Robust estimation of bacterial cell count from optical density

Optical density (OD) is widely used to estimate the density of cells in liquid culture, but cannot be compared between instruments without a standardized calibration protocol and is challenging to relate to actual cell count. We address this with an interlaboratory study comparing three simple, low-cost, and highly accessible OD calibration protocols across 244 laboratories, applied to eight strains of constitutive GFP-expressing E. coli. Based on our results, we recommend calibrating OD to estimated cell count using serial dilution of silica microspheres, which produces highly precise calibration (95.5% of residuals <1.2-fold), is easily assessed for quality control, also assesses instrument effective linear range, and can be combined with fluorescence calibration to obtain units of Molecules of Equivalent Fluorescein (MEFL) per cell, allowing direct comparison and data fusion with flow cytometry measurements: in our study, fluorescence per cell measurements showed only a 1.07-fold mean difference between plate reader and flow cytometry data

Reduction of Experimental Cerebral Malaria and Its Related Proinflammatory Responses by the Novel Liposome-Based β-Methasone Nanodrug

Cerebral malaria (CM) is a severe complication of and a leading cause of death due to Plasmodium falciparum infection. CM is likely the result of interrelated events, including mechanical obstruction due to parasite sequestration in the microvasculature, and upregulation of Th1 immune responses. In parallel, blood-brain-barrier (BBB) breakdown and damage or death of microglia, astrocytes, and neurons occurs. We found that a novel formulation of a liposome-encapsulated glucocorticosteroid, β-methasone hemisuccinate (nSSL-BMS), prevents experimental cerebral malaria (ECM) in a murine model and creates a survival time-window, enabling administration of an antiplasmodial drug before severe anemia develops. nSSL-BMS treatment leads to lower levels of cerebral inflammation, expressed by altered levels of corresponding cytokines and chemokines. The results indicate the role of integrated immune responses in ECM induction and show that the new steroidal nanodrug nSSL-BMS reverses the balance between the Th1 and Th2 responses in malaria-infected mice so that the proinflammatory processes leading to ECM are prevented. Overall, because of the immunopathological nature of CM, combined immunomodulator/antiplasmodial treatment should be considered for prevention/treatment of human CM and long-term cognitive damage

Improvement of AA5052 sheet properties by electromagnetic twin-roll casting

Electromagnetic fields were used in twin-roll casting (TRC) of aluminum alloy 5052 (AA5052) for improvement of the microstructure and mechanical properties. A static magnetic field induces an inhibiting effect on the melt in the cast-rolling area and reduces diffusion of the solutes. It also results in more nucleating opportunities and less segregation, thus enhancing the mechanical properties. However, the static magnetic field does not change the orientation of crystal growth and columnar crystals still exist in microstructure. On the other hand, an oscillating magnetic field can refine the suspended particles and induce strong convection. This leads to more uniform distribution of temperature and solute elements, simultaneously increasing nucleating opportunities and decreasing segregation, thereby enhancing the mechanical properties. An oscillating magnetic field also inhibits the orientation of crystal growth and makes finer and equiaxed grains