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Biomedical subjects

M L Ferreira

Publications and source records attributed to M L Ferreira.

At least 19 recordsLinked to original sources
PubMed2006

Computational study of the structure and behavior of aqueous mixed system sodium unsaturated carboxylate-dodecyltrimethylammonium bromide.

The mixed surfactant system sodium 10-undecenoate (SUD)-dodecyltrimethylammonium bromide (DTAB) was studied by computational simulation to determine the composition and structure of the mixed microstructures. Results were contrasted with experimental data obtained from literature and our own laboratory. The modelization predicts spherical or cylindrical micelles with a preferential composition of SUD-DTAB of about 1:2, while the system predicts a lamellar structure with a proportion of 1:1 when SUD is replaced by the saturated soap sodium undecanoate. The model also predicts the deep inclusion of bromide ions in the micelle Stern layer. All predictions were in agreement with previous experimental results.

Journal Article↗
PubMed2006

Isolation of Besnoitia besnoiti from infected cattle in Portugal.

Besnoitia besnoiti, an obligate intracellular protozoan parasite belonging to the phylum apicomplexa, is the causative agent of bovine besnoitiosis. Besnoitiosis is responsible for significant losses in the cattle industry of Africa and Mediterranean countries due to the high morbidity rate, abortion and infertility in males. The acute stage of disease is associated with the proliferative forms (tachyzoites) and is characterized by fever, whimpery, general weakness and swelling of the superficial lymph nodes. During the following chronic stage, a huge number of cysts are formed mainly in the subcutaneous tissues. This process is non-reversible, and chronic besnoitiosis is characterized by hyper-sclerodermia, hyperkeratosis, alopecia and, in bulls, atrophy, sclerosis and focal necrosis that cause irreversible lesions in the testis. In this paper we report on the identification of large cysts in the skin of a cow and a bull in Portugal, which presented loss of hair and enlargement and pachydermis all over the body. The observation of a two-layered cyst wall within the host cell, the encapsulation of the host cell by a large outer cyst wall, and the subcutaneous localization of the cysts within the host, were characteristic for B. besnoiti. The parasites were isolated from the infected animals and successfully propagated in Vero cells without prior passages in laboratory animals. Morphological characterization of B. besnoiti tachyzoites and the amplification of the 149 bp segment from the internal transcribed spacer 1 (ITS1), aided with specific primers, confirmed the identification of B. besnoiti.

Animals↗
PubMed2005

Frequent analytical/experimental problems in lipase-mediated synthesis in solvent-free systems and how to avoid them.

Compared with chemical catalysis, enzymatic catalysis is a relatively new topic. Experimental work involving lipases deserves careful attention and accurate procedures still need to be implemented. A rapid but careful survey of published data immediately demonstrates that experiments performed under similar conditions with similar reagents have led to very different results. The aim of this work is to point out the importance of accurate and systematic procedures in order to ensure the reproducibility of experimental data. We strongly believe that different results found by different labs are due to problems detected in the procedures used. Quantification of the immobilisation efficiency of lipase on several supports through UV/visible methods and sampling methods used to obtain correct enzymatic activity values are specifically analysed. After a brief review which demonstrates the big discrepancies found in the literature, original data from Candida rugosa lipase adsorption on polypropylene powder and its use in the solvent-free synthesis of ethyl oleate are introduced in order to exemplify the difficulties found in these kinds of systems. Several procedures described in the literature are assayed and the accuracy of the results obtained is carefully analysed. The aim of the whole analysis performed is that it would be useful for any powdered solid to be used as a support for a lipase in a solvent-free system for any synthesis reaction, especially for those involving a volatile reagent. Throughout this contribution, special emphasis is placed on how catalytic reaction results using enzymes (free and immobilised) are reported so as to allow comparison between published data, something which is usually difficult since very different units are used and often complementary data are not included.

Catalysis↗
PubMed2004

Theoretical and experimental study of the interaction of O2 and H2O with metallic zinc--discussion of the initial step of oxide formation.

The steps of Zn corrosion and ZnO formation using dry O2 or O2/water atmosphere were investigated in situ using an experimental and theoretical approach. The adsorption equilibrium and kinetics of O2/H2O on Zn have been measured at different temperatures and relative humidities using a Cahn 1000 vacuum recording electrobalance. The amounts adsorbed on Zn are different in the presence or absence of O2. SEM-EDAX, XPS, and XRD studies have been performed at the surface for different times of reaction. A theoretical study using the extended Hückel method has been done for the adsorption/reaction of H2O/O2 on Zn and on ZnO. A coherent explanation is presented for the initial steps of ZnO formation on Zn, for the steady state found for the ZnO growth, and for the experimental findings of the methods cited above.

Journal Article↗
PubMed2004

Skeletal muscle regeneration and Trypanosoma cruzi-induced myositis in rats.

Although Chagas' disease is known to provoke severe acute myositis, information on muscle regeneration is missing. The current paper shows that during T. cruzi infection in rats, skeletal muscle parasitism and the consequent inflammatory process are higher in muscle with a high proportion of type-I myofibres (soleus and diaphragm). Immunohistochemistry showed an acute inflammatory process characterized by ED1+ and ED2+ macrophages, CD8+ lymphocytes, and NK cells. Parasite-nest rupture provoked segmental degeneration of myofibres followed by regeneration. These phenomena were observed at both light and transmission electron microscopy levels. Myofibre regeneration involved activation of satellite cells assessed by the expression of MyoD, a muscle-specific transcription factor. Ultrastructural evidence of fusion of myoblast-like cells with the intact segment of degenerating fibres has been provided. At the chronic phase no signs of fibrosis were found, but sparse and small inflammatory foci were found. Our results argue against the relevant participation of autoimmunity phenomena in both acute and chronic phases and furnish a new view for explaining histopathological findings in human patient muscles.

Animals↗
PubMed2002

Effect of applying different "levels of evidence" criteria on conclusions of Cochrane reviews of interventions for low back pain.

The objective of this study was to examine the consistency of conclusions of Cochrane systematic reviews when different criteria are used to determine levels of evidence. We reanalyzed the data in six Cochrane reviews of conservative treatment of low back pain by applying three additional sets of "levels of evidence" criteria. Overall agreement between the conclusions attained with the different levels of evidence criteria was only "fair" (multirater kappa coefficient 0.33; 95% CI 0.28 to 0.38). For example, the four sets of levels of evidence criteria produced four conclusions on the efficacy of back school: "strong evidence that back schools are effective," "weak evidence," "limited evidence," and "no evidence." Pairwise agreement between the four pooling systems ranged from slight to substantial (kappas ranging from 0.10 to 0.80). Different rules for determining levels of evidence in systematic reviews produce markedly different conclusions on treatment efficacy. Crown

Evidence-Based Medicine↗
PubMed2002

Protective effect of clenbuterol on duodenal epithelium during food restriction in rats.

The aim of the study was to examine the effect of the beta2-adrenoceptor, clenbuterol, on the duodenal epithelium of food-restricted rats. Clenbuterol was administered as a dietary admixture (4 mg/kg diet) to three groups of male Wistar rats (n = 8) housed individually in metabolic cages and fed ad libitum for 15 days at 110% and 160% of the estimated requirement for energy maintenance. Untreated groups at each energy intake level were also included. Samples of the duodenum were examined by light microscopy. Compared with control animals, clenbuterol treatment significantly increased body mass in all diet groups, although it induced no changes in mean food intake. Gastrointestinal (GIT) dry mass was increased by clenbuterol only in the most severely-restricted-diet group. In this group, clenbuterol treatment increased GIT tissue nitrogen (23%), more than it did in the ad libitum group (13%). In all treated groups, clenbuterol induced significant hypertrophy of duodenal enterocytes and circular muscle layers, and the diameter of lymphatic vessels increased. In the clenbuterol-treated, restricted-diet groups the height of the brush borders of enterocytes increased. It is concluded that clenbuterol has a protective effect on the intestinal structure in rats on restricted as well as ad libitum diets.

Adrenergic beta-Agonists↗
PubMed2000

Candida albicans meningitis: clinical case.

Candida spp. meningitis is still a rare clinical situation, although it is becoming more frequent. Literature references to it and therapeutic options are scarce. We present a case of a young male, HIV-positive drug addict, with Candida albicans meningitis which was treated with oral fluconazole, having a good outcome.

AIDS-Related Opportunistic Infections↗
PubMed2000

Neutralizing human anti crotoxin scFv isolated from a nonimmunized phage library.

Combinatorial phage display technology offers a new possibility for making human antibodies which could be used in immune therapy. We explored the use of this technology to make human scFvs specific for crotoxin, the main toxic component of the venom of the South-American rattlesnake Crotalus durissus terrificus. Crotoxin, a phospholipase A2 neurotoxin constituted by the association of two subunits, exerts its lethal action by blocking neuromuscular transmission. This is the first report of human anticrotoxin scFvs (scFv 1, scFv 6 and scFv 8) isolated from a naive library of more than 1010 scFv clones with in vivo neutralizing activity. Nevertheless, differences are observed at the level of biological and immunological effects. Only scFv 8 is able to reduce the myotoxicity induced by crotoxin and scFv 1 is capable of altering the in vitro enzymatic activity of this toxin. All three scFvs recognize a region of one subunit located at the junction with the other one. Moreover these scFvs share strong amino acid homologies at the level of either the heavy or the light chain. Taken together, our results suggest that the use of human anticrotoxin scFvs may lead to a new and less aggressive passive immune therapy against poisoning by the venom of Crotalus durissus terrificus.

Amino Acid Sequence↗
PubMed2000

Brain and ocular metastases from a transmissible venereal tumour in a dog.

A five-year-old crossbred dog was referred with rapidly growing masses over its penis and right popliteal lymph node. The dog had severe blepharospasm, congestion of episcleral vessels and rubeosis iridis of the left eye. A presumptive diagnosis of transmissible venereal tumour (TVT) and iridocyclitis was made based on the results of fine needle aspiration. Chemotherapy with vincristine and prednisolone was initiated and after four months the dog made a complete recovery. However, the dog subsequently relapsed, showing miosis, blepharospasm and a well defined mass within the anterior chamber of the left eye. In addition, the dog exhibited generalised 'grand mal' type seizures. Computed tomographic (CT) examination of the brain revealed two distinct masses in the left frontal lobe. Because of the poor prognosis, the owners elected to have the dog euthanased. On histopathology, metastases of TVT in the left eye and left cerebral hemisphere were found, showing no specific staining for CD3, immunoglobulin (Ig) G, IgM and lambda light chains. It was therefore concluded that the tumour growth was progressive, and that there was an absence of local humoral immune response against TVT in this case.

Animals↗
PubMed1999

The medial preoptic area modulates the increase in plasma glucose and free fatty acid mobilization induced by acute cold exposure.

The effect of cold exposure (0 degrees C, 1 h) on free fatty acid (FFA) mobilization and plasma glucose was studied in freely moving male rats injected with adrenergic blockers (phentolamine or propranolol) into the medial preoptic area (MPOA). The rats were implanted with chronic jugular catheters for blood sampling and with unilateral intracerebral cannulas placed just above the MPOA. Blood samples were taken 2 min before and 10, 20, 40 and 60 min after cold exposure. After cold exposure plasma glucose and plasma FFA levels rose rapidly, reaching a peak at 20 min post-stimulus. Previous administration of phentolamine (50 nmol), but not propranolol (100 nmol), into the MPOA blocked the glycemic response to cold exposure. On the other hand, previous administration of propranolol, but not phentolamine, into the MPOA blocked the increased FFA mobilization in response to cold exposure. On the basis of these results, we propose that MPOA alpha-adrenergic synapses relay impulses activating the sympathetic outflow expressed by neurally mediated hyperglycemia, and beta-adrenergic synapses relay impulses activating the sympathetic outflow to the adipose tissue, increasing FFA acid mobilization.

Adrenergic alpha-Antagonists↗
PubMed1999

Longithorols A and B, novel prenylated paracyclophane- and metacyclophane-type hydroquinones from the tunicate Aplidium longithorax.

The tunicate Aplidium longithorax collected from Palau contained two novel prenylated paracyclophane- and metacyclophane-type hydroquinones, longithorols A (1) and B (2), in addition to longithorones A-I. Longithorols A and B were very unstable and were therefore isolated as their more stable pentaacetate forms, 3 and 4, respectively. The structures of 3 and 4 were determined by spectral data, especially 2D NMR data.

Animals↗
PubMed1999

Susceptibility to ankylosing spondylitis is independent of the Bw4 and Bw6 epitopes of HLA-B27 alleles.

We have characterized HLA-B27 alleles in a sample of the population from the Azores (n=46) with the aim of investigating the contribution of different subtypes to ankylosing spondylitis (AS). The study was carried out using PCR-SSOP and in some samples genomic sequencing was conducted. Some significant new finding have arisen from this study. First, B*2705,B*2702,B*2703,B*2707 and B*2708 alleles were found to be represented in this population. The polymorphism of B27 alleles found in a sample of the population from the Azores is higher than the Caucasian groups described. B*2703 and B*2707 have not previously been described to be represented in Caucasians and this could indicate admixtures with different populations of the world. In addition, the B*2708 allele was found to be associated with AS in a large family from the Azores. This association has not been previously reported in either ethnic group and needs to be confirmed in other population studies. This is of considerable interest since has only been described as a rare subtype underrepresented in the British population and has not been previously found to be associated with AS. B*2708 carries the sequence specifying the Bw6 epitope in contrast to most B27 alleles which carry a Bw4 sequence. Differences in this region (residues 77-83) can alter the F-pocket and affect T-cell recognition. The importance that these molecular changes can play in the pathogenesis of AS is discussed.

Azores↗
PubMed1999

Identification of a new Lesch-Nyhan syndrome mutation (HPRTBrasil) and analysis of potentially heterozygous females.

The mutation in the hypoxanthine-guanine phosphoribosyltransferase (HPRT) gene has been determined in two brothers affected with Lesch-Nyhan syndrome. Female members of the family who are at risk for being heterozygous carriers of the HPRT mutation were also studied to determine whether they carry the mutation. DNA sequencing revealed that the boys' mother is heterozygous for the mutation in her somatic cells, but that three maternal aunts are not heterozygous. Such carrier information is important for the future pregnancy plans of at-risk females. The mutation, an A-->T transversion at cDNA base 590 (590A-->T), results in an amino acid change of glutamic acid to valine at codon 197, and has not been reported previously in a Lesch-Nyhan syndrome male. This mutation is designated HPRTBrasil.

Adolescent↗
PubMed1999

[Brucellosis].

Brucellosis is a zoonosis, reported for the first time in 1859 by Marston, in Malta. It has also been referred to as Mediterranean Fever, Malta Fever and Bang's disease. Its causative agent was isolated by David Bruce in 1886; this was Brucella melitensis: five different strains were later described: B. abortus, B. suis, B. ovis, B. neotomae and B. canis. Recently, in 1994, the isolation of Brucella was reported in marine mammals, eventually pathogenic to man and unofficially designated "B. maris". Human brucellosis is still a public health problem in countries where the infection has not been eradicated from the animal hosts. When manifested, human disease may assume different courses, widely known, but whose physiopathology is still not totally clear. Much is already known about the agent's molecular biology and in vitro behaviour, but, doubts persist about its in vivo activity, including in human infection. We review some aspects of brucellosis, focusing on the pathogenesis, and referring to new and potential diagnostic methods, therapy and prevention.

Brucellosis↗
PubMed1998

Spinal cord protection in descending thoracic and thoracoabdominal aortic aneurysm repair.

During aneurysm repair of the descending thoracic or thoracoabdominal aorta, the likelihood of neurological complications increases greatly after only 30 minutes of spinal cord ischemia. However, the manifestation of paraplegia or paraparesis relates not only to aortic cross-clamping time, but to multiple factors that may include aortic dissection, previous aortic surgery, advanced age, preoperative renal insufficiency, rupture, and most significantly, aneurysm extent. At greatest risk is the patient with type II thoracoabdominal aortic aneurysm. For this patient the simple cross-clamp technique, which uses no protective surgical adjuncts, heightens the threat of neurological deficit. With the surgical adjuncts of cerebrospinal fluid drainage and distal aortic perfusion, the probability of neurological deficit is appreciably lowered.

Aortic Aneurysm, Abdominal↗