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Biomedical subjects

L Porretti

Publications and source records attributed to L Porretti.

24 records · Page 2Linked to original sources
PubMed1993

Role of lactate in platelet storage lesion.

It is known that lactate accumulation may cause a pH fall in platelet concentrates (PC) during storage, and this phenomenon causes platelet morphological lesions and loss of platelet in vivo viability. In this study, we added increasing amounts of lactate to identical PC in order to evaluate the role of hydrogen ion accumulation in determining platelet activation and lesion during storage. Six hours after PC preparation, lactate was added to PC1 and PC2 at 20 and 12 mM final concentrations, respectively, while PC3 served as control. In PC1, pH was lower than 6.3, and platelet function and discoid morphology were lost. PC2 were stored for 7 days at pH values ranging from 6.4 to 6.6, and most results of in vitro measurements reflecting platelet function such as osmotic reversal, ATP release and aggregation in response to different stimuli were not significantly inferior when compared to controls. The addition of lactate had no apparent effect on the rise of platelet activation markers P-Selectin, lysosome-like protein gp 53, platelet-bound fibrinogen and granulophysin, while a reduction of borderline significance was observed in glycoprotein Ib expression after pH reduction to values lower than 6.6. It is concluded that the rise of platelet activation markers during storage reflects platelet lesions different from those determined by lactate per se.

Blood Platelets↗
PubMed1992

Platelet quality after 15-day storage of platelet concentrates prepared from buffy coats and stored in a glucose-free crystalloid medium.

It has been reported previously that platelet concentrates (PCs) prepared from buffy coat pools diluted in a simple, glucose-free medium (BC-PCs) are effective in thrombocytopenic patients after 4 to 12 days of storage. Such preparations produce platelet increments similar to those of traditional PCs prepared from platelet-rich plasma (PRP-PCs) stored for 1 to 3 days. The purpose of this study was to obtain a series of in vitro measurements during storage to allow a more detailed characterization of BC-PCs and a more detailed comparison of BC-PCs with PRP-PCs. At the beginning of storage, the level of (alpha granule membrane protein-140 (GMP-140), a marker of platelet activation, was significantly higher on PRP-PC platelets, and BC-PCs were superior in measurements reflecting platelet function, such as osmotic reversal, ATP release, and aggregation with collagen. Compared to PRP-PCs, BC-PCs were superior in the percentage of discs, total ATP, and glycoprotein lb expression by Day 7. This superiority became more striking on Day 11. Overall, 15-day-old BC-PCs compared favorably to 7-day old PRP-PCs: BC-PCs were superior in ATP release and aggregation with collagen, but they were not significantly different for all other measurements reflecting platelet quality and function. Thus, the quality of platelets in BC-PCs was superior on Day 1, and this superiority progressed as storage continued. In addition, the metabolism of BC-PCs was favorable.(ABSTRACT TRUNCATED AT 250 WORDS)

Blood Platelets↗
PubMed1992

Immunoglobulin classes and subclasses of platelet antibodies in a case of post-transfusion purpura.

A multiparous white woman developed severe thrombocytopenia following transfusion of red blood cells. Six ineffective platelet transfusions (a total of 42 random donor concentrates) were given from day 0 to day +6, high-dose steroids from day +1, progressively tapered until day +30, and a total of 150 g of intravenous immunoglobulins from day +2 to day +6. As platelet count had not increased significantly by day +8, four plasma exchange procedures, each consisting of 2,000 ml of plasma exchanged with 5% albumin solution, were performed on days +8, +10, +14 and +18. Platelet count was 5, 50, 100 and 234 x 10(9)/l on days +8, +14, +26 and +32 (discharge), respectively. The patient's acute phase serum contained increased levels of platelet alloantibodies with anti-HPA-1a (PlA1, Zwa) specificity and a titer of 3,200. IgG1, IgG2 and IgG3 subclasses of platelet-reactive antibodies in the patient's serum were elevated, whereas IgG4, IgM and IgA were within the reference values. Levels of IgG1, IgG2 and IgG3 of antiplatelet antibodies showed a marked and parallel reduction during treatment, but were still above the reference values at the end of treatment and 1 year later, when the patient platelet count was normal. Although a failure of intravenous immunoglobulins cannot be proven in this case, plasma exchange seems to have contributed more than intravenous immunoglobulins to clinical remission.

Aged↗
PubMed1990

Comparison of platelet activation and membrane glycoprotein Ib and IIb-IIIa expression after filtration through three different leukocyte removal filters.

We evaluated three filters used for leukocyte removal from platelet concentrates: Imugard IG 500, Pall PL100 and Sepacell PL-10A. Filter performance, platelet activation and expression of membrane glycoproteins Ib and IIb-IIIa were evaluated. Imugard, Pall and Sepacell showed median postfiltration in vitro platelet recoveries of 88, 84 and 80%, and total residual leukocyte counts of 16.1, 7.5 and 0.6 x 10(6)/pool of 8 platelet concentrates, respectively. Mean platelet volume was reduced after filtration with all filters. Postfiltration values of glycoproteins Ib and IIb-IIIa, and of activation markers GMP 140 and gp 53 were not significantly different from prefiltration values. Filtration through Imugard, Pall and Sepacell did not induce significant platelet activation or modifications of platelet membrane glycoproteins Ib and IIb-IIIa.

Cell Separation↗
PubMedDate not supplied

Use of a rapid method for genotyping human platelet antigen systems in neonatal alloimmune thrombocytopenia.

We applied a polymerase chain reaction-sequence specific primer (PCR-SSP) method developed by other researchers to study 4 families of newborns with neonatal alloimmune thrombocytopenia (NAITP) in which serology had provided inconclusive human platelet antigen (HPA) typing data. This method allowed for the identification of the newborn HPAs which were incompatible with their respective mothers. They were HPA-2b, -1b, -3a, and -5b. This PCR-SSP is a useful tool for improving the ability to identify the incompatible HPA in NAITP.

Adult↗