Charge-selective Permeability of Dermo-epidermal Junction: Tracer Studies with Cationic and Anionic Ferritins

To investigate quantitatively the charge-selective permeability of the basement membrane (BM) of the dermo-epidermal junction (DEJ), tracer experiments using anionic and cationic ferritins were performed on an epidermal sheet, whose lamina densa was exposed on the dermal surface; its dermis was removed with forceps after the treatment of newborn rat skin with 10 mM dithiothreitol. The lamina densa and epidermal components of the sheets were electron microscopically well preserved, and anionic sites were ultrastructurally demonstrated on both the dermal and epidermal aspects of the lamina densa in the DEJ as clusters of cationic ferritins (CF) [isoelectric point (pI) > 9.5] or polyethyleneimine particles, indicating that the epidermal sheets were suitable for study of permeability.In tracer experiments, a large number of CF (pI 8.0-9.4) passed the lamina densa and formed clusters on both aspects of the lamina densa and in the intercellular space. The number of native anionic ferritins (NF) (pI 4.1-4.6) passing it was apparently much smaller than that of CF. When the epidermal sheets were pre-treated with protamine sulfate to neutralize the negative charges in the tissue, the number of NF penetrating the lamina densa was significantly larger than the number of those in the untreated sheet.These results indicate that the BM of the DEJ plays a role in a charge-selective filtration, although it is not as selective a barrier as the glomerular basement membrane

Lipocortin I (Annexin I) Is Preferentially Localized on the Plasma Membrane in Keratinocytes of Psoriatic Lesional Epidermis as Shown by Immunofluorescence Microscopy

Lopocortin I (LPC-I, also called annexin I) is a 35-kD protein that binds phospholidpids and actin ina a Ca++-dependetn manner. It is also a major substrate for EGF recepto/kinase and rotein kinase C,. and a putative inhibito of phospholipase A2, which produces chemical mediators to cause inflammation. Psoriasos (PS) is an inflammatory skin disease characterized by a rapid turnover of keratinocytes and a defect in keratinization with increased activities of phospholipase C and A2, and EGF receptor. To understand the mechanism of the PS lesion formation and the function of LPC-I, its didtribution was studied in the epiedermis of PS, subacure eczema and normal skin, and in tumor, cells of seborheic keratosis and Bowen's disease. This study involved immunofluorescence and immunoblotting using affinity-purified polyclonal and monclonal antibodies specific to LPC-I and to its Ca++- bound form. In normal, nonlesional PS and subacute eczema epidermis, LPC-I was detected , mainly in the cytoplasm of the suprabasal cells, although it was on the inner aspects of the plasma membrane in some parts of the granular layer. In lesional epidermis of PS it was localized mainly on the inner aspects of the plasma membrane, but not in the cytoplasm of the whole suprabasal cells as the Ca++-bond form, indicating a preferential localization of the plasma membrane. This membrane-binding of LPC-I was also observed in seborrheic keratosis, but not in Bowen's disease. These results suggest that the binding of LPC-I to the plasma membrane occurs actually in living cells, plays a role not necessarily disease specific, in the PS lesion formation, and has some relevance to normal or abnormal differentiation of keratinocytes

Equilibrium Statistics of Weakly Slip-Linked Gaussian Polymer Chains

We calculate the free energy and the pressure of a weakly slip-linked Gaussian polymer chains. We show that the equilibrium statistics of a slip-linked system is different from one of the corresponding ideal chain system without any constraints by slip-links. It is shown that the pressure of a slip-linked system decreases compared with the ideal system, which implies that slip-linked chains spontaneously form aggregated cluster like compact structures. These are qualitatively consistent with previous theoretical analyses or multi chain simulations. We also show that repulsive potentials between chains, which have been phenomenologically utilized in simulations, can cancel the artificial pressure decrease.Comment: 24 pages, 3 figures, to appear in J. Polym. Sci. B: Polym. Phy

Economic Policy and Political Capital

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