bluuebunny/crossref_metadata_2025 huggingface dataset:
Strategies toward predicting peptide cellular permeability from computed molecular descriptors
Authors: Goodwin J.T. , Conradi R.A. , Burton P.S. , Mao B. , Vidmar T.J.
Published: May 2003

Abstract: The therapeutic efficacy of an orally administered drug is dictated not only by its pharmacological properties such as potency and selectivity, but also its pharmacokinetic properties such as its access to the site of activity. Thorough evaluation of the physicochemical and biological barriers to drug delivery is essential to the selection and successful development of drug candidates. We have demonstrated previously that cellular permeability, as a primary component of drug delivery, is principally dependent upon the desolvation potential of the polar functionalities in the molecule and, secondarily, upon the solute lipophilicity [Conradi, R.A., Hilgers, A.R., Ho, N.F.H., Burton, P.S. (1992) The influence of peptide structure on transport across Caco‐2 cells. II. Peptide bond modification which results in improved permeability. Pharm. Res.9, 473–479]. Increasingly sophisticated computational methods are becoming available for describing molecular structural features proposed to correlate with such molecular physicochemical determinants of permeability. Herein we examine the relationships of various computationally derived molecular geometric descriptors for a set of peptides and peptidomimetics, in the context of experimentally measured hydrogen‐bond potentials and lipophilicities, with their cellular permeabilities. These descriptors include molecular volume, polar and non‐polar surface areas and projected molecular cross‐sectional areas. Particular attention is paid to the roles of solvation treatments and other computational factors in descriptor generation, deconvolution of cellular transport mechanisms and statistical analyses of the resulting data for the development of valid, structure‐based and mechanistically meaningful models of cellular permeability. No significant correlation of cellular permeability with computed descriptors was found. This was primarily because of our inability to identify surrogates for hydrogen‐bond desolvation potential for the solutes from among these descriptors.
Bombyxin exhibits an insulin‐like response to modification in the N‐terminal region of the A chain
Authors: Büllesbach E.E.
Published: May 2003

Abstract: Bombyxin is an insect neurohormone with an insulin‐like structure. The N‐terminal A chain helix, a region which is considered part of the active site in insulin, is almost identical between the two hormones. Bombyxin analogues with modifications at the N‐terminus of the A‐chain were synthesized and investigated for their ability to bind to bombyxin‐specific receptors. While N‐acetylation reduced the affinity to the bombyxin receptor to 18% the removal of glycine (A1) inactivated the hormone completely. Replacement of glycine (A1) by l‐amino acids caused a significant loss in activity (11%) while its replacement by d‐amino acid resulted in active bombyxin analogues (55%). Comparative CD spectroscopy indicated a change in structure for desGly(A1)bombyxin. Although the insect hormone does not have an insulin‐like function it exhibits mammalian insulin‐like structural sensitivity for A chain modifications.
Cyclic and linear bradykinin analogues: implications for B2 antagonist design
Authors: Hsieh K.‐H. , Stewart J.M.
Published: May 2003

Abstract: Bradykinin (BK, Arg‐Pro‐Pro‐Gly‐Phe‐Ser‐Pro‐Phe‐Arg) antagonists are potentially useful for treating inflammation, pain and severe trauma. To identify what chemical features might promote effective antagonism, we replaced Arg1 and Pro7 with structurally constrained and proteolytic‐resistant residues, such as Bip (biphenylalanine), Dip (diphenylalanine) or 2Ind (indane amino acid). To determine which BK folding might lead to favourable interactions with receptors, the effects of cyclo(3,8) vs. cyclo(5,8) analogues were compared. The resulting BK analogues were examined for their agonistic and antagonistic activities in guinea pig ileum, rat uterus and depressor assays. The results suggest that co‐planarity of the residue‐7 side chain with its backbone NH is important for potent agonism as well as antagonism, and a d‐directed side chain is crucial for antagonism. For residue‐1 an l‐orientation is important, and Dip1 may mimic a folded Arg1 side chain to elicit agonistic activities, with Bip1 mimicking an extended Arg1 side chain to elicit inhibitory activities. However, ileal and uterine receptors appear to prefer differently folded BK. For ileum, a BK conformation in which residues‐3 and ‐8 are proximal to each other, but apart from residue‐5, led to improved pA2.
Selective isopeptide bond formation: coupling ubiquitin67–76 with histone 2A114–128 by use of the transfer active ester condensation technique
Authors: Wang P. , Ramage R. , Layfield R. , Landon M. , Mayer R.J.
Published: May 2003

Abstract: A peptide, ubiquitin67–76‐histone 2A114–128 fragment (UBH2AF), was synthesized by selective formation of an isopeptide bond between the C‐terminus of ubiquitin67–76 and the ε‐amino group of lysine‐119 in histone 2A114–128 which contained 4 lysine residues at positions 118, 119, 125 and 127, respectively. The transfer active ester condensation technique, together with the Tnm amine protecting group, were used successfully in the peptide segment coupling reaction.

Leu67‐His‐Leu‐Val‐Leu‐Arg‐Leu‐Arg‐Gly‐Gly76

                   |

    Val114‐Leu‐Leu‐Pro‐Lys(NH2)‐Lys119‐Thr‐Glu‐Ser‐His‐His‐Lys(NH2)‐Ala‐Lys(NH2)‐Gly128

              UBH2AF
The effect of conformation on the membrane permeation of coumarinic acid‐ and phenylpropionic acid‐based cyclic prodrugs of opioid peptides
Authors: Gudmundsson O.S. , Jois S. D. S. , Velde D. G. Vander , Siahaan T.J. , Borchardt R.T. , Wang B.
Published: May 2003

Abstract: In an earlier study using Caco‐2 cells, an in vitro cell culture model of the intestinal mucosa, we have shown that the coumarinic‐based (3 and 4) and the phenylpropionic acid‐based (5 and 6) cyclic prodrugs were more able to permeate the cell monolayers than were the corresponding opioid peptides, [Leu5]‐enkephalin (1, H‐Tyr‐Gly‐Gly‐Phe‐Leu‐OH) and DADLE (2, H‐Tyr‐D‐Ala‐Gly‐Phe‐D‐Leu‐OH). In an attempt to explain the increased permeation of the cyclic prodrugs, we have determined the possible conformations of these cyclic prodrugs in solution, using spectroscopic techniques (2D‐NMR, CD) and molecular dynamics simulations. Spectroscopic as well as molecular dynamic studies indicate that cyclic prodrug 4 exhibits two major conformers (A and B) in solution. Conformer A exhibited a type I β‐turn at Tyr1‐D‐Ala2‐Gly3‐Phe4. The presence of a turn was supported by ROE cross‐peaks between the NH of D‐Ala2 and the NH of Gly3 and between the NH of Gly3 and the NH of Phe4. Conformer B of cyclic prodrug 4 consisted of type II β‐turns at the same positions. The type II turn was stabilized by hydrogen bonding, thus forming a more compact structure, whereas the type I turn did not exhibit similar intramolecular hydrogen bonding. Spectroscopic data for compounds 3, 5 and 6 are consistent with the conclusion that these cyclic prodrugs have solution structures similar to those observed with cyclic prodrug 4. The increased lipophilicity and well‐defined secondary structures in cyclic prodrugs 3–6, but not in the linear peptides 1 and 2, could both contribute to the enhanced ability of these prodrugs to permeate membranes.
The effect of conformation of the acyloxyalkoxy‐based cyclic prodrugs of opioid peptides on their membrane permeability
Authors: Gudmundsson O.S. , Vander Velde D.G. , Jois S.D.S. , Bak A. , Siahaan T.J. , Borchardt R.T.
Published: May 2003

Abstract:In an earlier study using Caco‐2 cells, anin vitrocell culture model of the intestinal mucosa, we have shown that the acyloxyalkoxy‐based cyclic prodrugs3and4of the opioid peptides [Leu5]‐enkephalin(1, H‐Tyr‐GLY‐Gly‐Phe‐Leu‐OH) and DADLE(2, H‐Tyr‐d‐Ala‐Gly‐Phe‐d‐Leu‐OH), respectively, were substrates for apically polarized efflux systems and therefore less able to permeate the cell monolayers than were the opioid peptides themselves. In an attempt to explain how structure may influence the recognition of these cyclic prodrugs as substrates by the apically polarized efflux systems, we have determined the possible solution conformations of3and4using spectroscopic techniques (2D‐NMR, CD) and molecular dynamics simulations. Spectroscopic as well as computational studies indicate that cyclic prodrug4exhibits a major and a minor conformer in a ratio of 3 : 2 where both conformers exhibit γ and β‐turn structures. Spectroscopic, as well as molecular dynamics, studies indicate that the difference between the two conformers involves acis/transinversion occurring at the amide bond between the promoiety and Tyr1. The major conformer has atransamide bond between the promoiety and Tyr1, whereas the minor conformer has acisamide bond. The spectroscopic data indicate that cyclic prodrug3has a structure similar to that of the major conformer in cyclic prodrug4. It has recently been reported that a particular arrangement of polar groups and spatial separation distances is required for substrate recognition by P‐glycoprotein. When the conformation of the acyloxyalkoxy linker was investigated in the major and minor conformers of cyclic prodrug4, with respect to distances between the polar functional groups, this ideal fixed spatial orientation was observed. Interestingly this same spatial orientation of polar functional groups was not observed for other cyclic prodrugs prepared by our laboratory using different chemical linkers (coumarinic acid and phenylpropionic acid) but the same opioid peptides that had previously been shown not to be substrates for the apically polarized efflux systems. Therefore, we hypothesize that the structure and/or the flexibility of the acyloxyalkoxy linker itself allows cyclic prodrugs3and4to adopt conformations that permit ideal arrangement of polar groups in the linker and their fixed spatial orientation. This possibly induces the substrate activity of cyclic prodrugs3and4for the apically polarized efflux systems.
Functional and structural consequences of aromatic residue substitutions within the kringle‐2 domain of tissue‐type plasminogen activator
Authors: Chang Y. , Nilsen S.L. , Castellino F.J.
Published: May 2003

Abstract: Aromatic amino acid residues within kringle domains play important roles in the structural stability and ligand‐binding properties of these protein modules. In previous investigations, it has been demonstrated that the rigidly conserved Trp25 is primarily involved in stabilizing the conformation of the kringle‐2 domain of tissue‐type plasminogen activator (K2tPA), whereas Trp63, Trp74, and Tyr76 function in ω‐amino acid ligand binding, and, to varying extents, in stabilizing the native folding of this kringle module. In the current study, the remaining aromatic residues of K2tPA, viz., Tyr2, Phe3, Tyr9, Tyr35, Tyr52, have been subjected to structure–function analysis via site‐directed mutagenesis studies. Ligand binding was not significantly influenced by conservative amino acid mutations at these residues, but a radical mutation at Tyr35 destabilized the interaction of the ligand with the variant kringle. In addition, as reflected in the values of the melting tempe0ratures, changes at Tyr9 and Tyr52 generally destabilized the native structure of K2tPA to a greater extent than changes at Tyr2, Phe3, and Tyr35. Taken together, results to date show that, in concert with predictions from the crystal structure of K2tPA, ligand binding appears to rely most on the integrity of Trp63 and Trp74, and aromaticity at Tyr76. With regard to aromatic amino acids, kringle folding is most dependent on Tyr9, Trp25, Tyr52, Trp63, and Tyr76. As yet, no obvious major roles have been uncovered for Tyr2, Phe3, or Tyr35 in K2tPA.
Binding and internalization of an ICAM‐1 peptide by the surface receptors of T cells
Authors: Gürsoy R.N. , Siahaan T.J.
Published: May 2003

Abstract: The objective of this work was to evaluate the binding characteristics of a cyclic peptide, cyclo (1, 12)‐Pen1‐Pro2‐Arg3‐Gly4‐Gly5‐Ser6‐Val7‐Leu8‐Val9‐Thr10‐Gly11‐Cys12‐OH (cIBR), to Molt‐3 T cells. This cIBR peptide is derived from sequence numbers 11–20 of intercellular adhesion molecule‐1 (ICAM‐1). Binding studies were performed using a fluorescence‐labeled peptide (FITC‐cIBR) in which the fluorescence marker fluorescein 5‐isothiocyanate (FITC) was conjugated to the N‐terminal of the cIBR peptide. The binding affinity of the FITC‐cIBR peptide to Molt‐3 T cells was evaluated using a FACScan flow cytometer. The binding specificity of the FITC‐cIBR peptide was also confirmed by inhibition of binding using unlabeled peptide (cIBR). The results show that FITC‐cIBR binds to two populations of T cells with different affinities; population 1 has high cell numbers (75%) but low affinity, and population 2 has high binding affinity but low cell numbers (25%). Binding to both populations was saturable and could be inhibited by the unlabeled peptide (cIBR), suggesting a receptor‐mediated binding process. In addition to binding, receptor‐mediated internalization was also observed for population 2; this was confirmed by confocal microscopy and temperature‐dependence studies at 37°C and 4°C. The binding and internalization of this peptide may be carried out by surface receptors on Molt‐3 T cells such as LFA‐1. In the future, the binding and internalization of cIBR peptide can be utilized as a method of targeted drug delivery to leukocytes for the treatment of leukocyte‐related diseases.
Structural recognition of an ICAM‐1 peptide by its receptor on the surface of T cells: conformational studies of cyclo (1, 12)‐Pen‐Pro‐Arg‐Gly‐Gly‐Ser‐Val‐Leu‐Val‐Thr‐Gly‐Cys‐OH
Authors: Gürsoy R.N. , Jois D. S. S. , Siahaan T.J.
Published: May 2003

Abstract: The purpose of this study is to elucidate the solution conformation of cyclic peptide 1 (cIBR), cyclo (1, 12)‐Pen1‐Pro2‐Arg3‐Gly4‐Gly5‐Ser6‐Val7‐Leu8‐Val9‐Thr10‐Gly11‐Cys12‐OH, using NMR, circular dichroism (CD) and molecular dynamics (MD) simulation experiments. cIBR peptide (1), which is derived from the sequence of intercellular adhesion molecule‐1 (ICAM‐1, CD54), inhibits homotypic T‐cell adhesion in vitro. The peptide hinders T‐cell adhesion by inhibiting the leukocyte function‐associated antigen‐1 (LFA‐1, CD11a/CD18) interaction with ICAM‐1. Furthermore, Molt‐3 T cells bind and internalize this peptide via cell surface receptors such as LFA‐1. Peptide internalization by the LFA‐1 receptor is one possible mechanism of inhibition of T‐cell adhesion. The recognition of the peptide by LFA‐1 is due to its sequence and conformation; therefore, this study can provide a better understanding for the conformational requirement of peptide–receptor interactions. The solution structure of 1 was determined using NMR, CD and MD simulation in aqueous solution. NMR showed a major and a minor conformer due to the presence of cis/trans isomerization at the X‐Pro peptide bond. Because the contribution of the minor conformer is very small, this work is focused only on the major conformer. In solution, the major conformer shows a trans‐configuration at the Pen1–Pro2 peptide bond as determined by HMQC NMR. The major conformer shows possible β‐turns at Pro2‐Arg3‐Gly4‐Gly5, Gly5‐Ser6‐Val7‐Leu8, and Val9‐Thr10‐Gly11‐Cys12. The first β‐turn is supported by the ROE connectivities between the NH of Gly4 and the NH of Gly5. The connectivities between the NH of Ser6 and the NH of Val7, followed by the interaction between the amide protons of Val7 and Leu8, support the presence of the second β‐turn. Furthermore, the presence of a β‐turn at Val9‐Thr10‐Gly11‐Cys12 is supported by the NH–NH connectivities between Thr10 and Gly11 and between Gly11 and Cys12. The propensity to form a type I β‐turn structure is also supported by CD spectral analysis. The cIBR peptide (1) shows structural similarity at residues Pro2 to Val7 with the same sequence in the X‐ray structure of D1‐domain of ICAM‐1. The conformation of Pro2 to Val7 in this peptide may be important for its binding selectivity to the LFA‐1 receptor.
Structural and functional characterization of an epitope in the conserved C‐terminal region of HIV‐1 gp120
Authors: Ferrer M. , Sullivan B.J. , Godbout K.L. , Burke E. , Stump H.S. , Godoy J. , Golden A. , Profy A.T. , Van Schravendijk M.R.
Published: May 2003

Abstract: Through an integrated study of the reactivity of a monoclonal antibody, 803‐15.6, with synthetic peptides and native recombinant HIV‐1 envelope glycoprotein gp120, we have obtained structure–functional information on a region of rgp120 not yet elucidated by X‐ray crystallography. mAb 803‐15.6 binds with high affinity and broad cross‐clade specificity to the conserved C‐terminal region (amino acids 502–516) of HIV‐1 rgp120. Phage display selection from a random peptide library identified the core binding motif as AXXKXRH, homologous to residues 502–508. Using quantitative binding analyses, the affinity of mAb 803‐15.6 for native, monomeric recombinant gp120HXB2 (rgp120) was found to be similar to that for the synthetic gp120 peptide (502–516). Circular dichroism studies indicate that the synthetic peptide largely has a random coil conformation in solution. The results therefore suggest that the 803‐15.6 epitope is fully accessible on rgp120 and that this region of rgp120 is as flexible as the synthetic peptide. Residues 502–504 are on the edge of a putative gp41 binding site that has been postulated to change conformation on CD4 binding. However, the affinity of mAb 803‐15.6 for rgp120 is not affected by binding of CD4 and vice‐versa. These results suggest either that the 502–504 region does not change conformation upon CD4 binding, or that recombinant gp120 does not undergo the same changes as occur in the native viral gp120–gp41 oligomer. The detailed characterization of the 803‐15.6 epitope may be useful for further study of the role of the C5 region of gp120 in the viral attachment and fusion process.
Expression analysis of glycogen synthase kinase‐3 in human tissues
Authors: Lau K.‐F. , Miller C.C.J. , Anderton B.H. , Shaw P.‐C.
Published: May 2003

Abstract: Human glycogen synthase kinase‐3 (GSK‐3) is a multisubstrate, proline‐directed kinase that phosphorylates tau, β‐amyloid and neurofilaments. In this study, the expression levels of the two GSK‐3 isoforms, α and β, RNA and proteins in different human tissues were examined. Northern analysis demonstrated that GSK‐3α is encoded by a 2.6‐kb mRNA and GSK‐3β by 8.3‐ and 2.8‐kb mRNAs. The two GSK‐3β mRNA species were variably expressed in different tissues. Northern and quantitative polymerase chain reaction demonstrated that both GSK‐3α and GSK‐3β mRNA were prominently expressed in testis, thymus, prostate and ovary but were low in adult lung and kidney. Western blot analysis showed that the 51‐kDa GSK‐3α protein was highly expressed in lung, ovary, kidney and testis, whereas the 46‐kDa GSK‐3β protein was highly expressed in lung, kidney and brain. The differential expression of GSK‐3α and GSK‐3β mRNA and proteins and the lack of relationship between transcription and translation in some tissues indicate that GSK‐3α and GSK‐3β are subject to different means of regulation.
Conformation of a novel tetrapeptide inhibitor NH2‐d‐Trp‐d‐Met‐Phe(pCl)‐Gla‐NH2bound to farnesyl‐protein transferase
Authors: Bogusky M.J. , Pitzenberger S.M. , Garsky V.M. , Culberson J.C. , Koblan K.S. , Wallace A. , Pessi A.
Published: May 2003

Abstract:Farnesyl‐protein transferase (FPTase) catalyzes the post‐translational farnesylation of the cysteine residue located in the C‐terminal tetrapeptide of the Ras oncoprotein. Prenylation of this residue is essential for membrane association and cell‐transforming activities ofras. Inhibitors of FPTase have been demonstrated to display antitumor activity in both tissue culture and animal models, and thus represent a potential therapeutic strategy for the treatment of human cancers. A synthetic tetrapeptide library, which included an expanded set of 68 l‐,d‐ and noncoded amino acids, has been screened for inhibitors of FPTase activity. The tetrapeptide, NH2‐d‐Trp‐d‐Met‐l‐Phe(pCl)‐l‐Gla‐NH2was shown to be competitive with the isoprenyl cosubstrate, farnesyl diphosphate (FPP) but not with the peptide substrate, the C‐terminal tetrapeptide of the Ras protein. The FPTase‐bound conformation of the inhibitor, NH2‐d‐Trp‐d‐Met‐l‐Phe(pCl)‐l‐Gla‐NH2was determined by NMR spectroscopy. Distance constraints were derived from two‐dimensional transferred nuclear Overhauser effect (TRNOE) experiments. Ligand competition experiments identified the NOEs that originate from the active‐site conformation of the inhibitor. Structures were calculated using a combination of distance geometry and restrained energy minimization. The peptide backbone is shown to adopt a reverse‐turn conformation most closely approximating a type II′β‐turn. The resolved conformation of the inhibitor represents a distinctly different structural motif from that determined for Ras‐competitive inhibitors. Knowledge of the bound conformation of this novel inhibitor provides a template and future direction for the design of new classes of FPTase antagonists.
Insertion of an electronegative sulfur atom in the side chain of position 5 of angiotensin II: changes in the tachyphylactic properties of the peptide
Authors: Zalcberg H. , Assimomytis N. , Magafa V. , Manessi‐Zoupa E. , Cordopatis P. , Shimuta S.I.
Published: May 2003

Abstract: Angiotensin II (AII) analogs bearing n‐Leu, Met or S‐substituted groups for cysteine at position 5 were studied regarding their agonistic and tachyphylactic properties. It was shown that these analogs lowered the relative affinity towards the AT1 receptor as determined by contractile responses, which could be due to the removal of the β‐branching residue at position 5. Insertion of a sulfur atom in a different position away from the attached backbone carbon atom presented no significant difference in EC50 values for these analogs. Interestingly, the S‐bearing analogs at position 5 were full agonists but the tachyphylactic property was lost, in contrast to [n‐Leu5]AII, which still induced reduction of the contractile responses. Nevertheless after replacing the Asp with Sar in position 1 (Sar1) tachyphylaxis was again established. It is concluded that the insertion of Met or an S‐substituted cysteine into the side chain at position 5 of AII may promote interactions with its receptor due to the slight electronegative character of the sulfur atom and changes in the restricted conformational freedom of the Ile5 residue in the AII molecule. This was overcome by Sar1, probably through interactions due to its fully protonated N‐terminal amino group and favoring the conformation responsible for the tachyphylaxis phenomenon.
Determination of structural elements related to the biological activities of a potent decapeptide agonist of human C5a anaphylatoxin
Authors: Vogen S.M. , Prakash O. , Kirnarsky L. , Sanderson S.D. , Sherman S.A.
Published: May 2003

Abstract: The structural features related to the biologic activities of a potent, response‐selective decapeptide agonist of human C5a, YSFKPMPLaR (C5a65–74, Y65, F67, P69, P71, d‐Ala73), were identified by NMR analysis in H2O, DMSO and TFE. This investigation showed that the KPM residues in H2O and the SFKPM residues in DMSO exhibited an extended backbone conformation, whereas a twisted conformation was found in this region in TFE. In H2O, the C‐terminal region (PLaR) adopted a distorted type II β‐turn or a type II/V β‐turn. In the type II/V β‐turn, Leu72 exhibited a conformation typical of a type II β‐turn, whereas d‐Ala73 exhibited a conformation characteristic of a type V β‐turn. Furthermore, a γ‐turn involving residues LaR overlapped with the type II/V β‐turn. In DMSO, the C‐terminal region had the analogous turn‐like motif (type II/V β‐turn overlapping with γ‐turn) found in H2O. In TFE, no β‐turn motifs were formed by the PLaR residues. These turn‐like motifs in the C‐terminal region of the peptide in both H2O and DMSO were in agreement with the biologically important conformations predicted earlier by a structure–function analysis of a related panel of decapeptide analogs. The motifs determined by the NMR analysis of YSFKPMPLaR in H2O and DMSO may represent structural elements important for C5a agonist activity and thus can be used to design the next generation of C5a agonist, partial agonist and antagonist analogs.
Large‐scale synthesis of hematoregulatory nonapeptide SK&F 107647 by fragment coupling
Authors: Hiebl J. , Baumgartner H. , Bernwieser I. , Blanka M. , Bodenteich M. , Leitner K. , Rio A. , Rovenszky F. , Alberts D.P. , Bhatnagar P.K. , Banyard A.F. , Baresch K. , Esch P.M. , Kollmann H. , Mayrhofer G. , Weihtrager H. , Welz W. , Winkler K. , Chen T. , Patel R. , Lantos I. , Stevenson D. , Tubman K.D. , Undheim K.
Published: May 2003

Abstract: Linear and convergent routes for the large‐scale preparation of the hematoregulatory nonapeptide (Glp‐Glu‐Asp)2‐DAS‐(Lys)2 (2, SK&F 107647) were investigated. A convergent approach (‘3 + 2’‐route employing Boc‐and benzyl ester protecting groups) was selected for the preparation of multihundred‐gram quantities of 2. Key steps were the preparation and the coupling of tripeptide hydrochloride (HCl.H)2‐DAS‐(Lys(Z)‐OBn)2 (6, DAS=2,7‐L,L‐diaminosuberic acid) and tripeptide Glp‐Glu(OBn)‐Asp(OBn)‐OH (26). Several coupling reagents were investigated in order to reduce the amount of epimerization of this fragment coupling. TDBTU [O‐(3,4‐dihydro‐4‐oxo‐1, 2, 3‐benzotriazin‐3‐yl‐1, 1, 3, 3‐tetramethyluronium tetrafluoroborate] was identified as the condensation reagent of choice. Using this synthetic route > 97% pure final product in an overall yield of 35% calculated on di‐Boc protected 2,7‐L,L‐diaminosuberic acid was prepared.
Effect of conformation on the conversion of cyclo‐(1,7)‐Gly‐Arg‐Gly‐Asp‐Ser‐Pro‐Asp‐Gly‐OH to its cyclic imide degradation product
Authors: Bogdanowich‐knipp S.J. , Jois S.D.S. , Siahaan T.J.
Published: May 2003

Abstract:The objective of this study was to explain the increased propensity for the conversion of cyclo‐(1,7)‐Gly‐Arg‐Gly‐Asp‐Ser‐Pro‐Asp‐Gly‐OH (1), a vitronectin‐selective inhibitor, to its cyclic imide counterpart cyclo‐(1,7)‐Gly‐Arg‐Gly‐Asu‐Ser‐Pro‐Asp‐Gly‐OH (2). Therefore, we present the conformational analysis of peptides1and2by NMR and molecular dynamic simulations (MD). Several different NMR experiments, including COSY, COSY‐Relay, HOHAHA, NOESY, ROESY, DQF‐COSY and HMQC, were used to: (a) identify each proton in the peptides; (b) determine the sequential assignments; (c) determine thecis–transisomerization of X–Pro peptide bond; and (d) measure the NH–HCαcoupling constants. NOE‐ or ROE‐constraints were used in the MD simulations and energy minimizations to determine the preferred conformations of cyclic peptides1and2. Both cyclic peptides1and2have a stable solution conformation; MD simulations suggest that cyclic peptide1has a distorted type I β‐turn at Arg2‐Gly3‐Asp4‐Ser5 and cyclic peptide2has a pseudo‐type I β−turn at Ser5‐Pro6‐Asp7‐Gly1. A shift in position of the type I β‐turn at Arg2‐Gly3‐Asp4‐Ser5 in peptide1to Ser5‐Pro6‐Asp7‐Gly1 in peptide2occurs upon formation of the cyclic imide at the Asp4 residue. Although the secondary structure of cyclic peptide1is not conducive to succinimide formation, the reaction proceeds via neighbouring group catalysis by the Ser5 side chain. This mechanism is also supported by the intramolecular hydrogen bond network between the hydroxyl side chain and the backbone nitrogen of Ser5. Based on these results, the stability of Asp‐containing peptides cannot be predicted by conformational analysis alone; the influence of anchimeric assistance by surrounding residues must also be considered.
Molecular dynamics study of disulfide bond influence on properties of an RGD peptide. J. Peptide Res., 1999, 53, 188–200.
Authors: Wang Y. , Goh S.‐Y. , Kuczera K.
Published: May 2003

We regret that equations 1–5 on pages 191 and 192 of the above article were printed incorrectly. The correct equations and accompanying text are displayed below. We apologize for any confusion caused.
Lipophilic derivatization of synthetic peptides belonging to NS3 and E2 proteins of GB virus‐C (hepatitis G virus) and its effect on the interaction with model lipid membranes
Authors: Rojo N. , Gómara M.J. , Haro I. , Alsina M.A.
Published: May 2003

Abstract: The synthesis by solid‐phase methodologies of peptides belonging to structural and non‐structural proteins of GB virus C as well as its N‐α‐acylation with myristate and palmitate fatty acids is described. To explore the peptide–lipid interactions we have used liposomes composed of dipalmitoylphosphatidylcholine as model membranes and complementary spectroscopic and calorimetric techniques. Our results show that structural and more clearly the structural lipophilic peptide sequences incorporated into lipid bilayers perturb the packing of lipids and affect their thermotropic properties, more than the non‐structural selected sequence. However, the binding of the synthetic sequences to lipid membranes occurred without any restructuration of the peptides.
Solid‐phase synthesis of polymyxin B1 and analogues via a safety‐catch approach
Authors: de Visser P.C. , Kriek N.M.A.J. , van Hooft P.A.V. , Van Schepdael A. , Filippov D.V. , van der Marel G.A. , Overkleeft H.S. , van Boom J.H. , Noort D.
Published: May 2003

Abstract: As part of a program towards the development of novel antibiotics, a convenient method for solid‐phase synthesis of the cyclic cationic peptide polymyxin B1 and analogues thereof is described. The methodology, based on cleavage‐by‐cyclization using Kenner's safety‐catch linker, yields crude products with purities ranging from 37–67%. Antibacterial assays revealed that analogues 23–26, in which the (S)‐6‐methyloctanoic acid moiety is replaced with shorter acyl chains, exhibit distinct antimicrobial activity. The results suggest that the length of the acyl chain is rather critical for antimicrobial activity. On the other hand, substitution of the hydrophobic ring‐segment D‐Phe‐6/Leu‐7 in polymyxin B1 with dipeptide mimics (i.e. analogues 27–33) resulted in almost complete loss of antimicrobial activity.
Syntheses of cyclic prodrugs of RGD peptidomimetics with various macrocyclic ring sizes: evaluation of physicochemical, transport and antithrombic properties
Authors: He H.T. , Xu C.R. , Song X. , Siahaan T.J.
Published: May 2003

Abstract: The objective of this work was to synthesize cyclic prodrugs 1a–d of RGD peptidomimetics 2a–d with various ring sizes (n[CH2] = 1, 3, 5 and 7) and to evaluate the effect of ring size on their transport, physicochemical, enzymatic stability, and antithrombic properties. The syntheses of cyclic prodrugs 1a–d were achieved by converging two key intermediates, Boc‐Phe‐O‐CH2‐OCO‐OpNP (5) and H2N‐(CH2)n‐CO‐Asp(OBzl)‐OTce (8a–d), to give linear precursors Boc‐Phe‐O‐CH2‐OCO‐HN‐(CH2)n‐CO‐Asp(OBzl)‐OTce (9a–d). The N‐ and C‐terminus protecting groups were removed from 9a–d to give 10a–d. Linear precursors 10a–d were cyclized, and the remaining Bzl‐protecting group was removed to produce cyclic prodrugs 1a–d in around 20% overall yield. The linear RGD peptidomimetics (2a–d) were synthesized using standard Boc‐amino acid chemistry by solution‐phase method. Increasing the ring size by adding methylene groups also increases the hydrophobicity of the cyclic prodrugs and parent RGD peptidomimetics. The transport properties of cyclic prodrugs 1c and 1d were 2.6‐ and 4.4‐fold better than those of parent compounds 2c and 2d, respectively. These results suggest that increasing the hydrophobicity of the cyclic prodrugs and parent RGD peptidomimetics enhanced their transport properties. The hydrodynamic radii of the cyclic prodrugs were also smaller than those of their respective parent compounds, suggesting that the change in size may contribute to their transport properties. The chemical stability of the cyclic prodrugs was affected by the ring size, and the cyclic prodrug with the larger ring size (i.e. 1d) was more stable than the smaller one (i.e. 1a). All the cyclic prodrugs were more stable at pH 4 than at pH 7 and 10. Prodrug‐to‐drug conversion could be induced by isolated esterase as well as esterase found in human plasma. An increase in the length of methylene group (n[CH2] = 1, 3, 5, 7) enhanced the antithrombic activity of the prodrugs and the parent compounds. In summary, the ring size of cyclic prodrugs affected their transport, physicochemical, and antithrombic properties.
Immunofluorescence findings in granuloma faciale: report of two cases
Authors: Zirwas Matthew J. , Abell Edward , Ruben Alan , Silverman Alan R. , Wolff Jeffrey , Deng Jau‐Shyong
Published: May 2003

Background:  Immunofluorescence findings in granuloma faciale have been infrequently described. Reported findings include granular IgA, IgG, IgM, and C3 deposits in the dermoepidermal junction, in blood vessel walls, and on connective tissue fibers; IgG in the basement membrane zone, and IgG around blood vessels.

Observations:  We report two cases of granuloma faciale in which biopsy specimens were sent for routine pathology as well as immunofluorescence. Additional work‐up included serologic testing for markers of lupus erythematosus (LE). Immunofluorescence in both cases revealed granular IgA, IgG, IgM, C3, and C5‐9 deposits along the dermoepidermal junction only. Blood vessel walls and connective tissue fibers were spared. Serologic studies for markers of LE were negative.

Conclusion:  Immunofluorescence findings were essentially identical to those which would be expected in cutaneous LE; however, the combination of negative serologic studies for LE, histopathologic findings typical of granuloma faciale, and clinical findings most consistent with granuloma faciale allowed the diagnosis of granuloma faciale to be rendered with certainty. Interpretation of results of direct immunofluorescence of skin should be correlated with clinical presentation, histopathological findings and other laboratory results in order to render final diagnosis of a given patient.
Metastasis of cutaneous malignant melanoma to angiolipoma: the tumor‐to‐tumor metastasis phenomenon
Authors: Alonso Soledad , Rodríguez‐Peralto José Luis , Pérez‐Espejo Gustavo
Published: May 2003

Background:  Although the phenomenon of tumor‐to tumor metastasis is not rare, it has been reported in only eight cases with malignant melanoma as the primary tumor.

Methods:  This case describes a patient with cutaneous malignant melanoma that metastasized to an angiolipoma. To our knowledge this is the second case of a malignant melanoma metastasizing to another primary cutaneous tumor and the first to do so in a lipoma.

Conclusion:  In this report we present the clinical and histopathologic features of this special case and review the relevant literature.
Cutaneous myoepithelial neoplasms: clinicopathologic and immunohistochemical study of 20 cases suggesting a continuous spectrum ranging from benign mixed tumor of the skin to cutaneous myoepithelioma and myoepithelial carcinoma
Authors: Mentzel Thomas , Requena Luis , Kaddu Steven , Soares de Aleida Luis M. , Sangueza Omar P. , Kutzner Heinz
Published: May 2003

Background:  Myoepithelial neoplasms, both benign and malignant, are rare but well‐established clinicopathologic entities in the salivary glands, the breast, and the lung. Despite similarities between cutaneous sweat glands and glandular structures in the above‐mentioned organs as well as the presence of regular myoepithelial cells around cutaneous eccrine/apocrine glands, the concept of cutaneous myoepithelial neoplasms is still debatable and not commonly accepted.

Methods:  Twenty cutaneous myoepithelial neoplasms have been studied histologically and immunohistochemically.

Results:  Nine neoplasms showed features of benign mixed tumor of the skin (chondroid syringoma) (five females and four males, age range 19–65 years, all cases arose in the head and neck region). Two cases represented the eccrine and seven the apocrine subtype. Interestingly, in three cases of the apocrine subtype, solid areas composed predominantly of myoepithelial cells were detected; these neoplasms were designated as benign mixed tumors with prominent myoepithelial cells. Nine cutaneous neoplasms were composed of spindled, epithelioid, and plasmocytoid cells without ductal differentiation and immunohistochemically stained variably positive for vimentin, epithelial and myogenic markers, S‐100 protein, calponin, and glial fibrillary acidic protein (four females and five males, age range 3–71 years, four cases arose in the head and neck region and one case each on the finger, the thigh, the lower leg, the foot, and the breast, respectively); these neoplasms were designated as cutaneous myoepitheliomas. Two morphologically malignant neoplasms with cytologic and immunohistochemical features of myoepithelial cells arose on the face of a 70‐year‐old female and a 79‐year‐old male patient; these neoplasms were designated as malignant cutaneous myoepitheliomas (cutaneous myoepithelial carcinomas).

Conclusions:  The study suggests a continuous spectrum of cutaneous myoepithelial neoplasms ranging from benign mixed tumor of the skin to cutaneous myoepithelioma and cutaneous myoepithelial carcinoma. Further studies with extended follow‐up information are necessary to establish prognostic factors.
Tick mouth parts occlusive vasculopathy: a localized cryoglobulinemic vasculitic response
Authors: Galaria Noreen A. , Chaudhary Omer , Magro C. M.
Published: May 2003

Background:  The histologic hallmark of most arthropod bite reactions is a deep, wedge‐shaped perivascular and interstitial infiltrate comprising lymphocytes, neutrophils, and eosinophils.

Methods:  We present a case series of six patients in whom tick bite reactions, when examined microscopically, were found to mimic mixed cryoglobulinemic vasculitis.

Results:  Though different in histology, clinically these lesions were indistinguishable from typical tick bite reactions.

Conclusion:  As five of our six biopsy specimens were found to still harbor retained tick parts, it is possible that the actual retention of tick parts was involved in evoking this localized cryoprecipitate reaction.
Granular parakeratosis: a case report and literature review
Authors: Wallace Christopher A. , Pichardo Rita O. , Yosipovitch Gil , Hancox John , Sangueza Omar P.
Published: May 2003

Background:  Granular parakeratosis is suspected to result from an error in epidermal differentiation, leading to variably pruritic, hyperpigmented‐to‐erythematous patches and plaques. Characteristic histopathologic features include a thickened stratum corneum, compact parakeratosis with retention of keratohyalin granules, vascular proliferation, and ectasia. The pathogenesis of this entity is uncertain.

Methods:  We present a case of axillary granular parakeratosis and review the literature.

Results:  The lesion showed a thickened stratum corneum with compact parakeratosis, slight epidermal hyperplasia, and a sparse perivascular lymphohistiocytic infiltrate. Keratohyalin granules were diffusely present within the parakeratotic stratum corneum, and the retained granular layer showed focal vacuolization.

Conclusions:  Granular parakeratosis is a rare form of parakeratosis most often seen in the axilla, although other intertriginous areas may be affected. Unique histopathologic findings allow for a specific diagnosis to be made. Although an irritant contact reaction appears causative, mechanical irritation may also play a role in inducing these skin changes.
An unusual dematiaceous fungal infection of the skin caused by Fonsecaea pedrosoi: a case report and review of the literature
Authors: Hamza Sate H. , Mercado Patricia J. , Skelton Henry G. , Smith Kathleen J.
Published: May 2003

Background:  A case of an unusual dematiaceous fungal infection of the skin in a 43‐year‐old man with diabetes mellitus treated with steroids for reactive airway disease is presented. He developed chromoblastomycosis in the left wrist and was treated with antifungals and multiple surgical excisions.

Results:  Histologic examination of the excised tissue revealed widespread suppurative granulomatous inflammation in the dermis and subcutaneous tissue. Thick‐walled internally septated brown fungal cells were found both inside multinucleated giant cells and extracellularly. Non‐to‐lightly pigmented septate hyphal elements, however, were also identified with special stains and, in retrospect, on one of the routinely stained sections. In culture, the organism was reported to initially grow as soft white colonies that soon turned to black and velvety.

Conclusions:  The two unusual features of this case include the controversial report of the organism's initial growth in culture as soft white colonies and the presence of hyphal elements in addition to the sclerotic bodies in the dermis and subcutaneous tissue. This has not been reported before in human cases of dermal infection by Fonsecaea pedrosoi.
Expression of neurotrophin receptor Trk‐C in nevi and melanomas
Authors: Xu Xiaowei , Tahan Steven R. , Pasha Terri L. , Zhang Paul J.
Published: May 2003

Background:  Neurotrophins (NTs) are growth factors for neurons and other neural crest‐derived cells. Their functions are mediated by 75‐kDa low‐affinity glycoprotein receptor (p75) NT receptor and a family of tyrosine kinase receptors (Trks) that includes Trk‐A, ‐B, and ‐C. Signal transduction through the Trk receptors has been shown to regulate growth and apoptosis of tumors of neuronal origin. In addition, Trk oncogenes have been shown to be rearranged in some non‐neuronal neoplasms. Recently, immunoexpression of NT‐3 has been shown to be significantly higher in melanomas than in banal nevi on cryostat tissue.

Methods:  Since the biologic function of NT‐3 is mediated primarily through Trk‐C, we investigated Trk‐C immunoexpression on paraffin sections of 10 compound nevi and 63 melanomas.

Results:  The expression of Trk‐C was relatively low in compound nevi (30%). Trk‐C expression was overall 62% in melanomas of various stages. Our data show that the expression of Trk‐C increased as melanoma progressed from in situ (58%) to papillary dermal invasion (91%), and then declined in deeper (57%) and metastatic melanomas (31%).

Conclusion:  These findings suggest a possible role of Trk‐C in the progression of early stages of melanoma.
Under the microscope: doctors, lawyers, and melanocytic neoplasms
Authors: Glusac Earl J.
Published: May 2003

Misdiagnosed melanoma remains one of the most common causes of lawsuits in histopathology. Reasons for this are discussed in conjunction with relevant literature, common errors in diagnosis, and strategies to avoid them.
Ofuji's disease with follicular mucinosis and its differential diagnosis from alopecia mucinosa
Authors: Lee J. Yu‐Yun , Tsai Ya‐Ming , Sheu Hamm‐Ming
Published: May 2003

Objectives:  Ofuji's disease (OD) or eosinophilic pustular folliculitis and human immunodeficiency virus‐associated eosinophilic folliculitis (HIV‐EF) both show eosinophil‐rich folliculocentric infiltrates, and it is not clear whether they are distinguishable pathologically. Follicular mucinosis (FM) has been observed in lesions of EF; such cases need to be differentiated from alopecia mucinosa (AM).

Methods:  We compared various pathologic features in 13 cases of OD, 10 cases of non‐OD‐typed papular EF (seven HIV‐positive and three HIV‐negative), and five cases of AM.

Results:  All cases of EF showed eosinophilic infiltrates affecting mainly the isthmus or/and sebaceous gland. Eosinophil‐rich pilosebaceous pustules or/and microabscesses were noted in 69% of the biopsy specimens of OD, 73% of papular EF, 71% of HIV‐EF, and 0% of AM. Mucin deposits, often abundant, were found in sebaceous lobules or/and isthmus in 41% of OD and 100% of AM. Compared with AM, OD with FM tended to show more numerous eosinophils, less abundant mucin, and most significantly, eosinophilic infundibular pustule or sebaceous microabscess.

Conclusion:  Our study suggests that OD and HIV‐EF are indistinguishable pathologically and the diagnosis requires clinical correlation. FM was not uncommonly seen in lesions of OD. OD with FM may be difficult to differentiate from FM, especially in cases presenting with non‐annular or non‐pustular lesions, but the diagnosis might be facilitated by finding eosinophil‐rich pustule, microabscess, or infiltrate in pilosebaceous units microscopically.
Atypical fibroxanthoma with prominent sclerosis
Authors: Bruecks Andrea K. , Medlicott Shaun A. , Trotter Martin J.
Published: May 2003

Background:  Malignant cutaneous spindle cell lesions with marked sclerosis are uncommon. Only a few cases of cutaneous leiomyosarcoma and dermatofibrosarcoma protuberans with sclerosis have been published.

Methods:  We report a case of atypical fibroxanthoma (AFX) with prominent sclerosis and hyalinization occurring on the scalp of an 81‐year‐old male.

Results:  Histopathologic examination revealed an exophytic, well‐delineated, focally ulcerated tumor arising in sun‐damaged skin. The lesion was composed of atypical spindle cells arranged in a fascicled and vaguely storiform pattern. Occasional multinucleated giant cells were present. The tumor cells were strongly positive for CD99 (O13), vimentin, and smooth muscle actin, and focally positive for CD68. There was striking sclerosis with hyalinization throughout the lesion.

Conclusions:  Rarely, AFX may exhibit marked sclerosis with areas of complete replacement of tumor by hyalinized collagen. In a small biopsy, such hyalinization may be a diagnostic pitfall leading to an erroneous diagnosis.
Optoelectronic measures in the analysis of running target shooting
Authors: Mononen K. , Viitasalo J. T. , Era P. , Konttinen N.
Published: May 2003

In this study, we examined the construct validity and practical significance of an optoelectronic shooting training system (Noptel ST 2000 Sport) for the technical analysis of running target shooting. A total of 37 male shooters of three different skill levels participated in the study. Principal component analysis revealed four common factors of 16 variables describing the aiming trajectory of the rifle barrel: (i) Holding area, (ii) Accuracy of aiming, (iii) Cleanness of triggering and (iv) Time on target. These factors were suggested to describe the essential components of running target shooting. According to the discriminant analysis, the shooters of various skill levels seemed to discriminate successfully into three groups when the aiming trajectory data were analysed. Finally, the aiming trajectory variables represented a 43% of the total variance in the shooting score. In summary, the present data indicated that the optoelectronic shooting training system had practical significance and supported the technical analysis of rifle barrel movement in running target shooting. A sub‐set of variables, which reflect the essential information of running target shooting performance, were outlined for training and coaching purposes.
Soccer injuries in childhood
Authors: Kakavelakis K. N. , Vlazakis S. , Vlahakis I. , Charissis G.
Published: May 2003

A prospective study of soccer injuries, involving 287 male youth players, from the ages of 12–15 was conducted in 24 Greek soccer clubs, during the course of one year. A total of 193 players sustained 209 injuries. The incidence of injuries was 4.0 injuries per 1000 h of soccer time per player, and the most common types of injuries were sprains and strains. Surprisingly, it was found that an increase of injury incidences occurred during practice. Fifty‐eight injuries required medical assistance. The majority of injuries (80%) were located in the lower extremities. Collision with other players was the most common activity at the time of injury, accounting for 40% of all injuries. The conclusion of this study and the evidence from other studies suggests that youth soccer is a relatively low risk sport. However, a substantial amount of injuries could be prevented. It is necessary to identify the risk factors, which are associated with these types of injuries.