Soehendra's Stent Retriever as a pusher.
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Biliary Tract↗
Biomedical subjects
C Navarrete
Publications and source records attributed to C Navarrete.
MLL-AF4 gene fusions in normal newborns.
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Bone Marrow↗
A special report: histocompatibility testing guidelines for hematopoietic stem cell transplantation using volunteer donors. Quality Assurance and Donor Registries Working Groups of the World Marrow Donor Association.
The World Marrow Donor Association has formulated guidelines for establishing the extent and quality of histocompatibility testing for unrelated donor registries, umbilical cord blood banks, and transplant centers involved in international exchange of hematopoietic stem cells for allogeneic transplantation. Registry and cord blood bank guidelines suggest that, at a minimum, initial HLA typing should be performed for three HLA loci, HLA-A, -B, and -DR, at low resolution/split antigen level. DNA-based testing methods should be utilized for HLA-DR typing. DNA-based testing for HLA-A and -B should replace serologic testing of new volunteer donors and cord blood units as robust protocols and reagents become available to the laboratories. Transplant center guidelines for typing of patient, family and to confirm the HLA types of potential unrelated donors should include, at the minimum, typing HLA-A, B, and -DR loci using primarily DNA-based testing methods at allele level resolution for DRB1 and low resolution/split antigen level for HLA-A and -B. It is strongly recommended that the typing of a patient and the selected donor be performed using the same set of reagents, methodology, and interpretation criteria with fresh tissue samples to ensure HLA identity. Guidelines for laboratory accreditation, approaches to quality assurance and quality control for HLA testing, and suggestions for the format of the HLA database of donor types are also outlined.
Bone Marrow Transplantation↗
A special report: histocompatibility testing guidelines for hematopoietic stem cell transplantation using volunteer donors.
The World Marrow Donor Association has formulated guidelines for establishing the extent and quality of histocompatibility testing for unrelated donor registries, umbilical cord blood banks, and transplant centers involved in international exchange of hematopoietic stem cells for allogeneic transplantation. Registry and cord blood bank guidelines suggest that, at a minimum, initial HLA typing should be performed for three HLA loci, HLA-A, -B, and -DR, at low resolution/split antigen level. DNA-based testing methods should be utilized for HLA-DR typing. DNA-based testing for HLA-A and -B should replace serologic testing of new volunteer donors and cord blood units as robust protocols and reagents become available to the laboratories. Transplant center guidelines for typing of patient, family and to confirm the HLA types of potential unrelated donors should include, at the minimum, typing HLA-A, B, and -DR loci using primarily DNA-based testing methods at allele level resolution for DRB1 and low resolution/ split antigen level for HLA-A and -B. It is strongly recommended that the typing of a patient and the selected donor be performed using the same set of reagents, methodology, and interpretation criteria with fresh tissue samples to ensure HLA identity. Guidelines for laboratory accreditation, approaches to quality assurance and quality control for HLA testing, and suggestions for the format of the HLA database of donor types are also outlined.
Hematopoietic Stem Cell Transplantation↗
Cord blood banking: volume reduction of cord blood units using a semi-automated closed system.
Clinical evidence indicates that placental/umbilical cord blood (CB) is an alternative source of haematopoietic stem cells for bone marrow reconstitution. To establish a CB bank large panels of frozen, HLA-typed CB units need to be stored. Cryopreserved, unprocessed CB units require vast storage space. This study describes a method, using the Optipress II Automated Blood Component Extractor (Opti II) from Baxter Healthcare Corporation, to reduce the volume of the CB collection, preserving the quantity and quality of the progenitor cells, in a closed system. The CB collection was transferred to a triple bag system, centrifuged to produce a buffy coat layer and processed using a standard Opti II protocol to separate the whole blood into three components: plasma, buffy coat and buffy coat-depleted red cell concentrate. The buffy coat volume was standardised to 25 ml; mean reduced volume of 24.5 ml (s.d. 1.5 ml) with 53% red cell depletion. Good recovery of cells was observed: 92%, 98%, 96% and 106% recovery of nucleated, mononuclear, CD34+ and total colony-forming cells, respectively. Using this method for processing CB units reduces storage requirement by two-thirds but preserves the quantity and quality of the progenitor cells.
Blood Banks↗
Histocompatibility testing guidelines for hematopoietic stem cell transplantation using volunteer donors: report from The World Marrow Donor Association. Quality Assurance and Donor Registries Working Groups of the World Marrow Donor Association.
The World Marrow Donor Association has formulated guidelines for establishing the extent and quality of histocompatibility testing for unrelated donor registries, umbilical cord blood banks, and transplant centers involved in international exchange of hematopoietic stem cells for allogeneic transplantation. The ability to identify unrelated stem cell donors in one country for patients in another country requires cooperation and standardization in many areas. The adoption of guidelines for histocompatibility testing, such as those summarized in this report, will facilitate these opportunities and rapidly provide accurately typed donors for patients in need.
Adult↗
Cord blood banking in London: the first 1000 collections.
The London Cord Blood Bank was established with the aim of collecting, processing and storing 10000 unrelated stem cell donations for the significant number of children in the UK requiring transplantation, for whom a matched unrelated bone marrow donor cannot be found. Collection is performed at two hospitals by dedicated cord blood bank staff after delivery of the placenta. Mothers are interviewed regarding medical, ethnic and behavioural history by nurse counsellors and sign a detailed consent form. Donations are returned to the bank for processing. Volume reduction is undertaken by a simple, closed, semi-automated blood processing system, with excellent recovery of progenitor cells. Units are cryopreserved and stored in the vapour phase of liquid nitrogen. Blood samples from mothers and cord blood donations are tested for the UK mandatory red cell and microbiology markers for blood donors. Donations are typed for HLA-A, B and DR at medium resolution (antigen split) level using sequence-specific oligonucleotide probing and sequence-specific priming techniques. The selection of collection hospitals on the basis of ethnic mix has proven effective, with 41.5% of donations derived from non-European caucasoid donors. Bacterial contamination of collections has been dramatically reduced by implementation of improved umbilical cord decontamination protocols.
Blood Banks↗
Intracellular cytokine profile of cord and adult blood lymphocytes.
Umbilical cord blood (CB) transplantation is thought to be associated with a reduced risk of severe graft-versus-host-disease (GVHD) compared with bone marrow transplantation (BMT). The cytokine cascade is known to be important in the pathogenesis of GVHD; however, previous studies investigating the cytokine secretion pattern of CB cells have been contradictory because of variations in experimental techniques. In this study, the cytokine profile of cord and adult blood lymphocytes and lymphocyte subsets has been assessed at the single-cell level by flow cytometry, using CD4/CD8 and CD45RA/CD45RO markers. Cord and adult blood mononuclear cells were stimulated with phorbol 12-myristate 13-acetate (PMA) and ionomycin in the presence of monensin. After 4 to 24 hours of incubation, interleukin-2 (IL-2), IL-4, interferon-gamma (IFN-gamma), and tumor necrosis factor-alpha (TNF-alpha) production was measured by three-color flow cytometry. The results show that cord blood lymphocytes (CBL) produce less IL-2, IL-4, IFN-gamma, and TNF-alpha than adult peripheral blood lymphocytes (ABL). Further subset analysis showed that in CBL the majority of cytokine producing cells were CD4(+)CD45RA+, whereas in ABL the cytokine-producing cells were both CD4(+)CD45RO+ and CD8(+)CD45RO+. These results suggest that the reduced incidence of GVHD in CB transplantation may partly due to the altered cytokine profile seen in CBL.
Adult↗
T-cell receptor variable alpha (TCRAV) polymorphisms in European, Chinese, South American, AfroCaribbean, and Gambian populations.
Interactions involving the T-cell receptor (TCR) and major histocompatibility complex (MHC) are fundamental to the generation of a specific immune response. The study of interpopulation differences in TCR genes may identify those genes which are subject to selection, and also provides useful information for future genetic studies in these populations. In this study we present analysis of five TCRAV polymorphisms, for V5S1, V6S1, V8S1, V17S1, and V21S1 loci in five human populations by single-strand conformational polymorphism (SSCP) analysis. Caucasian, Chinese, Gambian, AfroCaribbean, and South American Indians (Mapuches) showed marked interpopulation variation for both the silent (V5S1, V17S1, and V21S1) and coding (V6S1 and V8S1) polymorphisms. In general the alleles were conserved in the different populations, but new, additional variants were found for V5S1 and V17S1 in Gambians and Caucasians. V6S1 overall showed the highest nucleotide diversity, and V6S1 genotype distributions were skewed away from expected values in Chinese and Mapuches. Analysis of allelic associations showed a general lack of linkage disequilibrium between the loci, which was reflected by the absence of strong population-specific haplotypes.
Adult↗
Advances in therapeutic endoscopic treatment of common bile duct stones.
Advances in cannulation techniques and instruments have helped in difficult bile duct cannulation and thus stone extraction. For small common bile duct (CBD) stones, endoscopic papillary balloon dilatation has been proposed as an alternative to endoscopic papillotomy (EPT). The technique must undergo further evaluation before recommending its routine use. For most patients with bile duct stones, EPT remains the method of choice. Out of 8204 patients treated in three surgical endoscopy centers (Chile, Germany, and India), 86% to 91% of all CBD stones could be extracted subsequently after EPT using a Dormia basket; 4% to 7% required mechanical lithotripsy (ML) before removal and 3% to 10% of the patients needed other sophisticated techniques, such as electrohydraulic lithotripsy (EHL), laser-induced shock-wave lithotripsy (LISL), or extracorporeal shock-wave lithotripsy (ESWL). The local expertise and availability of equipment determines the choice of method used. In general, EHL or LISL is used for impacted CBD stones including stones in Mirizzi syndrome refractory to ML. ESWL is best suited for intrahepatic stones. Permanent stenting can be offered to poor risk patients instead of extensive procedures to clear the bile duct. Using currently available nonsurgical techniques, fewer than 1% of all patients with bile duct stones still require surgical intervention.
Algorithms↗
The London Cord Blood Bank.
Cord blood (CB) contains a sufficient number of haemopoietic progenitor cells and can be used as an alternative to bone marrow transplantation. To date, a number of transplants using cord blood-derived stem cells from HLA-identical siblings and unrelated donors have been successfully performed. However, only approximately 30% of patients have an HLA-identical sibling while the rest are reliant on finding an HLA-compatible unrelated donor. This is particularly difficult for patients from ethnic minorities since the majority of unrelated bone marrow donor volunteers are from Caucasoid ancestry. The London Cord Blood Bank was established to provide an additional source of stem cells for all patients requiring bone marrow transplantation.
Blood Banks↗
Use of cord blood progenitor cells as an alternative for bone marrow transplantation.
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Bone Marrow Transplantation↗
Soluble histocompatibility class I antigens and beta 2-microglobulin in pregnant females and cord blood samples.
Pregnancy can be considered a successful transplantation of allogeneic paternal tissue to the mother. Soluble HLA class I serum levels have been found to increase during solid organ rejection episodes and during graft-versus-host disease after bone marrow transplantation. We wished to determine whether significant changes in sHLA class I and beta 2-microglobulin light chain levels occurred during pregnancy, because these may reflect adaptive changes permitting the acceptance of the fetal graft. Serum samples were obtained from women at different stages of pregnancy and in the postpartum period. Cord blood samples and serum samples from nonpregnant female and male controls living in the same geographic area in Southern Chile were also studied. The levels of sHLA class I heterodimers were determined by an ELISA sandwich technique; beta 2-microglobulin levels were measured by MEIA IMX-Abbott. There was a significant elevation of sHLA class I levels in the first 2 trimesters of pregnancy, followed by a significant drop below normal levels at the end of pregnancy, with normalization in the post-partum period. beta 2-microglobulin levels did not change significantly during pregnancy and did not correlate with sHLA class I levels. In cord blood samples, sHLA class I levels were lower and beta 2-microglobulin levels higher than those of adult controls and of mothers at the time of delivery. The variations in sHLA class I levels during pregnancy may reflect or contribute to immunoregulatory events related to the acceptance of the fetal graft.
Adult↗
Lesson of the week. Acute non-cardiogenic lung oedema after platelet transfusion.
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Acute Disease↗
CD34 counts to predict the adequate collection of peripheral blood progenitor cells.
An essential prerequisite for successful procurement of sufficient autologous peripheral blood progenitor cells (PBPC) for engraftment is the optimal timing of collection. A number of surrogate markers of peripheral blood progenitor cells were analysed to identify a single test which could predict the optimum time to harvest, providing at least 2 x 10(6) CD34+ cells/kg patient body weight. The study comprised 95 patients undergoing varied mobilisation regimens with chemotherapy and G-CSF for both solid tumours and haematological malignancies. One hundred and fifty-seven PBPC harvests were collected. Full blood counts (FBC) and CD34+ cell enumeration was performed on blood samples taken during the mobilisation period and immediately prior to leucapheresis (pre-harvest). All PBPC collections were assayed for colony-forming cells and CD34+ cells in addition to a FBC. The white cell count on the day of harvest showed only weak correlation with the total number of CD34+ cells in the collection (r = 0.30). In contrast, the absolute number of circulating CD34+ cells strongly correlated with the CD34+ cell and CFU-GM yield of the corresponding apheresis product. Provided the mobilisation sample contained > or =20 x 10(6) CD34+ cells/ml, 94% of single collections, performed the following day, contained > or =2 x 10(6) CD34+ cells/kg.
Adolescent↗
Management of alloimmunized, refractory patients in need of platelet transfusions.
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Histocompatibility Antigens Class I↗
A clinically significant anti-HLA-A2 detectable by extended incubation cytotoxicity and flow cytometric techniques but not by a standard NIH lymphocytotoxicity test.
A previously transfused female patient, known to have a platelet defect, was transfused with platelets prior to surgery. After the 18th unit she felt unwell, developed fever, rigor, became nauseous, and vomited. Her blood pressure decreased from 140/90 to 80/50 mm Hg. Passive transfer of donor granulocytes or red cell antibodies were excluded as a cause. Therefore, a serum sample from the patient was investigated for the presence of antibodies to human leukocyte antigens (HLA) using a standard National Institutes of Health (NIH) lymphocytotoxicity test, but antibodies were not detected. However, an extended incubation cytotoxicity test demonstrated the presence of an anti-HLA-A2, and indirect immunofluorescence flow cytometry showed the presence of an IgG1 antibody reacting with 50 percent of cells in a random pool of lymphocytes. One week later, multispecific HLA antibodies were detectable by both NIH and extended incubation cytotoxicity tests. Flow cytometry showed a 16-fold increase in the amount of IgG antibodies and the appearance of an IgM component. Such clinically important HLA antibodies can be detected by extended incubation cytotoxicity and flow cytometric assays prior to becoming reactive in a standard NIH cytotoxicity technique.
Journal Article↗
[Chronic pancreatitis. A recent national experience with its surgical management].
BACKGROUND: The prevalence of chronic pancreatitis in Chile is not known and there is no local information about the surgical treatment of this disease. AIM: To review retrospectively the results of surgical treatment of chronic pancreatitis. MATERIAL AND METHODS: The charts of 17 patients (12 male), aged 7 to 65 years old, with chronic pancreatitis that were operated in three different Chilean regions, were reviewed. RESULTS: Seven patients had previous endoscopic therapeutic procedures (papillotomy in 4 and stent placing in 3). Seven patients had been subjected to previous biliary surgical procedures. Indications for surgery were severe pain in 14 patients, the suspicion of a pancreatic carcinoma in 4 patients, an infected pseudocyst in one and massive bleeding of multiple pseudo-aneurysms in a pseudocyst in one patient. Twelve patients were subjected to decompressions and 5 to pancreatic resections. There was no operative mortality and one transient pancreatic fistula. After an average follow up of 22 months, pain improved in 94% of cases, pancreatic cancer was diagnosed in one patient and 79% of subjects gained weight. One patient became insulin dependent, one increased his insulin requirements and one had transient steatorrhea, since she could not afford pancreatic enzyme replacement therapy. CONCLUSIONS: The multidisciplinary approach of patients with chronic pancreatitis, with selective use of surgery, may greatly improve their quality of life.
Adolescent↗