Effect of fusidic acid on migration and chemiluminescence of polymorphonuclear leukocytes

Incubation of polymorphonuclear leukocytes (PMNs) in fusidic acid resulted in a decrease of random migration and chemiluminescence. The effects were dose-dependent but moderate, with statistical significance only at concentrations of 50 mg/l or more. At concentrations used for therapy of bacterial infections and AIDS, fusidic acid was not shown to be deleterious to these aspects of PMN function.     

Symptomatic and subclinical infection with rotavirus P[8]G9, rural Ecuador

During the past decade, rotavirus genotype G9 has spread throughout the world, adding to and sometimes supplanting the common genotypes G1-G4. We report evidence of this spread in a population sample within rural Ecuador. A total of 1,656 stool samples were collected from both patients with diarrhea and from asymptomatic residents in 22 remote communities in northwestern Ecuador from August 2003 through February 2006. Rotavirus was detected in 23.4% of case-patients and 3.2% of controls. From these 136 rotavirus-positive samples, a subset of 47 were genotyped; 72% were of genotype G9, and 62% were genotype P[8]G9. As a comparison, 29 rotavirus-positive stool samples were collected from a hospital in Quito during March 2006 and genotyped; 86% were of genotype P[8]G9. Few countries have reported P[8]G9 rotavirus detection rates as high as those of the current study. This growing prevalence may require changes to current vaccination programs to include coverage for this genotype.     

Integron-containing IncU R plasmids pRAS1 and pAr-32 from the fish pathogen Aeromonas salmonicida

A 45-kb R plasmid, pRAS1, that confers resistance to tetracyclines, trimethoprim, and sulfonamides was isolated in 1989 from an atypical strain of the fish pathogen Aeromonas salmonicida. This plasmid could be transferred by conjugation to Escherichia coli with a high degree of efficiency (frequency, 0.48). The following year pRAS1 was isolated from A. salmonicida subsp. salmonicida in the same area. Incompatibility group U plasmid pRAS1 contained a drug resistance-determining region of 12 kb consisting of a class 1 integron similar to In4 of Tn1696 but with a dfrA16 gene cassette inserted. Close to IS6100 at the right end of Tn4 was a truncated Tn1721. Restriction enzyme analysis showed that R plasmid pAr-32, isolated from A. salmonicida in Japan in 1970, had the same backbone structure as pRAS1, while the drug resistance-determining region contained a complex class 1 integron with an aadA2 cassette; the chloramphenicol resistance gene catA2, as in In6 of pSa; and a duplicate of the 3' conserved segment of the integron.     

Sulfonamide resistance in Neisseria meningitidis strains liberating various amounts of free endotoxin

The relationship between sulfonamide susceptibility and the ability to liberate endotoxin was studied in 50 strains of Neisseria meningitidis. The endotoxin activity was investigated by the Limulus lysate test in growing cultures of 25 sulfonamide-resistant and 25 sensitive strains. The sulfonamide-resistant strains tended to have a higher endotoxin activity in cultures grown for 6 h than sensitive ones, and had also a higher amount of free, filtrable endotoxin.     

Lack of ability to synthesize tissue factor by endothelial cells in intact human saphenous veins

It is well established that cultured endothelial cells are induced to generate tissue factor activity when incubated with either endotoxin or thrombin. In this study a perfusion system was used on 3-4 cm long human saphenous veins. The veins were perfused with thrombin (2.5 U/ml), endotoxin (30 ng/ml) or just medium for 3 h at 37 degrees C. After the perfusion, the veins were treated with collagenase, and EC were collected and subjected to tissue factor activity measurements. Some perfused veins were examined for tissue factor activity on the vessel wall by allowing factor VII and factor X to interact with the lumen of the intact vessels, followed by quantitation of generated factor Xa in a chromogenic assay. No formation of tissue factor activity could be found after perfusion in either collagenase-dissolved endothelial cells or in the coupled chromogenic assay for tissue factor activity performed in the lumen of the vessel. Our data strongly suggest that endothelial cells in intact endothelium may behave quite differently from isolated endothelial cells stimulated in cell cultures.     

Serum opsonins to serogroup B meningococci in meningococcal disease

The opsonic activity to serogroup B meningococci (B:15:P1.16) was measured in sera from 101 patients with meningococcal disease using a chemiluminescence method. On admission to hospital the opsonic activity was lower in 12 patients who died than in survivors (p = 0.0007). A close association was observed between the opsonic activity and the duration of symptoms before admission, the severity of the disease, and the levels of IgG antibodies to the outer membrane complex (15:P1.16). The opsonic activity was low in 2 premorbid sera compared to healthy controls. The mean opsonic activity peaked 2 weeks after admission and was still high 3-5 years later. Meningococcal strains of different serogroups, serotypes and subtypes induced a similar increase in opsonic activity to B:15:P1.16 meningococci. No increase in activity was observed in sera from patients with meningitis and septicemia caused by other bacteria. Serum opsonins seem to be of significant importance in the host defence against serogroup B meningococci.     

Clonal studies in the myelodysplastic syndrome using X-linked restriction fragment length polymorphisms

We used the X-linked restriction fragment length polymorphism (RFLP)-methylation strategy to study the clonal basis of the myelodysplastic syndrome (MDS) in seven patients. RFLP-methylation analysis was performed on cell populations from bone marrow (BM) aspirates and peripheral blood using probes specific for the hypoxanthine phosphoribosyltransferase (HPRT) or phosphoglycerate kinase (PGK) gene regions. Density gradient centrifugation methods were used to separate granulocytes and monocytes, and T lymphocytes were positively selected by CD2 (a pan-T marker) immunoconjugated magnetic beads. Cell populations from BM aspirates in 6 of the 7 patients with MDS showed a monoclonal pattern of X-inactivation. The neutrophilic and T-lymphocytic cell fractions were analyzed in 4 of the 6 patients, and the monocytic cell fraction in one of these, and all fractions analyzed showed a similar monoclonal pattern. In 2 of the latter 4 patients, both of whom had normal karyotypes, DNA from a skin biopsy showed a polyclonal pattern. Our data suggest that MDS is a clonal disorder, even in the absence of detectable cytogenetic abnormalities, and that the abnormal clone is capable of myeloid, monocytic, and lymphoid differentiation.