Normal human dermis has been analyzed using stereological methods to estimate the quantitative modifications of collagen and elastic fibers in relation to age, sex, and body region. Forty-five skin biopsies from the trunk or the limbs of 26 males and 19 females of different age were fixed in glutaraldehyde and osmium tetroxide and embedded in epoxy resin. The relative volumes of collagen and elastic fibers were calculated by the point counting method on 1 micron semithin sections. Photographic sampling was performed on four consecutive dermis layers: the papillary layer and three consecutive layers of reticular dermis. The data were subjected to analysis of variance which showed that all the factors studied exert a significant influence on the relative amounts of collagen and elastic fibers. The fractional volume of collagen fibers is constant throughout all dermis layers analyzed and is always higher in females than in males, except for the second and third decades of life. Collagen fiber density increases with age in both sexes up to 30-40 years, when it starts decreasing. Both the relative volumes and the diameters of elastic fibers increase from papillary to deep reticular dermis. In reticular dermis of both sexes there is an increment of elastic fiber density in the first decade of life, followed by a drop particularly marked in males. After 20 years, the relative volume of elastic fibers displays a decreasing trend in females, whereas it increases in males, attaining the highest values beyond the 40s.

Under the hypotheses of a structurally related binding site for antagonists of G-protein coupled receptors and the ability of cyclic pentapeptides of chiral sequence D1L2D3D4L5 to form rigid structures with which probe the pharmacophoric specificity of these receptors, inhibitors of substance P were designed based on available structure-activity relationships. ITF 1565, cyclo[D-Trp1-Pro2-D-Lys3-D-Trp4-Phe5], antagonized substance P activity mediated by type 1 neurokinin receptor (NK1) whereas it acted weakly against NK2 and did not inhibit endothelin at all. The preferential conformation of the peptide was obtained from nmr spectroscopy and computer calculations, and shown to contain the same beta II-turn and gamma'-turn found in other cyclic pentapeptides with the same chiral sequence. The structure of the peptide was compared with that of the beta-D-glucose molecule that has been proposed as a semirigid scaffold for antagonists of G-protein coupled receptors. The gamma'-turn of the cyclic peptide superimposed well with beta-D-glucose in the chair conformation. Furthermore, when the side chains were considered, the aromatic groups of the two molecules were found to generally overlap. These results support the view of G-protein coupled receptors as possessing structurally similar binding sites for antagonists and suggest that cyclic pentapeptides of chiral sequence D1L2D3D4L5 may be useful as semirigid scaffolds for the design of antagonists of this family of receptors.

1 The ability of three modi®ed tetrapeptides, representing fragments of the C-reactive protein (CRP) sequence and stabilized in the ®rst peptide bond by retro-inverso modi®cation, to a ect the secretion of nitric oxide (NO) was studied in macrophages of BALB/c mice. 2 These tetrapeptides, resembling the aminoacid sequence of tuftsin (CRP I, H-gThr-(R,S)mLys-ProLeu-OH, ITF 1192; CRP II, H-gGly-(R, S)mLys-Pro-Arg-OH, ITF 1127; CRP III, H-gThr-(R,S)mLysPro-Gln-OH, ITF 1193), were able to induce NO synthesis by peritoneal macrophages in a dosedependent manner; the most stimulating dose was 1000 ng ml 71 for CRP II and 100 ng ml 71 for CRP I and CRP III. NO synthesis was not strictly dependent on lipopolysaccharide (LPS) activation. 3 The enhanced e ect of retro-inverso CRP-related analogues on the expression of iNOS (inducible NO synthase) was con®rmed by higher levels of iNOS activity in the cytosol and by the increase in iNOS protein, as evaluated by Western blot analysis, in macrophages stimulated by CPR compared with untreated ones. 4 The production of NO by retro-inverso CRP-peptide analogues was signi®cantly inhibited by dexamethasone (20 mM), N G -monomethyl-L-arginine (L-NMMA) (500 mM) and pyrrolidine dithiocarbamate (PDTC) (100 mM). 5 Retro-inverso CRP-peptide analogues stimulated macrophages to produce high levels of interleukin-1 (IL-1) and tumour necrosis factor-a (TNF-a) in the presence of LPS. 6 Retro-inverso CRP-peptide analogues stimulated NO synthesis by the enhancement of endogenously produced IL-1 and TNF-a, as the treatment of peritoneal macrophages with LPS in the presence of neutralizing anti-IL-1 and anti-TNF monoclonal antibodies (mAbs) reduced retro-inverso analogueinduced NO secretion. Data indicate a predominant role for IL-1a in the induction of NO secretion by retro-inverso analogues. 7 These results suggest that retro-inverso CRP derived analogues act as costimulators of NO and cytokine synthesis in macrophages. The mechanisms by which they cause iNOS induction appear to be strongly dependent on the activation of nuclear factor-kB (NF-kB).

Organic chemistryOrganic chemistry Z 0200 Peptides for the Pharmaceutical Market: Chemical Synthesis and Downstream Processing on an Industrial Scale -[7 refs.]. -(CAPPELLETTI, S.; ANNONI, P.; DI GREGORIO, G.; STARACE, O.; PINORI, M.; Chim. Oggi 20 (2002) 7-8, 47-50; Pept. Unit, Chemi SpA, Cinisello Balsamo, I-20092 Milano, Italy; Eng.) -Lindner 36-233

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