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Biomedical subjects

Silvia Ferrari

Publications and source records attributed to Silvia Ferrari.

13 recordsLinked to original sources

Relation between ADAMTS13 activity and ADAMTS13 antigen levels in healthy donors and patients with thrombotic microangiopathies (TMA).

We have established a new, enzyme-linked immunosorbent assay (ELISA) for the detection of ADAMTS13 antigen using purified polyclonal rabbit anti-human ADAMTS13 IgG. Normal plasma ADAMTS13 antigen levels span a concentration of 740-1420 ng/ml (median 1080 ng/ml) resulting in an ADAMTS13 activity to antigen ratio of 0.48 to 1.68 U/mug. In a cohort of HUS patients, ADAMTS13 antigen was in the normal range, whereas in hereditary TTP patients antigen levels were low to undetectable, in concordance with severe deficient ADAMTS13 activity. Plasma of acquired TTP patients was found to contain free as well as autoantibody-bound ADAMTS13. We also present evidence for circulating anti-ADAMTS13 antibody/ADAMTS13 antigen immune complexes not only in acutely ill or actively treated patients but also in patients who have already achieved clinical remission. This new developed ADAMTS13 antigen ELISA assay allows rapid determination of ADAMTS13 antigen levels in human plasma but is of limited predictive value for the diagnosis or treatment of acquired TTP due to the detection of ADAMTS13 in antibody complexes.

ADAM Proteins↗

Modulation of ADAMTS13 secretion and specific activity by a combination of common amino acid polymorphisms and a missense mutation.

Sequence analysis of the ADAMTS13 locus of 2 patients with hereditary thrombotic thrombocytopenic purpura (TTP) revealed the homozygous presence of 4 single nucleotide polymorphisms (SNPs) (R7W, Q448E, P618A, A732V) and a rare missense mutation (R1336W). Analysis of the individual effect of any amino acid exchanges showed that several sequence variations can interact with each other, thereby altering the phenotype of ADAMTS13 deficiency. Introduction of polymorphisms R7W, Q448E, and A732V had no or only minor effects on ADAMTS13 secretion. In contrast, P618A, R1336W, and the A732V-P618A combination strongly reduced ADAMTS13-specific activity and antigen levels. Surprisingly, R7W and Q448E were positive modifiers of ADAMTS13 secretion in the context of P618A and A732V but neither could rescue the severely reduced specific activity conferred by P618A. However, in the context of R1336W, polymorphisms R7W and Q448E enhanced the detrimental effect of the missense mutation and led to undetectable enzyme activity. We show that dependent on the sequence context, the same polymorphisms might be either positive or negative modifiers of gene expression. Our results might therefore be widely relevant to understanding the influence of polymorphisms on the phenotypic expression of complex diseases.

ADAM Proteins↗

Smooth function approximation using neural networks.

An algebraic approach for representing multidimensional nonlinear functions by feedforward neural networks is presented. In this paper, the approach is implemented for the approximation of smooth batch data containing the function's input, output, and possibly, gradient information. The training set is associated to the network adjustable parameters by nonlinear weight equations. The cascade structure of these equations reveals that they can be treated as sets of linear systems. Hence, the training process and the network approximation properties can be investigated via linear algebra. Four algorithms are developed to achieve exact or approximate matching of input-output and/or gradient-based training sets. Their application to the design of forward and feedback neurocontrollers shows that algebraic training is characterized by faster execution speeds and better generalization properties than contemporary optimization techniques.

Algorithms↗

Flow cytometric analysis of circulating dendritic cell subsets and intracellular cytokine production in advanced breast cancer patients.

Patients with advanced cancer are known to have dysfunctions of the immune system. Dendritic cells (DCs) are potent antigen-presenting cells that play a crucial role in antitumor immune response. At least two peripheral blood DC subsets have been described: myeloid-derived CD11c+CD123- DCs (DC1) and lymphoid-derived CD11c-CD123+ DCs (DC2). Upon interaction with T cells, DC2 seemed to support the generation of a Th2 response, while DC1 predominantly prime a Th1 response. Our study was aimed at investigating the number of circulating DCs, and their subsets and functions in 32 patients with advanced breast cancer that achieved an objective response after a standard-dose sequential chemotherapy (CT), compared to 40 healthy controls. Circulating DC subsets and intracellular cytokine production in CD4+ and CD8+ subsets were analyzed using a tri-color flow cytometry assay. DC subsets were identified in peripheral blood, calculating their percentage gated as lin- HLA-DR+ and using BDCA-1, BDCA-2 and BDCA-3 specific markers, as DC1 and DC2 according to expression of CD11c and CD123, respectively. Intracellular cytokines were evaluated in CD4+(Th1 and Th2) and CD8+ (Tc1 and Tc2) T lymphocytes. The mean percentage of BDCA-1+BDCA-2+BDCA-3 was similar to that of DC1+DC2 (p=ns). The mean percentage of DCs and DC1/DC2 ratio were slightly decreased before CT in cancer patients compared with healthy controls (p=ns). After CT, the percent-age of DC1 further decreased (p=0.02). The production of IFN-gamma (Th1 and Tc1) significantly decreased (p<0.03) while that of IL-4 (Th2 and Tc2) increased (p=0.04), thus confirming a shift toward a Th2 CD4 and Tc2 CD8 phenotype and the predominance of type 2 DCs. Our results could help clarify the mechanisms of the immune response or immune status of patients with advanced breast cancer that undergo cytotoxic CT and contribute to improve the selection of potential candidates for active immunotherapy trials.

Adult↗

von Willebrand factor cleaving protease (ADAMTS-13) and ADAMTS-13 neutralizing autoantibodies in 100 patients with thrombotic thrombocytopenic purpura.

The congenital or acquired deficiency of the von Willebrand factor (VWF) cleaving protease, ADAMTS-13 has been specifically associated with a diagnosis of thrombotic thrombocytopenic purpura (TTP), a microangiopathy characterized by the formation of occlusive platelet thrombi. The mechanisms of TTP were investigated in 100 patients diagnosed on the basis of the presence of at least three of the following: thrombocytopenia, haemolytic anaemia, elevated serum levels of lactate dehydrogenase and neurological symptoms. Plasma levels of ADAMTS-13 were severely reduced (<10% of normal) in 48%, moderately reduced (between 10% and 46%) in 24% and normal (>46%) in 28%. A neutralizing antibody was the cause of the deficiency in 38% of the cases, with a higher prevalence of this mechanism (87%) in the 48 patients with severely reduced ADAMTS-13. Double heterozygosity for a 29 base pair (bp) deletion and a nucleotide insertion and homozygosity for a 6 bp deletion in the ADAMTS13 gene were identified only in two patients born from consanguineous marriages. In conclusion, this study indicated that ADAMTS-13 was normal in nearly one-third of patients with TTP and that ADAMTS-13 deficiency was not associated with the presence of neutralizing antibodies in more than half of the patients.

ADAM Proteins↗

Performance of different prediction equations for estimating renal function in kidney transplantation.

Numerous formulas have been developed to estimate renal function from biochemical, demographic and anthropometric data. Here we compared renal function derived from 12 published prediction equations with glomerular filtration rate (GFR) measurement by plasma iohexol clearance as reference method in a group of 81 renal transplant recipients enrolled in the Mycophenolate Mofetil Steroid Sparing (MY.S.S.) trial. Iohexol clearances and prediction equations were carried out in all patients at months 6, 9 and 21 after surgery. All equations showed a tendency toward GFR over-estimation: Walser and MDRD equations gave the best performance, however not more than 45% of estimated values were within +/-10% error. These formulas showed also the lowest bias and the highest precision: 0.5 and 9.2 mL/min/1.73 m2 (Walser), 2.7 and 10.4 mL/min/1.73 m2 (MDRD) in predicting GFR. A significantly higher rate of GFR decline ranging from -5.0 mL/min/1.73 m2/year (Walser) to -7.4 mL/min/1.73 m2/year (Davis-Chandler) was estimated by all the equations as compared with iohexol clearance (-3.0 mL/min/1.73 m2/year). The 12 prediction equations do not allow a rigorous assessment of renal function in kidney transplant recipients. In clinical trials of kidney transplantation, graft function should be preferably monitored using a reference method of GFR measurement, such as iohexol plasma clearance.

Adult↗

Doppler ultrasonography in posttransplant renal artery stenosis: a reliable tool for assessing effectiveness of revascularization?

BACKGROUND: Renal artery stenosis is usually treated by angioplasty and stenting, but the effectiveness of graft perfusion is difficult to establish on clinical grounds. METHODS: We compared changes in Doppler ultrasound parameters such as resistive index and peak systolic velocity with concomitant changes in renal vascular resistances, renal blood velocity, and wall shear stress measured before and 1 month after percutaneous transluminal angioplasty and stenting in 12 renal transplant patients with renal artery stenosis. RESULTS: After revascularization, peak systolic velocity and resistive index normalized in all patients. Changes in peak systolic velocity (-72%; P<0.001 vs. basal) were positively correlated (P<0.0001; r=0.87) with those in renal blood velocity (-88%; P<0.01 vs. basal) and with those (P<0.0005; r=0.80) in wall shear stress (-97%; P<0.005). Changes in resistive index (+21%; P<0.005) were negatively correlated (P=0.009; r=0.51) with those in renal vascular resistances (-40%; P<0.01). Changes in Doppler parameters (resistive index and peak systolic velocity) reflected those in renal vascular resistances and renal blood velocity with 100% sensitivity and specificity. CONCLUSIONS: Doppler ultrasound is a reliable, noninvasive, and easily available tool for identifying subjects who may benefit from kidney graft revascularization and to assess the effectiveness of the procedure.

Angioplasty, Balloon, Coronary↗

Lack of dendritic cell mobilization into the peripheral blood of cancer patients following standard- or high-dose chemotherapy plus granulocyte-colony stimulating factor.

BACKGROUND: Dendritic cells (DC), the most specialized antigen-presenting cells, can be detected in the peripheral blood (PB) and divided into two subsets of populations, DC1 and DC2, endowed with different functions. The aim of this study was to evaluate the effect on DC release and on their subsets of three regimens utilized to mobilize CD34+ cells into the PB in cancer patients and in normal CD34+ cell donors. PATIENTS AND METHODS: The mobilizing sequences were: standard-dose epirubicin+taxol+granulocyte-colony-stimulating factor (G-CSF; 15 patients with advanced breast cancer), high-dose cyclophosphamide (CTX)+G-CSF (10 patients with breast cancer patients and 7 with non-Hodgkin's lymphoma, NHL), and G-CSF alone (5 normal donors of CD34+ cells for allogeneic transplantation). Comparative data were obtained from the steady-state PB of 20 healthy volunteers. For flow cytometric analysis, DC were gated as negative for specific lineage markers (CD3, CD11b, CD14, CD16, CD56, CD19, CD20, CD34) and positive for HLA-DR. The DC1 and DC2 subsets were defined as CD11c and CDw123 positive, respectively. RESULTS: The percentages of DC at baseline and the time of CD34+ cell peak were: 0.48 and 0.51 for standard-dose chemotherapy (CT); 0.55 and 0.63 for breast cancer after high-dose CTX+G-CSF; 0.53 and 0.71 for NHL after high-dose CTX+G-CSF; and 0.51 and 0.54 for normal donors of CD34+ cells after G-CSF alone (all p=n.s.). Mean DC1/DC2 ratios in each study group at the time of CD34+ cell peak were 0.10, 0.12, and 0.18, respectively. Finally, in the group of healthy volunteers, the percentage of circulating DC was 0.95 and the mean DC1/DC2 ratio was 1.28. CONCLUSION: To our knowledge, this is the first report that demonstrates that both standard-dose or high-dose CT, when utilized together with G-CSF, do not induce DC mobilization into the PB, whereas a reversed DC1/DC2 ratio is observed. Furthermore, a lack of significant DC mobilization after G-CSF alone was also seen, in contrast to what was previously observed by others. These data should be taken in account when evaluating clinical correlations between DC number and CPC engraftment in both the transplantation setting, when monitoring the effects on the immune system of combinations of new drugs and/or cytokines, and when high numbers of DC are required for both experimental and clinical applications.

Adult↗

Renal transplantation: can we reduce calcineurin inhibitor/stop steroids? Evidence based on protocol biopsy findings.

How to combine antirejection drugs and which is the optimal dose of steroids and calcineurin inhibitors beyond the first year after kidney transplantation to maintain adequate immunosuppression without major side effects are far from clear. Kidney transplant patients on steroid, cyclosporine (CsA), and azathioprine were randomized to per-protocol biopsy (n = 30) or no-biopsy (n = 29) 1 to 2 yr posttransplant. Steroid or CsA were discontinued or reduced on the basis of biopsy to establish effects on drug-related complications, acute rejection, and graft function over 3 yr of follow-up. Serum creatinine, GFR (plasma clearance of iohexol), RPF (renal clearance of p-aminohippurate), CsA pharmacokinetics, and adverse events were monitored yearly. At the end, patients underwent a second biopsy. Per-protocol biopsy histology revealed no lesions (n = 5, steroid withdrawal), CsA nephropathy (n = 13, CsA discontinuation/reduction), or chronic rejection (n = 12, standard therapy). Reducing the drug regimen led to overall fewer side effects related to immunosuppression as compared with standard therapy or no-biopsy. Steroids were safely stopped with no acute rejection or graft loss. Complete CsA discontinuation was associated with acute rejection in the first four patients. Lowering CsA to low target CsA trough (30 to 70 ng/ml) never led to acute rejection or major renal function deterioration. Biopsy patients on conventional regimen had no acute rejection, one graft loss, no significant change in GFR, and significant RPF decline. No-biopsy controls: no acute rejection, one graft loss, significant decline of GFR and RPF. By serial biopsy analysis, severe lesions did not develop in patients with steroid discontinuation in contrast to patients on standard therapy over follow-up. CsA reduction did not adversely affect histology. Per-protocol biopsy more than 1 yr after kidney transplantation is a safe procedure to guide change of drug regimen and to lower the risk of major side effects.

Adult↗

Anemia and epoetin alfa in high-dose chemotherapy programs for breast cancer patients.

Breast cancer patients undergoing therapeutic regimens of high-dose chemotherapy (HDCT) with circulating progenitor cell support often develop anemia. As a general consideration in the transplantation setting, red blood cell transfusions are normally required in patients who have passed the myeloablative phase after HDCT. In the initial 30-day period immediately following HDCT, the number of red blood cell units that are transfused will usually depend on a number of factors, including whether the transplantation was allogeneic or autologous. Observations and results from clinical studies have shown that the establishment of normal erythropoiesis varies depending on the source of the transplanted cells, resulting in different transfusion requirements. Several studies support the use of recombinant human erythropoietin (rHuEPO, epoetin alfa) after HDCT to ameliorate anemia and reduce transfusion requirements. Studies have also shown that administration of epoetin alfa prior to the myeloablative phase is an effective method for reducing red blood cell transfusion requirements in breast cancer patients receiving HDCT. Epoetin alfa in combination with other cytokines has been shown to positively affect the mobilization phase of hematopoietic progenitor cells for autografting. Furthermore, treatment with epoetin alfa could prove useful in bone marrow transplant recipients who experience delayed anemia. Recent studies that have addressed these topics in breast cancer indicate that, when used in the appropriate setting, epoetin alfa may play a role as a tool to decrease the need for red blood cell transfusion in patients undergoing HDCT plus autologous circulating progenitor cell support.

Anemia↗

Interrater reliability, prevalence, and relation to ICD-10 diagnoses of the Diagnostic Criteria for Psychosomatic Research in consultation-liaison psychiatry patients.

The Diagnostic Criteria for Psychosomatic Research (DCPR) have been proposed by an international group of psychosomatic investigators as an operationalized tool for the assessment of psychological distress in medical patients. The aims of the present study were to evaluate interrater reliability, the distribution of DCPR syndromes, and their relationship with ICD-10 diagnostic categories. One hundred consecutive patients who were referred for psychiatric consultation in a university general hospital consented to assessment for DCPR syndromes as elicited in a joint interview conducted by two researchers. The results showed excellent interrater agreement, with kappa values for the 11 DCPR syndromes ranging from 0.69 to 0.97. More patients met criteria for one or more of the DCPR (87%) than for an ICD-10 diagnosis (75%). Four DCPR syndromes were particularly prevalent: demoralization, alexithymia, illness denial, and type A behavior. DCPR criteria appear to be a useful, reliable, and promising approach in the assessment and description of psychological distress in medical patients. They may serve as a focus of intervention studies in this population.

Adult↗

Impact of topotecan-based chemotherapy on the immune system of advanced ovarian cancer patients: an immunophenotypic study.

The effects of topotecan-based chemotherapy (CT) on peripheral blood lymphocyte (PBL) subsets were evaluated in ovarian cancer patients. Fourteen patients with epithelial ovarian cancer, at the diagnosis or relapsed after platinum-based CT, were treated with: a) topotecan in association with carboplatin and taxanes as first line CT; b) topotecan alone or c) topotecan in association with carboplatin both as second line of treatment after platinum. The phenotype of PBL was determined before starting treatment and immediately before each CT course by flow cytometric analysis. Before starting CT, the absolute number of lymphocytes and the CD2+, CD3+, CD4+ subsets were significantly lower in pre-treated patients and not significantly altered in CT-naive patients with respect to a cohort of 20 healthy donors utilized as control. Lymphocytes co-expressing CD4+/CD8+ were significantly higher in both subgroups of patients than in normal donors. CD4+/CD45RA+ and CD4+/CD45RO+ subsets were significantly decreased in pre-treated patients and normal in CT-naive patients. CD3+/HLA-DR+ T cell population significantly increased in CT-naive patients at baseline. During CT and after its discontinuation, no relevant changes were recorded for both subgroups of patients with respect to the baseline in lymphocyte absolute count, CD2+, CD3+, CD4+, CD4+/CD45RO+ subsets, while CD4+/CD45RA+ subpopulation was significantly decreased in CT-naive patients. CD8+, CD19+, CD20+, CD16+, CD56+, CD2+/CD25+ subsets did not differ statistically comparing to normal donors both at baseline and during CT. The treatment was well tolerated and no patient developed non-neutropenic infection. Topotecan-based therapy does not have a negative impact on PBL in either CT-naive or in pretreated ovarian cancer patients. This information should be considered when utilizing topotecan with other anticancer drugs in the adjuvant setting as well as when dose-intensification of topotecan with stem cell support is planned.

Adult↗