bluuebunny/crossref_metadata_2025 huggingface dataset:
Psychotische Störungen und Drogenmissbrauch bei Jugendlichen
Authors: Fleischhaker C. , Schulz E. , Priemer K. , Remschmidt H.
Published: May 2003

Zusammenfassung: Fragestellung: Der Zusammenhang zwischen Drogenabusus und psychotischen Symptomen wird anhand einer klinischen Inanspruchnahmepopulation der Klinik für Psychiatrie und Psychotherapie des Kindes- und Jugendalters der Philipps-Universität Marburg evaluiert. Methodik: Es wurden alle Patienten mit einem komorbiden Drogenabusus unter Verwendung einer Kinder- und Jugendlichen Version des IRAOS (Instrument of the retrospective assessment of the onset of schizophrenia, Häfner et al., 1990) in die Evaluation eingeschlossen. Patienten mit einer drogeninduzierten Psychose (n = 8) wurden im Vergleich zu schizophren erkrankten Patienten mit komorbidem Substanzabusus (n = 19) und zu Patienten mit anderen psychiatrischen Erkrankungen und Substanzabusus (n = 30) untersucht. Ergebnisse: Diese drei Gruppen unterschieden sich signifikant anhand der Belastung mit prämorbiden Symptomen und anhand der Charakteristika des Erkrankungsbeginns. Schlussfolgerungen: Anhand des IRAOS ergibt sich, dass sich schizophren erkrankte Patienten mit komorbidem Substanzabusus von Patienten mit einer drogeninduzierten Psychose anhand des Verlaufs der initialen Psychopathologie und prämorbiden Auffälligkeiten unterscheiden lassen.
Gibt es einen zeitlichen Zusammenhang von Substanzmissbrauch und Psychose bei Jugendlichen?
Authors: Holtmann M. , Becker K. , Schmidt M. H. , Hartmann M.
Published: May 2003

Zusammenfassung: Fragestellung: Es soll der zeitliche Zusammenhang zwischen Substanzmissbrauch und psychotischen Symptomen jugendlicher Patienten untersucht werden. Methodik: Die Krankenblätter aller in den Jahren 1976 bis 1997 erstmals wegen psychotischer Symptome in der Klinik für Psychiatrie und Psychotherapie des Kindes- und Jugendalters am Zentralinstitut für Seelische Gesundheit in Mannheim stationär aufgenommenen jugendlichen Patienten wurden retrospektiv im Hinblick auf komorbiden Substanzmissbrauch untersucht. Ergebnisse: Von 165 Patienten mit psychotischen Störungen lag bei 18 ein komorbider Gebrauch psychotroper Substanzen vor. Die Häufigkeit von begleitendem Substanzabusus stieg nach 1988 an, mit einem erneuten steilen Anstieg seit 1996. Zwei der 18 Jugendlichen begannen den Substanzmissbrauch erst nach dem Auftreten erster psychotischer Symptome, 13 hatten den Missbrauch längere Zeit zuvor begonnen; bei drei Patienten fielen der Beginn der psychotischen Symptome und des Abusus in denselben Monat. Eine enge zeitliche Beziehung zwischen psychotischen Symptomen und Drogenmissbrauch fand sich für Amphetamine (einschließlich Ecstasy), LSD und exzessiven Cannabisabusus. Schlussfolgerungen: Substanzmissbrauch stellt einen Risikofaktor für die Entwicklung psychotischer Störungen dar, ohne notwendigerweise eine direkt auslösende Wirkung zu haben.
Interindividuelle Unterschiede im typischen intellektuellen Engagement
Authors: Wilhelm Oliver , Schulze Ralf , Schmiedek Florian , Süß Heinz-Martin
Published: May 2003

Zusammenfassung. Leistungskriterien werden in der Regel unter Verwendung von Verfahren zur Erfassung maximalen Verhaltens erklärt. Es wird ein Ansatz präsentiert, der neben maximalem auch typisches Verhalten berücksichtigt, um die Vorhersage und Erklärung von Leistungskriterien zu verbessern. In vier Studien wurde mehreren Fragestellungen zum typischen intellektuellen Engagement (TIE) nachgegangen. In den Studien 1 bis 3 wurde ein übersetztes Messinstrument erstmals eingesetzt und psychometrisch evaluiert sowie diskriminant und konvergent validiert. In den Studien 2 und 3 wurde zusätzlich geprüft, inwieweit das neue Verfahren inkrementell Varianz an Schulnoten aufklärt. In Studie 4 wurde die Retestreliabilität des Verfahrens überprüft. Die empirischen Befunde sind weitgehend erwartungskonform und unterstützen die folgenden Schlussfolgerungen: Die Etablierung eines befriedigenden Messmodells, mit den drei Faktoren “intellektuelle Neugier“, “Kontemplation“ und “Lesen“, gelingt für eine Kurzfassung des Messinstruments. Konvergent ergeben sich sehr hohe Zusammenhänge mit Messinstrumenten gleicher Messintention. TIE sagt Schulleistungen nach Berücksichtigung maximalen intellektuellen Verhaltens inkrementell vorher.
Psychometrische Eigenschaften und Normen einer deutschsprachigen Fassung der Sensation Seeking-Skalen, Form V
Authors: Beauducel André , Strobel Alexander , Brocke Burkhard
Published: May 2003

Zusammenfassung. Die Sensation Seeking-Skalen, Form V (SSS-V) sind eines der am häufigsten eingesetzten Inventare zur Erfassung von Sensation Seeking. Allerdings wurden immer wieder geringe interne Konsistenzen und Probleme bei der Replikation der Faktorenstruktur, insbesondere für die Subskalen Experience Seeking und Boredom Susceptibility berichtet. Im Vergleich zu Alternativen hat die SSS-V allerdings den Vorteil einer differenzierteren Erfassung des Konstrukts, weshalb die neueren Inventare sich nicht durchsetzen konnten. Vor dem Hintergrund dieser Situation bestanden die Ziele der vorliegenden Arbeit in der Untersuchung der psychometrischen Eigenschaften einer von Marvin Zuckerman autorisierten deutschsprachigen SSS-V, der Gewinnung von Normen sowie optimierter Personenkennwerte anhand von Faktorwerten. Dazu wurde eine Stichprobe von 1526 Probanden (823 weiblich) im Alter von 16 bis 68 Jahren mit der SSS-V untersucht. Die vierfaktorielle Struktur der SSS-V konnte anhand einer exploratorischen Faktorenanalyse paarweiser Itemaggregate bestätigt werden. B-Gewichte zur Ermittlung von Faktorwerten sowie Normen für den deutschsprachigen Raum werden mit dieser Arbeit zur Verfügung gestellt.
Soziale Unterstützung bei der Krankheitsbewältigung: Die Berliner Social Support Skalen (BSSS)
Authors: Schulz Ute , Schwarzer Ralf
Published: May 2003

Zusammenfassung. Die Berliner Social Support Skalen (BSSS; Schwarzer & Schulz, 2000 ) unterscheiden sich von anderen Fragebogenverfahren zur sozialen Unterstützung durch ihren mehrdimensionalen Ansatz: Sowohl kognitive als auch behaviorale Aspekte sozialer Unterstützung können mit den insgesamt 6 Skalen (Wahrgenommene, Erhaltene und Geleistete Unterstützung, Bedürfnis und Suche nach Unterstützung, Protektives Abfedern) erhoben werden. Die vorliegende Untersuchung beruht auf einer Stichprobe von 457 Krebspatienten, die mehrmals vor und nach einer Operation befragt wurden. In dieser Studie erwiesen sich die Skalen als psychometrisch befriedigend. Zahlreiche Hinweise auf die Validität konnten ermittelt werden. Unter anderem war es möglich, auch die erhaltene Patientenunterstützung durch die Unterstützung seitens des Partners vorherzusagen. Das beschriebene Inventar steht unter http://www.coping.de zur Verfügung.
Psychometrische Überprüfung einer Kurzform des Fragebogens zur Psychotherapiemotivation - FPTM-23
Authors: Schulz Holger , Lang Klaus , Nübling Rüdiger , Koch Uwe
Published: May 2003

Zusammenfassung. Die Erfassung von Psychotherapiemotivation kann in der Grundlagenforschung, in Interventionsstudien, im Rahmen der Bedarfsplanung und der therapeutischen Praxis indiziert sein. Ziel dieser Arbeit ist es, eine auf 23 Items verkürzte Version des Fragebogen zur Psychotherapiemotivation FPTM ( Schulz et al., 2000 ; Schulz, Nübling & Rüddel, 1995 ) einer psychometrischen Prüfung zu unterziehen. Untersucht wurde eine weitgehend repräsentative Stichprobe von 4638 Patienten der stationären Psychotherapie. Die ursprüngliche 6-Faktorenstruktur konnte dabei vollständig repliziert werden, die gebildeten Skalen weisen zudem ausreichend hohe interne Konsistenzen auf. Es ergeben sich hypothesenkonforme Zusammenhänge u.a. zu verschiedenen Beschwerdemaßen, der Intention zur Mitarbeit, dem Wunsch nach einer konkreten Psychotherapieschule und der Eigeninitiative zur stationären Behandlung. Mit dem FPTM-23 wird ein ökonomisches Selbstbeurteilungsverfahren zur Diskussion gestellt, das faktorenanalytisch überprüft ist, zufriedenstellende psychometrische Kennwerte und erste positive Ergebnisse zur Konstruktvalidierung aufweist.
Der interaktionelle Ansatz in der Kognitionswissenschaft:
Authors: Tschacher Wolfgang , Scheier Christian
Published: May 2003

Zusammenfassung. Seit der kognitiven Wende besteht eine enge Anlehnung der Psychologie an die Computertechnologie und die Künstliche-Intelligenz-Forschung. Der “computationalistische“ Ansatz geht von einer (meist sequenziell gedachten) Abfolge symbolischer Verarbeitungsschritte aus. Zwischen Wahrnehmung und Handlung werden “höhere“ Prozesse wie Kategorisierung, Gedächtnis und Planung angenommen. Solche Prozesse sind als eigenständige Module ohne direkte Schnittstelle zur Umwelt gedacht. Dieser Ansatz wird in der vorliegenden Positionsarbeit wegen seiner inhärenten fundamentalen Probleme kritisiert. Alternative Forschungsprogramme fordern eine Hinwendung zu Situiertheit und “embodiment“ von Kognition, die nicht unabhängig von Umwelt und Verhalten verstanden werden kann. Eine neue Methode dieser interaktionellen Sicht stellen autonome Agenten (Roboter) dar. Konsequenzen für die Psychologie werden herausgearbeitet, zunächst eine theoretische Konzeptualisierung autonomer Agenten basierend auf der Theorie dynamischer Systeme und Synergetik. Kognition wird als komplexes System vieler sensomotorischer Schleifen konzipiert; kohärente und adaptive Wahrnehmungs-Handlungsprozesse emergieren unter Einwirkung von Affordanzen. Anhand von Beispielen aus der angewandten Psychologie wird gezeigt, dass diese Perspektive zu neuen Forschungsfragen und Erklärungsansätzen für empirische Befunde führt.
Induktive Vermutungen über die Anwendbarkeit von Theorien und Methoden nach erfolgreichen und gescheiterten Anwendungsfällen
Authors: Lütkemeier Elke , Westermann Rainer , Gerjets Peter
Published: May 2003

Zusammenfassung. In wissenschaftlichen Forschungskontexten und praktischen Handlungszusammenhängen werden häufig auf der Grundlage bisheriger Erfahrungen Vermutungen über die erfolgreiche Anwendbarkeit einer Theorie oder Methode auf neue Anwendungsfälle angestellt. Innerhalb der strukturalistischen Theorienkonzeption lassen sich derartige induktive Inferenzen als empirische Vermutungen beschreiben. In drei Experimenten werden die Determinanten empirischer Vermutungen untersucht. Die Untersuchungsergebnisse weisen auf die Notwendigkeit einer Differenzierung zwischen Informationsbewertung und Informationsauswahl hin. So werden induktive Vermutungen im Kontext der Informationsbewertung in gleichem Ausmaß von erfolgreichen und gescheiterten Anwendungen beeinflusst, wogegen im Kontext der Informationsauswahl erfolgreiche gegenüber gescheiterten Anwendungen bevorzugt werden.
Cystic fibrosis in Greece: molecular diagnosis, haplotypes, prenatal diagnosis and carrier identification amongst high‐risk individuals
Authors: Kanavakis E , Efthymiadou A , Strofalis S , Doudounakis S , Traeger‐Synodinos J , Tzetis M
Published: May 2003

Cystic fibrosis (CF) mutation analysis on 437 CF patients, characterized 80 different mutations (20 so far specific to our population) accounting for 91% of CF genes and generating 103 different genotypes. Eight mutations were common [F508del (53.4%), 621+1G>T (5.7%), G542X (3.9%), N1303K (2.6%), 2789+5G>A (1.7%), 2183AA>G (1.4%), E822X (1.4%), R1158X (1%)], 12 showed frequencies between 0.5% and 1%, while the remaining (60) were very rare (1 to 3 alleles). Denaturing gradient gel electrophoresis (DGGE) screening of 12 exons (3, 4, 7, 10, 11, 13, 14b, 16, 17b 20 and 21) detected 85.5% of CF alleles. Haplotypes for eight diallelic and three microsatellite markers have been characterized for the common, a few rare and novel Greek mutations. Results of 165 prenatal diagnoses (including 49 due to bowel hyperechogenicity), testing a total of 41 different parental genotypes, are reported. One hundred and sixteen prenatal tests resulted in 22 affected, 59 heterozygous, 34 normal fetuses and one incomplete diagnosis. Of the 49 echogenic bowel fetuses, 3 were heterozygotes. Carrier screening was initiated, with emphasis on individuals and couples in high‐risk groups – with a family history of CF, one partner with CF, and couples with male infertility seeking in vitro fertilization (IVF). Mutation analysis on 672 individuals (120 couples, 91 unaffected CF siblings, 283 CF family relatives and 58 general population subjects), identified a total of 176 heterozygotes and 7 couples where both partners were CF heterozygotes. Prenatal diagnosis was performed in 4 cases and 3 were counseled on the availability of a prenatal test.
Analysis of marker or complex chromosomal rearrangements present in pre‐ and post‐natal karyotypes utilizing a combination of G‐banding, spectral karyotyping and fluorescence in situ hybridization
Authors: Heng HHQ , Ye CJ , Yang F , Ebrahim S , Liu G , Bremer SW , Thomas CM , Ye J , Chen TJ , Tuck‐Muller C , Yu JW , Krawetz SA , Johnson A
Published: May 2003

The significance of complex chromosomal rearrangements presents a diagnostic dilemma. In the past, the use of G‐banding coupled with fluorescence in situ hybridization (FISH) has been the standard approach. The recent development of spectral karyotyping (SKY) and multicolor FISH (M‐FISH) has resulted in an increased accuracy of identification of marker or other complex chromosomal rearrangements. However, owing to the additional cost and time associated with SKY or M‐FISH, and the restricted availability of such imaging facilities in many centers, it is not feasible to perform these procedures routinely on every sample. In addition, the identification of an aberration by SKY or M‐FISH will often require confirmation by FISH. A practical approach is needed to take advantage of the complementary strengths of each method. In our center we utilize an algorithm that dictates the use of routine G‐banding for the initial preliminary evaluation of a patient, followed by SKY characterization if marker chromosomes or complex translocations are detected by the G‐banding analysis. According to this algorithm, FISH is used to verify the results once the origin of the abnormal chromosome has been determined by SKY. To demonstrate the effectiveness of this algorithm, we have analyzed both amniocyte and lymphocyte slides, using a combination of G‐banding, SKY, and FISH. Our results confirm that an algorithm which selectively uses SKY or M‐FISH will provide an efficient and improved method for pre‐ and post‐natal chromosomal analysis.
Hyperkeratosis and leukocytosis in transgenic mice carrying MHC class I chain‐related gene B (MICB)
Authors: Nomura E. , Sato M. , Suemizu H. , Watanabe T. , Kimura T. , Yabuki K. , Goto K. , Bahram S. , Inoko H. , Ito N. , Mizuki N. , Ohno S. , Kimura M.
Published: May 2003

Abstract: Major histocompatibility complex (MHC) class I chain‐related gene A and B (MICA and MICB) are located very close to HLA‐B. MICA is reported to be strongly associated with Behçet's disease (BD), a multisysytemic inflammation disorder characterized by oral apthous ulcers, skin lesions and genital ulcers. These two molecules are highly conserved at the amino acid levels. To determine the function of MICB in vivo and the relationship between the expression of MICB and BD experimentally, we produced several transgenic mouse lines (termed CAG‐MICB) expressing human MICB cDNA under a ubiquitous promoter. They exhibited a 50% increase in the number of white blood cells compared with their non‐transgenic littermates, and also exhibited a 10–20% reduction in body weight compared with non‐transgenic littermates. Exfoliation of the skin first appeared around 7 days after birth and disappeared after 2 weeks of age. This was repeatedly observed in the transgenic offspring of two independent CAG‐MICB lines examined. Histopathological analysis of skin of young mice exhibiting skin abnormalities revealed hyperkeratosis of the epidermis and thickening of the granular layer with slight infiltration of inflammatory cells in the dermis without any vasculitis. Other remarkable abnormalities associated with BD have not been observed in the CAG‐MICB lines. Furthermore, fluorescein angiography of eyes of the CAG‐MICB lines was performed, but there were no marked changes of BD‐related uveitis in the ocular fundus. These findings suggest that (i) MICB expression is related to temporary skin inflammation, and (ii) expression of MICB is not directly associated with BD.
Distribution of HLA‐A alleles in eight ethnic groups from Pakistan
Authors: Mohyuddin A. , Williams F. , Mansoor A. , Mehdi S.Q. , Middleton D.
Published: May 2003

Abstract: The extreme polymorphism found at some loci of the HLA system has made it an invaluable tool for population genetic analyses. In this study eight diverse ethnic groups from Pakistan were analyzed at the HLA‐A locus using sequence specific primers for polymerase chain reaction (PCR‐SSP) and then further typed to the allele level using a two‐stage sequence specific oligonucleotide probe (SSOP) strategy. Four of these ethnic groups (Burusho, Hazara, Kalash, Pathan) were from the north and four (Baloch, Brahui, Sindhi and Parsi) were from the south of Pakistan. Nine alleles were identified as unique to a particular ethnic group within Pakistan. Maximum variation was seen in the HLA‐A*02 allele family for which 11 alleles were detected in the eight Pakistani ethnic groups. The alleles that showed significant variation between the Pakistani ethnic groups include A*0101, A*0206, A*0209, A*0207, A*0217, A*1101, A*2402/09 N/11 N, A*2902, A*3301 and A*3001. A phylogenetic tree based on DA distances for HLA‐A allele frequencies separated the Pakistani populations from other world populations and also separated the only Dravidian speaking population of Pakistan, the Brahui, from the remaining Indo‐European speaking ethnic groups of Pakistan.
Synthesis and kinetics of cyclization of MHC class II‐derived cyclic peptide vaccine for diabetes
Authors: Berezhkovskiy L. , Pham S. , Reich E.‐P. , Deshpande S.
Published: May 2003

Abstract: Conformationally constrained cyclic peptides are known to be better vaccines because of their ability to mimic the native structure of a protein against which an immune response is sought. To test the hypothesis of using conformationally constrained, disease‐associated, MHC‐derived peptides as vaccines for the prevention of type I diabetes, a 22 amino acid nonobese diabetic(NOD) mouse MHC class II‐derived synthetic peptide was cyclized by the formation of end‐to‐end disulfide bonds and used to prevent diabetes and insulitis in NOD mice. The peptide was synthesized by Fmoc chemistry and cyclized using two methods: a commercially available cyclizing resin (Ekathiox) and air oxidation. When a 10 m excess of resin was used, the Ekathiox yielded a substantial amount of cyclic peptide with few or no side reactions. The kinetics of cyclization by air oxidation at different temperatures indicated that increasing both temperature and pH decreased the cyclization time significantly. Air oxidation at pH 10 at 37–55 °C yielded the desired product within 2 h.
Fluoroalcohols as structure modifiers in peptides and proteins: hexafluoroacetone hydrate stabilizes a helical conformation of melittin at low pH
Authors: Bhattacharjya S. , Venkatraman J. , Balaram P. , Kumar A.
Published: May 2003

Abstract: The effect of hexafluoroacetone hydrate (HFA) on the structure of the honey bee venom peptide melittin has been investigated. In aqueous solution at low pH melittin is predominantly unstructured. Addition of HFA at pH ≈ 2.0 induces a structural transition from the unstructured state to a predominantly helical conformation as suggested by intense diagnostic far UV CD bands. The structural transition is highly cooperative and complete at 3.6 m (50% v/v) HFA. A similar structural transition is also observed in 2,2,2 trifluoroethanol which is complete only at a cosolvent concentration of ≈ 8 m. Temperature dependent CD experiments support a ‘cold denaturation’ of melittin at low concentrations of HFA, suggesting that selective solvation of peptide by HFA is mediated by hydrophobic interactions. NMR studies in 3.6 m HFA establish a well‐defined helical structure of melittin at low pH, as suggested by the presence of strong NHi/NHi+1 NOEs throughout the sequence, along with many medium range helical NOEs. Structure calculations using NOE‐driven distance constraints reveal a well‐ordered helical fold with a relatively flexible segment around residues T10–G11–T12. The helical structure of melittin obtained at 3.6 m HFA at low pH is similar to those determined in methanolic solution and perdeuterated dodecylphosphocholine micelles. HFA as a cosolvent facilitates helix formation even in the highly charged C‐terminal segment.
A novel d‐leucine‐containing Conus peptide: diverse conformational dynamics in the contryphan family
Authors: Jacobsen R.B. , Jimenez E.C. , De la Cruz R.G.C. , Gray W.R. , Cruz L.J. , Olivera B.M.
Published: May 2003

Abstract: A Conus peptide family (the contryphans) is noteworthy because of the presence of a post‐translationally modified d‐amino acid in all members of the family. A new contryphan peptide, Leu‐contryphan‐P, was isolated from the venom of Conus purpurascens; the sequence of this peptide is:

Gly‐Cys‐Val‐D‐Leu‐Leu‐Pro‐Trp‐Cys‐OH

This is the first known occurrence of d‐leucine in a Conus peptide. The discovery of Leu‐contryphan‐P suggests that there may be branches of the contryphan peptide family that diverge much more in sequence than previously anticipated. Several natural contryphans provide dramatic examples of inter‐conversion between multiple conformational states in small constrained peptides. The contryphans that have 4‐trans‐hydroxyproline and d‐tryptophan in positions 3 and 4, respectively, exhibit two peaks under reverse‐phase HPLC conditions, indicating interconversion between two discrete conformations. However, [l‐Trp4]contryphan‐Sm (with l‐Trp substituted for d‐Trp) exhibits a single, broad peak that elutes later than the natural peptide, suggesting that d‐Trp stabilizes a conformation in which hydrophobic residues are buried. Leu‐contryphan‐P which has valine and d‐leucine instead of 4‐trans‐hydroxyproline and d‐tryptophan shows only a single peak that elutes much later than the other contryphans.
Design, synthesis and characterization of antimicrobial pseudopeptides corresponding to membrane‐active peptide
Authors: Oh J.E. , Hong S.Y. , Lee K.‐H.
Published: May 2003

Abstract: To obtain active and metabolically stable analogues, peptide backbone modifications have been incorporated into many biologically active peptides. In this study, we designed and synthesized pseudopeptides corresponding to the antimicrobial peptide that acted on the lipid membrane of the pathogen. Most pseudopeptides exhibited a longer half‐life than the peptide in the presence of serum as well as a considerable activity against test bacteria and fungi. Circular dichroism spectra and retention times of the pseudopeptides helped us to elucidate the effect of the incorporation of backbone modifications on the structural parameters necessary for the activity, indicating that α‐helical structure was the most important factor for the activity and hydrophobicity had a considerable effect on the activity. Backbone modifications employed in this study can be a useful tool for structure–activity relationship studies and the development of therapeutic agents from membrane‐active antimicrobial peptides.
The solution structure of uperin 3.6, an antibiotic peptide from the granular dorsal glands of the Australian toadlet, Uperoleia mjobergii
Authors: Chia B.C.S. , Bowie J.H. , Carver J.A. , Mulhern T.D.
Published: May 2003

Abstract: Uperin 3.6 (GVIDA5AKKVV10NVLKN15LF‐NH2) is a wide‐spectrum antibiotic peptide isolated from the Australian toadlet, Uperoleia mjobergii. With only 17 amino acid residues, it is smaller than most other wide‐spectrum antibiotic peptides isolated from amphibians. In 50% (by vol.) trifluoroethanol, an NMR study and structure calculations indicate that uperin 3.6 adopts a well‐defined amphipathic α‐helix with distinct hydrophilic and hydrophobic faces. Examination of the activities of synthetic modifications of uperin 3.6 reveal that the three lysine residues are essential for antibiotic activity.
Development of a photoreactive parathyroid hormone antagonist to probe antagonist–receptor bimolecular interaction
Authors: Bisello A. , Behar V. , Greenberg Z. , Suva L.J. , Rosenblatt M. , Chorev M.
Published: May 2003

Abstract: Parathyroid hormone (PTH) and PTH‐related protein (PTHrP) exert their calciotropic activities by binding to a specific seven‐transmembrane‐helix‐containing G protein‐coupled receptor mainly located in bone and kidney cells. In order to map in detail the nature of hormone–receptor interaction, we are employing ‘photoaffinity scanning’ of the bimolecular interface. To this end, we have developed photoreactive benzophenone (BP)‐containing PTH analogs which can be specifically and efficiently cross‐linked to the human (h) PTH/PTHrP receptor. In this report, we describe the photocross‐linking of a BP‐containing PTH antagonist, [Nle8,18,D‐2‐Nal12,Lys13(ε‐BP),2‐Nal23,Tyr34]bPTH(7‐34)NH2 (ANT) to the recombinant hPTH/PTHrP receptor stably expressed in human embryonic kidney cells (HEK‐293, clone C‐21). This photoreactive antagonist has high affinity for the hPTH/PTHrP receptor and inhibits agonist‐induced cyclase activity and intracellular calcium release. The photo‐induced cross‐linking of the radioiodinated antagonist (125I‐ANT) to the recombinant hPTH/PTHrP receptor followed by SDS–PAGE analysis reveals a single radiolabeled band of ≈ 85 kDa, similar to that observed after cross‐linking of a radioiodinated BP‐containing agonist. The formation of this covalent 125I‐ANT – hPTH/PTHrP receptor conjugate is competed dose‐dependently by a variety of unlabelled PTH‐ and PTHrP‐derived agonists and antagonists. This is the first report of a specific and efficient photocross‐linking of a radioiodinated PTH antagonist to the hPTH/PTHrP receptor. Therefore, it provides the opportunity to study directly the nature of the bimolecular interaction of PTH antagonist with the hPTH/PTHrP receptor.
Synthesis and cytostatic activities of didemnin derivatives*
Authors: Schmidt U. , Griesser H. , Haas G. , Kroner M. , Riedl B. , Schumacher A. , Sutoris F. , Haupt A. , Emling F.
Published: May 2003

Abstract: The highly cytostatic didemnins contain a 23‐membered cyclopeptolide with a side chain attached to the backbone through the amine group of threonine. Thirty‐six derivatives varying the side chain were prepared, but only compounds with D‐MeLeu attached to threonine show remarkable biological activities. To protect the macrocycle from degradation by lipases the two ester bonds were replaced successively by amide bonds. Although these variations have a major effect on the conformation and rigidity of the ring, the compound which contains exclusively amide bonds is highly active, equivalent to acetyl‐didemnin A.
Isolation and characterization of a novel superoxide dismutase from fungal strain Humicola lutea 110
Authors: Dolashka‐angelova P. , Hristova R. , Genova L. , Angelova M. , Pashova S. , Stoeva S. , Voelter W. , Stefanov B.
Published: May 2003

Abstract: A novel thermostable MnSOD was purified to electrophoretic homogeneity from the fungal strain Humicola lutea 110. The preparation of the pure metalloenzyme was performed using treatment with acetone followed by ion exchange and gel permeation chromatography. We found that the activity of this enzyme comprises about 80% of the total superoxide dismutase activity in the crude extract, containing two proteins: MnSOD and Cu/ZnSOD. The MnSOD has a molecular mass of ≈ 76 kDa and 7200 U/mg protein specific activity. It is a tetrameric enzyme with four identical subunits of 18 860 Da each as indicated by SDS‐PAGE, amino acid analysis and mass spectrometry. N‐terminal sequence analysis of MnSOD from the fungal strain revealed a high degree of structural homology with enzymes from other eukaryotic sources. Physico‐chemical properties were determined by absorption spectroscopy and circular dichroism measurements. The UV absorption spectrum was typical for an MnSOD enzyme, but displayed an increased absorption in the 280 nm region (ε280 = 10.4 mM−1. cm−1), attributed to aromatic amino acid residues. The CD data show that MnSOD has two negative Cotton effects at 208 and 222 nm allowing the calculation of its helical content. The ellipticity at 222 nm is 6800 deg.cm2.dmol−1 and thus similar to the values reported for other MnSODs. The MnSOD from H. lutea 110 is stable over a wide range of pH (4.5–8), even in the presence of EDTA. The enzyme is thermostable at 70–75°C, and more stable than MnSODs from other sources.
Convenient preparation of [Orn(Tfa)2]‐ and [Orn(Boc)2, Orn(Tfa)2′]gramicidin S, versatile unsymmetrically protected derivatives of gramicidin S
Authors: Yamada K. , Ando K. , Takahashi Y. ‐I. , Yamamura H. , Araki S. , Kawai M.
Published: May 2003

Abstract: Treatment of gramicidin S (GS) with trifluoroacetic anhydride afforded a derivative in which only one of the two Orn side chains was trifluoroacetylated in 72% yield, furnishing the first efficient method for the preparation of a monoprotected derivative of GS. The mono(Tfa) derivative [Orn(Tfa)2]GS was treated with di‐tert‐butyl dicarbonate to yield dually protected derivative [Orn(Boc)2,Orn(Tfa)2′]GS from which another monoprotected derivative [Orn(Boc)2]GS was prepared in high yield. These unsymmetrically protected GS derivatives are versatile starting materials for the preparation of various other GS derivatives. As an example of application of the unsymmetrically protected derivatives, a dimeric GS derivative was prepared via a singly p‐nitrobenzenesulfonyl(NBS)‐activated derivative [Orn(Boc)2,Orn(NBS)2′]GS.
Effects of amounts of additives on peptide coupling mediated by a water‐soluble carbodiimide in alcohols
Authors: Nozaki S.
Published: May 2003

Abstract: The optimal amounts of 1‐hydroxybenzotriazole (HOBt), 3,4‐dihydro‐3‐hydroxy‐4‐oxo‐1,2,3‐benzotriazine (HOOBt) and 1‐hydroxy‐7‐azabenzotriazole (HOAt) for enhancement of peptide coupling mediated by 1‐ethyl‐3‐(3‐dimethylaminopropyl)carbodiimide (EDC) hydrochloride in alcoholic solvents were found to be less than equimolar against the carboxyl component or the carbodiimide. In comparison with the use of equimolar additives, the use of less equimolar ones was more effective in suppressing the competitive ester formation and in increasing the yield of desired peptides. EDC hydrochloride/around 0.1 equimolar HOAt or HOOBt were efficient reagents for peptide synthesis in the media.
NMR analysis of human salivary mucin (MUC7) derived O‐linked model glycopeptides: comparison of structural features and carbohydrate–peptide interactions
Authors: Naganagowda G.A. , Gururaja T. E. L. , Satyanarayana J. , Levine M.J.
Published: May 2003

Abstract: Two series of glycopeptides with mono‐ and disaccharides, [GalNAc and Galβ (1–3)GalNAc]O‐linked to serine and threonine at one, two or three contiguous sites were synthesized and characterized by 1H NMR. The conformational effects governed by O‐glycosylation were studied and compared with the corresponding non‐glycosylated counterparts using NMR, CD and molecular modelling. These model peptides encompassing the aa sequence, PAPPSSSAPPE (series I) and APPETTAAPPT (series II) were essentially derived from a 23‐aa tandem repeat sequence of low molecular weight human salivary mucin (MUC7). NOEs, chemical shift perturbations and temperature coefficients of amide protons in aqueous and non‐aqueous media suggest that carbohydrate moiety in threonine glycosylated peptides (series II) is in close proximity to the peptide backbone. An intramolecular hydrogen bonding between the amide proton of GalNAc or Galβ (1–3)GalNAc and the carbonyl oxygen of the O‐linked threonine residue is found to be the key structure stabilizing element. The carbohydrates in serine glycosylated peptides (series I), on the other hand, lack such intramolecular hydrogen bonding and assume a more apical position, thus allowing more rotational freedom around the O‐glycosidic bond. The effect of O‐glycosylation on peptide backbone is clearly reflected from the observed overall differences in sequential NOEs and CD band intensities among the various glycosylated and non‐glycosylated analogues. Delineation of solution structure of these (glyco)peptides by NMR and CD revealed largely a poly l‐proline type II and/or random coil conformation for the peptide core. Typical peptide fragments of tandem repeat sequence of mucin (MUC7) showing profound glycosylation effects and distinct differences between serine and threonine glycosylation as observed in the present investigation could serve as template for further studies to understand the multifunctional role played by mucin glycoproteins.
Comparative gene transfer efficiency of low molecular weight polylysine DNA‐condensing peptides
Authors: McKenzie Donald L. , Collard Wendy T. , Rice Kevin G.
Published: May 2003

Abstract: In a previous report (M.S. Wadhwa et al. (1997) Bioconjugate Chem.8, 81–88), we synthesized a panel of polylysine‐containing peptides and determined that a minimal repeating lysine chain of 18 residues followed by a tryptophan and an alkylated cysteine residue (AlkCWK18) resulted in the formation of optimal size (78 nm diameter) plasmid DNA condensates that mediated efficient in vitro gene transfer. Shorter polylysine chains produced larger DNA condensates and mediated much lower gene expression while longer lysine chains were equivalent to AlkCWK18. Surprisingly, AlkCWK18 (molecular weight 2672) was a much better gene transfer agent than commercially available low molecular weight polylysine (molecular weight 1000–4000), despite its similar molecular weight. Possible explanations were that the cysteine or tryptophan residue in AlkCWK18 contributed to the DNA binding and the formation of small condensates or that the homogeneity of AlkCWK18 relative to low molecular weight polylysine facilitated optimal condensation. To test these hypotheses, the present study prepared AlkCYK18 and K20 and used these to form DNA condensates and conduct in vitro gene transfer. The results established that DNA condensates prepared with either AlkCYK18 or K20 possessed identical particle size and mediated in vitro gene transfer efficiencies that were indistinguishable from AlkCWK18 DNA condensates, eliminating the possibility of contributions from cysteine or tryptophan. However, a detailed chromatographic and electrospray mass spectrometry analysis of low molecular weight polylysine revealed it to possess a much lower than anticipated average chain length of dp 6. Thus, the short chain length of low molecular weight polylysine explains its inability to form small DNA condensates and mediate efficient gene transfer relative to AlkCWK18 DNA condensates. These experiments further emphasize the need to develop homogenous low molecular weight carrier molecules for nonviral gene delivery.
Synthesis of hydrazinopeptides using solid‐phase N‐electrophilic amination: extension to the Fmoc/tert‐butyl strategy and chemistry of the N–N bond in strong acid media
Authors: Bonnet D. , Samson F. , Rommens C. , Gras‐masse H. , Melnyk O.
Published: May 2003

Abstract: The synthesis of hydrazinopeptides using solid‐phase N‐electrophilic amination was extended to the Fmoc/tert‐butyl strategy. Both Boc/benzyl and Fmoc/tert‐butyl strategies led to the isolation of by‐products arising from the partial instability of the N–N bond during the final cleavage and deprotection step. Two paths of decomposition have been shown: the cleavage of the N–N bond leading to the regeneration of the amine and a Hofmann‐type elimination yielding original dianisyl adducts. Our data suggest that the Fmoc/tert‐butyl strategy is better suited for the synthesis of hydrazinopeptides.
An evaluation of fMLP pocket dimensions and features using formyltetrapeptides
Authors: Cavicchioni G. , Varani K. , Niccoli S. , Rizzuti O. , Spisani S.
Published: May 2003

Abstract: The formyltetrapeptides for‐Met‐Leu‐Leu‐Phe‐OMe 1, for‐Met‐Leu‐Aib‐Phe‐OMe 2, for‐Met‐Leu‐Ac6c‐Phe‐OMe 3, for‐Met‐Leu‐Pro‐Phe‐OMe 4, for‐Met‐Pro‐Pro‐Phe‐OMe 5, for‐Met‐Aib‐Aib‐Phe‐OMe 6, for‐Met‐Pro‐Aib‐Phe‐OMe 7 and for‐Met‐Aib‐Pro‐Phe‐OMe 8 were synthesized and biologically tested on human neutrophils in an attempt to evaluate the specific receptor pocket dimensions and features. Our results indicate that the shift in the Phe residue to the fourth position in these compounds strongly reduces chemotactic response, but is efficacious in triggering superoxide anion production and lysozyme release (order of potency 3 > 2 > 1 > 4 > 6 > 8 > 5 > 7). The potency of the two latter responses correlates well with the affinity data obtained in binding experiments.
Spot synthesis: observations and optimizations
Authors: Kramer A. , Reineke U. , Dong L. , Hoffmann B. , Hoffmüller U. , Winkler D. , Volkmer‐engert R. , Schneider‐mergener J.
Published: May 2003

Abstract: Positionally addressable syntheses of peptides on continuous cellulose membranes (spot synthesis) have often been reported in detail, but important questions dealing with synthesis quality, reproducibility and subsequent binding assays have largely been under‐emphasized. In this report we have investigated some of these problems. The most important results were: (i) the signal intensity of ligate binding to cellulose‐bound peptides and the affinity of the corresponding soluble peptides show good correlation, illustrated by three different ligate binding assays; (ii) reducing peptide density on the cellulose avoids the ‘ring spot’ effect, i.e. where less binding is observed in the spot‐center compared to the rim. We recommend a peptide density of 10 nmol/cm2 as a reasonable starting point for further optimization; (iii) statistical analysis of binding assay reproducibility with more than 15 000 peptides resulted in a mean standard signal deviation of 0.18; and (iv) optimization of side‐chain deprotection revealed that a 30‐min pretreatment of the cellulose with 90% trifluoroacetic acid followed by the standard deprotection protocol resulted in higher purity of the synthesized products.
A convergent liquid‐phase synthesis of salmon calcitonin
Authors: Lee Y.S. , Lee H.J. , Pozdnyakov P.I. , Samukov V.V. , Kim H.J.
Published: May 2003

Abstract: Salmon calcitonin (sCT) was prepared in good yield and high purity by the condensation of Nα‐Boc‐cyclic decapeptide, Boc‐C1SNLSTC7VLG‐OH (1,7‐disulfide), with protected docosapeptide (Psc)LSQE(OPse)LHK(Psc)LQTYPRTNTGSGTP‐NH2·3TFA, followed by deprotection of Boc with trifluoroacetic acid and Psc/Pse with piperidine. The 2‐(phenylsulfonyl)ethoxycarbonyl (Psc) and2‐(phenylsulfonyl)ethyl (Pse) protecting groups were recently developed. The two peptides were built up by stepwise and fragment condensation using appropriate Nα‐Boc‐amino acids and subsequent deprotection in solution. The synthetic sCT exhibited hypocalcemic potency of more than 4000 IU/mg in rats.
Spectrophotometric monitoring in continuous‐flow Boc‐based solid‐phase peptide synthesis
Authors: Baru M.B. , Mustaeva L.G. , Gorbunova E. YU. , Vagenina I.V. , Kitaeva A. , Baru M.B. , Cherskii V.V.
Published: May 2003

Abstract: It has been demonstrated that SPPS with Boc amino group protection can be monitored spectrophotometrically if it is performed in a continuous‐flow reactor of variable volume. It is shown that this approach provides useful and adequate evidence on the beginning/end‐point of most steps of the SPPS cycle. At the deprotection step the spectrophotometric monitoring enables real‐time recording of the initial and final moments of the process. When synthesizing a ‘difficult’ polyalanine sequence, we were able to monitor variation in the deprotection dynamics associated with the aggregation phenomena. The time actually necessary for the Boc protecting group removal appeared to be significantly smaller than that usually preset in the available Boc‐SPPS protocols.
Characterization of monomeric and dimeric B domain of Staphylococcal protein A
Authors: Karimi Afshin , Matsumura Masazumi , Wright Peter E. , Dyson H. Jane
Published: May 2003

Abstract: Both monomeric and dimeric constructs of the B domain of protein A from Staphylococcus aureus have been characterized by NMR, CD and fluorescence spectroscopy. The monomeric form of the protein was synthesized using a novel method incorporating the use of a recombinant, folded, chimeric protein. A comparison of the recombinant monomeric form with the commercially available dimeric form indicates that, although the dimer retains the integrity of the three‐helix bundle structure present in the monomer, there are interdomain contacts in the dimeric form. A single long‐lived water molecule in the hydrophobic core of the three‐helix bundle of monomeric protein A may represent an important stabilizing factor for the three‐helix bundle topology.
Influence of lipophilic groups in cationic α‐helical peptides on their abilities to bind with DNA and deliver genes into cells
Authors: Niidome T. , Urakawa M. , Takaji K. , Matsuo Y. , Ohmori N. , Wada A. , Hirayama T. , Aoyagi H.
Published: May 2003

Abstract: For the purpose of achieving gene transfer into cells mediated by peptides with a short chain length, we employed two kinds of amphiphilic α‐helix peptides, mastoparan (INLK‐ALAA‐LAKK‐IL‐NH2) obtained from wasp venom and an α‐helix model peptide (LARL‐LARL‐LARL‐NH2). Furthermore, to strengthen the hydrophobicity of the peptide required for the formation of the aggregates with the DNA, we modified these peptides using several lipophilic groups, i.e. acyl groups with a single chain, a dialkylcarbamoyl group and a cholesteryloxycarbonyl group. We examined the ability of the peptides and their derivatives to bind and aggregate with plasmid DNA, the structural change in the peptides caused by binding with the DNA and the in vitro gene transfer abilities into COS‐7 cells. As a result, mastoparan was found to acquire the DNA binding ability by introduction of the lipophilic group. The conformational change in the peptides depended on the hydrophobicity of the introduced acyl group. The DNA complex of most lipophilic mastoparan derivatives could be incorporated into the cells via the endocytosis pathway. In the case of the helix model peptide, the acyl group with a moderate chain length was required for the formation of the aggregate which is competent for incorporation into the cells. In this study, we succeeded in giving such short peptides sufficient gene transfer ability by modifying them with some lipophilic groups. However, the influence of the modification by the lipophilic groups on the formation of aggregates with DNA and the gene transfer ability depended on the structure of the peptide portion. These results indicate that consideration of total hydrophobicity balance is needed for the design of an efficient gene carrier peptide.
Peptides with antimicrobial activity of the brevinin‐1 family isolated from skin secretions of the southern leopard frog, Rana sphenocephala
Authors: Conlon J.M. , Halverson T. , Dulka J. , Platz J.E. , Knoop F.C.
Published: May 2003

Abstract: Three peptides with growth‐inhibitory activity towards the Gram‐negative bacterium Eschericia coli were isolated from electrically stimulated secretions from the skin of the southern leopard frog, Rana sphenocephala. Structural characterization demonstrated that the peptides [brevinin‐1Sa, minimum inhibitory concentration (MIC) = 55µm; brevinin‐1Sb, MIC = 17 µm; brevinin‐1Sc, MIC = 14 µm] represent new members of the brevinin‐1 family of antimicrobial peptides, previously isolated from several other species of frogs of the genus Rana. Their high concentration in skin secretions and extreme variability in amino acid sequence suggest that the brevinin family of peptides may be of value as molecular markers for the identification and taxonomic classification of Ranid frogs.
A spectroscopic and molecular modeling study on novel pseudopeptides exhibiting biological activity
Authors: Pispisa B. , Stella L. , Venanzi M. , Palleschi A.
Published: May 2003

Abstract: A series of pseudopeptides, containing two fluorophores, such as naphthalene (N) and indole (I), and exhibiting interesting biological activity as tachykinin receptor antagonists, were investigated by electronic absorption, CD and steady‐state fluorescence experiments. In polar solvents (e.g. methanol), bioactivity is coupled with a stacked, charge‐separated complex between I and N, the amount of which depends on the stereochemical features and conformational mobility of the central scaffold in the molecules examined. This agrees with the idea that dipolar charged, spatially close, aromatic moieties are important topochemical elements in the mechanism of action of these receptor antagonists. Molecular mechanics calculations allowed us to build up hypothetical, low‐energy conformations of a few representative pseudopeptides, whose structural features are consistent with the experimental findings.
Synthesis and characterization of the human CC chemokineHCC‐2
Authors: Escher S.E. , Sticht H. , Forssmann W.G. , Rösch P. , Adermann K.
Published: May 2003

Abstract: Human CC chemokine 2 (HCC‐2) is a novel member of the chemokine peptide family that induces chemotaxis of monocytes, T lymphocytes and eosinophils via activation of the CCR‐1 and CCR‐3 receptors. Fmoc chemistry was optimized and used to synthesize the biologically active 66‐residue peptide HCC‐2‐(48–113). Introduction of the three disulfide bonds was achieved by oxidative folding in the presence of the redox system cysteine/cystine. Alternatively, a semiselective approach utilizing a mixed Acm/Trt protection scheme for disulfide formation was applied. It was found that, without participation of the two HCC‐2‐specific cysteine residues in positions 64 and 104, the two typical chemokine disulfides are formed predominantly during oxidative folding. In addition, the mutant [Ala64,104]HCC‐2‐(48–113) lacking the third disulfide bond that discriminates HCC‐2 from most other chemokines was synthesized. For disulfide bond formation, oxidative folding was compared with the use of Acm/Trt protection. HCC‐2‐(48–113) and the mutant [Ala64,104]HCC‐2‐(48–113) were further analyzed by CD and one‐dimensional 1H NMR‐spectroscopy. Both peptides adopt a similar stable secondary and tertiary structure in solution.
Disulfide assignment of the C‐terminal cysteine knot of agouti‐related protein (AGRP) by direct sequencing analysis
Authors: Young Y. , Zeni L. , Rosenfeld R.D. , Stark K.L. , Rohde M.F. , Haniu M.
Published: May 2003

Abstract: We have assigned the disulfide structure of Md‐65 agouti‐related protein (Md65‐AGRP) using differential reduction and alkylation followed by direct sequencing analysis. The mature human AGRP is a single polypeptide chain of 112 amino acid residues, consisting of an N‐terminal acidic region and a unique C‐terminal cysteine‐rich domain. The C‐terminal domain, a 48 amino acid peptide named Md65‐AGRP, was expressed in Escherichia coli cells and refolded under different conditions from the mature recombinant protein. The disulfide bonds in the cystine knot structure of Md65‐AGRP were partially reduced using tris(2‐carboxyethyl) phosphine (TCEP) under acidic conditions, followed by alkylation with N‐ethylmaleimide (NEM). The procedure generated several isoforms with varying degrees of NEM alkylation. The multiple forms of Md65‐AGRP generated by partial reduction and NEM modification were then completely reduced and carboxymethylated to identify unreactive disulfide bonds. Differentially labeled Md65‐AGRP were directly sequenced and analyzed by MALDI mass spectrometry. The results confirmed that Md65‐AGRP contained the same disulfide structure as that of Md5‐AGRP reported previously [Bures, E. J., Hui, J. O., Young, Y. et al. (1998) Biochemistry37, 12172–12177].