Putative mechanism of the itch-scratch circle: repeated scratching decreases the cutaneous level of prostaglandin D2, a mediator that inhibits itching

In atopic dermatitis, scratching of the skin as a reaction to itching causes injury to the skin, which, in turn, further increases the itching resulting in the establishment of the so-called itch-scratch circle. We have shown that prostaglandin (PG) D2 plays an inhibitory role against pruritus in mice with atopic-like dermatitis; therefore, we examined the relationship between scratching and the cutaneous PGD2 level using an artificial scratching model with a wire brush. Mechanical scratching induced a temporary increase of the skin PGs levels (PGE2, PGD2, 6-ketoPGF1alpha, PGF2alpha). The skin PGD2 level and the ability of PGD2 production decreased at 48 h after repeated scratch, compared to that of normal skin, not so after single scratch. Immunohistochemical analysis and Western blotting revealed a decrease in the levels of cyclooxygenase-1 (COX-1) and hematopoietic PGD synthase in mechanically scratched skin. The reduced ability of the skin for PGD2 production following mechanical scratching could be caused by this decrease in the expression levels of COX-1 and PGD2 synthase. The results suggest that repeated scratching in mice decreases the ability of the skin to produce PGD2, which is an endogenous mediator that inhibits pruritus, resulting in the establishment of the itch-scratch circle.     

Design and synthesis of opioidmimetics containing 2',6'-dimethyl-L-tyrosine and a pyrazinone-ring platform

Twelve 2',6'-dimethyl-L-tyrosine (Dmt) analogues linked to a pyrazinone platform were synthesized as 3- or 6-[H-Dmt-NH(CH(2))(n)],3- or 6-R-2(1H)-pyrazinone (n=1-4). 3-[H-Dmt-NH-(CH(2))(4)]-6-beta-phenethyl-5-methyl-2(1H)-pyrazinone 11 bound to mu-opioid receptors with high affinity (K(i)mu=0.13 nM; K(i)delta/K(i)mu=447) with mu-agonism (GPI IC(50)=15.9 nM) and weak delta-antagonism (MVD pA(2)=6.35). Key factors affecting opioid affinity and functional bioactivity are the length of the aminoalkyl chain linked to Dmt and the nature of the R residue. These data present a simplified method for the formation of pyrazinone opioidmimetics and new lead compounds.     

Taxodistines A and B, abietane-type diterpenes from Taxodium distichum

Two new abietane-type diterpenes, taxodistines A (1) and B (2), have been isolated by the guidance of inhibitory effect of tubulin polymerization from the fruits of Taxodium distichum and the structures were elucidated by using 2D NMR data. Taxodistine B (2) showed inhibition of tubulin polymerization.     

Antidiabetic copper(II)-picolinate: impact of the first transition metal in the metallopicolinate complexes

In order to examine the effect of metallopicolinate complexes with first transition metals and develop complexes that are more active than an insulinomimetic leading compound such as oxovanadium(IV)-picolinate complex, VO(pa)2, 10 metallopicolinate complexes were prepared, and their in vitro insulinomimetic and in vivo antidiabetic activities were evaluated. The in vitro activity was estimated by determining the inhibitory effects of these complexes on free fatty acid release from isolated rat adipocytes treated with epinephrine. Among the complexes, Cu(pa)2, and Mn(pa)3 exhibited higher activity than their respective metal ions and better activity than VO(pa)2. Since Cu(pa)2 was non-toxic in the cultured rat hepatic M cells, this complex was given streptozotocin (STZ)-induced type 1-like diabetic mice by single intraperitoneal injection, and found that this complex exhibited a higher hypoglycemic effect than the VO(pa)2 complex. Based on these results, we propose that Cu(pa)2 may be a potent alternative antidiabetic agent.     

Involvement of Ca(2+)/calmodulin-dependent protein kinases in mycelial growth of the basidiomycetous mushroom, Coprinus cinereus

Although multifunctional Ca(2+)/calmodulin-dependent protein kinases (CaM-kinases) are widely distributed in animal cells, the occurrence of CaM-kinases in the basidiomycetous mushroom has not previously been documented. When the extracts from various developmental stages from mycelia to the mature fruiting body of Coprinus cinereus were analyzed by Western blotting using Multi-PK antibodies, which had been generated to detect a wide variety of protein serine/threonine kinases (Ser/Thr kinases), a variety of stage-specific Ser/Thr kinases was detected. Calmodulin (CaM) overlay assay using digoxigenin-labeled CaM detected protein bands of 65 kDa, 58 kDa, 46 kDa, 42 kDa, and 38 kDa only in the presence of CaCl(2), suggesting that these bands were CaM-binding proteins. When the CaM-binding fraction was prepared from mycelial extract of C. cinereus by CaM-Sepharose and analyzed with Multi-PK antibodies, two major immunoreactive bands corresponding to 65 kDa and 46 kDa were detected. CaM-binding fraction, thus obtained, exhibited Ca(2+)/CaM-dependent protein kinase activity toward protein substrates such as histones. These CaM-kinases were found to be highly expressed in the actively growing mycelia, but not in the resting mycelial cells. Mycelial growth was enhanced by the addition of CaCl(2) in the culture media, but inhibited by the addition of EGTA or trifluoperazine, a potent CaM inhibitor. This suggested that CaM-dependent enzymes including CaM-kinases play crucial roles in mycelial growth of basidiomycete C. cinereus.     

Differentiation of murine B cells induced by chondroitin sulfate B

A two-step culture system was used to investigate the role of chondroitin sulfate (CS) B, which is mitogenic to B cells, in differentiation of B cells. Mouse spleen B cells were incubated for 3 days with CSB in the presence of interleukin (IL)-4 and IL-5. After washing, the cells were replated at 10(5) viable cells/well and recultured without CSB in the presence of IL-4 and IL-5. CSB dose-dependently increased IgM production, the greatest enhancement being 450%. Dextran sulfate had a similar effect, whereas other glycosaminoglycans, CSA, CSC, heparin and hyaluronic acid, were marginally effective. Treatment of B cells with CSB resulted in increases in the number of IgM-secreting cells and numbers of CD138-positive cells and CD45R/B220-negative cells. CSB-induced IgM production was inhibited by the protein kinase C (PKC) inhibitor GF109203X but not by the phosphatidylinositol 3-kinase (PI3K) inhibitor wortmannin. These results demonstrated that CSB promoted differentiation of B cells in the presence of IL-4 and IL-5 and suggested that PKC but not PI3K is crucial for CSB-induced IgM production.     

Terminal differentiation of keratinocytes was damaged in type 2 diabetic mice

Molecular Biology Reports - Although skin manifestations are common in diabetic patients, its characteristics are poorly identified. This study explored the differentiation process of keratinocytes...