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Biomedical subjects

R Conte

Publications and source records attributed to R Conte.

At least 55 records · Page 3Linked to original sources
PubMed1998

Alloimmunization against human platelet antigen 2 (HPA2) in a series of multi-transfused beta-thalassemia patients.

In our study we investigated the presence of anti-human platelet antigen (HPA) alloantibodies in a series of 10 beta-thalassemia major patients submitted for more than 10 years to periodic blood transfusions (every 2-3 weeks). We found that 2 out of the 10 patients developed anti-HPA2a + HPA1b and anti-HPA2b antibodies. Our results highlight that HPA alloimmunization in multitransfused patients is a real possibility.

Adult↗
PubMed1997

De novo hepatitis B and C viral infection after liver transplantation.

Hepatitis B (HBV) and hepatitis C (HCV) viral infections often recur after orthotopic liver transplantation (OLT), but viral infections acquired with OLT have not been widely investigated. The aim of the study was to evaluate the incidence, evolution, and diagnostic problems of de novo HBV and HCV infections in liver transplant recipients with long-term follow-up. Altogether 121 transplant recipients entered the study. HBV, HDV, and HCV infections were diagnosed by means of serology and the polymerase chain reaction (PCR). Three patients became hepatitis B surface antigen (HBsAg)-positive after OLT, all of whom showed signs of persistent viral replication. Twelve patients became anti-HCV-positive after OLT: After clearance of passive antibodies, active anti-HCV seroconversion was usually delayed. The viral genome was detected in 9 of 12 patients, with fluctuations of viremia during their follow-up. The other three patients, who were HBsAg-positive before and after OLT, were repeatedly HCV-RNA-negative despite persistent anti-HCV reactivity. Four pre-OLT HBsAg-positive patients had evidence of HBV-related liver transplant disease. The remaining 8 of 12 patients experienced repeated alanine aminotransferase increases more than two times normal after transplant. De novo infections due to primary hepatotropic viruses were frequent after OLT in our experience. Early diagnosis of infection, especially when the HCV is involved, may be problematic and should be taken into account in patients showing persistent aminotransferase abnormalities. Monitoring viral markers and accurate evaluation of biopsy specimens are mandatory. The interference between HBV and HCV might play a role in the replicative cycle of one or both viruses in co-infected patients.

Antibodies, Viral↗
PubMed1997

Process control of filtered red blood cells: which counting method?

Various counting methods have been described and reported for process control of leuco-epleted blood components. The recent production of high-efficiency leucocyte removal filters intensifies the need for sensitivity in determining the ever lower residual concentration of white cells (WBCs) in filtered units. In order to assess which method was the most efficient and feasible in the laboratory for the control of WBC-reduced packed red blood cells, we compared the sensitivity of four counting methods: Nageotte chamber analysis, flow cytometry, the fluorochrome method by Borzini and Nageotte chamber analysis as modified by Prati. We observed a difference in the post-filtration WBC content depending on which method of counting was used and we feel it reasonable to ask what method should be employed in blood component process control. The answer must naturally consider that the method is for use by a large number of laboratories, while the sensitivity of the method needs to be appropriate to the goal desired.

Erythrocyte Count↗
PubMed1997

A new tool in white blood cell reduction for packed red cells: 5 log depletion.

The recent development of new filters used for leucocyte reduction aims at restricting the number of leucocytes to a threshold where their undesirable effects can be minimized or excluded. In this paper we describe the performance of a new filter named BIO R01 MAX and claimed by the manufacturer to perform 5 Log10 depletion. The results show that the efficiency of the filter reached 5 Log10 depletion and the absolute number of white blood cells in the post-filtration units is always less than 2 x 10(4) with considerable safety in the prevention of transfusion reactions.

Erythrocyte Transfusion↗
PubMed1997

Immunohematological study in newborn infants with erythroblastosis fetalis transfused in utero.

The present study reports immunohematological data (anti-erythrocyte titer, anti-erythrocyte functional activity, percentage of sensitized erythrocytes) in 11 patients with erythroblastosis fetalis transfused in utero (IUTd). At birth it was possible to define two groups of newborns: one with low (group 1) and one with high (group 2) percentage of circulating sensitized erythrocytes, respectively. The presence of a low rate of sensitized red cells at birth in IUTd infants did not reduce the number of exchange transfusions required postnatally. On the contrary, babies of this group were affected by a more severe disease as shown by higher anti-erythrocyte maternal titer, higher anti-erythrocyte functional activity and a higher degree of fetal hemolysis. The persistence of hemolysis after birth, in spite of the absence of sensitized circulating erythrocytes, may be due to intramedullary hemolysis.

Blood Transfusion, Intrauterine↗
PubMed1996

Concomitant mobilization of plasma cells and hematopoietic progenitors into peripheral blood of multiple myeloma patients: positive selection and transplantation of enriched CD34+ cells to remove circulating tumor cells.

One advantage of the use of peripheral blood stem cells (PBSCs) over autologous bone marrow would be a reduced risk of tumor cell contamination. However, the level of neoplastic cells in the PB of multiple myeloma (MM) patients after mobilization protocols is poorly investigated. In this study, we evaluated PB samples from 27 pretreated MM patients after the administration of high dose cyclophosphamide (7 g/m2 or 4 g/m2) and granulocyte-colony stimulating factor for the detection of myeloma cells as well as hematopoietic progenitors. Plasma cells containing intracytoplasmic lg were counted by microscope immunofluorescence after incubation with appropriate antisera directed against light- and heavy-chain lg. Moreover, flow cytometry studies were performed to determine the presence of malignant B-lineage elements by using monoclonal antibodies against the CD19 antigen and the monotypic light chain. Before initiation of PBSC mobilization, circulating plasma cells were detected in all MM patients in a percentage ranging from 0.1% to 1.8% of the mononuclear cell fraction (mean value, 0.7% +/- 0.4% SD). In these patients, a higher absolute number of PB neoplastic cells was detected after chemotherapy and granulocyte colony-stimulating factor. Kinetic analysis showed a pattern of tumor cell mobilization similar to that of normal hematopoietic progenitors with a maximum peak falling within the optimal time period for the collection of PBSCs. The absolute number of plasma cells showed a 10 to 50-fold increase as compared with the baseline value. Apheresis products contained 0.7% +/- 0.2% SD of myeloma cells (range, 0.2% to 2.7%). Twenty-three MM patients were submitted to PBSC collection. In 10 patients, circulating hematopoietic CD34+ cells were highly enriched by avidin-biotin immunoabsorption, were cryopreserved, and used to reconstitute bone marrow function after myeloablative therapy. The median purity of the enriched CD34+ cell population was 89.5% (range, 51% to 94%), with a 75-fold increase as compared with the pretreatment samples. The median overall recovery of CD34+ cells and colony-forming unit-granulocyte-macrophage was 58% (range, 33% to 95%) and 45% (range, 7% to 100%), respectively. Positive selection of CD34+ cells resulted in 2.5- to 3-log depletion of plasma cells and CD19+ B-lineage cells as determined by immunofluorescence studies, although DNA analysis of CDR III region of IgH gene showed the persistence of minimal residual disease in 5 of 6 patient samples studied. Myeloma patients were reinfused with enriched CD34+ cells after myeloablative therapy consisting of total body irradiation (1,000 cGy) and highdose melphalan (140 mg/m2). They received a median of 4 x 10(6) CD34+ cells/kg and showed a rapid reconstitution of hematopoiesis; the median time to 0.5 x 10(9) neutrophils and to 20 and 50 x 10(9) platelets per liter of PB was 10, 11, and 12 days, respectively. These results, as well as other clinically significant parameters, did not significantly differ from those of patients (n = 13) receiving unmanipulated PBSCs after the same pretransplant conditioning regimen. In summary, our data show the concomitant mobilization of tumor cells and hematopoietic progenitors in the PB of MM patients. Positive selection of CD34+ cells reduces the contamination of myeloma cells from the apheresis products up to 3-log and provides a cell suspension capable of restoring a normal hematopoiesis after a total body irradiation-containing conditioning regimen.

Adult↗
PubMed1996

The human leukocyte antigen (HLA)-C-specific "activatory" or "inhibitory" natural killer cell receptors display highly homologous extracellular domains but differ in their transmembrane and intracytoplasmic portions.

Natural killer cells express clonally distributed receptors specific for major histocompatibility complex class I molecules. The human leukocyte antigen (HLA)-C-specific receptors have been molecularly identified and cloned. They exist not only as inhibitory (p58) but also as activatory (p50) receptors. Here we show that p50 and p58 are highly homologous in their extracellular regions formed by two Ig-like domains. In contrast, major differences exist in their transmembrane and cytoplasmic portions. Whereas p 58 displays a 76-84-amino acid cytoplasmic tail containing an unusual antigen receptor activation motif, p50 is characterized by a shorter 39-amino acid tail. In addition, whereas p58 has a nonpolar transmembrane portion, p50 contains the charged amino acid Lys. These data strongly suggest that receptors with identical HLA-C allele specificity can mediate functions of opposite sign owing to their different transmembrane/cytoplasmic portions.

Amino Acid Sequence↗
PubMed1996

Fingerprinting of HLA class I genes for improved selection of unrelated bone marrow donors.

The degree of matching of HLA genes between the selected donor and recipient is an important aspect of the selection of unrelated donors for allogeneic bone marrow transplantation (UBMT). The most sensitive methods currently used are serological typing of HLA class I genes, mixed lymphocyte culture (MLC), IEF and molecular genotyping of HLA class II genes by direct sequencing of PCR products. Serological typing of class I antigenes (A, B and C) fails to detect minor differences demonstrated by direct sequencing of DNA polymorphic regions. Molecular genotyping of HLA class I genes by DNA analysis is costly and work-intensive. To improve compatibility between donor and recipient, we have set up a new rapid and non-radioisotopic application of the 'fingerprinting PCR' technique for the analysis of the polymorphic second exon of the HLA class I A, B and C genes. This technique is based on the formation of specific patterns (PCR fingerprints) of homoduplexes and heteroduplexes between heterologous amplified DNA sequences. After an electrophoretic run on non-denaturing polyacrylamide gel, different HLA class I types give allele-specific banding patterns. HLA class I matching is performed, after the gel has been soaked in ethidium bromide or silver-stained, by visual comparison of patients' fingerprints with those of donors. Identity can be confirmed by mixing donor and recipient DNAs in an amplification cross-match. To assess the technique, 10 normal samples, 22 related allogeneic bone marrow transplanted pairs and 10 unrelated HLA-A and HLA-B serologically matched patient-donor pairs were analysed for HLA class I polymorphic regions. In all the related pairs and in 1/10 unrelated pairs, matched donor-recipient patterns were identified. This new application of PCR fingerprinting may confirm the HLA class I serological selection of unrelated marrow donors.

Base Sequence↗
PubMed1996

Erythropoietin course in newborns with Rh hemolytic disease transfused and not transfused in utero.

This study reports the Hb, erythropoietin (Epo), and reticulocyte course at different postnatal ages (range, 8-83 d) of 56 blood samples from 30 newborns (range, one or two blood samples from each newborn) with erythroblastosis fetalis (18 intrauterine transfused (IUTd) and 12 non-IUTd). Hb, Epo, and reticulocyte values were not statistically different in IUTd and non-IUTd cases. As age increased, decreasing Hb values and increasing Epo levels were observed. The reticulocyte count was relatively low in all but six cases. There was an inverse correlation between Epo and Hb (r = -55, p < 0.001), but no correlation was found between Hb and reticulocytes or between Epo and reticulocytes. When groups were formed on the basis of Hb levels, anemic newborns showed higher serum Epo than did nonanemic patients (p < 0.02). In the present study we found a significant increase in Epo levels in anemic newborns without a rise in the reticulocyte count. These results suggest that other mechanisms, rather than low Epo production, could be involved in the pathogenesis of this anemia. Persisting anti-D antibodies, probably at a medullary level, may destroy erythrocyte precusors, leading to anemia with a low reticulocyte count.

Aging↗
PubMed1996

G-CSF in an infant donor: a method of reducing harvest volume in bone marrow transplantation.

We report the case of a 4-year-old female with high-risk ALL in first CR who received a BMT from an 11-month-old matched sibling treated with G-CSF in order to obtain an adequate number of mononuclear cells in a limited volume of bone marrow. The absence of toxicity, efficacy of the procedure and quality of the post-transplant clinical outcome suggest such treatments are feasible and useful to overcome problems caused by donor age and/or body weight. In view of this experience we demonstrate how such an approach leads to a notable reduction in risks and in bone marrow donation costs.

Bone Marrow Transplantation↗
PubMed1996

[Use of compression anastomosis devices in digestive surgery].

In this summary the authors report their experience of the clinical utilization in digestive surgery of a new compression anastomosis device consisting of a biofragmentable ring (BAR-Valtrac). From January 1993 through August 1994 26 patients underwent operations with Valtrac application: 22 for malignant colo-rectal neoplasms, 3 for diverticular disease and 1 for Crohn disease. The authors have performed 8 ileo-colic, 16 colo-colic and 2 colo-rectal anastomoses. There was no perioperatively mortality. Valtrac was discharged post-operatively between XVI and XXVIII days. There were no anastomotic leakage, bleeding or obstruction. Six months postoperatively an endoscopic control carried out in the 50% of the patients showed no anastomotic stenoses. These results, in association with those ones reported by the literature, confirm that anastomoses performed with Valtrac are safe, reliable and allow the same of better results than stapled anastomoses.

Adult↗
PubMed1995

Amino acid substitutions can influence the natural killer (NK)-mediated recognition of HLA-C molecules. Role of serine-77 and lysine-80 in the target cell protection from lysis mediated by "group 2" or "group 1" NK clones.

Natural killer (NK) cells have been shown to express a clonally distributed ability to recognize HLA class I alleles. The previously defined NK clones belonging to "group 1" recognize HLA-C*0401 (Cw4) and other HLA-C alleles sharing Asn at position 77 and Lys at position 80. Conversely, the "group 2" NK clones recognize HLA-Cw*0302 (Cw3) and other HLA-C alleles characterized by Ser at position 77 and Asn at position 80. We assessed directly the involvement of these two residues in the capacity of NK cell clones to discriminate between the two groups of HLA-C alleles. To this end, Cw3 and Cw4 alleles were subjected to site-directed mutagenesis. Substitution of the amino acids typical of the Cw3 allele (Ser-77 and Asn-80) with those present in Cw4 (Asn-77 and Lys-80) resulted in a Cw3 mutant that was no longer recognized by group 2 NK cell clones, but that was recognized by group 1 clones. Analysis of Cw3 or Cw4 molecules containing single amino acid substitutions indicates roles for Lys-80 in recognition mediated by group 1 clones and for Ser-77 in recognition mediated by group 2 clones. These results demonstrate that NK-mediated specific recognition of HLA-C allotypes is affected by single natural amino acid substitutions at positions 77 and 80 of the heavy chain.

Amino Acid Sequence↗
PubMed1995

Anti-CD30 immunotoxins with native and recombinant dianthin 30.

Immunotoxins were prepared with a Ber-H2 (anti-CD30) monoclonal antibody and native or recombinant dianthin 30, a ribosome-inactivating protein from Dianthus caryophyllus (carnation). Both immunotoxins selectively inhibited protein synthesis by CD30+ cell lines D430B (lymphoblastoid, infected with Epstein-Barr virus), L428 and L540 (both from Hodgkin's lymphoma). IC50 values (concentrations, as dianthin, causing 50% inhibition) ranged from 324 pM to 479 pM (immunotoxin with native dianthin 30) or from 45 pM to 182 pM (immunotoxin with recombinant dianthin 30). The effect of either immunotoxin on protein synthesis by the CD30+ cell line K562 (from a chronic myeloid leukaemia) was not different from that of free dianthin (IC50 higher than nM).

Antibodies, Monoclonal↗
PubMed1995

Detection of platelet-associated antibodies by flow cytometry in hematological autoimmune disorders.

We describe our experience in the evaluation of platelet-associated immunoglobulins (PAIg) by flow cytometry in comparison to solid-phase assay in patients affected by idiopathic thrombocytopenic purpura and by Evans syndrome. Results show that the analysis of PAIg by flow cytometry is easy and reliable and correlates well with data obtained by the solid-phase technique. In addition, flow cytometry allows the evaluation of samples containing small numbers of platelets (< 20,000/mm3); the analysis is objective, not influenced by personal experience. Moreover, flow cytometry appears simple enough to be performed in a routine laboratory, and data might be retrieved to perform batch analysis. Our results appear to indicate that PAIg flow cytometry might be a sensitive tool for the evaluation of patients with autoimmune thrombocytopenia.

Autoantibodies↗