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Biomedical subjects

C Navarrete

Publications and source records attributed to C Navarrete.

At least 19 recordsLinked to original sources

Granulocyte transfusions for treating infections in patients with neutropenia or neutrophil dysfunction.

BACKGROUND: Transfusions of granulocytes have a long history of usage in clinical practice to support and treat severe infection in high risk groups of patients with neutropenia or neutrophil dysfunction. However, there is considerable current variability in therapeutic granulocyte transfusion practice, and uncertainty about the beneficial effect of transfusions given as an adjunct to antibiotics on mortality. OBJECTIVES: To determine the effectiveness of granulocyte transfusions compared to no granulocyte transfusions for treating infections in patients with neutropenia or disorders of neutrophil function in reducing mortality. SEARCH STRATEGY: Randomised controlled trials (RCTs) were searched for in the Cochrane Central Register of Controlled Trials (CENTRAL) in 2003. Searching was also undertaken on the OVID versions of Medline and Embase using an RCT search filter strategy. SELECTION CRITERIA: RCTs involving transfusions of granulocytes, given therapeutically, to patients with neutropenia or disorders of neutrophil dysfunction. DATA COLLECTION AND ANALYSIS: Two reviewers completed data extraction independently. Relative risk (RR) with 95% confidence intervals (CI) using the random effects model were reported for dichotomous outcomes. Pre-specified subgroup analyses were done and reported eg granulocyte dose. MAIN RESULTS: Eight parallel RCTs were included with 310 total analysed patient episodes. Different policies were applied for the schedule of transfusion, method of granulocyte procurement and process of donor selection including leucocyte compatibility. Each study used different criteria for neutropenia (range < 0.1 to < 1.0 x 10(9)/L) and definition of infection requiring treatment. For mortality, which was extracted from six trials, the summary RR = 0.64 in favour of transfusion (95% CI 0.33, 1.26), but with evidence of significant statistical heterogeneity (Chi-square 11.3 and I(2) = 56%). The data for the combined RR for mortality for the four studies transfusing higher granulocyte doses greater than 1x10(10) indicated a significant summary RR= 0.37 (95% CI 0.17, 0.82); Chi-square 3.9, I(2) 23%. Data on rates of reversal of infection could be extracted from four studies, and the combined RR was 0.94 (95% CI 0.71, 1.26), again with evidence of heterogeneity. In addition to the observed clinical diversity between all studies, uncertainty about the quantitative and qualitative analyses for these studies is compounded by methodological deficiencies. AUTHORS' CONCLUSIONS: Currently, there is inconclusive evidence from RCTs to support or refute the generalised use of granulocyte transfusion therapy in the most common neutropenic patient populations, that is caused by myeloablative chemotherapy with or without haematopoietic stem cell support. Contemporary well designed prospective trials are required to evaluate the efficacy of this intervention in these patient populations and to establish definitively whether it has clinical benefit. In such studies, average numbers of collected granulocytes for adults should be (at least) greater than 1x10(10).

Cause of Death↗

Diagnosis of transfusion-associated graft-vs.-host disease: the importance of short tandem repeat analysis.

Transfusion-associated graft-vs.-host disease (TA-GvHD) can occur following transfusion of blood products containing immunocompetent lymphocytes, usually from HLA homozygous donors, into immunocompromised patients sharing one HLA haplotype with the donor. The diagnosis of TA-GvHD may be delayed due to the initial nonspecific clinical features involved. Investigations to detect the presence of donor-derived cells in the blood and/or affected tissues of the recipient are essential to confirm the diagnosis. We report the investigation of suspected TA-GvHD using short tandem repeat (STR) analysis, to detect the presence of donor cells (chimerism), in an immunocompetent patient admitted for coronary artery bypass surgery. Peripheral blood and skin biopsies (from affected and nonaffected sites) from the patient and peripheral blood samples from the implicated donors were taken for HLA typing and STR analysis. STR analysis revealed the presence of donor material in the patient's peripheral blood sample and in DNA extracted from the affected skin biopsy but not the unaffected biopsy, suggesting lymphocytes from this donor were responsible for the development of TA-GvHD. Furthermore, HLA typing results supported the diagnosis of TA-GvHD. These data demonstrate the use of STR and HLA analysis as effective tools in the diagnosis of TA-GvHD.

Aged↗

Changes in the survival of patients with systemic lupus erythematosus in childhood: 30 years experience in Chile.

The objective of this study was to analyse the survival rate and cause of death in children with systemic lupus erythematosus (SLE) during the past 30 years in Chile. A retrospective analysis was performed between 1969 and 2000 on patients attending pediatric rheumatology centres in Santiago, Chile. Survival and causes of death in 31 children followed from 1969 to 1980 fulfilling the 1982 American College of Rheumatology criteria for SLE and treated with oral steroids were compared with 50 other patients who were treated with oral steroids and an aggressive treatment of IV bolus of cyclophosphamide (38 patients) and azathioprine (12 patients). Global survival at five and 10 years follow-up for the patients studied from 1969 to 1980 was 68 and 40%, respectively. During the second study period these values were significantly improved and global survival reached 95% at five years and 90% at 10 years follow-up (P < 0.05). Survival at 10 years follow-up for patients with lupus nephropathy increased from 28% (study period 1964-1980) to 86% (study period 1984-2000). Twelve children died (38%) during the 1964-1980 study period. The causes of death were six due to kidney failure, three due to infectious conditions and another three of unknown causes. During the 1980-2000 study period mortality reached 6% (three cases), two cases died of a lupus flare-up and one case due to infection. In the last three decades, we have seen an important increase in the survival of children with SLE, especially in those patients with renal involvement. Management with immunosuppressive drugs, such as IV cyclophosphamide or azathioprine has changed the prognosis in these children. These results demonstrate that our children with SLE increased their life expectancy but are now faced with new types of morbidity because of the sequelae related to the disease itself.

Adolescent↗

Renovascular disease is associated with low producer genotypes of the anti-inflammatory cytokine interleukin-10.

Cytokines are important mediators of inflammatory and proliferative responses in disease states including atherosclerosis. Genetic variations in cytokine production could potentially influence the outcome of these responses. The aim of this study was to determine whether cytokine gene polymorphism might influence the development of atherosclerotic renal artery stenosis. Sixty-six patients with atherosclerotic renal artery stenosis and 100 normal healthy individuals were genotyped for interleukin-10 (IL-10), tumor necrosis factor-alpha (TNF-alpha), IL-6, and IL-2 promoter region polymorphism. TNF-a, TNF-d, and IL-10 microsatellite polymorphisms were also analyzed. The frequency of the anti-inflammatory cytokine IL-10 promoter (-1082 A positive) GA and AA genotypes which are associated with low production were higher in the patient group when compared to the control group. The AA-TT-AA homozygous genotype combination of three single-nucleotide polymorphisms at -1082, -819, and -592 in the IL-10 gene was also observed at a higher frequency in the patient group compared to the controls. The frequency of TNF-alpha, IL-6, and IL-2 polymorphisms did not show any significant difference between the patient and control groups. To correlate IL-10 genotypes with differences in IL-10 protein expression, in vitro mRNA and protein levels were analyzed in lipopolysaccharide-stimulated peripheral blood mononuclear cells from 22 patients with renal artery stenosis and 33 controls. Individuals genotyped as A positive at position -1082 produced lower levels of IL-10 protein and had lower copy numbers of mRNA when compared to individuals genotyped as A negative in both patient and control groups. The increased frequency of the low producer IL-10 promoter, -1082 A-positive genotype in patients with renal artery stenosis, suggests that IL-10 may protect against the development of atherosclerotic renovascular disease.

Aged↗

Molecular studies of anti-HLA-A2 using light-chain shuffling: a structural model for HLA antibody binding.

Human leukocyte antigen (HLA) A2 is one of the most immunodominant HLA antigens. Through a process of light-chain variable domain (VL) shuffling, we analyzed the VL domains' role in anti-HLA-A2/A28-binding site diversity. This was achieved by combining a VH3-30-encoded HLA-A2/A28-specific heavy-chain variable domain with 10(4) non-immune VL domains. Twelve HLA-A2/A28-specific antibodies were subsequently identified. VL gene analysis demonstrated an absence of Vlambda domains and that all have VkappaI-encoded light chains. The affinities correlated with the VkappaI gene present, with the seven highest affinity antibodies using Vkappa domains encoded by the O18 gene segment. A 300-fold difference in affinity was observed between the 12 antibodies, and homology modeling demonstrated a correlation between electrostatic surface potential of the antigen-binding site and affinity for HLA. Overlap between the T-cell receptor-binding site and that of the antibodies was indicated by inhibition of cytotoxic T-lymphocyte killing of peptide-pulsed target cells. A model of antibody binding to HLA-A2 suggested contact with both alpha helices of the HLA molecule, such that the antigen-binding site spans the peptide-binding groove. These data increase the understanding of antibody recognition of HLA and may facilitate the production of clonotypic antibodies with peptide-specific binding.

Antibodies, Monoclonal↗

Clinical graft evolution of lymphocytes, polymorphonuclear cells, and antigen expression in tubular renal cells in the urine sediment of 20 renal allograft recipients.

Urinary samples from 20 kidney transplant recipients were studied to determine the cellular composition of the sediments using an immunocytological (IC) technique. The expression of HLA class I (A, B, C) and class II (DR, DQ, DP), CD2, CD3, CD4, CD8, and interleukin (IL)-2 receptor (IL-2R) on lymphocytes was assessed using a panel of monoclonal antibodies. The results were correlated with graft function and with the number of episodes of acute renal graft rejection (AR) during a period of 6 months posttransplantation. The cellular infiltration of lymphocytes (LC) and polymorphonuclear cells (PMNC) also was studied using a standard cytology (SC) technique. During this period, 17 of 30 episodes of graft dysfunction due to AR occurred in 12 patients: 8 to acute tubular necrosis (ATN) (n = 8); 4 to cyclosporine (CsA) toxicity (n = 4) and 1 to amphotericin toxicity (n = 1). The diagnosis of AR was made clinically by 3 independent observers, using biopsy in some cases. The immunocytology showed a significantly increased expression of HLA-DR, DO, and DP namely, greater than 20% positivity in 10% of samples on the tubular epithelial cells (TEC) of patients presenting with versus without AR (P < or =.001). In addition, a high correlation was observed between the expression of IL-2R and the presence of AR (p < or =.002). The standard cytology results showed a significantly increased percentage of LC and decreased percentage of PMNCs in samples obtained 2 days prior to the clinical manifestations of patients who developed AR (P =.001). A greater level of expression of antigen determinants was observed prior to AR. These results suggest that immunocytology of urinary sediments, which is a noninvasive technique, has enormous clinical potential for the differential diagnosis of AR, ATN, and CsA toxicity. In our study, the use of HLA class IL-specific monoclonal antibodies (Abs) gave a 100% specificity, 95% sensitivity, and 95% predictability. Although our results also indicate a potential value in the increased IL-2R expression, these findings must be confirmed by further studies. Furthermore, the combination of both immunologic and SC techniques in urinary sediments allows early detection of AR and is cost effective and simple features that could be used routinely for follow-up of renal transplant recipients.

Adult↗

Are human platelet alloantigens (HPA) minor transplantation antigens in clinical bone marrow transplantation?

The role of human platelet alloantigens (HPA) in clinical bone marrow allotransplantation was investigated. The leading hypothesis was that HPA alloepitopes act as minor histocompatibility antigens and aggravate graft-versus-host disease (GVHD). To exclude the effect of MHC disparity, only HLA identical donor-recipient pairs were entered into the study. The influence of HPA compatibility on overall survival, occurrence of relapses and haematopoietic recovery was also investigated. A total of 223 patients who received a graft from an HLA-identical sibling, genotyped for HPA -1, -2, -3, -4 and -5, were observed over a post-transplant period of 24 months following the protocol recommended by EBMT. The data from patients having received grafts from HPA compatible donors were compared to data from patients having received grafts that were mismatched in HPA allotypes in the GVH direction. Analysis of the incidence of acute and chronic (GVHD), overall survival, relapse incidence, haematopoietic recovery and some other clinical parameters did not reveal any significant difference between the HPA-matched and -mismatched groups of patients, regardless of their age. Our results give no evidence that HPA-1, -2, -3 and -5 alloantigens should be considered minor transplantation antigens in clinical bone marrow transplantation.

Adult↗

Treatment of common bile duct injuries during laparoscopic cholecystectomy: endoscopic and surgical management.

The increase of laparoscopic cholecystectomy has resulted in an increase of bile duct injuries. The purpose of this article is to define the types of injury, their occurrence and frequency, and their management by endoscopic and surgical techniques. Three investigations were included in the present study. 1. A 3-year retrospective study among 29 hospitals with 25,007 laparoscopic cholecystectomies. 2. An 8-year prospective study at our institution of 6488 patients. 3. A prospective endoscopic study of 94 patients with injuries and strictures of the common bile duct (CBD) after laparoscopic cholecystectomy. A special classification for bile duct injuries was developed. Among 25,007 patients from 29 hospitals, a total of 74 lesions were detected with an incidence of 0.29%. At our institution, 20 cases were seen (0.29%) with type I, II, and III injuries. The 94 cases managed by endoscopic procedure were submitted to endoscopic retrograde cholangiopancreatography (ERCP) and papillotomy, with placement of several stents 5 to 10 F during 8 months. The results of this procedure have been excellent to good in 76% of the cases up to 3 years of follow-up. According to our previous and present experience, bile duct injuries after laparoscopic procedure are two times higher than after open procedure. The best treatment is the prevention of these injuries by careful surgical technique. If they occur, the best moment to repair them is during surgery. If they are noticed after the operation, endoscopic or surgical procedures can be employed.

Adult↗

HLA-B typing by reference strand mediated conformation analysis using a capillary-based semiautomated genetic analyzer.

The application of reference strand conformation analysis (RSCA) to HLA-A typing using the ABI PRISM 310 capillary based genetic analyzer has recently been described. This study outlines the development and validation of capillary RSCA for HLA-B typing. Mobility values for 93 HLA-B alleles were defined following electrophoresis of known controls through the system. Three fluorescently labelled references, labelled with three different dyes can be electrophoresed simultaneously. The technique was validated by comparing results from 296 cord blood donors with those obtained using reverse SSO. Following capillary RSCA 14.5% of samples required confirmatory typing, compared with a repeat rate of 5.1% following reverse SSO. In samples where no other typing was necessary there was 100% correlation between the two methods. Capillary RSCA for HLA-B typing is quick, easy to implement, and with the introduction of new FLRs and gel matrices has the potential to evolve into a high resolution typing method.

Alleles↗

PCR-PRINS-FISH analysis of structurally abnormal sex chromosomes in eight patients with Turner phenotype.

According to cytogenetic analysis, about 50% of Turner individuals are 45,X. The remaining cases have a structurally abnormal X chromosome or are mosaics with a second cell line containing a normal or abnormal sex chromosome. In these mosaics, approximately 20% have a sex marker chromosome whose identity cannot usually be determined by classical cytogenetic methods, requiring the use of molecular techniques. Polymerase chain reaction (PCR), primed in situ labeling (PRINS), and fluorescence in situ hybridization (FISH) analyses were performed in 8 patients with Turner syndrome and 45,X mosaic karyotypes to determine the origin and structure of the marker chromosome in the second cell line. Our data showed that markers were Y-derived in 2 patients and X-derived in the remaining 6 patients. We were also able to determine the breakpoints in the two Y chromosomes. The use of cytogenetic and molecular techniques allowed us to establish unequivocally the origin, X or Y, of the marker chromosomes in the 8 patients with Turner phenotype. This study illustrates the power of resolution and utility of combined cytogenetic and molecular approaches in some clinical cases.

Adolescent↗

An international survey of unrelated umbilical cord blood banking.

OBJECTIVES: To investigate operational and technical practices within the field of cord blood banking. MATERIALS AND METHODS: Cord blood banks world-wide were invited to participate in a survey of collection, processing and testing. The survey covered a 12-month period up to August 1998. RESULTS: Replies were received from 18 cord blood banks. Analysis of the survey responses demonstrated wide variations in many aspects of cord blood banking. CONCLUSION: There is a need for standardization to ensure adoption of best practice.

Blood Banks↗

The isolation and characterisation of human monoclonal HLA-A2 antibodies from an immune V gene phage display library.

Molecular cloning techniques and V gene phage display have revolutionised the production of human monoclonal antibodies. Antibodies of a defined specificity can be obtained by selecting phage display libraries on antigen in a process known as panning. We have applied these techniques to the isolation of three HLA-A2-specific single chain variable domain fragments (scFv) from a patient alloimmunised by blood transfusion. Analysis of specificity with cells of HLA genotyped donors revealed the following: i) in addition to the major reactivity with HLA-A2, cross-reactivity with the HLA-A28 epitope; and ii) inhibition of scFv binding to the antigen by the patients' antibodies. The heavy chain variable genes of all three were derived from the germline gene Cos-3, carry the hallmarks of somatic hypermutation, and are most likely derived from clonally related B cells. The light chain variable domains were encoded by DPK1 and DPK8 from the VkappaI family. These data show that phage display can be used to clone HLA-specific alloantibodies that recognise the native antigen from alloimmunised patients.

Amino Acid Sequence↗

Dendritic cells can be successfully generated from CD34+ cord blood cells in the presence of autologous cord blood plasma.

Dendritic cells (DCs) are currently being considered as adjuvants in immunotherapy. Depending on their source and culture conditions, they show different features and maturation states. Dendritic cells can be generated from monocytes and CD34+ haematopoietic stem cells, from both adult and cord blood. Here, we report the generation of mature DCs from enriched CD34+ cord blood (CB) cells using autologous cord blood plasma (ACBP) as a source of serum proteins and factors. In the presence of ACBP, CD34+ cells proliferated and differentiated resulting in a population of cells with a dendritic phenotype as assessed by morphology and flow cytometry analyses. The DC population obtained using ACBP showed higher levels of HLA class II molecules, co-stimulatory molecules including CD40, CD80 or CD86, and the dendritic cell marker CD83, compared with those generated in adult blood serum (ABS). Furthermore, the DCs generated in the presence of ACBP were more potent stimulatory cells in the mixed lymphocyte:dendritic cell reactions (MLDCR), compared to cells generated in ABS. Similar results were obtained using homologous cord blood plasma (HCBP). These results show that ACBP can support the generation of DCs from CD34+ progenitor cells when only GM-CSF and TNFalpha are used as differentiating cytokines.

Adult↗

Detection of Gov system antibodies by MAIPA reveals an immunogenicity similar to the HPA-5 alloantigens.

The glycosylphosphatidylinositol-linked platelet protein CD109 carries the biallelic alloantigen system Gov. There is limited information on the incidence of Gov alloantibodies in neonatal alloimmune thrombocytopenia (NAITP), post-transfusion purpura (PTP) and platelet refractoriness. We adapted the monoclonal antibody-specific immobilization of platelet antigens (MAIPA) assay to the detection of Gov antibodies and determined their incidence in 605 archived samples (112 with HPA antibodies) referred for the aforementioned conditions. Here, we show that CD109 expression was reduced upon platelet storage in saline or by cryopreservation, but was stable when stored as whole blood or therapeutic platelet concentrate. Fourteen of the 605 samples contained Gov alloantibodies (anti-Gova, n = 10; anti-Govb, n = 4), with the majority in platelet refractoriness (n = 9) and, of the remaining five, four in NAITP and one in PTP. In seven cases, no other HPA antibodies were detected, three being NAITP cases. The incidence of Gov antibodies was significantly lower than HPA-1 system antibodies (n = 87), but equalled the number of HPA-5 system antibodies (n = 14) and outnumbered HPA-2 and -3 system antibodies (10 altogether).

Alleles↗