[Significant negative correlation between fasting plasma insulin and ambulatory blood pressure in patients on chronic hemodialysis]

Positive correlation between blood pressure and insulin is well established in patients with essential hypertension. The aim of the present study was to examine the relationship between fasting plasma insulin level and ambulatory blood pressure (ABPM) in patients with chronic renal failure. The study group consisted of 20 patients (11 females, 9 males, mean age 39 +/- 12 years) on chronic haemodialysis (mean 2.5 years). Fasting plasma insulin (FPI) was measured by radioimmunoassay. The patients were investigated before and after haemodialysis. FPI significantly increased after haemodialysis from 18.4 +/- 12.0 to 40.1 +/- 31.9 mIU/l (p < 0.01), while creatinine concentration decreased from 1158 +/- 130 to 910 +/- 159 mumol/l (p < 0.001). Night-time systolic blood pressure (SBP) was significantly lower during the day of haemodialysis (141.9 +/- 19.6 mmHg vs. 136 +/- 27.7 mmHg, p < 0.05). 24-hour and daytime SBP was nonsignificantly lower after haemodialysis. 24-hour diastolic blood pressure (DBP) was significantly lower during the day of haemodialysis (92.9 +/- 12.5 mmHg vs. 87.3 +/- 14.3 mmHg, p < 0.05), as well as daytime (94.9 +/- 12.1 mmHg vs. 88.8 +/- 14.6 p < 0.05) and night-time DBP (88.9 +/- 16.0 mmHg vs. 83.8 +/- 17.4 mmHg p < 0.05). FPI was found to be significantly negatively correlated with 24-hour, daytime and night-time SBP on the day of haemodialysis (r = -0.63, p < 0.005; r = 0.64, (p < 0.005 and r = -0.54, p < 0.05, respectively). The significant negative correlation between FPI and 24-hour SBP suggests that insulin could reveal its hypotensive effect after the haemodialysis.

Human neutrophil responses to pathogenic Escherichia coli are receptor-specific and selectively augmented by recombinant human tumor necrosis factor-alpha

The effect of recombinant human tumor necrosis factor-alpha (rhTNF alpha) on neutrophil (PMNL) response to uropathogenic Escherichia coli was assessed. A strain expressing mannose-sensitive adhesins (type 1 fimbriae) stimulated significant primary granule, secondary granule, and leukotriene B4 (LTB4) release. The same strain grown to suppress fimbrial expression and three non-type 1-fimbriated strains stimulated only background low-level PMNL activation. The binding of the type 1-fimbriated strain to PMNL was inhibitable by D-mannose and concanavalin A, while that of non-type 1-fimbriated strains was not but was inhibited by antibodies to the PMNL complement receptors 1 and 3. TNF alpha (10(-9) M) synergistically augmented the non-type 1-fimbriated E. coli-stimulated LTB4 release and additively increased secondary granule release without affecting primary granule release. In contrast, none of the responses to the type 1-fimbriated strain were augmented by TNF alpha. In the absence of mannose-sensitive adhesins, the activation of PMNL by E. coli may involve both complement receptors 1 and 3 and be augmented by TNF alpha.

The influence of net surface charge on the interaction of uropathogenic Escherichia coli with human neutrophils

Escherichia coli strains, grown to suppress fimbrial expression, synthesised enhanced quantities of polysaccharide capsule, which significantly lessened their binding to heparin sepharose columns. In the presence of poly-L-lysine, these strains were strongly retained on the columns confirming their highly anionic nature. Uropathogenic strains of E. coli expressing type 1 fimbrial adhesins activated the respiratory burst, the degranulation response and the release of leukotrienes from human neutrophils (PMN) to a significantly greater extent than the same strains grown in a medium to suppress this fimbrial expression. The addition of the poly-cation poly-L-lysine, however, selectively increased neutrophil activation in response to these non-fimbriate strains. This dose-dependent effect was reversed by the addition of heparin suggesting a mechanism dependent on surface charge. The results of this study suggest that non-specific mechanisms involving the neutralisation of surface charge, in addition to specific receptor and adhesin mediated events could affect neutrophil activation at sites of infection.

Variable expression of P fimbriae in Escherichia coli urinary tract infection

Fresh urinary isolates were examined by immunofluorescence with polyclonal rabbit antibodies against type 1 and P fimbriae. This procedure showed P-fimbriate Escherichia coli in 22 of 24 samples from patients with asymptomatic bacteriuria, 24 of 26 samples from patients with cystitis, and 6 of 6 samples from patients with pyelonephritis. Type 1 fimbriae were expressed by less than 40% of isolates in all three groups. There was no relation between the presence of symptoms or the site of infection and fimbrial expression, of P or type 1, by bacteria adherent to freshly isolated uroepithelial cells.