Rare complication of doxorubicin-induced complete heart block in a patient with Hodgkin's lymphoma: a case report.

Anthracyclines are associated with cardiotoxic manifestations that are mainly dose-dependent, with onset varying from a few days to many years after stopping treatment. Frequent monitoring for toxic manifestations, early detection, cessation of anthracycline use and appropriate treatment is the key to preventing morbidity and mortality. Complete heart block with doxorubicin use in Hodgkin's lymphoma is rarely reported, and is a severe toxic manifestation necessitating withdrawal or changing of regimen to etoposide + bleomycin + vinblastine + dacarbazine (EBVD), as in this case.

Study of Peripheral Mononuclear Cells and CD34 Levels as a Predictive Marker for Initiating Apheresis in Autologous Stem Cell Transplant.

Background: Autologous HCT in multiple myeloma is done as upfront treatment in newly diagnosed transplant eligible patients after induction chemotherapy. In addition, it is standard for relapsed, aggressive non-Hodgkin lymphoma (NHL) and classical Hodgkin lymphoma (HL), and is curative in ~40% to 45% of patients. Over a decade, many efforts were made to find helpful parameters to predict an optimal time for initiating an efficient peripheral blood stem cell collection so that adequate stem cells are collected.  It has been well accepted that CD34+ cell count in peripheral blood before leukapheresis is the best parameter to predict CD34 cell yield. However, white blood cell count, mononuclear cell count, and other easily obtained parameters are still used to guide the clinical practice of peripheral blood stem cell mobilization and collection.  Materials and Methods: In the present study, we analyzed the correlation between peripheral blood MNC and Apheresis CD34 levels and also between peripheral blood CD34 by flow cytometry and apheresis CD34 levels. Results: We found that there was a statistically insignificant weak correlation between peripheral MNC and apheresis CD34. There was a statistically significant strong correlation between peripheral CD34 and apheresis CD34. Conclusion: The results show that peripheral blood MNC was analogous indicating that no reliable prediction can be done for CD34 cells collected in apheresis while peripheral CD34 by flow cytometry is the strongest predictor for initiating stem cell collection.

Characterization of (Boc-Cys/Sec-NHMe)2 and (Boc-Cys/Sec-OMe)2 : Evidence of local conformational difference between disulfide and diselenide.

Conformations of disulfide and diselenide were compared in (Boc-Cys/Sec-NHMe)2 and (Boc-Cys/Sec-OMe)2 using X-ray crystallography, nuclear magnetic resonance (NMR) spectroscopy, density functional theory (DFT), and circular dichroism (CD) spectroscopy. Conformations of disulfide/diselenide in polypeptides are defined based on the sign of side chain torsion angle χ3 (-CH2 -S/Se-S/Se-CH2 -); negative indicates left-handed and positive indicates right-handed orientation. In the crystals of (Boc-Cys-OMe)2 and (Boc-Sec-OMe)2 , the disulfide exhibits a left-handed and the diselenide a right-handed orientation. Characterization of cystine and selenocystine derivatives in solution using 1 H-NMR, natural abundant 77 Se NMR, 2D-ROESY, and chemical shift analysis coupled to DMSO titration has indicated the symmetrical nature and antiparallel orientation of Cys/Sec residues about the disulfide/diselenide bridges. Structural calculations of cystine and selenocystine derivatives using DFT further support the antiparallel orientation of Cys/Sec residues about disulfide/diselenide. The far-ultraviolet (UV) region CD spectra of cystine and selenocystine derivatives have exhibited the negative Cotton effect (CE) for disulfide and positive for diselenide confirming the difference in the conformational preference of disulfide and diselenide. In the previously reported polymorphic structure of (Boc-Sec-OMe)2 , the diselenide has right-handed orientation. In the X-ray structures of disulfide and diselenide analogues of Escherichia coli protein encoded by curli specific gene C (CgsC) retrieved from Protein Databank (PDB), disulfide has left-handed and the diselenide right-handed orientation. The current report provides the evidence for the local conformational difference between a disulfide and a diselenide group under unconstrained conditions, which may be useful for the rational replacement of disulfide by diselenide in polypeptide chains.

Disulfide engineering on temporin-SHf: Stabilizing the bioactive conformation of an ultra-short antimicrobial peptide.

In Silico searching for short antimicrobial peptides has revealed temporin-SHf as the short (8AA), hydrophobic, broad spectrum, and natural antimicrobial peptide. Important drawback associated with temporin-SHf is the susceptibility of its bioactive conformation for denaturation and proteolytic degradation. In the current report, disulfide engineering strategy has been adopted to improve the stability of bioactive conformation of temporin-SHf. The functionally non-critical Leu4 and Ile7 residues at i and i + 3 position of helical conformation of temporin-SHf were mutated with cysteine disulfide. Designed [L4C, I7C]temporin-SHf was synthesized, characterized using NMR spectroscopy, and accessed for antimicrobial activity. [L4C, I7C]Temporin-SHf adopts helical conformation from Phe3 to Phe8 in the absence of membrane-mimetic environment and retains broad spectrum antimicrobial activity. The reduction potential of cysteine disulfide of [L4C, I7C]temporin-SHf is -289 mV. Trypsin-induced digestion and serum-induced digestion have confirmed the advantage of cysteine disulfide in imparting proteolytic stability to temporin-SHf. Disulfide-stabilized temporin-SHf may serve as a good model for the rational design of temporin-SHf based antibiotics for treatment of infectious diseases.

Retention of strong intramolecular hydrogen bonds in high polarity solvents in binaphthalene-benzamide derivatives: extensive NMR studies.

Advanced multidimensional NMR techniques have been employed to investigate the intramolecular hydrogen bonds (HBs) in a series of N,N'-([1,1'-binaphthalene]-2,2'-diyl)bis(benzamide) derivatives, with the site-specific substitution of different functional groups. The existence of intramolecular HBs and the elimination of any molecular aggregation and possible intermolecular HBs are ascertained by various experimental NMR techniques, including solvent polarity dependent modifications of HB strengths. In the fluorine substituted derivative, direct evidence for the engagement of organic fluorine in HB is obtained by the detection of heteronuclear through-space correlation and the coupling between two NMR active nuclei where the transmission of spin polarization is mediated through HBs (1h J FH). The extent of reduction in the strength of 1h J FH on dilution with high polarity solvents directly provided the qualitative measure of HB strength. The HB, although becoming weakened, does not get nullified even in pure high polarity solvent, which is attributed to the structural constraints. The rate of exchange of a labile hydrogen atom with the deuterium of the solvent permitted the measurement of their half-lives, that are correlated to the relative strengths of HBs. The experimental NMR findings are further validated by XRD and DFT-based theoretical computations, such as, NCI and QTAIM.

Design of a heme-binding peptide motif adopting a ß-hairpin conformation.

Heme-binding proteins constitute a large family of catalytic and transport proteins. Their widespread presence as globins and as essential oxygen and electron transporters, along with their diverse enzymatic functions, have made them targets for protein design. Most previously reported designs involved the use of α-helical scaffolds, and natural peptides also exhibit a strong preference for these scaffolds. However, the reason for this preference is not well-understood, in part because alternative protein designs, such as those with ß-sheets or hairpins, are challenging to perform. Here, we report the computational design and experimental validation of a water-soluble heme-binding peptide, Pincer-1, composed of predominantly ß-scaffold secondary structures. Such heme-binding proteins are rarely observed in nature, and by designing such a scaffold, we simultaneously increase the known fold space of heme-binding proteins and expand the limits of computational design methods. For a ß-scaffold, two tryptophan zipper ß-hairpins sandwiching a heme molecule were linked through an N-terminal cysteine disulfide bond. ß-Hairpin orientations and residue selection were performed computationally. Heme binding was confirmed through absorbance experiments and surface plasmon resonance experiments (KD = 730 ± 160 nm). CD and NMR experiments validated the ß-hairpin topology of the designed peptide. Our results indicate that a helical scaffold is not essential for heme binding and reveal the first designed water-soluble, heme-binding ß-hairpin peptide. This peptide could help expand the search for and design space to cytoplasmic heme-binding proteins.

Reduction of coherent scattering noise with multiple receiver Doppler.

Doppler ultrasound (US) velocity estimates are inherently subject to error as a result of both Doppler ambiguity and coherent scattering. The coherent scattering error is a result of changes in the phase of the returned echo as particles enter and leave the sample volume. This phase depends on the distance from the transmitter to the scatterer and then to the receiver. This distance, in turn, depends on the angle of the receiver. A numerical simulation has been used to determine whether velocity estimates obtained from receiver probes at different angles are independent of one another. If so, then it is possible to obtain an improved velocity estimate from the combination of several receivers at different angles. The simulation results show that the cross-correlation between velocity estimates is reduced to 0.3 when receiver probes are oriented 5 degrees apart. These results suggest a new Doppler method that can significantly reduce velocity estimation error.