Real-Time PCR-Based Mismatch Amplification Mutation Assay for Specific Detection of CS6-Expressing Allelic Variants of Enterotoxigenic Escherichia coli and Its Application in Assessing Diarrheal Cases and Asymptomatic Controls

Enterotoxigenic Escherichia coli (ETEC) expressing the colonization factor CS6 is widespread in many developing countries, including India. The different allelic variants of CS6, caused by point mutations in its structural genes, cssA and cssB, are designated AIBI, AIIBII, AIIIBI, AIBII, and AIIIBII. A simple, reliable, and specific mismatch amplification mutation assay based on real-time quantitative PCR (MAMA-qPCR) was developed for the first time for the detection of CS6-expressing ETEC, along with the identification of allelic variations. The assay was based on mismatched nucleotide incorporation at the penultimate base at the 3' ends of the reverse primers specific for cssA and cssB and was validated using 38 CS6-expressing ETEC isolates. This strategy was effective in detecting all the alleles containing single-nucleotide polymorphisms. Using MAMA-qPCR, we also tested CS6 allelic variants in 145 ETEC isolates from children with acute diarrhea and asymptomatic infections, with the latter serving as controls. We observed that the AIBI and AIIIBI allelic variants were mostly associated with cases rather than controls, whereas the AIIBII variants were detected mostly in controls. In addition, the AIBI and AIIIBI alleles were frequently associated with ETEC harboring the heat-stable toxin gene (est) alone or with the heat-labile toxin gene (elt), whereas the AIIBII allele was predominant in ETEC isolates harboring the elt gene. This study may help in understanding the association of allelic variants in CS6-expressing ETEC with the clinical features of diarrhea, as well as in ETEC vaccine studies

Spectrally resolved ion imaging from laser produced plasmas using CR-39 detectors

Intense laser-produced plasmas generate bright, ultrashort bursts of accelerated ions. Reducing the required laser intensity and increasing the repetition rate of the laser to generate high energy ions is important, and mesoscopic particle targets are an attractive option to address this issue. Newer experimental strategies to measure ion energies and their angular distribution are needed in studies of such systems. In this paper, we outline a method to simultaneously measure these quantities using a single CR39 film. Although CR-39 detectors are known for ion imaging or spectroscopy, combining these specially for lower ion energies and applications to low-intensity laser experiments is not common. The paradigm chosen in our study is to consider the spatial distribution of nuclear tracks on a CR-39 sheet, while simultaneously separating them by their track diameter. Our method achieves an energy resolution of about 100 keV and a spatial resolution of tens of micrometers. In addition, ion species other than protons, i.e., carbon and oxygen, can also be imaged in an energy-resolved manner. © 2021 Author(s)

Clinical significance of quantitative blood cultures in newborn infants

Aim: To evaluate quantitative blood culture as a secondary test on a positive blood culture for the diagnosis of sepsis in newborn infants

Transient myeloproliferative disorder and hepatic failure in a newborn with Down syndrome

Approximately 10% of Down syndrome (DS) newborn develops transient leukemia (TL) also known as transient myeloproliferative disorder (TMD). Rarely, hepatic fibrosis (HF) and severe hepatic dysfunction have been reported in a patient with TL/TMD. Platelet-derived growth factor (PDGF) in combination with TGF-β1 is responsible for HF in such patients. Not only fibrosis of liver, diffuse fibrosis of other organ such as lung, kidney and pancreas are also seen in TMD patients. The triad of DS, TMD and HF is extremely rare. We report a DS neonate with endocardial cushion defect who developed TMD and died due to hepatic failure