Inter-group conflict affects inter-brain synchrony during synchronized movements.

Interpersonal synchrony refers to alignment in time of interacting individuals. Recent neuroimaging findings indicate that the inferior frontal gyrus (IFG) - a core region of the observation-execution system - is not only activated during tasks that involve synchrony, but also coupled between interaction partners, suggesting a key role for the IFG in mediating interpersonal synchrony. In this study we investigated whether inter-brain synchrony (IBS) is modulated by inter-group relationships. We examined this question in the context of the Israeli-Palestinian conflict - one of the world's most prolonged and intractable conflicts. Using functional Near Infra-Red Spectroscopy (fNIRS) hyperscanning, we measured IBS among ingroup vs. inter-group dyads (same-nationality dyads and Jewish-Palestinian dyads, respectively) while they performed a task entailing 2D movement synchrony. The results point to an increase in behavioral synchrony and greater enjoyment in the ingroup dyads, compared to the inter-group dyads. Critically, IBS in the left IFG significantly increased throughout task and it was higher among ingroup compared to inter-group dyads. Our findings highlight the effect of group membership on IBS plasticity.

Ultrastructural characteristics of the spleen in hairy cell leukemia.

Eighteen spleens derived from patients with hairy cell leukemia (HCL) were analyzed by correlative scanning and transmission electron microscopy. In 15 of the cases, the white pulp areas were markedly decreased or absent when compared to normal spleens, although few hairy cells were observed within this region. In only one case did the white pulp appear normal. In all HCL cases, hairy cells were observed within normal, dilated, and abnormal sinuses. The abnormal sinuses contained hairy cells of typical morphology attached to other hairy cells, to endothelial lining, and to erythrocytes. The degree of sinus filling by hairy cells varied from loosely- to tightly-packed. Endothelial cells exhibiting degenerative changes, such as swelling with smooth surfaces and dilated intercellular spaces, were frequently seen. These results indicate that in addition to the previously described overcrowding of the spleen by hairy cells, the splenic tissue itself is considerably altered and sometimes severely damaged in patients with HCL.

Mechanism of interferon action in hairy cell leukemia: a model of effective cancer biotherapy.

Hairy cell leukemia (HCL) is one of the few malignancies for which alpha-interferon (IFN alpha) is considered effective first-line therapy. However, the mechanisms of action of this agent in vivo have been the subject of much debate; in particular, the issue of whether clinical improvement in IFN-alpha-treated HCL patients is dependent upon enhancement of host defenses or upon direct actions of IFN alpha upon the hairy cell remains unresolved. In this review, we examine the evidence supporting both lines of argument and synthesize this information within the framework of clinical studies of IFN alpha in HCL, the purpose being to determine which proposed mechanisms of IFN alpha action are indeed effective in vivo. From our analysis, it appears that the beneficial effects of IFN alpha upon immune function are important in decreasing the frequency of infectious complications of HCL but that these effects are probably not responsible for hairy cell elimination and cannot therefore account for major responses to IFN alpha therapy. We conclude that the primary mechanism of action of IFN alpha in HCL involves the induction of hairy cell differentiation towards a stage less responsive to growth factor stimulation, the primary consequence being proliferative inhibition. These effects may mimic events that occur during normal lymphocyte development, suggesting that the benefits of biotherapeutic agents might best be harnessed via studies of the effects of multiple and sequential biological response modifiers upon the growth and differentiation patterns of normal and malignant cells. Hairy cell leukemia could thus serve as an excellent model in which to investigate combined cancer biotherapy; the implications of our present understanding of IFN alpha in HCL to the biotherapy of cancer are discussed.

Evaluation of cryopreserved allograft venous conduits in dogs.

We investigated the effects of cryopreservation, immunosuppression, and antibiotic treatment on the patency and histologic appearance of venous conduits in the arterial circulation. Twenty-eight dogs received arterial replacements with autograft vein, fresh allograft, and two types of cryopreserved allograft vein implanted into both carotid and both femoral arteries. All animals were given aspirin, and half were given cyclosporine. After 3 months the vein grafts were harvested. Patency and light, transmission, and scanning electron microscopic criteria were scored to evaluate quality of preservation of the endothelium, the appearance of rejection, and the effects of cryopreservation with and without antibiotic pretreatment. The results show that patency is not statistically different based on graft type or treatment modality. The histologic appearance among the various vein types was remarkably similar at 3 months, with the exception of a cellular infiltrate present most prominently in the fresh allografts and least in the fresh autografts. Cyclosporine, even at a low dose, decreased the incidence of cellular infiltration. Preservation of endothelium was generally good in the cryopreserved allografts both with and without antibiotic pretreatment. In general, the effects of cryopreservation, cyclosporine, and antibiotics ameliorated the effects of venous allografting into an arterial position.

Killing of Burkitt-lymphoma-derived Daudi cells by ultraviolet-inactivated vaccinia virus.

Interaction of active and UV-inactivated vaccinia virus at high multiplicity caused cytological changes and inhibition in cellular protein and DNA synthesis, thus arresting the multiplication of Burkitt-lymphoma-derived Daudi cells and eventually killing the cells. Adsorption to the cells but the lack of penetration was evident by immunofluorescence, electron microscopy and [3H]thymidine-labeled virus incorporation. Viral DNA synthesis or virus replication was not demonstrated. Thus, it appears that the massive adsorption of viral particles, active or UV-inactivated, or possibly a "toxic" component that resides in the virion, damages the plasma membrane and may be responsible for killing the cells by a mechanism of lysis from without.

HDS: Establishment of a New Cell Line from a Hairy Cell Leukemia Patient with Resistance to Alpha-Interferon Therapy.

A new cell line, designated "HDS", was established in a suspension culture derived from the peripheral blood of a patient with hairy cell leukemia (HCL) who developed clinical resistance to alpha-interferon (aIFN) therapy. The patient exhibited a clinical picture characteristic of HCL, including splenomegaly, cytopenias, and tartrate-resistant acid phosphatase (TRAP)-positive "hairy" cells in blood and marrow. Chromosomal studies revealed that the cultured cells possess the chromosomal abnormality +12. Cytochemical and immunologic studies show the HDS cell line had the phenotype of a B-lymphocyte. HDS cells expressed the HLA-DR and CD19 surface antigens, but were negative for early B (CD10) and T (CD2, CD3) cell markers. The cells are also negative for other T-cell, granulocytic and monocytic markers and for typical HCL markers such as CD11c and CD22. However, the expression of these antigens was induced by in-vitro treatment of the cells with the differentiation-inducing agent tetradecanoyl phorbol acetate (TPA). Ultrastructural analyses of the cultured cells revealed a display of surface microvilli mixed with ruffles in a classical hairy cell pattern. It is therefore highly likely that the HDS cells represent HCL cells in an atypical stage of differentiation.

B-cell growth factor-induced and alpha-interferon-inhibited proliferation of hairy cells coincides with modulation of cell surface antigens.

alpha-Interferon (IFN-alpha) induced unique ultrastructural alterations in peripheral blood and splenic hairy cell leukemia (HCL) cells (14 of 20 cases) treated in vitro. To further investigate the effects of B-cell growth factor (BCGF) and IFN-alpha on target hairy cells (HCs), we utilized immunogold labeling in conjunction with scanning electron microscopy. This methodology, in contrast to other immunological methods, facilitated direct view of the expression, density, and rearrangement of selected antigens/receptors on individual cells before and after BCGF or IFN-alpha treatment. In addition to inducing proliferation of HCL cells, BCGF enhanced the expression of interleukin 2 receptors (CD25; T-activated cell antigen) with no change in the expression of class I and class II human leukocyte antigen. On the other hand, IFN-alpha did not exert a noticeable proliferative effect on HCL cells but rather inhibited the proliferation of BCGF-treated cells. In addition, IFN-alpha treatment revealed an enhanced expression of class I (4 of 9) and class II (12 of 15) human leukocyte antigen on target HCs. Two-day exposure of HCs to IFN-alpha resulted in enhanced expression of CD25 (11 of 14), whereas a decrease in CD25 expression was recorded in 4 of 5 cases treated with IFN-alpha for 3 days. Also, no significant change in the expression of two other HCL-related surface antigens, CD22 (S-HCL-1; Leu-14) and CD11c(S-HCL-3; Leu-M5), was recorded following up to 3 days of IFN-alpha or BCGF treatment. However, a 5-day exposure to IFN-alpha resulted in a significant decrease in expression of CD11c on treated HCs. Finally, the IFN-alpha-induced immunoultrastructural changes in target HCs were primarily encountered in cells from HCL cases classified as responders to in vivo IFN-alpha therapy. Our data add support to the concept that the effect of IFN-alpha in HCL is mediated by impairment of the response to B-cell growth factors and induction of further differentiation of the target cells.

Involvement of interferon-system in the regulation of cell growth and differentiation.

In this report we review the current knowledge on the involvement of the interferon (IFN) system in the regulation of cell growth and differentiation. We also summarize our own data which provide evidence for the strong correlation between IFN-mediated growth-arrest of transformed cells and the elevated enzymatic activity of an IFN-induced protein. Similarly, it is demonstrated that elevated levels of IFN-induced proteins accompany the early phases of in-vitro cell differentiation. IFN-treatment of NIH/3T3 mouse fibroblasts transformed by Moloney-murine sarcoma virus (MSV) resulted in a significant reduction in the rates of cell growth, protein synthesis and cloning efficiency. In parallel, 2-5A-synthetase activity was induced ten-fold above the background level. Treatment of these cells for 3 days with 450 international units (IU)/ml of IFN followed by its removal, resulted in a gradual increase in all parameters associated with cell growth while the 2-5A-synthetase activity was reduced to its normal level. However, almost no recovery occurred when cells were treated with 1,800 IU/ml. In parallel, 2-5A-synthetase activity remained highly elevated even at 3 days after the removal of IFN. In these cells, the expression of both c-myc and v-mos was reduced rapidly following IFN treatment. Upon removal of IFN after 24 h of treatment, the expression of both genes was resumed but with a different kinetics, suggesting that different mechanisms are responsible for the reduction in gene expression. In rat skeletal muscle cultures which differentiate to form myotubes, the level of both 2-5A-synthetase and protein kinase activities was transiently elevated, reaching a peak at 3 days followed by a decrease to background levels. This peak activity precedes the appearance of the major muscle differentiating proteins.

Involvement of HLA Antigens, Interleukin 2 Receptor and B-Cell Growth Factor in Interferon Action in Hairy Cell Leukemia.

Little is known about the mechanism(s) by which alpha-interferon (aIFN), when used as a biotherapeutic agent, suppresses the malignant cells and restores the normal phenotype of cells in patients with hairy cell leukemia (HCL). In previous studies using scanning electron microscopy (SEM) we found that alFN induced unique membrane alterations in target hairy cells in vitro. In addition, aIFN was shown to enhance the expression of HLA class II antigens on HCL cells, to induce the production of new proteins in such cells, and to lower the high levels of soluble IL-2 receptors in the serum of HCL patients. In the light of these results, and the fact that restoration of natural killer cell activity occurs in aIFN-treated patients well after the hematologic profile begins to improve, our studies have focused on the hypothesis that IFNs act directly on the target malignant cells, leading to the elimination of these cells either by inhibiting the proliferation of the malignant cells and/or triggering changes in the differentiation status of the malignant cells that lead to suppression (cytoconversion) of the malignant phenotype. We review the current hypotheses regarding alFN action on leukemic cells, with special reference to its potential antagonism with BCGF.

Interferon-induced surface alterations in hairy cells. A review.

Hairy cells (HCs), derived from the peripheral blood and spleen of hairy cell leukemia (HCL) patients, constantly displayed both ruffles and microvilli. HCs which were kept in culture for up to three days exhibited extremely polarized and active surfaces with elongated microvilli and exaggerated "spiked" ruffles. Cells derived from 11 cases of HCL were treated with alpha-interferon (IFN) in-vitro and examined by immuno-scanning electron microscopy (immuno-SEM). In 8 cases, up to one-third of the IFN-treated hairy cells displayed deformed surfaces with "bubbling" membrane and markedly villous bud-like formations. Monoclonal antibodies (MoAb), used in conjunction with immuno-gold labeling, facilitated better correlation between these morphological changes and the immunological profiles of the cells before and after interferon treatment in-vitro. Immuno-SEM analyses revealed no remarkable changes in the labeling of HCs with Leu-14 and Leu-M5 MoAbs before and after IFN treatment, even in cases showing membrane changes. However, a significant increase in the labeling intensity for HLA-DR and HLA-DQ was noticed in HCs from cases where IFN-induced membrane changes were evident. A review of the literature on membrane changes in IFN-treated cells proposes that such immuno-ultrastructural alterations might reflect unique interferon-induced membrane reorganization in the target malignant cells.

The effect of cultivation and interferon treatment on the surface morphology of hairy cell leukemia cells.

The ability of interferon to induce alterations in the surface morphology of malignant B cells from 4 patients with hairy cell leukemia (HCL) was investigated under scanning electron microscopy. Peripheral blood hairy cells showed the same surface features as those isolated from spleens involved with HCL, and constantly exhibited both ruffles and microvilli. Cultured hairy cells displayed extreme polarization of their surface microprojections, and very active surfaces with elongated microvilli and broad-based ruffles were evident. All 4 cases of HCL were treated with recombinant human leukocyte interferon in vitro, and one-third of the HCs from 3 cases displayed deformed surfaces with "bubbling" membrane and altered microprojections. Most of these IFN-treated hairy cells appeared to be larger in size compared to the untreated control cells, and frequently showed a villous bud-like formation at their extremity. The possibility that these unique surface alterations reflect IFN-induced changes in the cytoskeletal proteins and/or membrane components is discussed in light of the clinical efficacy of in vivo IFN treatment in HCL.

Topical modes in the preparation of human spleen specimens for routine scanning electron microscopy studies.

Various preparatory techniques were used to improve scanning electron microscopy images of the fine structure of vascular, cellular, and cordalreticular components of normal human spleens. The progressive method of fixation (GTGO) applied in the present study, allowed air drying of the tissues and rendered the specimens conductive even in newly fractured surfaces. Vascular perfusion proved necessary only in studies of the splenic blood vessels, while a simple immersion of tissue blocks in the washing solution resulted in better images of the white pulps. Interstitial (transsplenic) perfusion was found to be superior to vascular perfusion for routine preparation of spleen tissues, and freeze-cracking did not necessarily lead to improved images of the specimen's surfaces. Combined with proper washing and shaping protocols, the GTGO procedure is shown to be a superior mode of specimen preparation, abolishing most traditional artifacts and obtaining clear images of the complex splenic tissue.

Unique scanning electron microscopic features of hairy cells in hairy-cell leukemia. A review and current status.

Past scanning electron microscopy (SEM) reports demonstrated cell surface undulations, ridges, folds, and ruffles to support the monocytic/histiocytic nature of hairy-cell leukemia (HCL) cells. On the other hand, SEM studies illustrating spikes, villi, and microvilli on the cell surfaces favored the lymphocytic nature of hairy cells (HCs). The evidence for the 'hybrid' nature of the HCs has emerged from the demonstration of concurrent display of monocytic (ruffles) and lymphocytic (microvilli) surface features on each cell. Utilizing improved methods of sampling, fixation, and drying, the current status is that all HCs display microvilli and ruffles simultaneously. However, two distinct morphological types of HCs are acknowledged: cells showing ruffled areas next to clumps of microvilli (type A), and cells displaying microvilli interspersed among ruffles (type B). Each of the HCL cases reported in our studies had cells with either type A or type B surface features. Amazingly, these unique SEM features correlate well with the prevalent trend to classify HCs as malignant (villous) B-lymphocytes imitating (ruffled) monocytes in some functional respects.

Megakaryocyte interaction with subendothelial extracellular matrix is associated with adhesion, platelet-like shape change, and thromboxane A2 production.

We have examined the morphological and secretory behavior of rat and guinea pig megakaryocytes exposed for up to 24 hours to extracellular matrix produced by cultured bovine endothelial cells. By phase-contrast microscopy of living cells and in more detail by scanning electron microscopy, the megakaryocytes showed a nonreversible adherence, an extensive formation of filopodia around the periphery like the rays of the sun, and a tendency toward flattening. These filopodia were generally linear with attenuated tips and were larger than, but resembled the filopodia of, rat or guinea pig platelets exposed to this extracellular matrix. In contrast, isolated megakaryocytes on glass or on uncoated plastic surfaces did not show these responses; adherence, in the face of gentle agitation before fixation, was minimal, with rare filopodia and no flattening. Megakaryocytes that interacted with the extracellular matrix produced significant amounts of thromboxane A2, but this did not occur on uncoated surfaces and could not be attributed to other contaminating cells in the megakaryocyte suspensions. The appearance in megakaryocytes of these typical platelet responses indicates that megakaryocytes acquire the functional capabilities of platelets by the synthesis and assembly of platelet substances and organelles. Thromboxane production by megakaryocytes stimulated by the extracellular matrix is a readily quantifiable measure of this capacity.

A new myelomonoblastic cell line (M20): analysis of properties, differentiation, and comparison with other established lines of similar origin.

A new myelomonoblastic cell line (M20) was established from the peripheral blood of a ten-year-old child with acute myeloblastic leukemia, using an improved method for supporting the initial stages of cell proliferation. The addition of irradiated macrophage monolayers to the proliferating cells appeared to overcome the deterioration of the primary cultures and enable them to continue proliferating until they became independent of this environment. The cell line that developed consisted of myeloblasts and promyelocytes characterized by light and scanning electron microscopy, cytochemistry, and enzymatic activities. The cells expressed Fc receptors and WT1 antigens but did not exhibit HLA-DR, HMA1, Epstein-Barr virus nuclear antigen, and surface Ig. The M20 cells produced colonies when cultured in semisolid medium and secreted lysozyme, prostaglandin E2, and interleukin 1. An attempt was also made to analyse the position of the M20 cells in the scheme of differentiation of the myelomonocytic lineage using different approaches. Treatment of the cells with 12-O-tetradecanoyl phorbol 13-acetate induced their adherence to plastic surfaces and partial maturation to macrophages as judged by morphological criteria, cytochemistry, and enzyme activities. However, comparison of the M20 cells to other well-established myelomonoblastic cell lines did not reveal any pattern suggesting a possible relationship between surface markers, cell function, and differentiation pathway of the various cell lines tested. Establishment of additional cell lines and identification of new markers may assist in defining the mechanisms involved in normal differentiation and malignant transformation of this cell lineage. In addition, such cell lines may also provide a tool for the quantitative recovery of a variety of monokines.

Hairy cell leukemia: reevaluation of cell surface features under the scanning electron microscope, using the "GTGO" air drying and critical point drying procedures.

In the present study, the GTGO--air drying (AD) preparatory procedure for scanning electron microscopy (SEM) was used to reevaluate the surface features of hairy cells (HCs) obtained from 18 patients with hairy cell leukemia (HCL). The GTGO-AD procedure, described in earlier studies, involves glutaraldehyde (G) fixation of suspended cells, followed by tannic acid (T)--guanidine hydrochloride (G) treatment of substrate-attached cells, immersion in osmium tetroxide (O), and subsequent air drying (from absolute Freon 113) of dehydrated cells. Both air-dried and critical point dried GTGO-treated cells from patients with lymphocytic, monocytic and hairy cell leukemias, displayed excellent preservation of their surface microvilli and/or ruffles with minimal cell shrinkage. Generally, only two types of hairy cells were identified: (i) cells displaying areas of ruffles alongside areas of clustered microvilli, and (ii) cells showing microvilli scattered among ruffles. Peripheral blood hairy cells showed the same features as those isolated from the spleens involved with HCL and consistently exhibited both ruffles and microvilli. In all studied cases, cells displaying only ruffles or microvilli were not frequently encountered, although ruffled cells with very short and delicate microvilli, and villous cells with small ruffles were seen. Hairy cells, kept in culture for up to 7 days, displayed extreme polarization of their microprojections and very active surfaces, with elongated microvilli and broad-based ruffles. In the light of these results, it is clear that GTGO-AD has much to offer in determining the surface features of circulating and cultured hairy cells and other types of leukemic cells.

Visualization of the fate of inactive influenza viruses in Daudi cells by electron microscopy.

The replication of active and inactivated influenza viruses in Daudi lymphoma cells was studied by immunofluorescence and electron microscopy. In a previous study, we demonstrated that active and heat-inactivated X47 (H3N2) virus arrested Daudi cell growth by inhibiting cellular DNA synthesis while formalin-treated X47 virus did not. Transmission electron microscopic studies revealed that both the active and the heat-inactivated X47 virus penetrated into the cells. Only the active X47 (XA) virus replicated completely in Daudi cells and produced new viral particles by budding. The formalin-treated X47 virus did not damage or change the cells, and although the viral particles remained adsorbed to the cells, there was little penetration. The heat inactivated X47 virus (which was the most effective, non-virulent, oncolytic agent we studied) was visualized as large aggregates of particles adsorbed to the cell surface by electron microscopy. The cells themselves formed clumps. The viral aggregation and cell clumping likely resulted from the loss of viral neuraminidase activity due to heat treatment. The penetration of heat-inactivated viral particles was massive and involved numerous particles. Production of new viral particles was not demonstrated in this study even though nucleocapsids from the original virus were found in the cytoplasm. Thus, it appears that the massive penetration of the viral particles into cells damages the plasma membrane and may be responsible for the oncolytic potential of the heat-inactivated virus on Daudi cells.

Optimum fixation conditions may allow air drying of soft biological specimens with minimum cell shrinkage and maximum preservation of surface features.

This paper focuses on the concept that traditional SEM artifacts, encountered in soft biological specimens, may be overcome by improving the physico-chemical properties of these samples rather than by applying sophisticated drying procedures. Emphasis is placed upon fixation strategies minimizing these artifacts and allowing the air drying of various specimens, even those showing very delicate surface microprojections. This attitude is illustrated by a variety of cells and tissues prepared for SEM by both conservative (i.e., critical point drying of samples treated with glutaraldehyde and/or osmium tetroxide) and reformative procedures, i.e., air drying of samples treated with glutaraldehyde, tannic acid, guanidine-HCl, and osmium tetroxide (GTGO-AD). The results clearly indicate that samples which were prepared by the GTGO procedure displayed very well preserved surface features with minimum shrinkage, even after being air dried.

Prolymphocytic leukaemia: surface morphology in 21 cases as seen by scanning electron microscopy and comparison with B-type CLL and CLL in 'prolymphocytoid' transformation.

The surface architecture of leukaemic cells obtained from 21 cases of proven prolymphocytic leukaemia (PLL) and eight cases of chronic lymphocytic leukaemia (CLL) with 'prolymphocytoid' transformation (PL-CLL) was compared with the cell surface morphology of leukaemic cells obtained from 46 cases of B-type CLL, using the scanning electron microscope (SEM). All cases were defined by cytochemistry, immunological markers and transmission electron microscopy prior to SEM examination. B-CLL cells showed the well-recognized spectrum of surface architecture described in earlier studies. The majority of cells had moderate numbers of short microvilli, although in a minority, cells with relatively smooth surfaces predominated. In seven of the eight cases of PL-CLL, cells were villous in nature and in this respect similar to CLL cells; however, more cells with dense microvilli were seen. The prolymphocytic cells were recognized by their larger size and in 18 of the 19 cases of B-derived PLL, villous cells predominated. Two cases of T-derived PLL showed variable cell surface morphology ranging from smooth to moderately villous. It appears that B-PLL cells are most frequently villous and display more surface microvilli than B-CLL cells. B-prolymphocytes display the surface features regarded as characteristic for neoplastic B-cells as seen in patients with B-type lymphoma and leukaemia.

Human peripheral blood mononuclear cells cultured in serum-free medium: a functional and morphological study using light and scanning electron microscopy.

Mononuclear cells of the human peripheral blood (PBMs), separated by the gradient-centrifugation technique, were cultured in serum-free medium. After separation into adherent cells (A-PBMs) and non-adherent cells (NA-PBMs), morphological differences between the two cell populations were observed. A-PBMs grew in serum-free culture for up to 70 days and the NA-PBMs for 30 days, without loss of viability. Cells were examined for phagocytosis of latex particles and prostaglandin secretion (PGE2 and thromboxane), in particular. Of all cells studied, the young adherent cells (3-7 days in culture) were the most efficient in performing these functions. In mixed cultures, containing A-PBMs and NA-PBMs, attachments between both cell types via elongated cytoplasmic extensions were seen. Toward the end of the culture period, a dense cellular network developed on the substrate of the culture chamber. This phenomenon has not been reported for PBMs culture using conventional serum-enriched media.