flavin-adenine-dinucleotide and Bacterial-Infections

Although blood neutrophils with toxic granulation provide an excellent means of evaluating acute bacterial infections, the methods are labor-intensive and their reproducibilities depend on the staining technique and the observer's judgment. We measured the flavin adenine dinucleotide (FAD) content of normal neutrophils and neutrophils with toxic granulation by flow cytometry after incubating them with bis(Zn(2+)-dipicolylamine) complex. A total of 122 blood samples (78 with neutrophils with toxic granulation, 44 with normal neutrophils without toxic granulation) were analyzed. The mean autofluorescence levels of neutrophils in the toxic granulation (+) group and toxic granulation (-) group were both 1.9 x 10(3) MESF (mean equivalent soluble fluorochrome) values. However, after incubating neutrophils with bis(Zn(2+)-dipicolylamine) complex for 15 min, the mean fluorescence intensities of neutrophils in the toxic granulation (+) and toxic granulation (-) groups were significantly enhanced by 71- and 19-fold to 138+/-78 x 10(3) MESF and 37+/-37 x 10(3) MESF, respectively (p <0.001). An MESF cutoff value of 79 x 10(3) showed a sensitivity of 93.2% and a specificity of 81.8% for neutrophils with toxic granulation. Similarly, the MESF level ratio, defined as the ratio of the MESF value after incubation with bis(Zn(2+)-dipicolylamine) complex to the autofluorescence MESF value, at a cutoff value of 41, showed a sensitivity of 92.3% and a specificity of 81.8% for the detection of neutrophils with toxic granulation. The MESF values of neutrophils after incubation with bis(Zn(2+)-dipicolylamine) complex did not correlate with the leukocyte (p >0.05) or neutrophil counts (p >0.05). In conclusion, measurement of FAD fluorescence intensity in neutrophils by flow cytometry after incubation with bis(Zn(2+)-dipicolylamine) complex is an easy, objective, and reliable method of detecting neutrophils with toxic granulation.

Topics: Acute Disease; Adolescent; Adult; Aged; Aged, 80 and over; Amines; Bacterial Infections; Child; Female; Flavin-Adenine Dinucleotide; Granuloma; Hematopoietic Stem Cell Transplantation; Humans; Indicators and Reagents; Leukemia; Leukocyte Count; Male; Middle Aged; Neutrophils; Picolinic Acids; Sepsis; Young Adult

Topics: Anti-Bacterial Agents; Bacterial Infections; Clinical Trials as Topic; Drug Approval; Drug Design; Drug Resistance, Bacterial; Flavin-Adenine Dinucleotide; Humans; Ketolides; Macrolides; United States

Like thymidylate synthase (TS) in eukaryotes, the thymidylate synthase-complementing proteins (TSCPs) are mandatory for cell survival of many prokaryotes in the absence of external sources of thymidylate. Details of the mechanism of this novel family of enzymes are unknown. Here, we report the structural and functional analysis of a TSCP from Thermotoga maritima and its complexes with substrate, analogs, and cofactor. The structures presented here provide a basis for rationalizing the TSCP catalysis and reveal the possibility of the design of an inhibitor. We have identified a new helix-loop-strand FAD binding motif characteristic of the enzymes in the TSCP family. The presence of a hydrophobic core with residues conserved among the TSCP family suggests a common overall fold.

Topics: Amino Acid Sequence; Anti-Bacterial Agents; Bacterial Infections; Bacterial Proteins; Binding Sites; Crystallography, X-Ray; Deoxyuracil Nucleotides; Flavin-Adenine Dinucleotide; Macromolecular Substances; Models, Molecular; Molecular Sequence Data; Molecular Structure; Protein Folding; Protein Structure, Tertiary; Thermotoga maritima; Thymidylate Synthase