ABSTRACT
PURPOSE: The localized heating of magnetic nanoparticles (MNPs) via the application of time-varying magnetic fields - a process known as magnetic field hyperthermia (MFH) - can greatly enhance existing options for cancer treatment; but for broad clinical uptake its optimization, reproducibility and safety must be comprehensively proven. As part of this effort, the quantification of MNP heating - characterized by the specific loss power (SLP), measured in W/g, or by the intrinsic loss power (ILP), in Hm2/kg - is frequently reported. However, in SLP/ILP measurements to date, the apparatus, the analysis techniques and the field conditions used by different researchers have varied greatly, leading to questions as to the reproducibility of the measurements. MATERIALS AND METHODS: An interlaboratory study (across N = 21 European sites) of calorimetry measurements that constitutes a snapshot of the current state-of-the-art within the MFH community has been undertaken. Identical samples of two stable nanoparticle systems were distributed to all participating laboratories. Raw measurement data as well as the results of in-house analysis techniques were collected along with details of the measurement apparatus used. Raw measurement data was further reanalyzed by universal application of the corrected-slope method to examine relative influences of apparatus and results processing. RESULTS: The data show that although there is very good intralaboratory repeatability, the overall interlaboratory measurement accuracy is poor, with the consolidated ILP data having standard deviations on the mean of ca. ± 30% to ± 40%. There is a strong systematic component to the uncertainties, and a clear rank correlation between the measuring laboratory and the ILP. Both of these are indications of a current lack of normalization in this field. A number of possible sources of systematic uncertainties are identified, and means determined to alleviate or minimize them. However, no single dominant factor was identified, and significant work remains to ascertain and remove the remaining uncertainty sources. CONCLUSION: We conclude that the study reveals a current lack of harmonization in MFH characterization of MNPs, and highlights the growing need for standardized, quantitative characterization techniques for this emerging medical technology.
Subject(s)
Hyperthermia, Induced , Humans , Hyperthermia , Magnetic Fields , Magnetics , Reproducibility of ResultsABSTRACT
High-resolution 13C NMR spectroscopy has been used to analyze the positional distribution of fatty acids in model triacylglycerols. A novel method for quantitative determination of the positional distribution of unsaturated chains in triacylglycerols simultaneously with the ratio of saturated/unsaturated acyl chains has been proposed, utilizing the chemical shift differences of the aliphatic atoms C4, C5, and C6. The use of HSQC-TOCSY spectra allows unequivocal proof of the position of the unsaturated chain as well as complete assignment of the 13C NMR signals in tripalmitin.
Subject(s)
Triglycerides/chemistry , Acylation , Carbon Isotopes , Fatty Acids/chemistry , Magnetic Resonance Spectroscopy , Molecular Structure , StereoisomerismABSTRACT
2',3'-Dihydroxy-4,4'-dimethoxychalcone (1) and 2',3',4-trihydroxy-4'-methoxy-chalcone, two new chalcones, were isolated from propolis from El Salvador. The compounds showed significant antibacterial and antifungal activity and moderate toxicity to Artemia salina nauplii.
Subject(s)
Anti-Infective Agents/chemistry , Artemia , Chalcone/chemistry , Propiophenones/chemistry , Propolis/chemistry , Animals , Anti-Bacterial Agents , Anti-Infective Agents/isolation & purification , Anti-Infective Agents/pharmacology , Antifungal Agents/chemistry , Antifungal Agents/isolation & purification , Antifungal Agents/pharmacology , Caffeic Acids/toxicity , Candida albicans/drug effects , Chalcone/isolation & purification , Chalcone/toxicity , Chromatography, Thin Layer , El Salvador , Escherichia coli/drug effects , Magnetic Resonance Spectroscopy , Microbial Sensitivity Tests , Models, Molecular , Molecular Conformation , Molecular Structure , Propiophenones/isolation & purification , Propiophenones/toxicity , Staphylococcus aureus/drug effectsABSTRACT
New 6 beta-aryl(alkyl)sulfonamidopenicillanic acids and their sulfoxides were synthesized by sulfonylation of 6 beta-aminopenicilanic acid or its beta-sulfoxide with an appropriate sulfonyl chloride. The corresponding 6 beta-sulfonamidopenicillanic acids sulfones were prepared by oxidation of the sulfoxides with potassium permanganate in aqueous medium. The obtained compounds reduced the minimum inhibitory concentrations of ampicillin against 8 reference and 7 clinically isolated strains.
Subject(s)
Penicillanic Acid/analogs & derivatives , beta-Lactamase Inhibitors , Bacteria/drug effects , Magnetic Resonance Spectroscopy , Microbial Sensitivity Tests , Penicillanic Acid/chemical synthesis , Penicillanic Acid/pharmacology , Spectrophotometry, InfraredABSTRACT
Fourier -transform infrared microscopic spectra of scrapie-infected nervous tissue measured at high spatial resolution (approximately 6 microm) were compared with those obtained from the purified, partly proteinase K digested scrapie isoform of the prion protein isolated from nervous tissue of hamsters infected with the same scrapie strain (263K) to elucidate similarities/dissimilarities between prion structure investigated in situ and ex vivo. A further comparison is drawn to the recombinant Syrian hamster prion protein SHaPrP(90-232) after in vitro conformational transition from the predominantly alpha-helical isoform to beta-sheet-rich structures. It is shown that prion protein structure can be investigated within tissue and that detectability of regions with elevated beta-sheet content as observed in microspectra of prion-infected tissue strongly depends on spatial resolution of the experiment.