Spectral Analysis Methods Based on Background Subtraction and Curvature Calculation Used in the Detection or Quantification of Hemolysis and Icterus in Blood-derived Clinical Samples.

Objective We aimed to find new methods to detect and quantify hemolysis and icterus which may cause assay biases. These methods need to determine each of these interferents in the presence of various other interferents. They also need to have less stringent requirements in development and implementation than those conventional analyzers currently must satisfy. Design and methods We developed two spectral analysis methods that obtain absorption signals of interest by background subtraction or by calculating the spectral curvatures near the peaks of interest. We optimized and tested the performance of these methods using a plasma sample set with permutations of the levels of hemolysis, icterus, and lipemia (using 510 samples in total). Results The processed signals correlated well with concentrations of hemoglobin and bilirubin, indicators of hemolysis and icterus, respectively. Through iterations of randomly splitting the samples for calibration and testing, the two new methods performed as well as those used on conventional analyzers. We demonstrated that the two methods can lessen the application requirements of 1) prior knowledge of the absorption spectra of individual interferents, 2) calibration over a wide concentration range for each interferent, and 3) the need for full-range spectrophotometers spanning most of the ultraviolet/visible spectrum. We also proposed a hardware setup to detect and quantify hemolysis or icterus with a camera and two optical filters. Conclusions This work indicates that new methods of spectral analysis can reduce practical constraints in the development of interference screening systems. These methods could also benefit other assays that rely on reading spectral signals.

Cytotoxic effects of cytoplasmic-targeted and nuclear-targeted gold and silver nanoparticles in HSC-3 cells--a mechanistic study.

Nanoparticles (NPs), in particular noble metal nanoparticles, have been incorporated into many therapeutic and biodiagnostic applications. While these particles have many advantageous physical and optical properties, little is known about their intrinsic intracellular effects in biological environments. Here, we report the possible cell death mechanisms triggered in human oral squamous cell carcinoma (HSC-3) cells after exposure to extracellular, cytoplasm, and nuclear localized AuNPs and AgNPs. NP uptake and localization, cell viability, ATP levels, modes of cell death, ROS generation, mitochondrial depolarization, and the levels and/or translocation of caspase-dependent and caspase-independent proteins were assessed under control and localized metal nanoparticle exposure. Exposure to AuNPs resulted the adoption of a quiescent cellular state, as AuNPs caused a decrease in intracellular ATP, but no change in viability or cell death populations. However, AgNP exposure significantly reduced HSC-3 cell viability and increased apoptotic populations, especially when localized at the cytoplasm and nucleus. Increased cell death populations were linked to an increase in intracellular ROS generation. Western blot analysis indicated cytoplasm localized AgNPs and nuclear localized AgNPs utilized a caspase-independent apoptotic pathway that involved the nuclear translocation of AIF and p38 MAPK proteins. These results demonstrate that the degree of cytotoxicity increases as AgNPs move from extracellular localization to nuclear localization, whereas changing AuNP localization does not trigger any significant cytotoxicity.

Identification of a tetraene-containing product of the indanomycin biosynthetic pathway.

The indanomycin biosynthetic gene (idm) cluster was recently identified from Streptomyces antibioticus NRRL 8167. The disruption of one of these genes, idmH, and the increased production of a previously unreported metabolite in this mutant is reported. The structure of this compound was elucidated and was shown to possess a linear tetraene. This metabolite is not a logical biosynthetic intermediate of indanomycin but instead is likely an alternate product of the pathway.