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Biomedical subjects

Mario Bonomini

Publications and source records attributed to Mario Bonomini.

13 recordsLinked to original sources
PubMed2007

Cellular properties of human erythrocytes preserved in saline-adenine-glucose-mannitol in the presence of L-carnitine.

L-Carnitine (LC) in the preservation medium during storage of red blood cells (RBC) can improve the mean 24-hr percent recovery in vivo and increase RBC life-span after reinfusion. The purpose of the study was to investigate the differences in the biochemical properties of RBCs stored in the presence or absence of LC, and the cell-age related responses to storage conditions and to LC. RBC concentrates in saline-adenine-glucose-mannitol (SAG-M) were stored in the presence or absence of 5 mM LC at 4 degrees C for up to 8 weeks. RBC subpopulations of different densities were prepared by centrifugation on Stractan density gradient. Cells were sampled at 0, 3, 6, and 8 weeks, and hematological and cellular properties analyzed (MCV, MCHC, 4.1a/4.1b ratio as a cell age parameter, intracellular Na(+) and K(+)). After 6 weeks, MCV of RBC stored in the presence of LC was lower than that of controls (6 weeks MCV: controls 95.4 +/- 1.8 fl; LC 91.5 +/- 2.0 fl; n = 6; P < 0.005). This was due to swelling of control cells, and affected mainly older RBCs. LC appeared to reduce or retard cell swelling. Among the osmotically active substances whose changes during storage could contribute to cell swelling, only intracellular Na(+) and K(+) differed between stored control RBCs and LC-treated cells. LC reduces the swelling of older cells during storage at 4 degrees C in SAG-M, possibly by acting on the permeability of cell membrane to monovalent cations.

Adenine↗
PubMed2006

Proteomics characterization of protein adsorption onto hemodialysis membranes.

Protein-adsorptive properties are a key feature of membranes used for hemodialysis treatment. Protein adsorption is vital to the biocompatibility of a membrane material and influences membrane's performance. The object of the present study is to investigate membrane biocompatibility by correlating the adsorbed proteome repertoire with structural feature of the membrane surfaces. Minidialyzers of identical structural characteristics composed of either cellulose diacetate or ethylenevinyl alcohol materials were employed to develop an ex vivo apparatus to investigate protein adsorption. Adsorbed proteins were eluted by a strong chaotropic buffer condition and investigated by 2-DE coupled to both MALDI-TOF mass spectrometry (MS) mass fingerprinting and fragmentation analysis on a nanoLC-MS/MS hybrid instrument. Membrane surface characterization included evaluation of roughness (atomic force microscopy), elemental chemical composition (X-ray-photoelectron-spectroscopy), and hydrophilicity (pulsed nuclear magnetic resonance). The present study identifies a number of different proteins as common or characteristic of filter material interaction, showing that proteomic techniques are a promising approach for the investigation of proteins surface-adsorbed onto hemodialysis membrane. Proteomic analysis enables the characterization of protein layers of unknown composition.

Adsorption↗
PubMed2006

Spinal cord stimulation in hemodialysis patients with critical lower-limb ischemia.

BACKGROUND: Spinal cord stimulation (SCS) has been proposed for the treatment of ischemic pain and the prevention or delay of amputation in patients with peripheral arterial occlusive disease (PAOD) who are unsuitable for vascular reconstruction. PAOD is common in patients with end-stage renal disease and is associated with substantial morbidity and mortality. Furthermore, many patients are not candidates for limb-sparing procedures and have to undergo primary amputation. METHODS: We report our experience with SCS in 8 hemodialysis patients with chronic lower-limb ischemia and not suitable for either primary surgical or angioplastic intervention or reintervention. Intensity of ischemic pain, quality of life, use of analgesic medications, limb survival, and outcome of skin ischemic lesions were evaluated before implantation of an SCS device and after 6 and 12 months of follow-up. RESULTS: No complications from SCS device implantation occurred. Both intensity of pain and quality of life significantly improved during follow-up. SCS allowed a decrease in pain medication intake in all patients. Limb survival at 1 year was 75%. Ischemic skin lesions before implantation of an SCS device did not ameliorate during the follow-up period, but the appearance of new lesions was not observed. CONCLUSION: Implantation of an SCS device in patients with end-stage renal disease with critical limb ischemia dramatically improves quality of life and pain relief. In patients assessed at Leriche-Fontaine stage 2 or 3, the treatment might delay the appearance of ischemic skin lesions and amputation. At these stages, presumed long-term benefits could justify the cost of SCS.

Aged↗
PubMed2005

Adherence of uremic erythrocytes to vascular endothelium decreases endothelial nitric oxide synthase expression.

BACKGROUND: High prevalence of atherosclerotic cardiovascular events accounts for much of the mortality among patients suffering from end-stage renal disease (ESRD). Endothelial dysfunction as a pathogenic mechanism might contribute to increasing the cardiovascular risk of ESRD. Reduced endothelium-dependent vasodilation has consistently been observed in chronic renal failure patients. Since nitric oxide (NO) is the principal endothelium-derived vasodilator, a reduction in the NO bioavailability may be envisaged in ESRD patients. METHODS: To clarify whether exposure to erythrocytes from ESRD patients might modulate NO release by the endothelium, we evaluated endothelial NO synthase (eNOS) protein levels (Western blot), eNOS mRNA quantity (real-time PCR), and NOS activity (conversion of L-[3H] arginine in L-[3H] citruline) in endothelial cultures stimulated by erythrocytes from healthy subjects and ESRD patients. RESULTS: A time-dependent decrease in eNOS protein levels was evident in cultures treated with erythrocytes from ESRD patients. This observation was consistent with the decreased eNOS mRNA quantities induced by erythrocytes from such patients. Moreover, compared to controls, NOS activity exhibited a significant reduction after incubation with erythrocytes from ESRD patients. The observed eNOS reduction induced by erytrocytes from ESRD patients was totally abolished by annexin V, able to mask red blood cell (RBC) surface-exposed phosphatidylserine. CONCLUSION: These findings suggest that adhesion of erythrocytes from ESRD patients to vascular endothelium may cause a decrease in the levels of eNOS mRNA and protein, and inhibition of NOS activity. This might contribute to endothelial dysfunction, and may play a role in the pathogenesis of cardiovascular disease in ESRD patients.

Aged↗
PubMed2004

Red blood cells may contribute to hypercoagulability in uraemia via enhanced surface exposure of phosphatidylserine.

BACKGROUND: The exposure of phosphatidylserine (PS) on the outer leaflet of the erythrocyte membrane may have several pathophysiological consequences, including the development of a procoagulant phenotype, a finding that seems relevant to the thrombotic risk seen in many disorders. METHODS: Because PS externalization increases in erythrocytes from patients suffering from chronic uraemia, which is frequently associated with a prothrombotic state, the possible relationship between erythrocyte PS exposure, erythrocyte procoagulant activity and plasma levels of several haemostatic markers was studied in a group of haemodialysed patients. RESULTS: Uraemic erythrocytes displayed increased procoagulant activity, which proved to be correlated directly with erythrocyte PS exposure. Pre-incubation of uraemic erythrocytes with annexin V, a protein with high affinity and specificity for PS, strongly inhibited in vitro thrombin generation induced by erythrocytes as compared with untreated red cells. Thrombin generation and activation of fibrinolysis were found to occur in uraemic patients, as substantiated by increased plasma levels of markers for thrombin generation (prothrombin fragment F1.2 and thrombin-antithrombin complex) and fibrinolysis (D-dimer and plasmin-antiplasmin complex), respectively. Significant correlations between prothrombin fragment F1.2 and D-dimer suggested that hyperfibrinolysis was secondary to thrombin generation. Correlations were also found between erythrocyte PS levels and plasma levels of haemostatic markers, including prothrombin fragment F1.2 (P = 0.007), thrombin-antithrombin complex (P = 0.00009), plasmin-antiplasmin complex (P = 0.0009) and D-dimer (P = 0.005). CONCLUSIONS: Our study suggests that increased PS exposure may cause a pathological erythrocyte procoagulant phenotype, which may be a factor inducing a hypercoagulable state in uraemia.

Annexin A5↗
PubMed2004

Removal of uraemic plasma factor(s) using different dialysis modalities reduces phosphatidylserine exposure in red blood cells.

BACKGROUND: Solute(s) retained during uraemia cause increased exposure of aminophospholipid phosphatidylserine (PS) on the outer surface of erythrocyte membranes, and this phenomenon may be involved in the pathophysiology of uraemia by promoting abnormal erythrocyte interactions. METHODS: We examined in a prospective randomized cross-over fashion the ability of various dialysis modalities to remove the circulating uraemic factor(s) causing increased PS externalization in red cells. Each patient was treated with haemodialysis (HD) and with on-line haemodiafiltration (HDF) using standard high-flux polysulphone membranes or with the new polisulphone-based Helixone membrane to compare the effects of dialysis technique and membrane type on PS exposure. Removal of PS was assessed indirectly by measuring PS-expressing normal erythrocytes exposed to uraemic plasma or to ultrafiltrate obtained at various time points during the extracorporeal session. RESULTS: Removal of the uraemic plasma factor(s) causing PS exposure was demonstrated by the reduced ability of uraemic plasma at the end of dialysis to induce PS exposure in normal erythrocytes, and by the capacity of ultrafiltrate from the dialysate side of the dialyzer membrane to markedly increase PS-positive red cells. However, the degree of removal varied according to the dialyzer type and to dialysis technique. Removal was greater for on-line HDF using the Helixone membrane, intermediate and comparable with HD with Helixone and with on-line HDF using standard polysulphone, and lower for HD using polysulphone membrane. The putative uraemic compound causing PS exposure seems to be highly lipophilic, somehow associated with plasma proteins, and apparently having a molecular weight between 10 and 10.8 kDa. CONCLUSIONS: Uraemia is associated with retention of compound(s) that are lipophilic, possibly protein-bound and which cause an abnormal exposure of PS in erythrocytes. Our findings, that such compound(s) can be removed during dialysis and at higher rates with convection techniques, indicate a potential benefit for uraemic patients. The present results also seem to confirm the marked ability of high-flux Helixone membranes to eliminate high molecular weight solutes.

Adult↗
PubMed2002

Enhanced adherence of human uremic erythrocytes to vascular endothelium: role of phosphatidylserine exposure.

BACKGROUND: The exposure of phosphatidylserine (PS) on the outer leaflet of erythrocyte membrane may have several pathophysiological consequences including increased erythrocyte adherence to endothelial cells, a finding that seems relevant in pathologies with reported vascular injury. METHODS: Because PS externalization increases in erythrocytes from patients suffering from chronic uremia, which is frequently associated with vascular damage, the adherence of uremic erythrocytes to human umbilical vein endothelial cell (HUVEC) monolayers and the role of PS exposure on such cell-cell interaction were studied. RESULTS: The number of uremic erythrocytes adhering to HUVEC was markedly greater than with normal erythrocytes and significantly correlated (r = 0.88) with the percentage of PS-exposing erythrocytes in the population. Adhesion to the monolayers was significantly decreased when uremic erythrocytes were preincubated with either annexin V or PS-containing liposomes, and was strongly greater for PS-positive than PS-negative fluorescence-activated cell sorter (FACS)-sorted uremic erythrocytes. Binding occurred preferentially in the gaps of HUVEC monolayers and was enhanced by matrix exposure. Uremic erythrocytes adhered to immobilized thrombospondin, and binding to endothelial cells was significantly reduced when monolayers were incubated with antibodies to thrombospondin. CONCLUSIONS: These findings suggest that PS externalization may promote increased uremic erythrocyte adhesion to endothelium, possibly via a direct interaction with matrix thrombospondin.

Adult↗
PubMed2002

Platelet activation markers in patients with nephrotic syndrome. A comparative study of different platelet function tests.

BACKGROUND/AIM: Enhanced platelet reactivity may play a significant role in the genesis of the hypercoagulable state of nephrotic syndrome. However, the role of platelet function testing in nephrosis is controversial, partly because the methods used to assess platelet function (platelet aggregation and immunoassays of plasma beta-thromboglobulin and platelet factor 4) have such marked methodological problems. In the present study, we evaluated several tests assessing platelet function in 18 adult patients with idiopathic nephrotic syndrome and normal renal function. METHODS: Platelet function was assessed by measurement of plasma beta-thromboglobulin (enzyme-linked immunosorbent assay, ELISA), plasma P-selectin (ELISA), circulating platelets exposing the activation-dependent antigens P-selectin (CD62P) and lysosomal GP53 (CD63) (flow cytometry), and by aggregation response to agonists such as ADP and collagen. Results were compared to those obtained in a group of 16 age- and gender-matched healthy subjects. RESULTS: Levels of plasma beta-thromboglobulin (p = 0.001), plasma P-selectin (p < 0.001), and CD62P/CD63-positive platelets (p < 0.001 for both) were increased in nephrotic patients as compared to healthy controls. Platelet hyperaggregability in vitro was found in 13/18 patients. The reproducibility of platelet activation markers, as assessed by blood sample collection a week later from all patients, was found to be higher for plasma P-selectin (Spearman correlation coefficient, R = 0.99) and circulating activated platelets (CD62P: R = 0.97; CD63: R = 0.96) than for plasma beta-thromboglobulin (R = 0.78). CONCLUSIONS: Pronounced platelet activation takes place in nephrotic syndrome and may contribute to the hypercoagulability of nephrosis. Whole blood flow cytometry assay of platelet activation and plasma P-selectin assay may represent useful tests to assess the hypercoagulable state in nephrotic patients.

Adult↗
PubMedDate not supplied

Uremic toxicity and anemia.

Inappropriate erythropoietin production is the main defect responsible for the anemia of chronic renal failure. However, many other factors can contribute. There is support for the existence in uremic serum of substances that can inhibit erythropoiesis and cause hemolysis, but it is still debated how far uremic retention solutes contribute to the pathogenesis of anemia during chronic renal failure. This article looks at the role of uremic toxicity in exacerbating the anemia of chronic renal failure.

Apoptosis↗