Pro- and antiinflammatory cytokines were measured on admission in 287 consecutive Vietnamese adults with severe falciparum malaria. Plasma interleukin (IL)-6, IL-10, and tumor necrosis factor (TNF)-alpha concentrations and the IL-6: IL-10 ratio were significantly higher in patients who died than in survivors (P<.001). On multivariate analysis, hyperparasitemia, jaundice, and shock were all associated independently with raised IL-6, IL-10, and interferon-gamma, and acute renal failure specifically with raised TNF-alpha levels. Cerebral malaria patients, particularly those without other vital organ dysfunction, had significantly lower levels of these cytokines (P=.006), reflecting a more localized pathology. Serial IL-6 and IL-10 measurements made on 43 patients who died and matched survivors indicated a relative deficiency in IL-10 production as death approached. Elevated plasma cytokines in severe malaria are associated with systemic pathologic abnormalities, not cerebral involvement. Both the overall magnitude of the cytokine responses and the eventual imbalance between the pro- and antiinflammatory responses are important determinants of mortality.

The Pseudomonas aeruginosa DNA gyrase gyrA gene was cloned and sequenced from strain PAO1. An open reading frame of 2,769 bp was found; it coded for a protein of 923 amino acids with an estimated molecular mass of 103 kDa. The derived amino acid sequence shared 67% identity with Escherichia coli GyrA and 54% identity with Bacillus subtUis GyrA, although conserved regions were present throughout the sequences, particularly toward the N terminus. Complementation of an E. coli mutant with a temperature-sensitive gyrA gene with the PAO1 gyrA gene showed that the gene is expressed in E. coli and is able to functionally complement the E. coli DNA gyrase B subunit. Expression of PAO1 gyrA in E. coli or P. aeruginosa with mutationally altered gyrA genes caused a reversion to wild-type quinolone susceptibility, indicating that the intrinsic susceptibility of the PAO1 GyrA to quinolones is comparable to that of the E. coli enzyme. PCR was used to amplify 360 bp of P. aeruginosa gyrA encompassing the so-called quinolone resistance-determining region from ciprofloxacin-resistant clinical isolates from patients with cystic fibrosis. Mutations were found in three of nine isolates tested; these mutations caused the following alterations in the sequence of GyrA Asp at position 87 (Asp-87) to Asn, Asp-87 to Tyr, and Thr-83 to Ile. The resistance mechanisms in the other six isolates are unknown. The results of the study suggested that mechanisms other than a mutational alteration in gyrA are the most common mechanism of ciprofloxacin resistance in P. aeruginosa from the lungs of patients with cystic fibrosis.The enzyme DNA gyrase is a type II DNA topoisomerase that is able to introduce negative superhelical coils into covalently closed bacterial DNA in an ATP-dependent process. Gyrase also plays a role in DNA replication, recombination, decatenation, and transcriptional regulation of some supercoiling-sensitive promoters (for a review, see reference 24). The gyrase holoenzyme is a tetramer of two A and two B subunits, the products of the gyrA and gyrB genes, respectively. The A subunits are responsible for DNA breakage and reunion, while the B subunits are the site of ATP hydrolysis. The enzyme has proven to be a good target for antimicrobial agents; the actions of the A subunits are inhibited by quinolones such as nalidixic acid and ciprofloxacin, while those of the B subunits are inhibited by coumarins such as coumermycin Al and novobiocin. The peptide antibiotic microcin B17 and the glycocinnamoylspermidine agent cinodine have also been shown to be inhibitors of DNA gyrase function (22,33). The contiguous gyrB-gyrA locus has been cloned and sequenced in Bacillus subtilis (19), Staphylococcus aureus (10), Mycoplasma pneumoniae (1), and Haloferax spp. (9). In Escherichia coli (32, 37), Klebsiella pneumoniae (3), Pseudomonas putida (23), Neisseria gonorrhoeae (31), and Campylobacter jejuni (34), the cloned gyrA and gyrB genes are not contiguous. The deduced amino acid sequences of the A and B subunits are very well conserved with...

A serologically typical strain of Burkholderia pseudomallei (strain 304b) was found to produce two S-type lipopolysaccharides (LPS) differing in the chemical structures of their O-polysaccharide (O-PS) components. Structural analysis revealed that one O-antigenic polysaccharide (O-PS I) is an unbranched high-molecularweight polymer of 1,3-linked 2-O-acetyl-6-deoxy-␤-D-manno-heptopyranose residues. The other LPS O antigen (O-PS II) is an unbranched polymer of repeating disaccharide units having the structure-3)-␤-D-glucopyranose-(1-3)-6-deoxy-␣-L-talopyranose-(1in which ca. 33% of the L-6dTalp residues bear 2-O-methyl and 4-O-acetyl substituents while the other L-6dTalp residues carry only 2-O-acetyl substituents. Analysis of a serologically atypical strain of B. pseudomallei (strain 824a) produced a single LPS O-PS which was chemically identical to the 6-deoxy-D-manno-heptan O-PS I. The production of two distinct LPS raises the interesting question of their relative immunogenicities and consequently their relative importance for diagnostic serology and for the possible development of conjugate vaccines.

Plasmodium falciparum–infected erythrocytes (IRBCs) have been shown to interact with a number of endothelial adhesion molecules expressed on transfectants, on cell lines, and as immobilized purified receptor proteins under flow conditions. However, the experiments were designed in such a way that maximal numbers of adhesion molecules were provided as substratum. Whether the interactive events actually occur on microvascular endothelium, where the distribution and expression of adhesion molecules may be less, remains undetermined. In this study, the cytoadherance of IRBCs on human dermal microvascular endothelial cells (HDMECs) as a model of human microvasculature was examined. IRBCs were observed to tether, roll, and adhere on resting HDMECs, which constitutively expressed CD36 and intercellular adhesion molecule-1 (ICAM-1) at an optimal shear stress of 1 dyne/cm2. Stimulation of HDMECs with tumor necrosis factor–α for 5 and 24 hours, which resulted in up-regulation of ICAM-1 and induction of vascular cell adhesion molecule-1 expression, significantly increased the percentage of rolling cells that adhered without affecting the rolling flux. In contrast, P-selectin expression on HDMECs induced by oncostatin M led to an increase in both rolling flux and adhesion. Inhibition studies with receptor-specific monoclonal antibodies revealed that adhesion of IRBCs on HDMECs was largely CD36 dependent, whereas rolling could be mediated by any of the adhesion molecules studied. Collectively, these findings indicate that IRBCs interact synergistically with multiple adhesion molecules on vascular endothelium. The rolling of IRBCs may be the rate-limiting step in cytoadherance, since it can be modulated by cytokines to enhance CD36-mediated IRBC adhesion.