Search PubMed⌕ Search

Biomedical subjects

M Santos

Publications and source records attributed to M Santos.

At least 91 records · Page 5Linked to original sources
PubMed1998

Performance characteristics of a new synthetic APTT reagent.

Performance characteristics of a totally synthetic activated partial thromboplastin time (APTT) reagent, recently available commercially, were evaluated and compared with a rabbit-brain extracted reagent. We found that the synthetic reagent, Synthasil, returned significantly higher normal APTT values than the brain-extracted reagent, Thrombosil. APTT ratios (APTT patients/normal mean APTT), yielded by Synthasil were higher in the majority of patients receiving heparin therapy. Synthasil also returned longer APTT values than did Thrombosil on normal plasma spiked with heparin. On patients with lupus anticoagulants, APTTs assayed with Synthasil were generally longer than with Thrombosil. However, the differences disappeared when APTT values were converted to ratios. Factors XII-, XI-, IX- and VIII-deficient plasmas supplemented with normal plasma to yield activities of 2-50%, generally gave longer APTTs with Synthasil than with Thrombosil. However, this was not always the case on plasmas from haemophilias A and B patients. No reduction in Synthasil activity was noted after the reagent had been left at 24 degrees C for 28 days.

Coagulation Protein Disorders↗
PubMed1998

Aspirin synergistically potentiates isoflurane minimum alveolar concentration reduction produced by morphine in the rat.

BACKGROUND: The combination of opioids and nonsteroidal antiinflammatory drugs is more analgesic than the summed effect of each drug administered separately. This synergism has been used to obtain analgesia in the postoperative period at doses at which side effects are minimal. The aim of this study is to evaluate the analgesic interaction between aspirin and morphine in the rat during isoflurane anesthesia. The reduction in minimum alveolar concentration of isoflurane (MAC(ISO)) was used as an objective measure of the analgesic potency of individual drugs and their use in combination. METHODS: Thirty-seven male Wistar rats were anesthetized with isoflurane in oxygen, and the MAC(ISO) was determined before and after the intravenous administration of aspirin and morphine. Rats were administered morphine alone (1, 3, and 10 mg/kg) or morphine (1 and 3 mg/kg) and aspirin (30 mg/kg). The MAC(ISO) was determined from alveolar gas samples at the time of tail clamp. The duration of MAC(ISO) reduction was recorded. RESULTS: Aspirin did not have an effect on MAC(ISO), (average, 1.35+/-0.1%), whereas the combination of morphine (1 and 3 mg/kg) and aspirin (30 mg/kg) produced a reduction in the dose of morphine needed to produce the same degree of MAC(ISO) reduction. Actual MAC(ISO+drug) data were as follows: 1 mg/kg morphine, 1.17+/-0.14%; 3 mg/kg morphine, 0.98+/-0.15%; 1 mg/kg morphine plus aspirin, 0.90+/-0.04%; 10 mg/kg morphine, 0.63+/-0.13%; and 3 mg/kg morphine plus aspirin, 0.64+/-0.06%. CONCLUSIONS: The synergistic effects of aspirin and morphine allow a clinically significant reduction in the requirements of isoflurane and isoflurane plus morphine, and these drug combinations may decrease the side effects associated with the use of single higher, equianalgesic doses of these drugs.

Analgesics, Opioid↗
PubMed1998

Costello syndrome in two Brazilian children.

The increasing number of children with Costello syndrome described world wide has helped in delineating further the characteristic features of this condition. We report here two children, seen in the Genetic Division of the Brasilia University Hospital, showing the main features of the syndrome: "coarse" face, redundant skin on the feet and hands, hyperextensible hand and finger joints, curly hair, growth and psychomotor retardation, and feeding problems. In addition, one of the patients developed hydrocephalus during the evolution of the disease, making the third published patient with this complication. We discuss the appropriateness of serial brain imaging studies in Costello syndrome in light of the relative frequency of central nervous system malformations.

Brazil↗
PubMed1998

Repeated pulmonary infection by Nocardia asteroides complex in a patient with bronchiectasis.

A rare case of pulmonary nocardiosis was presented in a nonimmunocompromised patient who had chronic airway obstruction and bronchiectasis without corticoid treatment. The microbial diagnosis was established after isolating Nocardia in bronchial aspirate and sputum samples. An in vitro study showed sensitivity only to imipenem, netilmicine, amikacin and ofloxacin. The evolution was chronic, with multiple clinical recurrences in spite of prolonged antibiotic treatment. Finally, the eradication of Nocardia was achieved with the combination of imipenem and amikacin.

Amikacin↗
PubMed1998

[The role of PET-FDG in questionable diagnosis of relapse in the presence of radionecrosis of brain tumors].

INTRODUCTION: Although CT and MR are sensitive techniques for the detection of cerebral tumours, both have limitations in distinguishing between tumour relapse (TR) and post-treatment radionecrosis (RN). PATIENTS AND METHODS: In this study we have determined the usefulness of metabolic imaging with PET-FDG in such situations. We assessed 70 patients with CNS tumours (22 low grade astrocytomas, 25 high grade astrocytomas, 3 oligodendrogliomas, 13 metastatic tumours and 7 other tumours. All had been treated with radiotherapy and other treatments such as radiosurgery, chemotherapy or different types of surgery, and presented clinical pictures which made it necessary to decide the differential diagnosis of relapse or radionecrosis. RESULTS: In the PET-FDG study visual and semiquantitative analysis was done by SUV (Standardized Update Value). Confirmation of the findings was obtained in 44 cases (24 TR and 20 RN). MR was doubtful or inconclusive in most cases, whilst with PET correct diagnosis was made in all cases. CONCLUSIONS: Metabolic imaging with PET-FGD is better than anatomostructural imaging techniques for differential diagnosis between tumour relapse and radionecrosis in CNS tumours which have been treated. Prospective studies are necessary for evaluation of SUV as a factor for prognosis of survival.

Adult↗
PubMed1997

Effect of enteral versus parenteral nutrition on leptin gene expression and release into the circulation.

Leptin, a putative satiety hormone in rodents, is acutely regulated by fasting and refeeding. To determine the role of satiety hormones that are secreted by the gastrointestinal tract on leptin regulation, leptin mRNA and serum concentrations were measured after feeding rats similar calories with standard chow or infusion of total parenteral nutrition into the duodenum or intravenously. We have demonstrated that leptin gene expression and hormone secretion into the circulation are stimulated equally in the three experimental paradigms; it is unlikely that satiety factors secreted by the intestinal tract play a significant role in leptin regulation. Furthermore, intravenous infusion of individual components of TPN demonstrated that intravenous glucose infusion was mostly responsible for stimulation of the leptin gene and hormone secretion.

Adipocytes↗
PubMed1997

Delays in malignant tumor development in transgenic mice by forced epidermal keratin 10 expression in mouse skin carcinomas.

The keratin cytoskeleton is formed in different epidermal compartments by distinct polypeptides. Basal, proliferative keratinocytes express keratin (K) 5 and K14, whereas, suprabasal, post-mitotic keratinocytes express K1 and K10. Changes in this keratin pattern have been found to occur in hyperproliferative skin disorders and, in particular, throughout mouse epidermal carcinogenesis. Whereas some keratins not found in normal epidermis (K6, K16, K13, and K8) are induced at different stages of tumor development, K1 and K10 expression is lost. To determine whether K1 and K10 loss is just a consequence of the altered differentiation program or an event required for tumor progression, we generated transgenic mice carrying the human keratin 10 gene (hK10) under the control of a bovine keratin 6 gene regulatory region, which is silent in normal skin but is induced and drives transgene expression in hyperproliferative skin keratinocytes and, therefore, in skin tumors. Transgenic animals subjected to a complete carcinogenesis protocol developed tumors that contained various amounts of transgenic hK10. Although no significant difference was found in tumor number or malignancy, tumor onset was significantly delayed in transgenic mice, indicating that the presence of K10 actually impairs tumor development.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1997

Novel stop mutation causing familial hypercholesterolemia in a Costa Rican family.

Combined heteroduplex single-strand conformation polymorphism (HEX-SSCP) analysis of the promoter and coding region of the low density lipoprotein receptor (LDLR) gene revealed a novel C to T mutation at nucleotide position 2056 in a Costa Rican patient with heterozygous familial hypercholesterolemia (FH). This nonsense mutation, Q665X, results in a termination codon in the epidermal growth factor (EGF) precursor homology domain of the mature LDLR.

Costa Rica↗
PubMed1997

Rat renal allograft tolerance is associated with local TGF-beta and absence of IL-2r expression within chimeric immunocytic foci.

Tolerance was induced in Lewis (LEW) rat renal allograft recipients of Brown Norway kidneys by multiple pretransplant donor-blood transfusions and prior limited cyclosporine A. Rat renal allograft tolerance was associated with the induction of systemic donor T cells (10%), an early phase of nonspecific suppressor-cell generation, followed by maturation of systemic antigen-specific suppressor cells, and renal cellular infiltrates that develop long-term in situ in the kidney graft model. It was hypothesized that these infiltrates represent chimeric immunocytic foci that are locally regulated via a TGF-beta-dependent mechanism. Both immunohistochemical staining and digital image analysis for cellular and extracellular TGF-beta, IL-2 receptor (CD25), and the BN Class I-MHC marker (OX-27) were performed. Control rejecting (REJ) kidneys did not demonstrate any differences with respect to levels of infiltrating immunocyte area vs long-term surviving (TOL) kidneys (3.9% vs 4.5%, P = .303). Immunostaining with the BN Class I MHC marker (OX-27) demonstrated high levels of chimerism within immunocyte foci of the tolerant grafts (OX-27 BN+immunocytes 49.0% +/- 5.1%). In situ cellular IL-2 receptor (CD25) expression was demonstrated in REJ kidney infiltrates but not within TOL immunocytic infiltrating foci, when measured as percent of total lymphocytes (REJ = 5.0% vs TOL = 0.4%, P = .031). Conversely, TGF-beta expression was significantly higher in immunocytes of TOL kidneys when measured as the number of DAB chromogen-staining pixels per total immunocyte area (TOL = .076 vs REJ = .047, P = .003). In conclusion, these results suggested that stable mixed immune chimerism (SMIC) plays an important role in DST-CyA-induced tolerance in situ. SMIC-induced tolerance may involve a local TGF-beta-dependent mechanism that is associated with in situ TGF-beta (+) and IL-2r (-) immunocytes.

Animals↗
PubMed1997

On the contribution of deleterious alleles to fitness variance in natural populations of Drosophila.

I have studied the consequences of habitat patchiness on the persistence times of deleterious alleles in a random mating population. Results based on computer simulations and supported by analytical approximations suggest that deleterious alleles remain approximately 1/(1-2FST) more generations in the patchy than in a comparable homogeneous population, where 0 < FST < or = 0.25 is the fraction of genetic variance due to the sample of families across patches in one generation. In natural populations of Drosophila, therefore, the contribution of deleterious mutants to the genetic variance in fitness might be larger than previously thought. A model of density-dependent viability selection, inspired by the suggestion that deleterious effects can substantially increase when the environment becomes harsher, also gives credence to the analytical results and illustrates that mean persistence times are very sensitive to changes in ecological parameters. If the density dependence model can be taken seriously, there is a clear difficulty in comparing observed and expected levels of genetic variance on the basis of the simplest mutation-selection balance model.

Alleles↗
PubMed1997

Resource subdivision and the advantage of genotypic diversity in Drosophila.

It is noted that maintenance of genetic heterogeneity in natural populations of Drosophila, through the effect that variation in genotypic diversity across breeding sites may have on their productivity, depends not only on the effective number of parents contributing gametes to a site, as previously shown by other authors, but also on the number of loci underlying the variation in fitness. Using Monte Carlo simulation, it is found that as the number of loci increases, the effect of resource subdivision on the establishment of an initially rare allele introduced into the population becomes virtually indistinguishable from the pure drift case. It seems unlikely that this mechanism can explain the maintenance of a significant proportion of genetic variation in natural populations of Drosophila, although it may still be important in preserving linked gene complexes such as inversions.

Animals↗
PubMed1997

Dietary ascorbic acid raises iron absorption in anaemic rats through enhancing mucosal iron uptake independent of iron solubility in the digesta.

We studied Fe absorption from FeSO4 in rats with Fe deficiency-induced anaemia that were given an Fe-sufficient purified diet without or with ascorbic acid (10.4 g/kg diet). Attention was focused on mucosal Fe uptake as measured in vivo by a double-isotope technique. Haemoglobin repletion and liver Fe levels were not affected when the ascorbic acid-supplemented diet was given, but apparent Fe absorption and retention of orally administered 59Fe were significantly enhanced. The distribution of Fe between liquid and solid phases of contents of both the stomach and the proximal intestine was not affected by the feeding of the ascorbic acid, but ascorbic acid significantly enhanced mucosal Fe uptake. It is concluded that ascorbic acid in the diet raises mucosal Fe uptake through a mechanism independent of the intestinal Fe solubility.

Anemia↗
PubMed1997

Genetic mapping of a major susceptibility locus for juvenile myoclonic epilepsy on chromosome 15q.

The epilepsies are a group of disorders characterised by recurrent seizures caused by episodes of abnormal neuronal hyperexcitability involving the brain. Up to 60 million people are affected worldwide and genetic factors may contribute to the aetiology in up to 40% of patients. The most common human genetic epilepsies display a complex pattern of inheritance. These are categorised as idiopathic in the absence of detectable structural or metabolic abnormalities. Juvenile myoclonic epilepsy (JME) is a distinctive and common variety of familial idiopathic generalised epilepsy (IGE) with a prevalence of 0.5-1.0 per 1000 and a ratio of sibling risk to population prevalence (lambda(s)) of 42. The molecular genetic basis of these familial idiopathic epilepsies is entirely unknown, but a mutation in the gene CHRNA4, encoding the alpha4 subunit of the neuronal nicotinic acetylcholine receptor (nAChR), was recently identified in a rare Mendelian variety of idiopathic epilepsy. Chromosomal regions harbouring genes for nAChR subunits were therefore tested for linkage to the JME trait in 34 pedigrees. Significant evidence for linkage with heterogeneity was found to polymorphic loci encompassing the region in which the gene encoding the alpha7 subunit of nAChR (CHRNA7) maps on chromosome 15q14 (HLOD = 4.4 at alpha = 0.65; Z(all) = 2.94, P = 0.0005). This major locus contributes to genetic susceptibility to JME in a majority of the families studied.

Chromosome Mapping↗
PubMed1997

Improved distribution of pulmonary flush solution to the tracheobronchial wall in pulmonary transplantation.

This report describes the experimental results obtained with conventional (pulmonary artery, PA) flushing versus retrograde perfusion (via left atrium, LA) using 99mTc-labeled macroaggregated albumin (MAA-99mTc) to ascertain the distribution throughout the tracheobronchial (TB) tree in 10 Large-White pigs. Lung preservation was achieved with 4 degrees C Euro-Collins solution (60 ml/kg) instilled via PA (n = 5) or LA (n = 5). Simultaneously, MAA-99mTc was given using the same respective route and the isotope uptake quantified at different TB levels after heart-lung block harvest and dissection of all tissue adjacent to TB: proximal and distal trachea and right and left main bronchi. Retrograde distribution resulted in a significantly higher 99mTc count compared to the PA route (p < 0.01).

Animals↗