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Biomedical subjects

C Tetta

Publications and source records attributed to C Tetta.

191 records · Page 11Linked to original sources
PubMedDate not supplied

Evidence for the involvement of the IgE-basophil-mastocyte system in human acute post-streptococcal glomerulonephritis.

Several findings reveal the involvement of the IgE-basophil-mastocyte-platelet-activating-factor (PAF) system in human acute post-streptococcal glomerulonephritis. In the acute phases of the disease there is a transient, marked reduction in the circulating metachromatically staining basophils, indicating an in vivo basophil degranulation. The blood reservoirs of PAF are depleted. The number of metachromatic mastocytes in renal biopsy samples was very low and morphological aspects of degranulation were present. In vitro, we demonstrated basophil degranulation and PAF release in presence of exogenous streptococcal Ags after recovery. These findings suggest that the IgE-basophil-mastocyte-PAF system may play a role in human pathology, as has been shown in immune complex (Ic) deposition in acute serum sickness in rabbits.

Acute Disease↗
PubMedDate not supplied

Immunological mechanisms of human platelet involvement.

Several immunological mechanisms of platelet involvement in inflammation are described. Basophils degranulate and release a platelet-activating factor (PAF) when challenged with anaphylotoxins, cationic proteins (CP) from polymorphonuclear cells (PMN) as well as with specific antigens from atopic patients. PAF is a newly-discovered mediator of anaphylaxis present in rabbit and human basophils. This factor is a small phospholipid, probably a lyso-1-phosphatidylcholine with a significant aggregating activity on rabbit and human platelets. PAF is released, together with a small amount of arachidonic acid, from basophils in the presence of anaphylotoxins, CP and specific antigens from atopic patients. The already well-known direct interaction between immune complexes (Ics) and human platelets is compared here with the mechanism of PAF-induced aggregation. It is shown that the latter process of aggregation differs from the former. Human platelet aggregation starts more rapidly in the presence of PAF than of Ics. PAF-induced aggregation is ADP-independent as it is not affected by ADP inhibitors. On the contrary, Ic-dependent aggregation is brought about by endogenous ADP release and therefore inhibited by ADP inhibitors. The interaction between Ics and platelets leads to the release of CP. The latter produce a cascade reaction involving basophils which degranulate and release PAF. A self-maintaining mechanism of tissue injury is thus triggered.

Adenosine Diphosphate↗
PubMedDate not supplied

Production of platelet activating factor by human neutrophils after backfiltration of endotoxin contaminated dialysate.

Lipopolysaccharide (LPS) from gram negative bacteria has been shown to prime human polymorphonuclear neutrophil (PMN) production of platelet activating factor (PAF). PAF is a lipid mediator of inflammation and endotoxic shock and is also involved in leukocyte activation occurring during hemodialysis; PAF induces leukopenia, degranulation of lysosomal granules, and adherence to hemodialysis membranes. Transmembrane passage of LPS has also been shown to occur. To evaluate the relevance of transmembrane passage of LPS on the priming of PMN derived production of PAF, we designed in vitro studies using an experimental circuit equipped with different membranes (Cuprophan, polysulfone, polymethylmethacrylate, polyamide) and recirculation of purified human PMNs. At different time intervals, PMNs were stimulated with FMLP (10 microM) after back-filtration of sterile and LPS contaminated dialysate. The results of these studies suggest that priming of PMN derived production of PAF was related to the percent of backfiltered LPS, and they emphasize the need for careful assessment of microbiologic quality to improve biocompatibility.

Electrophoresis, Polyacrylamide Gel↗
PubMedDate not supplied

Direct determination of blood recirculation rate in hemodialysis by a conductivity method.

Blood recirculation is one of the key factors of decreasing dialysis efficiency. Determination of recirculation rate (R) is necessary to optimize effective dialysis delivery and to monitor vascular access function. R can be directly measured by a conductivity method in paired filtration dialysis (PFD), a double-compartment hemodiafiltration system that permits direct access to plasma water via the ultrafiltration stream. Measurement of R, in this system, involves the first of two conductivity sensors integrated in a urea monitor (UMS, BelIco-Sorin, Mirandola, Italy), and two saline injections. The rise in conductivity (deltaC1) induced by a 2.7 ml bolus of hypertonic saline 20% (mg/dl) in the arterial line serves for calibration, and is followed by an equivalent injection into the venous line, giving rise to deltaC2. The ratio deltaC2/deltaC1 equals R. A comparison between R values obtained with this method and with the low-flow technique in 31 chronic dialysis patients during 138 PFD sessions is reported. Mean R+/-SD by the conductivity method was 5.1+/-2.0 and 5.7+/-2.0% after 65 and 155 minutes of PFD (correlation coefficient, r = 0.75), whereas it was 6.4+/-4.9% and 5.5+/-4.6% after 30 sec of low blood pump flow for urea and creatinine markers, respectively (r = 0.35). After 120 sec of low flow, mean R increased to 9.0+/-5.1 and 8.8+/-4.6% for urea and creatinine, respectively (r = 0.45). Considerable discrepancies were found in R values measured simultaneously with the two blood markers. Statistically significant differences were found between the two measurement modalities (blood-side and conductivity); the correlation coefficients (r) varied between 0.28 and 0.41. The observed differences in mean R results do not seem considerable from a clinical perspective. The best agreement between blood-side and conductivity R measurements was obtained with Rcreat after 30 sec of low flow. Overall, a wider distribution was found in R values from blood-side determinations, most likely consequent to variability in the dosing method. The conductivity method appears more accurate and simple in assessing total R, and can be readily automated and integrated into the dialysis machine. The authors, therefore, recommend evaluation of R using methods not based on chemical blood concentration values.

Adult↗