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Biomedical subjects

A Pereira

Publications and source records attributed to A Pereira.

At least 73 records · Page 4Linked to original sources
PubMed2000

Cost-effectiveness analysis and the selection of blood products.

A new generation of blood components and transfusion modalities aimed at further reducing real or hypothetical risks threatening the blood supply is available. Since the risk of infection with transfusion-transmitted viruses is already very low, many of these new interventions provide a minimal health benefit at a very high cost. It is even possible that risks inherent to the new technologies themselves could surpass the current risk of transfusion-transmitted viruses. For some of the new blood components, such as leukoreduced products, the poor cost-effectiveness projections may be substantially improved if the purported health benefits are eventually proved in appropriate randomized, controlled clinical trials. Meanwhile, cost-effectiveness analyses show that allocating more resources to improve the safety of donated blood may actually decrease the overall transfusion safety by subtracting resources from other areas of the health care system, so a realignment of costs with health benefits seems necessary.

Blood Component Removal↗
PubMed2000

Coexisting Anti-I/i Plus Anti Pr Cold Agglutinins in Individual Sera.

Background: Sera with high-titer cold agglutinins (CAs) of unclear or even of apparently definite specificity may contain mixtures of CAs with different specificities. The combination of anti-I plus anti-Sia-b1 CAs in sera of patients with Mycoplasma pneumoniae infections is well documented. No systematic studies on CA mixtures in sera of patients with other diagnoses are available. Material and Methods: Sera of 322 patients with high-titer CAs were exhaustively absorbed with sialidase-treated red blood cells (RBCs). By absorption, CAs against the sialidase-resistant I/i antigens are removed. If CAs reacting with untreated RBCs are left after absorption, they are directed against the sialidase- and protease-sensitive Pr(1,2,3) antigens or against the sialidase-labile but protease-resistant antigens of the Sia-I/b/Ib complex. If CA mixtures were found, specificities and isotypes of the CAs obtained by cold adsorption and warm elution were determined. Results: Three patients had mixtures of anti-i plus anti-Pr CAs, 2 patients had mixtures of anti-I plus anti-Pr CAs. Conclusion: The occurrence of CAs directed against biochemically different antigens in individual sera proves two autoimmune processes against the same cells (erythrocytes) in the same patient. One explanation for this constellation would be a postinfection cold agglutination in a patient with chronic CA disease. Copyright 2000 S. Karger GmbH, Freiburg

Journal Article↗
PubMed2000

Relative sensitivity of direct antiglobulin test, antibody's elution and flow cytometry in the serologic diagnosis of immune hemolytic transfusion reactions.

BACKGROUND AND OBJECTIVE: Current immunohematology practice dictates that serologic diagnosis of immune hemolytic transfusion reactions (IHTR) is based on the finding of a positive post-transfusion direct antiglobulin test (DAT). However, since DAT may fail to detect antibody-coated cells when they constitute a minor population amid a large number of non-sensitized ones, we investigated whether antibody detection in eluates or by flow cytometry is more sensitive than DAT in this context. DESIGN AND METHODS: Ten samples of red blood cells sensitized with allo- or autoantibodies were diluted in non-sensitized red blood cells to final concentrations ranging from 10% to 0.1%. DAT, antibody detection in eluates, and immunofluorescence by flow cytometry were performed on each mixture. RESULTS: DAT failed to detect sensitized cells in all but two cases in that only the 10% dilution yielded a positive DAT. Antibody detection in eluates and by flow cytometry was able to detect up to 1% sensitized cells in most cases. INTERPRETATION AND CONCLUSIONS: Antibody detection in eluates and by flow cytometry is more sensitive than DAT for detecting minor populations of IgG-coated cells. These techniques should be included in the routine investigation of suspected cases of IHTR.

Antibodies↗
PubMed2000

Tissue Doppler imaging: clinical topics for the new millenium.

INTRODUCTION: Tissue Doppler imaging is an echocardiographic technique that allows the selective visualization and quantification of myocardial signals. Its aim is to complement the conventional Doppler study, adding more and better information on specific topics of cardiovascular diseases. During the first seven years of the technique, much scientific work was produced and some clinical applications of the method have emerged. CLINICAL APPLICATIONS: I--non ischemic heart disease: The technique has been widely used in diastology, in hypertrophic cardiomyopathy, in heart transplant patients and in arrhythmology. II--ischemic heart disease: The quantitative assessment of regional diastolic and systolic function makes the technique very promising during stress echocardiography and during percutaneous transluminal coronary angioplasty. CONCLUSIONS: In 2000, tissue Doppler echocardiography is still a young, exciting and promising technique. Despite the fact that much has already been done, there is still a long way to go, implying a great amount of time and personal investment. How often do we feel that we are building a small part of the future?

Echocardiography, Doppler↗
PubMed1999

Different TBX5 interactions in heart and limb defined by Holt-Oram syndrome mutations.

To better understand the role of TBX5, a T-box containing transcription factor in forelimb and heart development, we have studied the clinical features of Holt-Oram syndrome caused by 10 different TBX5 mutations. Defects predicted to create null alleles caused substantial abnormalities both in limb and heart. In contrast, missense mutations produced distinct phenotypes: Gly80Arg caused significant cardiac malformations but only minor skeletal abnormalities; and Arg237Gln and Arg237Trp caused extensive upper limb malformations but less significant cardiac abnormalities. Amino acids altered by missense mutations were located on the three-dimensional structure of a related T-box transcription factor, Xbra, bound to DNA. Residue 80 is highly conserved within T-box sequences that interact with the major groove of target DNA; residue 237 is located in the T-box domain that selectively binds to the minor groove of DNA. These structural data, taken together with the predominant cardiac or skeletal phenotype produced by each missense mutation, suggest that organ-specific gene activation by TBX5 is predicated on biophysical interactions with different target DNA sequences.

Adult↗
PubMed1999

[European Asthma Study. Identifying and treating young adults with epidemiological criteria for asthma in five areas of Spain. Spanish Group of the European Asthma Study].

BACKGROUND AND OBJECTIVES: Asthma's great impact on public health stems from its chronicity and to high prevalence among all age groups and both sexes. To estimate the appropriateness of treatment and management of asthma in Spain during the period of 1991 and 1992, we analyzed data from the European Community Respiratory Health Survey (ECRHS). METHOD: The ECRHS was undertaken with a random sample of 20-to-44-year-olds in Albacete, Barcelona, Galdakao, Huelva and Oviedo. In total, 181 individuals with asthma were identified. Current asthma was defined as the presence of respiratory symptoms associated with asthma within the past 12 months and a positive methacholine challenge test. RESULTS: Subjects who were unaware of having asthma made up 57.5% (CI: 49.9-64.8%), and 35.9% (CI: 27.9-42.3%) were not following any specific treatment. Among asthmatics who reported having continuous or frequent respiratory symptoms, 25.9% (CI: 15.3-39.0%) were not following any treatment. CONCLUSION: Over half the individuals with asthma in 1991 to 1993 were unaware of having the disease at the time of the study or of ever having had it, and approximately one third were not in treatment. The delivery of appropriate treatment in asthma generally, and in asthma with continuous or frequent respiratory symptoms, was markedly inadequate during the period studied.

Adult↗
PubMed1999

Major vascular complications in essential thrombocythemia: a study of the predictive factors in a series of 148 patients.

To determine the clinicohematological factors predictive for the appearance of major vascular complications (MVC) in patients with essential thrombocythemia (ET), 148 consecutive such patients were retrospectively assessed for the development of MVC during a median follow-up of 58.5 months. Seventy-seven patients had vascular risk factors, and 37 a history of MVC at ET diagnosis. Forty-nine MVC were registered in 33 patients during the follow-up period. The actuarial probability of MVC was 27% at 6 years in the whole series, 35.6% for patients above 60 years, and 21.4% for patients younger than 60 years, whereas only one of the 36 patients younger than 45 years had MVC. At multivariate analysis, age >60 years, history of major ischemia and hypercholesterolemia were the variables associated with an increased MVC risk. These results suggest that all ET patients above 60 years should be treated, whereas in younger patients treatment decisions should be primarily based on the existence of risk factors for MVC.

Adolescent↗
PubMed1999

Levels of dopamine beta hydroxylase immunoreactivity in the preoptic hypothalamus of the ovariectomised ewe following injection of oestrogen: evidence for increased noradrenaline release around the time of the oestrogen-induced surge in luteinizing hormone.

We have measured dopamine beta hydroxylase (DBH) immunoreactivity in the preoptic hypothalamus as an index of release of noradrenaline in the ovariectomised (OVX) ewe at the time of an oestrogen-induced surge in luteinizing hormone (LH) release. OVX ewes (n=5) were given an injection of 50 microg oestradiol benzoate (or oil), which causes a surge in the secretion of LH. Blood samples were taken and sheep were killed 16 h later. Other groups (n=3) were given oil or oestrogen and killed 6 h later. Brains were collected for immunohistochemistry and image analysis. The number of DBH-stained cells and the integrated optical density of the cells was measured throughout the A1 field of the brainstem. The DBH staining was measured in the terminal beds of the hypothalamus. There was no difference between the controls and the EB-treated OVX ewes in the number of DBH positive cells or the optical density of DBH-staining cells in the A1 field. Within the preoptic area, there was reduced (P<0.02) DBH staining in the 16 h EB-treated ewes. There was no change in the DBH staining in the paraventricular nucleus or the arcuate nucleus of the hypothalamus. These data suggest that there is release of noradrenaline in the preoptic area at the time of the E-induced GnRH/LH surge in the OVX ewe.

Animals↗
PubMed1999

Cost-effectiveness of transfusing virus-inactivated plasma instead of standard plasma.

BACKGROUND: Virus inactivation of plasma intended for transfusion avoids the transmission of hepatitis B virus, hepatitis C virus, and HIV. However, because most plasma recipients also receive other blood components concomitantly, the procedure reduces but cannot eliminate the risk of transfusion-transmitted infection. As virus-inactivated plasma has just been licensed in the United States and other countries, a cost-effectiveness analysis is pertinent. STUDY DESIGN AND METHODS: A Monte Carlo simulation of a Markov model representing the possible outcomes of plasma recipients was used to derive costs and utilities of transfusing virus-inactivated plasma instead of standard plasma. Probability distributions for patients' age and sex and for the number of blood components transfused per case were determined in 924 plasma recipients in a tertiary-care hospital. Other values were obtained from the medical literature. Results of the baseline and sensitivity analyses are the mean (+/- SD) of 10 simulations with 10(7) patients per simulation. RESULTS: In the baseline analysis, transfusing virus-inactivated plasma instead of standard plasma prolonged the quality-adjusted survival by 1 hour and 11 minutes per patient, at a cost-effectiveness ratio of $2,156,398 +/- $257,587 per quality-adjusted life year gained. Cost-effectiveness was most sensitive to the patients' mean age, the incremental cost per unit of virus-inactivated plasma, the HIV and hepatitis C virus transmission rates, and the short-term mortality of plasma recipients due to their underlying diseases. CONCLUSIONS: Compared to most accepted medical procedures, the transfusion of virus-inactivated plasma produces little health benefit at a very high cost. This poor cost-effectiveness ratio is due to the low current risk of infection with transfusion-transmitted viruses and to the greater age and poor short-term prognosis of most plasma recipients.

Acquired Immunodeficiency Syndrome↗
PubMed1999

Function search in a large transcription factor gene family in Arabidopsis: assessing the potential of reverse genetics to identify insertional mutations in R2R3 MYB genes.

More than 92 genes encoding MYB transcription factors of the R2R3 class have been described in Arabidopsis. The functions of a few members of this large gene family have been described, indicating important roles for R2R3 MYB transcription factors in the regulation of secondary metabolism, cell shape, and disease resistance, and in responses to growth regulators and stresses. For the majority of the genes in this family, however, little functional information is available. As the first step to characterizing these genes functionally, the sequences of >90 family members, and the map positions and expression profiles of >60 members, have been determined previously. An important second step in the functional analysis of the MYB family, through a process of reverse genetics that entails the isolation of insertion mutants, is described here. For this purpose, a variety of gene disruption resources has been used, including T-DNA-insertion populations and three distinct populations that harbor transposon insertions. We report the isolation of 47 insertions into 36 distinct MYB genes by screening a total of 73 genes. These defined insertion lines will provide the foundation for subsequent detailed functional analyses for the assignment of specific functions to individual members of the R2R3 MYB gene family.

Arabidopsis↗
PubMed1999

A two-component enhancer-inhibitor transposon mutagenesis system for functional analysis of the Arabidopsis genome.

A modified Enhancer-Inhibitor transposon system was used to generate a series of mutant lines by single-seed descent such that multiple I insertions occurred per plant. The distribution of original insertions in the population was assessed by isolating transposon-flanking DNA, and a database of insertion sites was created. Approximately three-quarters of the identified insertion sites show similarity to sequences stored in public databases, which demonstrates the power of this regimen of insertional mutagenesis. To isolate insertions in specific genes, we developed three-dimensional pooling and polymerase chain reaction strategies that we then validated by identifying mutants for the regulator genes APETALA1 and SHOOT MERISTEMLESS. The system then was used to identify inserts in a class of uncharacterized genes involved in lipid biosynthesis; one such insertion conferred a fiddlehead mutant phenotype.

Arabidopsis↗
PubMed1999

ANTHOCYANINLESS2, a homeobox gene affecting anthocyanin distribution and root development in Arabidopsis.

The ANTHOCYANINLESS2 (ANL2) gene was isolated from Arabidopsis by using the maize Enhancer-Inhibitor transposon tagging system. Sequencing of the ANL2 gene showed that it encodes a homeodomain protein belonging to the HD-GLABRA2 group. As we report here, this homeobox gene is involved in the accumulation of anthocyanin and in root development. Histological observations of the anl2 mutant revealed that the accumulation of anthocyanin was greatly suppressed in subepidermal cells but only slightly reduced in epidermal cells. Furthermore, the primary roots of the anl2 mutant showed an aberrant cellular organization. We discuss a possible role of ANL2 in the accumulation of anthocyanin and cellular organization of the primary root.

Amino Acid Sequence↗
PubMed1999

[Integrins and metalloproteinases: an efficient collaboration in the invasive process].

During the invasive process, tumor cells must move through the extracellular matrix. They have to adhere to the extracellular matrix components, then proteolyse them and migrate on their fragments. This implicates integrins and proteinases, namely metalloproteinases. Numerous experiments which had been performed on various models, namely malignant melanomas proved that integrins have a major role in the transduction of signals from the outside to the inside of the cells, such signals enhancing the expression of the metalloproteinases or, in the contrary, inhibiting it. The modifications of this expression are dependent of extracellular matrix components and may be induced by the linking of specific antibodies to integrins. In some instances, the integrins localized on the tumor cell surface may act as receptors for extracellular matrix proteins and metalloproteinases at once, that may give to tumor cells an higher efficiency in the invasive process. Such mechanisms may result in interesting clinical perspectives for the control of metalloproteinases regulation in pathological processes.

Cell Communication↗
PubMed1999

[Cardiac involvement in metabolic diseases].

OBJECTIVE: To evaluate cardiac involvement in children with metabolic disease in the out patient clinic of the Pediatric Cardiology Unit of Maria Pia Children's Hospital and their follow-up. MATERIAL AND METHODS: Twenty-nine medical records belonging to out patients with metabolic disease in consultation at our unit were reviewed. The following data from each record was analyzed: sex, metabolic disease diagnosis, age and motive for referral to a pediatric cardiology unit, cardiology diagnosis, therapy and evolution. RESULTS: Seventeen patients were boys and 12 girls. The average age of referral was 7.2 years (SD 4.8). The motives for referral were: screening for heart disease, 16; heart murmur, 7; congestive heart failure, 3; heart murmur and fatigue, 2; poor weight gain, 1. The following metabolic diagnoses were made: lysosomal diseases, 21; mitochondrial citopathies, 5; disorder of beta-oxidation of fatty acids, 2; carbohydrate deficient glycoprotein syndrome (CDG syndrome), 1. The cardiologic evaluation was normal in ten patients (4 with lysosomal disease, 4 with mitochondrial citopathy, one disorder of beta-oxidation of fatty acids, the CDG syndrome). Mitral and aortic valve lesions predominated in lysosomal diseases (12/21); myocardial involvement alone was present in two patients, and both myocardial and valvular lesions were present in three. Dilated cardiomyopathy was the presented manifestation in two patients-one with mitochondrial citopathy and one with a disorder of beta-oxidation of fatty acids. Three patients died and 26 remain out-patients. One patient was submitted to valve surgery. The average duration of follow-up was 21 months (SD 24). COMMENTS: Lysosomal diseases were the most representative in our patients, as described in the literature. Heart valve disease was the most frequent alteration. Indication for heart valve surgery is dependent on systemic involvement of the primary disease. All children with a metabolic disease with eventual heart involvement should be evaluated periodically by a cardiology unit. On the other hand, it is mandatory to screen a cardiomyopathy of unknown cause for a metabolic disease. The authors draw attention to the importance of infectious endocarditis prophylaxis in this group of patients.

Ambulatory Care Facilities↗
PubMed1999

[The persistence of the left vena cava superior and the absence of the right vena cava superior: the implications in the implantation of a definitive pacemaker].

Persistent left superior vena cava and associated absence of the right superior vena cava is exceedingly rare. The authors present a case, diagnosed when a DDD pacemaker system was being implanted, and point out its rarity, possibility of diagnosis by non invasive methods and technical implications in transvenous electrode implantation.

Aged↗
PubMed1999

An enzyme-linked immunosorbent assay applicable to screen blood donors for IgA deficiency.

BACKGROUND AND OBJECTIVE: In order to build panels of IgA deficient blood donors, an assay is described that is sensitive, inexpensive and easily adaptable to the automated sample processors and turnaround times of blood banks. DESIGN AND METHODS: We developed a two-step enzyme-linked immunosorbent assay (ELISA) carried out in microwell plates coated with rabbit anti-human IgA antibody. Captured IgA was revealed with the same antibody conjugated to horseradish-peroxidase. The assay was adapted to the automatic pipetting system and ELISA processors used in routine blood donor screening. RESULTS: The assay sensitivity was 0.1 microg/mL. Intra-assay coefficient of variation (CV) for IgA concentrations between 0.1 and 100 microg/mL ranged from 0.69% to 3.80%. The median interassay CV was 3.05% (range: 1.2-7.9%). Coated plates can be stored frozen for at least 3 months without any loss in performance. The assay takes around 80 min to be performed. By using this ELISA we found 32 IgA-deficient individuals among 20,000 blood donors (prevalence 1:625). INTERPRETATION AND CONCLUSIONS: The ELISA has a good sensitivity, is reproducible, precise and timesaving. It is easily adaptable to the automated sample processors and operating procedures used in blood banks. This facilitates the building of panels of IgA-deficient blood donors.

Automation↗