recent success in repairing urinary bladder defects with grafts of urothelial and muscle cells seeded on a biodegradable collagen scaffold is an encouraging step towards assembling organs in vitro. Nevertheless, this is still far removed from the level of sophistication required to counter the ever increasing shortfall in supply of kidneys for transplantation. Various problems must be addressed if recent advances in the laboratory are to be translated into clinical practice. In many cases, it has yet to be established that cells derived from adults that retain plasticity are actually stem cells. There is also a pressing need for appropriate assays to ensure that, regardless of source, stem cells maintained in vitro are safe to transplant. Assays currently available for human ES cells are far from ideal. It is, in addition, important to ensure that differentiated cultures are pure and, depending on whether cell renewal is required or to be avoided, retain or lack appropriate stem cells. Neither autografts nor those obtained by so-called 'therapeutic cloning' are options for treating condition with an obvious genetic basis. Moreover, claims that some stem cells are more likely than others to yield successful allografts have yet to be confirmed and explained.     

The Hodgkin and Reed/Sternberg cell

Hodgkin and Reed/Sternberg (HRS) cells are the hallmark cells of Hodgkin's lymphoma (HL). They are large, often multinucleated with a peculiar morphology and an unusual immunophenotype, that does not resemble any normal cell in the body. Despite their rarity in HL tissues, HRS cells are the clonal tumour cells of HL. HRS cells in nearly all cases of HL derive from B cells, and only rarely from T cells. Notably, the pattern of somatic mutations in their rearranged immunoglobulin V genes suggests that they are derived from pre-apoptotic germinal center B cells. The pathogenesis of HL is still largely unresolved, but it is now clear that aberrant activation of several signalling pathways (such as the NFkappaB pathway) is of key importance for HRS cell survival. HRS or HRS-like cells are also found in several other diseases, e.g. as rare intermingled cells in some non-Hodgkin lymphomas and in infectious mononucleosis.     

Structures, Components and Functions of Secretory Tissues in Houttuynia cordata

Houttuynia cordata Thunb., traditionally used as a therapeutic plant in folk medicine, has shown antioxidant and anticancer activities. The species, as a core component of paleoherbs, is normally characterized based on the presence of different types of secretory tissue： oil cells, three types of secretory cells and glandular hairs. The aim of this work was to study the structural, componential, and the functional characteristics of the secretory tissues in both the floral and vegetative parts. The results indicate that oil cells and secretory cells are distributed in all organs of the plant, while glandular hairs are situated on the aerial stems and leaves. Both oil cells and glandular hairs initiate from the protoderm, but their developmental processes are different. Although three types of secretory cells initiate from different primary meristems, the developmental patterns of different secretory cells are the same. Also, although the origins of secretory cells are different from oil cells, their early developmental processes are the same. Histochemical results show that oil cells, secretory cells and glandular hairs produce flavonoids, phenolic compounds, tannins, lipids, aldehyde and ketone-compounds. In addition, there are terpenoids and pectic-like substances in oil cells, alkaloids in secretory cells of aerial stems, and terpenoids and alkaloids in glandular hairs. These compounds play very important roles in protecting plants from being eaten by herbivores （herbivory） and infected by microbial pathogens. The oil cell and secretory cell, as unicellular secretory tissues, are intermediates between the primitive surface glandular and secretory cavity and canal during the evolution of secretory structures.     

Isolation and characterization of flat cells, a subpopulation of the embryonic chick retina

When the embryonic neutral retina is dissociated into single cells which are maintained in stationary culture, the neuronal cells associate on the surfaces of a second population which we refer to as flat cells. The flat cells appear in the culture in significant numbers after 2 days and are required for neuronal cell attachment. We have been able to isolate pure flat cells from early cultures of mixed retina cells and have identified several antigens which support the concept that these cells are related to the glia. The cells have been tested by immunofluorescence for glial fibrillary acidic protein and have been found positive. Cell surfaces were labeled by transfer of tritiated galactose from UDP-galactose to endogenous acceptors in the presence of exogenous galactosyl transferase. After SDS-PAGE and fluorography, the surface glycoproteins of flat cells were seen to be significantly different from those of the original retina, and from chick fibroblasts. Immunoelectron microscope studies of detergent-extracted flat cells have demonstrated a complex network of intermediate filaments and actin fibers. We conclude that the flat cells are derived from the glia subpopulation of the retina and have adapted to the tissue culture environment by assuming this configuration. The unique surface properties of flat cells may be related to their role as an intermediate substrate between the neuronal cells and the tissue culture dish.     

Automated image detection and segmentation in blood smears.

A simple technique which automatically detects and then segments nucleated cells in Wright's giemsa-stained blood smears is presented. Our method differs from others in 1) the simplicity of our algorithms; 2) inclusion of touching (as well as nontouching) cells; and 3) use of these algorithms to segment as well as to detect nucleated cells employing conventionally prepared smears. Our method involves: 1) acquisition of spectral images; 2) preprocessing the acquired images; 3) detection of single and touching cells in the scene; 4) segmentation of the cells into nuclear and cytoplasmic regions; and 5) postprocessing of the segmented regions. The first two steps of this algorithm are employed to obtain high-quality images, to remove random noise, and to correct aberration and shading effects. Spectral information of the image is used in step 3 to segment the nucleated cells from the rest of the scene. Using the initial cell masks, nucleated cells which are just touching are detected and separated. Simple features are then extracted and conditions applied such that single nucleated cells are finally selected. In step 4, the intensity variations of the cells are then used to segment the nucleus from the cytoplasm. The success rate in segmenting the nucleated cells is between 81 and 93%. The major errors in segmentation of the nucleus and the cytoplasm in the recognized nucleated cells are 3.5% and 2.2%, respectively.     

Cerebellum- and forebrain-derived stem cells possess intrinsic regional character

The existence of stem cells in the adult nervous system is well recognized; however, the potential of these cells is still widely debated. We demonstrate that neural stem cells exist within the embryonic and adult cerebellum. Comparing the potential of neural stem cells derived from the forebrain and cerebellum, we find that progeny derived from each of these brain regions retain regional character in vitro as well as after homotopic transplantation. However, when ectopically transplanted, neurosphere-derived cells from either region are largely unable to generate neurons. With regard specifically to embryonic and adult cerebellar stem cells, we observe that they are able to give rise to neurons that resemble different select classes of cerebellar subclasses when grafted into the perinatal host cerebellum. Most notably, upon transplantation to the perinatal cerebellum, cerebellar stem cells from all ages are able to acquire the position and mature electrophysiological properties of cerebellar granule cells.     

Relation between spontaneous activity and cholinesterase activity of dissociated embryonic and young rat-heart and embryonic chick-heart cells studied in tissue culture

Summary The number of spontaneously beating single cells obtained both from rat and chick hearts disaggregated by trypsin, is age-dependent: it is higher in younger than in older hearts. Cholinesterase activity and glycogen content are high in the spontaneously active cells. Being dependent on animal age, many Cholinesterase and PAS-positive cells are present in cultures prepared from early hearts. Succinicacid dehydrogenase-activity is equally feeble in spontaneously active and inactive heart cells. Only in older, already differentiated cells, devoid of spontaneous activity, is it intense.     

Difference spectra, catalase- and peroxidase activities of isolated parenchymal and non-parenchymal cells from rat liver

The reduced minus oxidized difference spectra from isolated parenchymal and non-parenchymal cells from rat liver indicate that the non-parenchymal cells contain a considerable amount of peroxidase. This interpretation is favoured by the more than 30 times higher specific activity of peroxidase (EC 1.11.1.7) in the non-parenchymal cells as compared to the parenchymal cells. The catalase (EC 1.11.1.6) activity in the non-parenchymal cells is 4 times lower than in the parenchymal cells. These results are consistent with an antimicrobial function of the non-parenchymal cells in liver.     

Repair and mutagenesis survey of 8-hydroxyguanine in bacteria and human cells

8-Hydroxyguanine is one of the major products formed by the reactive oxygen species which are generated in living cells as a consequence of either the normal metabolic pathways or an exogeneous chemical or physical stress. The production of the oxidative damage is described and the different repair pathways of the oxidative lesions are analyzed from bacteria to human cells. Analysis of repair in human cells harboring different deficiencies in the nucleotide excision repair mechanism such as xeroderma pigmentosum cells from different complementation groups and cells from Cockayne's syndrome patients allows us to emphasize the possibility of the intervention of this repair mechanism on the elimination of oxidative damages. Finally, a repair model of oxidative lesions is proposed.