Rare case of Rosai Dorfman disease involving paranasal sinuses in paediatric patient: A case report

AbstractRosai Dorfman disease (RDD) is a rare, benign disease of unknown aetiology. It typically presents with massive, painless cervical lymphadenopathy but may have a varied presentation. We report a paediatric case of RDD with initial isolated involvement of nasal cavity and PNS with subsequent involvement of cervical lymph nodes. Endoscopic biopsy confirmed the pathological diagnosis and he was managed successfully with medical therapy. At 20month follow up there was no evidence of recurrence. The ideal protocol for the treatment is still debated. A long term follow-up is warranted to detect relapses. This case report is illustrated aiming at developing insights into management and diagnosis of such rare clinical entity in a paediatric patient

Analysis of short interproton distances in proline peptides as a guide in the interpretation of nuclear overhauser effects

The conformational dependence of interproton distances in model proline peptides has been investigated in order to facilitate interpretation of the results of Nuclear Overhauser Effect (NOE) studies on such peptides. For this purpose two model systems, namely, Ac-Pro-NHMe and Ac-Pro-X-NHMe have been chosen and used. In the former, short interproton distances detectable in NOE experiments permit a clear distinction between conformations with Pro ψ = -300 (helical region) and those in which ψ is around 1200 (polyproline region). For the latter, the variation of distances between the protons of methyl amide and the Pro ring have been studied by superimposing on the Ramachandran map in the (φ3, ψ3) plane. The results show that β-turns and non-β-turn conformations can be readily distinguished from NOE data and such long range NOEs should be detectable for specific non-β-turn conformations. NOEs involving Cβ and Cγ protons are particularly sensitive to the state of pyrrolidine ring puckering

Analysis of short interproton distances in proline peptides as a guide in the interpretation of nuclear overhauser effects

The conformational dependence of interproton distances in model proline peptides has been investigated in order to facilitate interpretation of the results of Nuclear Overhauser Effect (NOE) studies on such peptides. For this purpose two model systems, namely, Ac-Pro-NHMe and Ac-Pro-X-NHMe have been chosen and used. In the former, short interproton distances detectable in NOE experiments permit a clear distinction between conformations with Pro ψ=−30° (helical region) and those in which ψ is around 120° (polyproline region). For the latter, the variation of distances between the protons of methyl amide and the Pro ring have been studied by superimposing on the Ramachandran map in the (φ<SUB>3</SUB>, ψ<SUB>3</SUB>) plane. The results show that β-turns and non-β-turn conformations can be readily distinguished from NOE data and such long range NOEs should be detectable for specific non-β-turn conformations. NOEs involving C<SUP>β</SUP>and C<SUP>γ</SUP> protons are particularly sensitive to the state of pyrrolidine ring puckering

Analysis of short loops connecting secondary structural elements in proteins

The recognition by Ramachandran et al. (1) that the range of polypeptide chain conformation is limited by steric constraints constitutes the first step in defining the limits of the problem of protein folding. The srystal structures of globular proteins reveal intricate arrays of secondary structure modules, separated by irregular elements of the polypeptide chain termed as loops, which are uniquely assembled to yield the native folded conformation (2,3). While much early work in the area of protein structure analysis focused on the regular elements of the structure, it is becoming increasingly apparent that the less regular segments or loops merit detailed study (4-10). Protein engineering appeoaches which permit transfer of loops from one context to another or allow truncation of connecting elements (11-13), have provided a fresh impetus to the present study, short loops (&#8804;5 residues) connecting secondary structure modules are identitied from a data set of 65, largely non-homologous, protein crystal structures. Four types of super-secondary structural motifs involving &#945;-helices and b-strands viz. &#945;&#945;, &#946;&#946;, &#945;&#946; and &#946;&#945; are considered and the conformational and composotional properties of the connecting loops are examined. An analysis of the spatial orientation of the two linked secondary structural elements reveals reasonably frequent occurrence of an 'L'-shaped motif involving two orthogonally disposed B-strands