[SIN survey on quality control of dialysis water in Italy]. / Indagine SIN sui controlli delle acque di dialisi in Italia.

BACKGROUND: The importance of high quality water for dialysis is well established. This study aimed to obtain a picture of the Italian situation to develop national guidelines. METHODS: Questionnaire analysis was used to assess water quality control protocols and types of chemical and microbiological parameters monitored. Regions with responses from at least half the units were considered for the study. RESULTS: Eighteen out of 20 regions fulfilled the inclusion criteria; 297/469 dialysis units answered the questionnaire (5208 dialysis beds, 18213 patients). Eighty-one percent of Italian units follow a regular water quality control program. The reverse osmosis outlet is the sampling point used most for assessing chemical and microbiological parameters. The most common frequency in monitoring is < or =6 months. Fifteen chemical items, suggested by the Italian Farmacopea Ufficiale (FU), are periodically controlled by at least half the units. Aluminum is measured in about 70% of units, chloramines and volatile halogenated hydrocarbons, respectively, in 42 and 30% of units. According to the FU, bacterial counts at 22 degrees C (84%) and endotoxin determinations (60%) are the most common microbiological analyzes. CONCLUSIONS: The survey demonstrated protocol differences among the units, confirming the need for Italian guidelines to ameliorate and standardize dialysis water monitoring. More than half the units are following the FU, but we cannot rule out less strict monitoring only in non-participating units.

[Diagnostic aspects in the determination of antineutrophil cytoplasmic antibodies]. / Aspetti diagnostici nella determinazione degli anticorpi anti citoplasma dei neutrofili.

We propose a four step flow-chart to define ANCA positivity and antigenic target. 1st step: indirect immunofluorescence test on ethanol-fixed human granulocytes (IIF-E), as screening test. Different staining patterns can be observed: a granular cytoplasmic fluorescence (C-ANCA), a smooth or fine granular perinuclear fluorescence (P-ANCA) and an intermediate pattern (X-ANCA). Antinuclear antibodies (ANA) may mimic P-ANCA. 2nd step: IIF test on formalin-fixed human granulocytes (IIF-F) differentiates true P-ANCA from ANA: most of P-ANCA show cytoplasmic pattern, whereas ANA are negative. 3rd step: IIF test on monkey liver sections (IIF-M) investigates simultaneous ANA and P-ANCA positiveness. P-ANCA positive sera show an exclusive reactivity with neutrophils infiltrating the portal tract, whereas ANA react with hepatocytes nuclei. 4th step: to characterize antigenic target, a solid phase assay, using purified proteins as substrates, is performed. We found 17 C-ANCA (6 PR3, 3 MPO, 1 Lys, 1 Cat G and 6 unknown antigens) out of 173 patients screened with IIF-E. 21 P-ANCA positive sera have been investigated by IIF-F test: 15 showed a cytoplasmic pattern; EIA test gave the following results: 6 MPO, 2 LF, 5 unknown antigens; 2 cases were positive for two antigens, MPO & LF. Using IIF-M on the 6 IIF-F negative sera, we observed: 2 false positives (ANCA-/ANA-), one ANCA+/ANA+ (antigen LF), 3 ANCA+/ANA- (unknown antigens). The flow chart suggested allows to analyse in detail ANCA, using easily available commercial kits.

Relation between blood pH and ionized calcium during acute metabolic alteration of the acid-base balance in vivo.

We induced metabolic alkalosis and acidosis in 10 healthy volunteers in order to analyse in vivo relation between pH and ionized calcium (cCa2+). In the alkalinization test, 2.7 mol/kg NaHCO3 was injected. In the acidification test, volunteers took 4 mmol/kg NH4Cl. Blood pH and cCa2+ (mmol/l) mean values (SD) baseline, after alkalinization and acidification tests, were: 7.363 (0.018), 7.456 (0.031), 7.244 (0.031), 1.27 (0.03), 1.14 (0.03) and 1.38 (0.04). Mean slope of regression log cCa2+/pH was -0.39 (SD 0.11). Such a slope differs after in vivo or in vitro changes, due to the in vivo rapid restoration of equilibrium between the plasmatic and interstitial compartments following changes in water and electrolyte concentrations. The type of acid-base alteration-respiratory or metabolic-influences pH changes, and consequently the regression slope. The in vivo slope for log cCa2+/pH in normal subjects (-0.21) is much the same as in acute respiratory alterations (-0.17), whereas it differs in acute metabolic alterations (present study). Bicarbonates play different roles: the same changes in pH cause greater changes in cCa2+ after acute metabolic rather than respiratory alterations. Ca2+ homeostasis is maintained in acute respiratory acid-base imbalance, despite wide shifts in pH, whereas in acute metabolic alterations even small pH changes have striking repercussions on cCa2+. The experimental angular coefficient for in vivo acute metabolic acid-base alterations differs from the theoretical one calculated by Thode's differential equation (-0.25).