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Biomedical subjects

R Mazzara

Publications and source records attributed to R Mazzara.

At least 55 records · Page 3Linked to original sources
PubMed1993

Prothrombin fragment 1 + 2 and thrombin-antithrombin complex measurements indicate continuous and progressive intraoperative thrombin generation in liver transplantation.

Prothrombin fragment 1 + 2 (F1 + 2) and thrombin-antithrombin complex (TAT) have been measured in the different surgical phases in 40 patients undergoing 43 orthotopic liver transplantations (OLT), in order to study thrombin generation throughout the surgical procedure. F1 + 2 and TAT progressively rose from preoperative values (1.47 +/- 0.92 nmol/l and 22.41 +/- 19.15 ng/ml, respectively) to the end of anhepatic phase (5.97 +/- 2.20 nmol/l, 64.24 +/- 11.30 ng/ml), whereas changes in circulating antithrombin III (ATIII) were negligible in this period. Thrombin generation continued to slightly but significantly increase immediately after liver graft reperfusion (F1 + 2 6.87 +/- 1.65 nmol/l, TAT 89.32 +/- 7.54 ng/ml), and ATIII levels decreased from 70.61 +/- 12.28 to 57.16 +/- 9.57%. Higher preoperative values of F1 + 2 were associated with larger requirements of both packed red blood cells and fresh frozen plasma (FFP) in the host liver explantation phase, whereas the lowest basal levels of ATIII were related to a higher plasma expense in the whole OLT procedure. The activation of circulating prothrombin begins early in OLT, and adequate FFP infusion is capable of maintaining appropriate circulating thrombin-inhibitory activity.

Adolescent↗
PubMed1992

Contribution of perfusion techniques to the evaluation of the hemostatic effectiveness of platelet concentrates.

Perfusion systems allowing the morphometric analysis of platelet interactions with vessel subendothelium under flow conditions have been applied to evaluate the quality and function of stored platelets. Studies performed in vitro indicate that despite the existence of storage lesions, platelets in concentrates stored for up to 5 days retain their ability to interact with the subendothelium. Perfusion studies ex vivo with nonanticoagulated blood from anemic-thrombocytopenic patients have shown the critical hemorrheological role of red blood cells facilitating platelet interactions with subendothelium. Similar studies performed on severely thrombocytopenic patients who received transfusions of platelets stored at 4 degrees C indicate that incompletely viable platelets can contribute to primary hemostasis through procoagulant mechanisms. The latter results suggest that storage lesions which contribute to impairment of platelet function may result in enhancement of platelet procoagulant activities. Perfusion techniques have contributed to the evaluation of the hemostatic effectiveness of platelet concentrates. These techniques will provide a useful model to test the impact of new storage technologies on platelet hemostatic function.

Animals↗
PubMed1991

Evaluation of the transfusion effectiveness of various platelet concentrates by means of an in vitro perfusion technique.

An in vitro perfusion technique was used for the assessment of the effectiveness of platelet concentrates (PCs) administered to patients with bone marrow failure. Denuded rabbit arterial segments mounted in annular chambers were exposed to nonanticoagulated blood drawn directly from the antecubital vein. This perfusion system allows the direct visualization of platelet-subendothelium interactions. The deposition of platelets on exposed subendothelium and the presence of fibrin were evaluated morphometrically. Perfusions were performed before and 10 and 120 minutes after the transfusion of PCs that had been obtained by apheresis and administered immediately after collection (A) or separated by centrifugation of blood units and transfused 24 hours after storage at 22 degrees C (B) or 4 degrees C (C). Bleeding times were also determined systematically. The deposition of platelets on the subendothelium increased significantly (p less than 0.01) 10 minutes after transfusions of A and B PCs, but the presence of fibrin did not differ from pretransfusion values. Two hours after the administration of A or B PCs, the improvement of platelet deposition persisted. By then, the presence of fibrin increased markedly (p less than 0.01). The deposition of platelets was not modified after the transfusion of C PCs, but the presence of fibrin was augmented significantly at both posttransfusion times. Comparisons between bleeding times and morphometric results pointed to a possible role of fibrin formation in contributing to primary hemostasis.

Bleeding Time↗
PubMed1990

[Microangiopathic thrombotic syndromes in adults: results of treatment with intensive plasmapheresis].

The response to intensive plasmapheresis was evaluated in 13 patients (7 males, 6 females; median age 28 years) with microangiopathic thrombotic syndromes (MTS) who were treated at our center during the last 10 years. The most common initial clinical features were anemia, hemorrhage and neurologic abnormalities. Twelve patients had severe thrombocytopenia and 8 had renal failure. Fourteen plasmapheresis courses were carried out to treat 13 initial episodes and one relapse. The mean volumes of removed plasma and fresh frozen plasma infused at each exchange were 57 ml/kg and 41.7 ml/kg, respectively. Eight patients received antiplatelet drugs and/or corticosteroids. After a mean number of 10.6 exchanges per patient and course, complete remission (CR) was achieved in 7 cases (6 initial episodes and one relapse) and a partial response in 3. Four patients did not respond to therapy and died from progression of the disease. The early institution of plasmapheresis and the rapidity to respond were the only factors significantly associated with the achievement of CR.

Adolescent↗
PubMed1986

Plateletpheresis: a comparative study of six different protocols.

Six different protocols were employed in 710 plateletpheresis employing Haemonetics 30, Fenwal CS-3000, IBM 2997 dual stage channel, IBM 2997 single-stage channel, and Haemonetics V-50 "surge pump" method. When Haemonetics 30 and IBM 2997 single-stage channel procedures were used, 5.4 to 5.9 X 10(11) platelets were collected with significant leukocyte contamination (10.8 to 11.6 X 10(9)). With Fenwal CS-3000, dual-stage channel of IBM 2997 and Haemonetics V-50 "surge pump" there was less leukocyte contamination in concentrates (0.3 to 0.9 X 10(9)) as well as a lower platelet yield (3.4 to 4.3 X 10(11)). No difference in yield was observed when plateletpheresis was performed with ACD-A or ACD-B employing the single-stage channel of IBM 2997. Paresthesias was the most frequently seen side effect in donors, with a higher incidence when using ACD-A and IBM 2997.

Blood Component Removal↗
PubMed1985

Adverse effects secondary to the treatment with plasma exchange.

Side effects and their relationship with the material used were analyzed in 748 plasma exchanges (PE) performed in 75 patients. The total incidence of acute and mild adverse effects (chills and/or fever, paraesthesias, allergic reactions, acute anaemia, vasovagal reactions, abdominal pain and hypotension) was 18.04%. Two patients developed an episode of left cardiac insufficiency. One patient in whom all PE were performed with fresh frozen plasma (FFP) developed metabolic alkalosis. Three patients developed sepsis during treatment with repeated PE and immunosuppressive drugs; in these three patients a permanent vascular inlet was used (shunt or catheter). All patients in whom only FFP was used as replacement solution developed non-A, non-B hepatitis. Neither haemorrhagic nor thrombotic episodes were observed in these patients. It is of the greatest importance to choose the most suitable material for each patient and to develop a careful technique in order to avoid these complications during treatment with PE.

Abdomen↗