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Biomedical subjects

M Contreras

Publications and source records attributed to M Contreras.

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

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↗
PubMed1997

The impact of a picture archiving and communication system on nuclear medicine examination interpretation.

Radiographic correlation is essential for many of the examinations performed in nuclear medicine. The purpose of this study was to evaluate the impact of a picture archiving and communications system (PACS) on the function and efficiency of a nuclear medicine department at a tertiary care institution. We evaluated 250 consecutive noncardiac nuclear medicine imaging examinations and asked the interpreting physician the following questions: (1) Was PACS used in the interpretation of the study? (2) Did the use of PACS expedite examination completion or aid in study interpretation? And (3) Did the use of PACS permit a definitive diagnosis to be made? PACS was accessed for correlative radiographic images in 155 of the 250 (62%) nuclear medicine examinations. Images available on PACS for review aided in study interpretation in 74% (115 of 155) of cases. The use of PACS was thought to expedite examination completion in 55% (86 of 155) of cases. The system was accessed but not operational in only 1% of cases (2 of 155). PACS provides reliable, rapid access to multimodality correlative radiographic images that aid in the interpretation of nuclear medicine examinations. Such systems also increase the efficiency of a nuclear medicine service by allowing timely and conclusive interpretations to be made.

Evaluation Studies as Topic↗
PubMed1997

Annexin V, a new marker of platelet storage lesion: correlation with dMPV.

Released annexin V, an intracellular platelets glycoprotein, was used to determine the cellular injury which occurred during storage of platelet concentrates. Twenty-eight units of leuco-reduced apheresis platelet concentrates, obtained without leucocyte filtration, were analysed. Released annexin V showed a significant correlation with EDTA-induced shape changes of platelet (r = 0.62, P < 0.01) while poor correlation was found between released annexin V and pH or MPV. The combination of released annexin V with dMPV provides excellent markers of the platelet storage lesion for quality monitoring, based on morphological/functional integrities and cellular injury, which are of direct relevance to clinical efficacy of platelet concentrates.

Annexin A5↗
PubMed1997

Comparison of in vivo red cell survival of donations collected by Haemonetics MCS versus conventional collection.

The Haemonetics Multicomponents System (MCS) cell separator allows concurrent donation of red cells in addition to platelets and/or plasma, thus increasing the versatility of apheresis donations. In vivo survival of autologous red cells obtained by MCS was compared with red cells collected conventionally. In this cross-over controlled study, five male volunteers donated one unit of red cells by MCS and one unit of whole blood by the conventional manual method, 3 months apart. After storing donations in SAG-M for 35 days under standard conditions, radioactive (51Cr)-labelled autologous red cells were injected into each donor. The post-transfusion recovery (PTR) of red cells at 24 and 48 h did not show any significant difference between red cells obtained manually and by MCS, indicating that processing differences have no detrimental effects on red cell survival.

Blood Donors↗
PubMed1996

Topology of ATP-binding domain of adrenoleukodystrophy gene product in peroxisomes.

Adrenoleukodystrophy (X-ALD) is a demyelinating disorder characterized by the accumulation of saturated very-long-chain fatty acids (> C22:0) due to the impaired activity of lignoceroyl-CoA ligase. The gene responsible for the disease was found to code for a 84-kDa peroxisomal integral membrane protein. Its amino acid sequence has high homology with the ATP-binding cassette superfamily of transporters and it is predicted to have six membrane-spanning segments and a putative ATP-binding domain. To define the function of ALDP, we studied the topology of its ATP-binding domain by using antibodies (1D6) against a hydrophobic domain (amino acid residues 279 to 482) and antibodies (Abct) against the C-terminal 15-amino-acid hydrophilic domain (amino acid residues 731 to 745) of ALDP. The observation of punctate fluorescence in permeabilized ALD fibroblasts, using Abct antibodies but not with antibodies against catalase, suggests that the C-terminal segment of ALDP is projected toward the cytoplasm from the peroxisomal membrane. Trypsinization of intact peroxisomes under isotonic conditions abolishes the Abct antibody recognition site, whereas the 1D6 antibodies identify a degradation product of 43-kDa protein that has been protected and retained by the membrane. This again suggests that the C-terminal portion of the ALDP protein is located on the outside (cytoplasmic) face of the peroxisomal membrane. Additional support for this conclusion was obtained by purification of the ALDP C-terminal domain, released from purified rat liver peroxisomes incubated with the cytosolic fraction, using blue-Sepharose affinity chromatography. A 47-kDa peptide retained by the column was recognized by Western blot analysis with Abct antibodies against the C-terminal sequence of ALDP and this polypeptide on polyvinylidene difluoride membrane was able to bind [gamma-32P]ATP in vitro in the presence of Mg2+. These results demonstrate that the C-terminal peptide containing the ATP-binding domains of ALDP is on the cytoplasmic surface of the peroxisomal membrane where this domain may function as an ATPase to support the functional role of ALDP in the peroxisomal membrane.

ATP Binding Cassette Transporter, Subfamily D, Mem↗
PubMed1996

Determination of imidacloprid in vegetables by high-performance liquid chromatography with diode-array detection.

An HPLC method is described for the determination of imidacloprid residues in vegetables at levels ranging from 0.01 to 0.60 mg/kg. The selection of the extraction and clean-up procedure is discussed. Spectral data obtained with diode-array detection allow the identification of imidacloprid residues. Thermospray mass spectrometric studies were carried out in combination with HPLC. The mean recoveries and standard deviations were 95% and 4.7%, respectively, in the various crops tested. Registration of the analytical results for a control sample in quality control charts demonstrated the performance of the method. Data for incurred residues of imidacloprid in vegetable samples routinely applying the proposed method are also presented.

Chromatography, High Pressure Liquid↗