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Euphorbia serrata latex has initially ingenol-3-palmitate, which by action of silica gel is converted to ingenol-20-palmitate. The former is responsible for the irritant and cocarcinogenic activity of the latex on mouse ear and on mice back skin. [ABSTRACT FROM AUTHOR]

The present study was designed to elucidate the effects of the chemokine monocyte chemoattractant protein (MCP-1) on blood-brain barrier (BBB) permeability. Experiments were conducted under in vitro conditions (coculture of brain endothelial cells and astrocytes) to study the cellular effects of MCP-1 and under in vivo conditions (intracerebral and intracerebroventricular administration of MCP-1) to study the potential contribution of MCP-1 to BBB disruption in vivo. Our results showed that MCP-1 induces a significant increase in the BBB permeability surface area product for fluorescein isothiocyanate (FITC)-albumin under in vivo conditions, particularly during prolonged (3 or 7 days) exposure (0.096+/-0.008 versus 0.031+/-0.005 microL/g min in controls at 3 days, P<0.001). Monocyte chemoattractant protein-1 also enhanced (17-fold compared with control) the permeability of the in vitro BBB (coculture) model. At the cellular level, MCP-1 causes alteration of tight junction (TJ) proteins in endothelial cells (redistribution of TJ proteins determined by Western blotting and loss of immunostaining for occludin, claudin-5, ZO-1, ZO-2). Monocyte chemoattractant protein-1-induced alterations in BBB permeability are mostly realized through the CCR2 receptor. Absence of CCR2 diminishes any effect of MCP-1 on BBB permeability in vitro and in vivo. The permeability surface area product for FITC-albumin after 3 days exposure to MCP-1 was 0.096+/-0.006 and 0.032+/-0.007 microL/g min, in CCR2+/+ and CCR2-/- mice, respectively (P<0.001). Monocytes/macrophages also participate in MCP-1-induced alterations in BBB permeability in vivo. Monocytes/macrophages depletion (by clodronate liposomes) reduced the effect of MCP-1 on BBB permeability in vivo approximately 2 fold. Our results suggest that, besides its main function of recruiting leukocytes at sites of inflammation, MCP-1 also plays a role in 'opening' the BBB.

Intracerebroventricular infusions of an amiloride analog, benzamil, reduce blood pressure in several rat models of hypertension. This effect has been attributed to an inhibition of amiloride-sensitive Na+ channels in the brain. This study examines whether intracerebroventricular benzamil would prevent the onset of deoxycorticosterone acetate (DOCA)-salt-induced hypertension in rats and whether this effect correlates with an inhibition of ion transport through the known amiloride-sensitive cation channels at the blood-brain barrier. We also examine whether the effects of benzamil on blood pressure are mediated by a Na+ channel by comparing the effects of different amiloride analogs. Benzamil (0.15 and 0.5 microgram/h icv) did significantly attenuate the increase in blood pressure induced by DOCA treatment. This antihypertensive effect, however, was not associated with an alteration in a blood-brain barrier ion transport as assessed by measurements of blood-to-brain 22Na transport and cerebral spinal fluid Na+ and K+ concentrations. Indeed, intracerebroventricular infusion of dimethyl amiloride, an amiloride analog with low affinity for Na+ channels, also attenuated the increase in blood pressure induced by DOCA-salt treatment. Comparisons of the effects of benzamil, dimethyl amiloride, and 3,4-dichlorobenzamil, another amiloride analog, suggest that these antihypertensive effects are mediated by an inhibition of Na+/Ca2+ exchange in the brain.

Gliomas are known to express over a hundred antigens, and no doubt make many more unknown antigens. Major categories of glioma cell antigens include glial antigens, ECM antigens, muscle antigens, melanoma antigens, "tumor-specific" antigens, and cellular proliferation antigens. A strikingly low number of cultured gliomas express glial antigens. They commonly express not only ectodermal, but also mesenchymal ECM antigens. Tumor-specific antigens have been an elusive goal of neuro-oncologists, but there are bright new prospects in need of further study. These include direct screening of hybridoma supernatants on glioma tissue and targeting glycolipids, glycoproteins, and oncogene products. Cellular proliferation antigens will become increasingly important in predicting prognosis of gliomas. Proliferation antigens of cultured gliomas are under intense scrutiny at present. The extent and evolution of antigenic heterogeneity of neoplastic cells in gliomas raise basic biologic questions with profound clinical ramifications. Individual glioma cell lines may generate more than 30 subtypes of cells with minor to major differences in antigen expression. These include expression of antigens representing multiple different cell lineages. Mesenchymal drift is the tendency of gliomas to progressively lose glial and gain mesenchymal features. Models of in vivo mesenchymal drift occur in glioma cell culture where mechanisms are more easily investigated than in situ. Neither exogenous protein absorption nor fibroblast overgrowth explain the phenomenon. Cells with the mesenchymal marker, fibronectin, overgrow GFAP-positive cells during explanation of gliomas. Many of these fibronectin-positive cells express cytologic and growth characteristics of neoplasia. The source of these cells is unknown. A leading candidate for the source of these neoplastic fibronectin-positive cells is the proliferation of vascular and mesenchymal cell elements of glioma tissue commonly called "endothelial proliferations". However, these elements in tissue do not display the same abnormalities of neoplasia as the fibronectin-positive cells in culture. Understanding this "tissue/explant paradox" may solve the conundrum of mesenchymal drift. In the absence of a counterpart in tissue of these neoplastic fibronectin-positive cells so abundant in glioma cell cultures, mechanisms of mesenchymal drift other than overgrowth of neoplastic mesenchyme must be considered. The occurrence of "dual cells" which express antigenic markers of entirely different cellular lineages suggests the possibility that neoplastic glia generate mesenchymal drift by altered gene expression. Various studies which suggest the capacity of cultured gliomas to alter phenotypic expression of their genes are critically examined and their relevance to mesenchymal drift discussed.(ABSTRACT TRUNCATED AT 400 WORDS)

Multiple wells (M-wells) have been made over tissue sections on single microscopic slides to simultaneously localize binding specificity of many antibodies. More than 20 individual 4-microliter wells over tissue have been applied/slide, representing more than a 5-fold improvement in wells/slide and a 25-fold reduction in reagent volume over previous methods. More than 30 wells/slide have been applied over cellular monolayers. To produce the improvement, previous strategies of placing specimens into wells were changed to instead create wells over the specimen. We took advantage of the hydrophobic properties of paint to surround the wells and to segregate the various different primary antibodies. Segregation was complete on wells alternating with and without primary monoclonal antibody. The procedure accommodates both frozen and paraffin sections, yielding slides which last more than a year. After monoclonal antibody detection, standard histologic stains can be applied as counterstains. M-wells are suitable for localizing binding of multiple reagents or sample unknowns (polyclonal or monoclonal antibodies, hybridoma supernatants, body fluids, lectins) to either tissues or cells. Their small sample volume and large number of sample wells/slide could be particularly useful for early screening of hybridoma supernatants and for titration curves in immunohistochemistry (McKeever PE, Shakui P, Letica LH, Averill DR: J Histochem Cytochem 36:931, 1988).