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M C Santos

Publications and source records attributed to M C Santos.

At least 19 recordsLinked to original sources
PubMed2006

An assessment of time-dependent effects of lead exposure in algerian mice (Mus spretus) using different methodological approaches.

Time-dependent effects of lead (Pb) toxicity were studied in Algerian mice (Mus spretus) treated with Pb acetate via drinking water (1 g Pb acetate/L) for different periods of exposure (15, 45, and 90 d). End points included the determination of hepatic Pb concentration and the assessment of some morphophysiological, biochemical and cytogenetical parameters. A control group receiving distilled water was also monitored for comparative purposes. Hepatic Pb accumulation increased with the time of exposure and was significantly higher in treated mice when compared to controls. In association with significant body mass loss in Pb-exposed mice, for 15 and 45 d, a significant increase in the relative spleen mass was observed after 45 d of intoxication. Pb-exposed mice also showed significant decreases in red blood cells, hematocrit, and mean corpuscular hemoglobin. On the contrary, changes in plasma transferases (aspartate aminotransferase and alanine aminotransferase) and hepatic superoxide dismutase activities did not reach statistical significance. A significant increase in the frequency of micronucleated polychromatic bone marrow erythrocytes was also found in the 90-d-exposed mice, compared to nontreated mice and the other exposed groups. Exposure to Pb acetate resulted also in a slight time-dependent decrease of the polychromatic-normochromatic ratio. These results support the concept that a long-term chronic exposure to Pb induced alterations upon some morphophysiological and genetic parameters in Algerian mice.

Alanine Transaminase↗
PubMed2005

Optimization of random searches on regular lattices.

We investigate random searches on isotropic and topologically regular square and triangular lattices with periodic boundary conditions and study the efficiency of search strategies based on a power-law distribution P() approximately (-mu) of step lengths . We consider both destructive searches, in which a target can be visited only once, and nondestructive searches, when a target site is always available for future visits. We discuss (i) the dependence of the search efficiency on the choice of the lattice topology, (ii) the relevance of the periodic boundary conditions, (iii) the behavior of the optimal power-law exponent mu(opt) as a function of target site density, (iv) the differences between destructive and nondestructive environments, and finally (v) how the results for the discrete searches differ from the continuous cases previously studied.

Journal Article↗
PubMed2005

Determination of dopamine in synthetic cerebrospinal fluid by SWV with a graphite-polyurethane composite electrode.

This work describes an electroanalytical investigation of dopamine using cyclic voltammetry (CV) and the graphite-polyurethane composite electrode (GPU). In CV studies, well-defined redox peaks characterize the oxidation process at the GPU electrode, which is indicative of electrocatalytic effects associated with active sites on the GPU electrode surface. A new analytical methodology was developed using the GPU electrode and square wave voltammetry (SWV) in BR buffer solution (0.1 mol L(-1); pH 7.4). Analytical curves were constructed under optimized conditions (f=60s(-1), DeltaE(a)=50 mV, DeltaE(I)=2 mV) and detection and quantification limits of 6.4x10(-8) mol L(-1) (12.1 microg L(-1)) and 5.2x10(-6) mol L(-1) (0.9 mg L(-1)), respectively, were achieved. The precision of the method was checked by performing ten successive measurements for a 9.9x10(-6) mol L(-1) dopamine solution. For intra-assay and inter-assay precisions, the relative standard deviations were 1.9 and 2.3%, respectively. In order to evaluate the developed methodology, the determination of dopamine was performed with good sensitivity and selectivity, without the interference of ascorbic acid in synthetic cerebrospinal fluid, which indicates that the new methodology enables reliable analysis of dopamine.

Dopamine↗
PubMed2004

Trace element status (Se, Cu, Zn) in healthy Portuguese subjects of Lisbon population: a reference study.

Serum levels of selenium, copper, and zinc were systematically determined in healthy subjects of the Lisbon population. The sample consisted of 183 blood donors of both genders who were divided into two age groups: 20-44 and 45-70 yr of age; relationships with gender, age, the lipid profile, and tobacco consumption were investigated. In the female group, the intake of oral contraceptives and pregnancy were considered for the youngest women, and hormonal replacement therapy (HRT) was taken into account for the oldest ones. Serum concentrations of these elements were in the same range as those found for populations of other European countries. Differences between genders were observed for the three elements studied, with serum selenium and zinc concentrations higher in men and copper levels higher in women. Age-dependent differences were found for selenium: The oldest subjects (regardless gender) presented the highest concentrations of selenium in serum as further demonstrated by the positive correlation with age. In both pregnant and contraceptive-using women, copper was greatly increased, confirming the influence of estrogen status and/or oral contraceptive intake on increased serum copper levels. However, in postmenopausal women, HRT did not significantly affect serum copper levels. Selenium, copper, and zinc status were not different between normolipidemic and hyperlipidemic subjects for the same gender and age range, but selenium levels tended to increase with hyperlipidemia when considering the whole group of subjects. With respect to the lifestyle, higher serum zinc levels were found in tobacco-consuming men. Albumin serum levels were similar for all considered subgroups, except for the pregnant women, for whom a decrease in this parameter was observed. The present study allowed one to obtain reference values for this healthy group of population, which will serve for a comparative study with groups having pathological conditions, such as cardiovascular disease.

Adult↗
PubMed2003

Dynamical robustness of Lévy search strategies.

We study the role of dynamical constraints in the general problem of finding the best statistical strategy for random searching when the targets can be detected only in the limited vicinity of the searcher. We find that the optimal search strategy depends strongly on the delay time tau during which a previously visited site becomes unavailable. We also find that the optimal search strategy is always described for large step lengths l by a power-law distribution P(l) approximately l(-mu), with 1<mu(tau)</=2. Our findings appear to remain valid even if arbitrary energy costs of locomotion are considered.

Feeding Behavior↗
PubMed2003

Hepatic elemental contents and antioxidant enzyme activities in Algerian mice (Mus spretus) inhabiting a mine area in central Portugal.

In this study the effects of heavy metals (manganese, iron, copper, zinc) and selenium exposure on the hepatic activity of antioxidant enzymes, superoxide dismutase (SOD) and glutathione S-transferases (GST), were appraised on a seasonal basis in Algerian mice (Mus spretus) inhabiting an active copper mine area. A reference population of the same species was considered for comparative purposes. Different patterns of seasonal variation were found in both populations for the manganese, iron and selenium hepatic concentrations and SOD activity. When the two populations were compared, iron and selenium concentrations were enhanced in mice from the polluted area. In addition, SOD activity was significantly decreased in summer in exposed mice, but no other significant changes in SOD and GST activities between sites throughout the year were recorded. However, when seasonal data within each group of mice were pooled, significant differences were found between sites for the average concentrations of manganese, iron and selenium, which are higher in the polluted site. In addition, significant differences were obtained for the average values of SOD and of GST activities, due to simultaneously higher GST values and slightly lower SOD values in the polluted site. The population from the reference site was more homogeneous for all parameters measured than the population from the polluted area. These results, in particular the higher variability in data collected from mice exposed to heavy metals and selenium, combined with the negative associations between biochemical markers and heavy metals, may suggest, despite the good adaptability of the mice to their habitat, biochemical stress due to diminished environmental quality.

Animals↗
PubMed2003

Soluble intercellular adhesion molecule 1 in the peritoneal fluid of patients with endometriosis correlates with the extension of peritoneal implants.

OBJECTIVE: To investigate the correlation of the concentrations of soluble intercellular adhesion molecule 1 (sICAM-1) in the peritoneal fluid (PF) with the extent of peritoneal endometriotic lesions and with the presence of red lesions (RLs). STUDY DESIGN: Sixty-seven patients with endometriosis and 19 controls with normal pelvis had PF samples collected during laparoscopy. RESULTS: The concentrations of sICAM-1 in the PF of patients and controls were not different. Patients with peritoneal implant scores 4 or more had higher concentrations of sICAM-1 in the PF than those with implant scores less than 4 (P=0.018) and controls (P=0.031). No significant difference was found in sICAM-1 levels in patients with and without RLs. No correlation was detected between sICAM-1 and interleukin 1beta (IL-1beta) in either patients or controls. CONCLUSIONS: The increased concentrations of sICAM-1 in the PF of patients with greater implant scores may indicate an active shedding of the molecule from the endometriotic peritoneal tissue. No significant association was found with the presence of RLs. The levels of IL-1beta in the PF were not a relevant factor influencing the concentrations of sICAM-1.

Adult↗
PubMed2003

Peritoneal fluid concentrations of interleukin-8 in patients with endometriosis depend on the severity of the disorder and are higher in the luteal phase.

BACKGROUND: Previous evaluations of the relationship between the concentrations of interleukin-8 (IL-8) in the peritoneal fluid and endometriosis led to non-consistent results. Our purpose was to investigate the correlation of the concentrations of IL-8 in the peritoneal fluid with the stage of endometriosis, the presence of red lesions and the phase of the menstrual cycle. METHODS: Ninety-two patients with infertility (n = 87) or undergoing sterilization (n = 5) had peritoneal fluid samples collected at laparoscopy. IL-8 determinations were performed using an enzyme-linked immunosorbent assay. RESULTS: The concentrations of IL-8 in the peritoneal fluid of the 68 women with endometriosis were not significantly different from those of the 24 controls. Patients with moderate/severe stages had IL-8 significantly higher than controls (P = 0.008) and marginally higher than patients with minimal/mild endometriosis (P = 0.053). Concentrations of IL-8 were significantly higher in patients than in controls in the luteal phase. Red lesions were associated with significantly increased levels of peritoneal fluid IL-8 only in the luteal phase. CONCLUSIONS: Our findings reinforce the importance of IL-8 in the pathogenesis of endometriosis.

Adult↗
PubMed2003

Specific immunotherapy for severe latex allergy.

We studied 4 patients (3 adult females + 13y old boy) with latex allergy. All patients had anaphylaxis related with latex and oral-latex-fruit syndrome. All 3 females had severe symptoms in the workplace. The boy had spina bifida with 9 previous surgeries and needed further surgical interventions. Positive skin prick tests (SPT), the presence of serum latex specific IgE (CAP-RAST, Pharmacia-Upjohn, Sweden- class 3 in the 3 females and class 4 in the boy) demonstrated the sensitisation. All 4 patients were treated with specific immunotherapy (SIT) with aqueous extract (ALK-ALK-ABELLO SA, Spain) administered subcutaneously at the hospital, by a modified rush schedule. A maintenance dose (MD) of 0.35_g protein was established according to the magnitude of local reactions (LRs). In one patient a higher dose induced the appearance of a systemic reaction (SR) 40 min after administration, which promptly remitted with treatment. After reaching MD, all 3 females remained assymptomatic at workplace. A challenge test with latex gloves was performed. Two months after MD was reached 2 females had no symptoms and one other had mild symptoms of rhinoconjunctivitis. The boy was subjected to a surgical intervention with no allergic reaction. We also observed a reduction on skin reactivity to latex in all patients by prick tests. We consider SIT with latex to be highly effective, safe and well tolerated provided we use this dose of the allergenic extract.

Adolescent↗
PubMed2001

Response of antioxidant enzymes in freshwater fish populations (Leuciscus alburnoides complex) to inorganic pollutants exposure.

Evidence is accumulating indicating the importance of antioxidant enzyme activity measurements in eco-toxicological studies, as they may constitute markers for exposure to a large variety of pollutants. Variation of antioxidant enzymes, superoxide dismutase (SOD) and glutathione S-transferases (GST) and the effect of heavy metals and selenium exposure on these enzymes were investigated in the livers of Iberian endemic minnows (Leuciscus alburnoides complex) captured in a copper (Cu) mining area. Higher hepatic levels of copper and selenium were always observed in fish captured at the polluted site relative to the reference area population, reflecting the environmental monitoring results. A seasonal fluctuation in zinc and selenium levels for both populations was also observed which could be related to gonad maturation. The activity of SOD did not show significant regional alterations, but a seasonal variation occurred presumably associated with the Leuciscus life cycle. The GST activity was higher in the fish population from the polluted area (except in spring) and GST variability was associated with selenium and copper levels when both regions were compared. The increased GST activity was probably a metabolic adaptation to the continuous exposure to higher levels of those elements.

Adaptation, Physiological↗
PubMed2001

Origin of quantum chaos for two particles interacting by short-range potentials.

We address the problem of two confined one-dimensional particles of arbitrary masses interacting by general short-range potentials. We study under what conditions quantum chaos emerges for the system by analyzing its spectrum statistics. We show that these conditions are directly connected with a specific feature of the underlying classical dynamics, namely, the ergodicity in the changes of the particles momenta. Quantum mechanically this prevents one from obtaining the exact wave function through the Bethe ansatz. Possible extensions for many-body systems are also discussed.

Journal Article↗
PubMed2001

Effect of specific immunotherapy versus loratadine on serum adhesion molecules.

OBJECTIVE: To evaluate comparatively the effect on serum ICAM-1 and VCAM-1 values of specific immunotherapy versus loratadine in the treatment of allergic rhinitis. POPULATION: 65 patients with mild to moderate House Dust Mite allergic rhinitis. METHODS: Patients were divided into three groups, according to patients' preference: a control group with patients receiving only rescue therapy (antihistamines and/or nasal cromoglycate when needed); an antihistamine group with patients receiving daily loratadine 10 mg (and nasal cromoglycate as rescue therapy); an immunotherapy group with patients receiving subcutaneous house dust mite specific immunotherapy (and antihistamines or nasal cromoglycate when needed). In all groups we measured soluble ICAM-1 and VCAM-1 serum levels before the start of the study period and at the end of the study period. The duration of the study was one year for the control group and for the immunotherapy group. In patients taking daily antihistamines we measured serum adhesion molecules one month after the beginning of the therapy. We used Student's T test for statistical analysis. RESULTS: Patients in the control group didn't have significant variations in serum ICAM-1 (p = 0.239) or VCAM-1 (p = 0.38) levels. Patients receiving loratadine showed significant decreases in serum VCAM-1 levels (p = 0.0012) but not in serum ICAM-1 levels (p = 0.224). Patients receiving immunotherapy also showed a similar pattern, with significant decreases in serum VCAM-1 levels (p = 0.012) but not in serum ICAM-1 levels (p = 0.254). CONCLUSIONS: Specific house dust mite immunotherapy and regular daily loratadine therapy are able to lower significantly serum levels of soluble VCAM-1. However, this effect, which can be interpreted as an anti-inflammatory action, is not applied to soluble ICAM-1 levels, which raises the possibility of a differential action of these therapies on the mechanisms of allergic inflammation. Patients on rescue medication alone did not show any significant differences in these parameters.

Adolescent↗
PubMed2001

Immunotherapy in allergic rhinitis.

Allergen specific immunotherapy (IT) represents a cornerstone of allergic rhinitis treatment and his efficacy has been confirmed, through open and double blind trials and meta-analysis. In the last few years non invasive routs for IT (oromucosal, nasal) were developed gained general acceptation mainly in children and were validated by WHO. The efficacy of IT could be markers, the pattern of specific antibody response or by the effect on sequential nasal challenges. We have evaluated the effect of IT in allergic rhinitis by different methods. Nasal IT decreased mean symptoms and pharmacological scores as well as in seasonal as in perennial rhinitis. The same decrease has been observed after oromucosal IT. The effect of IT in allergic inflammation has been confirmed by a decrease in the level of soluble adhesion molecule sVCAM-1 which is related to eosinophilic inflammation but not statistically for sICAM-1. We have also evaluated the immunoblotting pattern or specific IgE after oromucosal IT for house dust mites. For D. pteronyssinus in 4 patients the bands intensity decreased and in 3 patients the bands decreased and in 10 disappeared. IT decreases tryptase and ECP in nasal lavage after sequential nasal challenges. Therefore IT decreases clinical scores, inflammation markers, specific IgE immunoblotting bands and response to allergen challenge. These different results confirm his efficacy and usefulness in allergic rhinitis.

Allergens↗
PubMed2000

Combination of clinical factors predictive of growth of small choroidal melanocytic tumors.

OBJECTIVE: To better define the effect of individual risk factors and combinations thereof on the growth of small choroidal melanocytic tumors. DESIGN: Retrospective analysis. SETTING: Clinical practice of ocular oncology. PATIENTS: The study included 1287 patients with small suspicious choroidal melanocytic tumors, measuring 3 mm or less in thickness, managed with observation. RESULTS: On multivariate analysis, the clinical risk factors predictive of growth of small choroidal melanocytic tumors include tumor thickness greater than 2.0 mm, posterior tumor margin touching the disc, visual symptoms, orange pigment, and subretinal fluid. Tumor growth was detected in 4% of those patients with no risk factors. Growth was detected in approximately 36% of patients with 1 risk factor, 45% of patients with 2 risk factors, 50% of patients with 3 risk factors, 51% of patients with 4 risk factors, and 56% of patients with all 5 risk factors. The combination of risk factors offering the greatest risk for growth was tumor thickness greater than 2.0 mm, tumor margin touching disc, and subretinal fluid that was associated with tumor growth in 63% of the affected patients. The relative risk for growth was 1.9 for 1 factor, 3.8 for 2 factors, 7.4 for 3 factors, 14.1 for 4 factors, and 27.1 for all 5 risk factors combined. CONCLUSIONS: Five risk factors for growth of small choroidal melanocytic tumors have been identified. The combinations of various factors increase the risk for tumor growth from 4% if no factors are present to more than 50% if 3 or more risk factors are present. These factors may be important when counseling patients with small suspicious choroidal melanocytic tumors.

Choroid Neoplasms↗
PubMed2000

Trace element status (Se, Cu, Zn) and serum lipid profile in Portuguese subjects of San Miguel Island from Azores'archipelago.

Data on selenium, copper and zinc in serum of Portuguese inhabitants of the city of Ponta Delgada-Azores Archipelago are reported for the first time. The subjects are of both sexes, aged 20 to 60 years, and non-abusers of alcohol, tobacco or drugs. Serum concentrations of these elements are in the same range than those found for populations of Lisbon and of some other European countries. Differences between sexes are observed, with serum selenium and zinc levels being higher in males than in females, and the copper levels being higher in females as compared to males. These results can be explained by the hormonal status and/or oral contraceptive steroids intake, particularly for copper. Concerning lipid profile, the majority of individuals have serum lipid parameters within the normal range. In addition, no difference in trace element levels between normo and hyperlipidemic individuals is observed and no conclusive results about the relationship of all evaluated parameters to alcohol, tobacco and drug consumption are observed, in agreement with data obtained in the population of Lisbon.

Adult↗
PubMed2000

Tumour necrosis factor alpha concentrations in the peritoneal fluid of infertile women with minimal or mild endometriosis are lower in patients with red lesions only than in patients without red lesions.

Tumour necrosis factor alpha (TNFalpha) of peritoneal fluid is believed to have important pro-inflammatory and angiogenic activities in the complex mechanisms of development of peritoneal endometriotic lesions. We have evaluated the concentrations of TNFalpha and macrophages in peritoneal fluid of infertile women with minimal or mild endometriosis and related them to the presence of peritoneal red lesions alone (red lesions only group; n = 11) or their absence (non-red lesions group; n = 36). A group of 39 infertile normo-ovulatory patients with normal pelvic anatomy was used as controls. TNFalpha concentrations did not differ between controls and either group of patients. Patients with red lesions only had significantly lower concentrations of TNFalpha in peritoneal fluid (P < 0.05) and had a higher proportion of samples with undetectable concentrations (P < 0.05) than patients without red lesions. The significant difference in TNFalpha concentrations was present when comparing the groups of patients in the proliferative phase but not in the secretory phase. Macrophage concentrations were not different in the groups. Our findings are compatible with an impairment of macrophage function and therefore lend support to the theory that an inappropriate immunological response of the peritoneal environment to regurgitated endometrium may play a part in the initial phases of endometriotic implants.

Adult↗
PubMed1999

Thermotherapy for retinoblastoma.

OBJECTIVE: To evaluate the results of thermotherapy for retinoblastoma. DESIGN: Prospective, nonrandomized analysis of the treatment method. PARTICIPANTS: A total of 188 retinoblastomas in 80 eyes of 58 patients who were treated with thermotherapy. MAIN OUTCOME MEASURES: Tumor response and ocular adverse effects. RESULTS: Of 188 retinoblastomas treated with thermotherapy, mean tumor base was 3.0 mm and tumor thickness was 2.0 mm. Complete tumor regression was achieved in 161 tumors (85.6%), and 27 tumors (14.4%) developed recurrence. Using univariate analysis, the predictors of local tumor recurrence were male sex (P = .005), no color change ("no visible take") in tumor after treatment (P = .01), increasing number of treatment sessions (P = .002), and previous use of chemoreduction (P = .02). By multivariate analysis, the most important predictors of local tumor recurrence were male sex (P = .01) and previous use of chemoreduction (P = .03), the latter likely reflecting the fact that these tumors were initially larger with more ominous findings, and required chemoreduction therapy to reduce them to a size amenable to focal treatment with thermotherapy. When evaluating thermotherapy variables as a function of tumor size, it was apparent that larger tumors (> or =3.0-mm base) required greater energy and time than did smaller tumors (<3.0-mm base). Comparison of treatment variables for larger vs smaller tumors was as follows: number of treatment sessions, 3.3 vs 2.3; spot size, 1.7 vs 1.3 mm; power, 540 vs 370 mW; treatment duration, 49 vs 14 minutes; and coupling of thermotherapy with chemotherapy, 79% vs 48% of cases (P < or =.001 for each variable). Complications of thermotherapy in the 80 eyes included focal iris atrophy in 29 eyes (36%), peripheral focal lens opacity in 19 eyes (24%), retinal traction in 4 eyes (5%), retinal vascular obstruction in 2 eyes (2%), and transient localized serous retinal detachment in 2 eyes (2%). There were no cases of corneal scarring, central lens opacity, iris or retinal neovascularization, or rhegmatogenous retinal detachment. All eyes with focal lens opacity demonstrated adjacent focal iris atrophy. By multivariate analysis, the predictors of thermotherapy-induced focal iris atrophy were increasing number of treatment sessions (P = .001) and increasing tumor base (P = .02). CONCLUSIONS: Thermotherapy is used for relatively small retinoblastomas without associated vitreous or subretinal seeds. This treatment provides satisfactory control for selected retinoblastomas, with 86% of tumors demonstrating lasting regression. Tumors that measure 3.0 mm or larger in base at the time of thermotherapy require more intense treatment than smaller tumors and are at greatest risk for ocular complications such as focal iris atrophy and focal paraxial lens opacity.

Chemotherapy, Adjuvant↗