PubMed Health⌕ Search

Biomedical subjects

B Bizzi

Publications and source records attributed to B Bizzi.

At least 19 recordsLinked to original sources
PubMed1992

Increased thromboxane biosynthesis in patients with polycythemia vera: evidence for aspirin-suppressible platelet activation in vivo.

Increased thromboxane (TX) production and modified aspirin sensitivity has been detected in vitro in platelets isolated from patients with polycythemia vera. To verify the relevance of these capacity-related measurements to the actual rate of TXA2 biosynthesis in vivo and its suppression by oral aspirin, we have investigated the urinary excretion of major enzymatic metabolites of TXB2 in 17 patients with polycythemia vera and 23 gender- and age-matched controls. Urinary 11-dehydro-TXB2 and 2,3-dinor-TXB2 were measured by previously validated radioimmunoassays. In addition, urinary immunoreactive leukotriene (LT) E4 was measured to explore the 5-lipoxygenase pathway of arachidonate metabolism. Polycythemic patients had significantly (P < .001) higher excretion rates of both 11-dehydro-TXB2 (1,033 +/- 1,050 v 117 +/- 45 pmol/mmol creatinine; mean +/- SD) and 2,3-dinor-TXB2 (725 +/- 676 v 82 +/- 43 pmol/mmol creatinine) than controls. In contrast, urinary LTE4 was not significantly different. Enhanced metabolite excretion did not correlate with the platelet count or with the hematocrit value, and was not related to the current treatment or to a clinical history of thrombotic complications. Platelet TX receptor studies did not show any significant changes in the binding characteristics of two different ligands. A platelet-selective regimen of aspirin therapy (50 mg/d for 7 to 14 days) was associated with greater than 80% suppression in metabolite excretion in nine patients. These results are consistent with abnormal stimuli operating in polycythemia vera to induce a selective enhancement in the platelet biosynthesis of TXA2 without changes in receptor binding. This in vivo abnormality in platelet biochemistry can be largely suppressed by low doses of aspirin.

Adult↗
PubMed1992

Hematological causes of venous thrombosis in young people: high incidence of myeloproliferative disorder as underlying disease in patients with splanchnic venous thrombosis.

Thrombotic events occur frequently in myeloproliferative disorders, namely polycythaemia vera and essential thrombocythaemia. Standard diagnostic criteria are designed quite stringent, so that a number of patients could be underdiagnosed. Spontaneous erythroid colonies formation from bone marrow or peripheral blood in the absence of exogenous erythropoietin is considered a reliable index of myeloproliferative disorder even at early stages. Endogenous erythroid colonies (EECs) formation was assessed in 43 patients having recently suffered from venous thrombosis prior to 45 years and without a previous diagnosis of hematological disease favouring thrombosis. A screening for coagulative abnormalities associated with thrombophilia was also carried out: in 5 patients (11.6%) a plasmatic thrombogenic defect was found (quantitative deficiency of antithrombin III, 1 case, protein C, 2 cases, protein S, 1 case, and plasminogen, 1 case). In 10 patients (2 males and 8 females) (23.2%) EECs assay was positive, allowing diagnosis of myeloproliferative disease even though 7 of them did not fulfill standard diagnostic criteria. In the other 3 patients who met the criteria for diagnosis of overt myeloproliferative disease the thrombotic event was the inaugural manifestation. In all these EECs-positive patients thrombosis involved mesenteric and portal veins (n = 4), hepatic veins (n = 3), portal vein (n = 2), mesenteric vein (n = 1). One of them was simultaneously affected from congenital protein C deficiency. Thus latent or atypical forms of myeloproliferative disease as well as the overt stages were the most frequent recognized cause of splanchnic venous thrombosis, accounting for 55% of the cases of our series. On the contrary no EECs-positive subject was found among the 25 patients with other sites of thrombosis.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

Effects of a preformed extracellular matrix on long-term serum-free bone marrow culture.

The extracellular matrix (ECM) produced by the stromal layer plays a key role in the regulation of commitment and differentiation of hematopoietic cells. Long-term bone marrow culture (LTBMC) allows analysis of the stromal microenvironment. Recently, serum-free LTBMC has been described, but the formation of a classical adherent layer was never observed under these conditions. We have evaluated the effect(s) of a chemically well defined ECM on serum-free and serum-dependent LTBMC. In serum-dependent cultures ECM did not induce a significant increase of hematopoiesis. In serum-free conditions, a marked improvement of hematopoiesis was observed, both in terms of CFU-GM and BFU-E yield and in duration of cultures. A confluent stromal layer was observed only in the presence of ECM. The present results indicate that the addition of ECM to serum-free cultures provides a standardized culture condition, while improving progenitor cell recovery and allowing formation of a confluent stromal layer. Moreover, ECM+LTBMC may provide a model to study the effect(s) of adhesive proteins and hematopoietic growth factors normally present in serum.

Blood↗
PubMed1991

Effect of fibrinogen concentration on the velocity of platelet aggregation.

The relationship between fibrinogen binding to its receptor and platelet aggregation has been investigated by comparing 125I-fibrinogen binding and aggregation velocities of gel-filtered platelets in the presence of adenosine diphosphate (ADP). Aggregometric responses at various fibrinogen concentrations are found to be bell-shaped and show a maximum at fibrinogen concentrations (Fmax) similar to the 125I-fibrinogen hemisaturating doses. At higher and lower fibrinogen concentrations, platelet aggregation velocities decrease in a parallel manner. Lowering ADP concentration increases Fmax, in agreement with the modulatory effect of ADP on fibrinogen binding to platelets. Variations of fibrinogen in the range of physiopathologic plasma concentrations affect platelet aggregation induced by any ADP dose. These results clarify the relationship between the fibrinogen binding process and aggregation and demonstrate that plasma fibrinogen concentration has a major influence on the velocity of platelet aggregation.

Adenosine Diphosphate↗
PubMed1991

Arterial thrombosis as clinical manifestation of congenital protein C deficiency.

A 49-year-old man was hospitalized for slight paresis of the upper left limb. Thrombosis of the right internal carotid artery was documented by arteriography and digital angiography, which showed evidence of an anastomotic blood flow. He went on anticoagulation treatment. Five years later, after an uneventful period, he was referred to our center for the occurrence of a superficial thrombophlebitis: diagnosis of congenital protein C deficiency was possible in the patient as well as in two of his relatives. Two other subjects with congenital protein C deficiency belonging to two different kindreds, whose illness was diagnosed in our center, suffered from myocardial infarction and TIA, respectively, as the only clinical manifestation; a fourth case, previously described, with recurrent superficial thrombophlebitis, suffered from a TIA when on treatment with stanozolol. These cases indicate that arterial thrombosis or TIA is not an uncommon event in congenital protein C deficiency, even in patients without other risk factors for arterial thrombosis.

Adult↗
PubMed1991

Autologous peripheral blood stem cell transplantation in malignancies involving bone marrow.

Six patients suffering from refractory malignancies (3 NHL, 1 MM, 1 AML, 1 neuroblastoma) received high dose of chemotherapy and autologous peripheral blood stem cell transplantation (APBSCT). The recruitment of PBSC was performed using conventional salvatage schedules of therapy. The patients received a median of 8.69 MNC/kg bw and 20.87 CFU-GM x 10(4)/kg bw. Prompt engraftment occurred in all patients and the median number of days to achieve WBC greater than 1 x 10(9)/l was 16.5 (range 7-26), PMN greater than 0.5 x 10(9)/l was 21.5 (range 6-37) and PLTs greater than 50 x 10(9)/l was 17.5 (range 4-31). Four patients achieved a complete remission. One patient (neuroblastoma) died of progressive disease after a partial response. One patient died in relapse because of drug related toxicity.

Adolescent↗
PubMed1991

A comparison between two different procedures for bone marrow processing: a semiautomated procedure vs manual starch sedimentation.

After high-dose chemotherapy, autologous cryopreserved bone marrow infusion is employed to restore rapidly the compromised hematopoietic function. An efficient bone marrow processing reduces the infusion toxicity produced by hemolized red cells, granulocytes and platelets clumping and DMSO amount; moreover it increases freezing efficacy, a critical step in autologous bone marrow grafting techniques. Gravity sedimentation technique with 6% hydroxyethyl-starch (HES) or a semiautomated procedure using a blood cell processor were used in our center to manipulate ex-vivo the collected bone marrow. In our experience we compared these two different procedure and we evaluated their efficiency.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1990

Association of Graves' disease and prekallikrein congenital deficiency in a patient belonging to the first CRM+ prekallikrein-deficient Italian family.

Severe prekallikrein (Fletcher factor) deficiency was diagnosed in a 49-year-old woman and in 3 of her siblings. Functional prekallikrein (PKK) activity was found below 1% by clotting assay and 20% by amidolytic assay in all the affected subjects; PKK cross-reacting material (CRM) was present in all the patients (antigen levels from 34% to 54%). This is the first CRM+ PKK-deficient family identified in Italy. The index patient was affected from Graves' disease: such association was previously reported in another patient with PKK congenital defect.

Cross Reactions↗
PubMed1990

Mesenteric vein thrombosis in protein S congenital deficiency.

Mesenteric vein thrombosis is considered an uncommon clinical presentation of protein S congenital deficiency. In the two patients with mesenteric vein thrombosis here reported an isolated deficiency of protein S was diagnosed; family investigation recognized protein S deficiency also in five relatives of one of them.

Adult↗
PubMed1989

Inhibition of fibrinogen binding to human platelets by blockage of Na+/H+ exchange.

Binding of ADP to platelets enhances the binding of fibrinogen to Gp IIb-IIIa, the specific platelet receptor for adhesive proteins. The linkage between ADP and fibrinogen binding is indirect since ADP does not bind to the same receptor as fibrinogen. We have recently proposed that a third component, once affected by ADP binding, induces a conformational transition of the fibrinogen receptor from the low to the high affinity state, which is responsible for platelet aggregation [De Cristofaro, R., Landolfi, R., Castagnola, M., De Candia, E., Di Cera, E., & Wyman, J. (1988) Proc. Natl. Acad. Sci. USA 85, 8473-8476]. In the present study we provide evidence that this component should be identified with the platelet Na+/H+ antiport. Inhibition of the antiport by pharmacological agents such as amiloride, or else by decreasing extracellular Na+, results in a marked decrease of fibrinogen binding to platelets.

Adenosine Diphosphate↗
PubMed1989

Carbon monoxide and oxygen binding to human hemoglobin F0.

Differential binding curve measurements of carbon monoxide and oxygen binding to human hemoglobin F0 under near-physiological conditions (0.1 M NaCl and 15 mM 2,3-diphosphoglyceric acid, pH 7.35, and 37 degrees C) have allowed a detailed description of the binding and linkage between these two gaseous ligands. Comparison with human hemoglobin A0 under identical solution conditions shows that fetal hemoglobin F0 binds oxygen and carbon monoxide with higher affinity than human hemoglobin A0, but with the same cooperativity. Construction of the partition coefficient surface for carbon monoxide and oxygen binding reveals a failure of Haldane's laws for both hemoglobins. Linkage graphs are used to explore the phenomenological properties of the system. The graphs provide a quantitative description of the mechanism of carbon monoxide toxicity on oxygen transport by hemoglobin in vivo and demonstrate striking similarities between the functional properties of fetal and adult hemoglobins.

Carbon Monoxide↗
PubMed1989

Central nervous system acute promyelocytic leukaemia: a report of three cases.

Authors report 3 cases of acute promyelocytic leukaemia, in which the central nervous system was involved in the first period of relapse. The clinical features of these patients are discussed. Authors conclude that central nervous system involvement in acute promyelocytic leukaemia must be considered a very bad prognostic sign, because in these cases a rapidly progressive course may be expected.

Bone Marrow Examination↗