Biomedical subjects
Marcela Contreras
Publications and source records attributed to Marcela Contreras.
Stem cell medicine: umbilical cord blood and its stem cell potential.
The ultimate aim of stem cell research is to improve patient outcomes and quality of life, and/or to effect a cure for a variety of inherited or acquired diseases. Improved treatments rely on developments in stem cell therapies and the discovery of new therapeutic drugs that regulate stem cell functions. These complement each other for the repair, regeneration and replacement of damaged or defective tissues. Stem cells may be sourced or derived from blood and tissues postnatally ('adult' stem cells), from the fetus (fetal stem cells) or from the blastocyst in the developing embryo prior to implantation (embryonic stem cells), each forming a unique component of the revolution in stem cell research and therapies. This review will concentrate on recent developments in the use of haemopoietic stem cells from umbilical cord blood for the transplantation of patients with haematological disorders. It will conclude with a summary of the potential of other umbilical cord blood-derived stem cells for tissue repair or regeneration.
Appropriateness and safety of blood transfusion.
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Acute transplant rejection induced by blood transfusion reaction to the Kidd blood group system.
Many renal transplant centres now try to avoid blood transfusion prior to renal transplantation, to avoid alloimmunization due to antibody production against donor antigens usually present on contaminating white cells. Post- or peri-operative transfusions are usually not considered to present problems, since the patient is heavily immunosuppressed. We present a patient who suffered a rare transfusion reaction, that we believe may have initiated a severe vascular rejection of a kidney transplant, probably mediated by Kidd blood group antigens.
The London Cord Blood Bank: analysis of banking and transplantation outcome.
Cord blood units (n = 5500) stored at the London Cord Blood Bank, including 59 units transplanted into a high risk and heterogeneous group of patients, were analysed. Transplant outcome data was available for 44 patients with a median clinical follow-up of 14 months (range 3-44 months). Over 40% of the collected units were of ethnic minority origin with a median volume of 79 ml (range 40-240 ml) and a median total nucleated cell (TNC) count of 11.9 x 10(9)/l (range 10.0-24.8 x 10(9)/l). The average patient's weight was 28 kg (range 5-80 kg) and the median age was 8 years (range 0.7-40 years). The median number of nucleated cells infused was 4 x 10(7)/kg (range 1.10-16 x 10(7)/kg). Neutrophil engraftment of 0.5 x 10(9)/l was observed in 33 (74+/-%) patients with an average time of 28 days (range 11-60). The Kaplan-Meier estimate of acute graft-versus-host disease (grade II >) at day 100 was 37 +/- 7% and in 27 (62%) patients, it was grade I or absent. The overall survival and disease-free survival at 2 years was 49 +/- 8% and 41 +/- 8%, respectively. Two years after transplantation the survival rate was 69% and 54% for patients receiving a 6/6 or 5/6 HLA matched units, respectively. Infection was the main cause of transplanted related mortality in these patients.
Evaluation of a modified commercial assay in detecting antibody to hepatitis C virus in oral fluids and dried blood spots.
Oral fluid testing is an effective alternative to serum antibody testing for surveillance of human immunodeficiency virus (HIV) and hepatitis B infections, and is being extended to hepatitis C infections. The objective of this study was to determine and compare the sensitivity and specificity of a modified commercial assay for the detection of antibody to hepatitis C virus (anti-HCV) in oral fluids collected by two different oral fluid collection devices (the Epitope OraSure trade mark and Sarstedt Salivette ) and in dried fingerprick blood spots. In this study, 253 anti-HCV seropositive patients and 394 blood donors (all anti-HCV negative) were recruited between August 2000 and January 2001. Each participant provided oral fluid specimens by OraSure and Salivette, and at least one dried blood spot. Serum specimens were collected from the patients whenever possible. For those injecting drug users who did not provide a serum specimen, HCV status was established on the basis of previous testing. All the nonserum samples were tested for the presence of anti-HCV, using a modified Ortho HCV 3.0 SAVe enzyme-linked immunosorbent assay (ELISA) protocol. The recommended preliminary cutoffs for the modified ELISA were suboptimal. Further, the sensitivity, specificity, and positive and negative predictive values could be improved by varying the cutoff and taking into account the likely prevalence of HCV in the population under investigation. For instance, given a population with a 50% prevalence of anti-HCV, the optimal sensitivities of the modified assay on OraSure, Salivette, and dried blood spots were 92%, 83%, and virtually 100%, respectively, in contrast to 83%, 59%, and 99% using the preliminary cutoffs. The respective optimal specificities were 99%, 93%, and 100%. In conclusion, oral fluids collected by the OraSure device provide an extremely useful method to conduct public health surveillance of not only HIV, but also hepatitis C, among injecting drug users. In addition, dried blood spot specimens may be useful for surveillance and could be employed as a first line diagnostic specimen.