A microfluidic competitive immuno-aggregation assay for high sensitivity cell secretome detection

We report a high-sensitivity cell secretome detection method using competitive immuno-aggregation and a micro-Coulter counter. A target cell secretome protein competes with anti-biotin-coated microparticles (MPs) to bind with a biotinylated antibody (Ab), causing decreased aggregation of the functionalized MPs and formation of a mixture of MPs and aggregates. In comparison, without the target cell secretome protein, more microparticles are functionalized, and more aggregates are formed. Thus, a decrease in the average volume of functionalized microparticles/aggregates indicates an increase in cell secretome concentration. This volume change is measured by the micro-Coulter counter, which is used to quantitatively estimate the cell secretome concentration. Vascular endothelial growth factor (VEGF), one of the key cell secretome proteins that regulate angiogenesis and vascular permeabilization, was used as the target protein to demonstrate the sensing principle. A standard calibration curve was generated by testing samples with various VEGF concentrations. A detection range from 0.01 ng/mL to 100.00 ng/mL was achieved. We further demonstrated the quantification of VEGF concentration in exogenous samples collected from the secretome of human mesenchymal stem cells (hMSCs) at different incubation times. The results from the assay agree well with the results of a parallel enzyme-linked immunoabsorbent assay (ELISA) test, indicating the specificity and reliability of the competitive immuno-aggregation assay. With its simple structure and easy sample preparation, this assay not only enables high sensitivity detection of VEGF but also can be readily extended to other types of cell secretome analysis as long as the specific Ab is known.     

Conformation of bovine nitrosylhemoglobins: an ESR study

The structural properties of nitrosylhemoglobins from two bovine species, namely cow and buffalo, have been investigated using electron spin resonance spectroscopy. Bovine hemoglobins show sensitivity to the presence of chloride ions and organic phosphates. ESR spectral features indicate a stable deoxy quaternary conformation of the molecule when compared to normal adult human hemoglobin A. Amino acid substitutions at the amino terminal end of the beta chain and at other sites of the alpha and beta chains seems to shift the allosteric equilibrium towards the T state in bovine hemoglobins. The results also confirm the intrinsically low oxygen affinity of bovine hemoglobins under physiological conditions.     

Pactamycin Production by Streptomyces pactum

The optimal fermentation conditions for the production of pactamycin, a new antitumor antibiotic, by Streptomyces pactum var. pactum were investigated. The optimal pH range for growth was 6.5 to 7.0. The optimal temperature for the growth of the culture and the production of the antibiotic was investigated in a medium containing Cerelose, blackstrap molasses, Pabst yeast, Kay Soy, CaCO₃, and KCl. Since maximal growth and maximal production efficiency was obtained at 32 C, all subsequent fermentations were conducted at this temperature. Pactamycin was bound to the mycelium in different amounts, depending on the fermentation conditions, and could be extracted with acetone. Good yields (216 μg/ml) of pactamycin could be obtained in a medium containing Cerelose, soy-peptone, calcium carbonate, and potassium chloride. Analysis of the biochemical changes during fermentation indicated that pactamycin was produced during the later autolytic phase.     

Comparative Studies with Three Antibiotics Binding to Deoxyribonucleic Acid

The effects of the three antibiotics U-12,241, nogalamycin, and U-20,661 on (i) deoxyribonucleic acid (DNA) and ribonucleic acid (RNA) synthesis in KB cell cultures and cell-free systems of bacterial and mammalian origin and on (ii) oxidative phosphorylation in rat liver mitochondria were compared. Nogalamycin and U-12,241 inhibited RNA synthesis more strongly than DNA synthesis in all test systems. Antibiotic U-20,661 inhibited DNA and RNA synthesis equally in whole mammalian cells and their corresponding cell-free systems. The RNA polymerase from Escherichia coli, however, was at least 100 times more sensitive to U-20,661 than was the DNA polymerase. U-12,241 caused significant uncoupling of oxidative phosphorylation in mitochondria.     

Exploration and validation of diphosphate‐based Plasmodium LytB inhibitors using computational approaches

LytB or IspH is an indispensable enzyme and a suitable drug target of Plasmodium falciparum that participate in isoprenoid biosynthesis of nonmevalonate pathway (MEP). Recently, we have investigated the structural dynamics of Plasmodium LytB and proposed some novel diphosphate‐based inhibitors using molecular modeling and docking studies. Here, we have tried to characterize those previously screened molecules by quantitative structure activity relationships and pharmacophore‐based analyses, as well as validated the dynamics of their interactions with LytB protein. Five total compounds having PubChem CID 516 , 125696 , 165275 , 448012 , and 9921431 were predicted with significant inhibitory activity by quantitative structure activity relationships and pharmacophore models. Again, the molecular dynamics simulation results showed that these five compounds are able to form stable complexes with the receptor through many direct and water mediated interactions. The binding free energies calculated by Poisson‐Boltzmann surface area method resulted within the range between ?99.77 and ? 43.74 kcal/mol, which favoured their profound inhibitory affinity. Residues of LytB like His41, His74, Ser222, Ser223, and Asn224 in LytB were the main protagonists in contributing the majority of interaction energies to the ligands. Finally, the ADMET, toxicity, and drug‐likeness scores also affirm these compounds to be considered for further development of new antimalarial inhibitor in the future.     

Dimensions of global population projections: what do we know about future population trends and structures?

The total size of the world population is likely to increase from its current 7 billion to 8–10 billion by 2050. This uncertainty is because of unknown future fertility and mortality trends in different parts of the world. But the young age structure of the population and the fact that in much of Africa and Western Asia, fertility is still very high makes an increase by at least one more billion almost certain. Virtually, all the increase will happen in the developing world. For the second half of the century, population stabilization and the onset of a decline are likely. In addition to the future size of the population, its distribution by age, sex, level of educational attainment and place of residence are of specific importance for studying future food security. The paper provides a detailed discussion of different relevant dimensions in population projections and an evaluation of the methods and assumptions used in current global population projections and in particular those produced by the United Nations and by IIASA.     

Isolation of two antifungal compounds fromNeolitsea cuipala and their activity against some plant pathogenic fungi

Zeylanidine and zeylanicine isolated fromNeolitsea cuipala fruit peels are found to be potential antifungal agents againstHelminthosporium oryzae, Fusarium oxysporum, Alternaria solani, Curvularia varuciformis andColletotrichum gleosporioides.