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Biomedical subjects

M Ferreira

Publications and source records attributed to M Ferreira.

At least 19 recordsLinked to original sources
PubMed2007

Depuration of PCBs and DDTs in mullet under captivity clean conditions.

Contaminated mullet (Mugil cephalus) from Douro estuary was allowed to depurate in clean water and fed with uncontaminated food. Levels of PCBs and DDTs in muscle and liver, and ethoxyresorufin O-deethylase (EROD) activity were measured at day 0, 21, 120 and 270. In specimens captured in the estuary total PCB and total DDT concentrations were 311 and 65 ng g(-1) in muscle and 686 and 115 ng g(-1) in liver, respectively. At day 21, after an initial 10-15 days period of starvation, organochlorines levels increased in both analyzed tissues. Thereafter levels of all PCB congeners and DDT compounds decreased in muscle, and at the end of the 270 days were 49 ng g(-1) and 13 ng g(-1), respectively. These decreases were correlated to the lipids consumption. In liver no relationship between those variables was observed, suggesting different elimination processes and eventual exchange of contaminants between muscle and liver. EROD activities decreased in the first days of depuration experiment, but showed no relations with analysed organochlorines.

Animal Feed↗
PubMed2006

Lupus erythematosus tumidus: an underestimated entity.

There have been few reports of lupus erythematosus tumidus (LET) in the literature. Most of textbooks of dermatology or dermatopathology mention this entity only briefly, if at all. The authors describe an additional case of this underdiagnosed disorder that further supports its existence as a separate entity in the spectrum of the variants of chronic cutaneous lupus erythematosus. Although most cases are reported in the European countries, to our knowledge, this is the first case documented in Portugal. The clinical, photobiological and histological features as well as differential diagnosis, treatment and prognosis are also discussed.

Dermatologic Agents↗
PubMed2006

"Downhill" varices. A rare cause of esophageal hemorrhage.

"Downhill" varices or upper esophageal varices are a rare cause of proximal digestive tract hemorrhage with only 16 cases described in the literature. In our series, hemorrhage due to "downhill" varices represents 0.1% of all acute esophageal variceal bleeding. Their etiology differs from that of the usual "uphill" varices secondary to portal hypertension, and the clinical management should be directed to vascular obstruction if present. We report a case of an 89-year-old male with hemorrhagic "downhill" varices not associated, as usually, with superior vena cava obstruction or compression, but with severe pulmonary hypertension and drug-related hemorrhagic risk factors, whose removal proved sufficient to prevent rebleeding.

Aged, 80 and over↗
PubMed2006

Treatment for acute lymphoblastic leukemia in children is associated with papillary carcinoma of thyroid, but not with thyroid disfunction.

AIM: The treatment of acute lymphoblastic leukemia (ALL) in children may cause sequelae, some appearing only at long-term follow-up. We investigated the thyroid gland morphology and the function of the pituitary-thyroid axis in a group of patients treated for ALL in childhood. METHODS: A cohort study was conducted at a tertiary medical center. Thirty-three children (22 males and 11 females; age: 11.9+/-3 years; range: 6 to 18 years) were studied. The mean age at the time of chemotherapy and prophylactic cranial irradiation (12-24 Gy) was 5.5+/-2.6 years (range: 1 to 14 years). The average length of the follow-up was 6.1+/-3 years (range: 2 to 12 years). Thyroid morphology (n=33) was evaluated by palpation and ultrasonography. Thyroid function (n=30) was evaluated measuring total T3 and T4, and by the thyrotrophin-releasing hormone (TRH) test. Prolactin secretion was assessed before and after injection of TRH to evaluate the diagnostic test accuracy. RESULTS: One out of the 33 children (3%) was found to have a papillary carcinoma of thyroid four years after ALL treatment. Thyroid function was normal in all the patients, however one case (3%) showed high TSH (9.2 microU/mL) and prolactin (37.5 ng/mL) basal levels, but normal responses to TRH (TSH = 17.8 microU/mL; prolactin = 82.3 ng/mL). These hormonal alteration were not confirmed at follow-up: TSH = 1.6 microU/mL and prolactin = 13.7 ng/mL. CONCLUSIONS: In this cohort of patients, the treatment of ALL was associated with one case of thyroid carcinoma, but it did not produce adverse effect on the thyroid function, at least after a follow-up lasted on average 6 years.

Adolescent↗
PubMed2005

The effect of long-term depuration on phase I and phase II biotransformation in mullets (Mugil cephalus) chronically exposed to pollutants in River Douro Estuary, Portugal.

Pollutants such polycyclic aromatic hydrocarbons (PAHs) are released into the environment by urban communities and industries and the enzymes that catalyse the biotransformation of pollutants play a key role regarding the accumulation of these compounds in fish species inhabiting these areas. In this study the relationship between phase I (EROD activity) and phase II (GST activity) and PAH metabolites was measured in grey mullet (Mugil cephalus) after capture in the Douro estuary, and after long-term depuration in an unpolluted laboratory environment. The results showed a significant decrease in EROD activity after 1 month and in bile metabolites after 4 months in captivity, with both maintaining reduced levels at 4 and 8 months depuration. Liver GST activity did not showed significant changes. This study provides evidence that Douro estuary waters contain bioavailable PAHs that can be associated with the induction of cytochrome P450, and that mullets have the ability to metabolise and eliminate PAHs.

Animals↗
PubMed2005

Oxidative stress biomarkers in two resident species, mullet (Mugil cephalus) and flounder (Platichthys flesus), from a polluted site in River Douro Estuary, Portugal.

Exposure of marine animals to certain pollutants can enhance reactive oxygen species (ROS) production with subsequent damage to macromolecules and alterations in oxidant defences levels. Aimed at correlating the tissue concentration of certain contaminants (PCBs, DDT) with antioxidant defence levels and oxidative damages, two fish species with different life strategies (mullet, Mugil cephalus, and flounder, Platichthys flesus) were collected in the Douro Estuary (NW Portugal). After capture, the fish were left to depurate for 1 month in clean seawater. The levels of the two antioxidant enzyme activities revealed that they are species-dependent with mullet's livers showing higher superoxide dismutase (SOD) (13.2+/-0.5 U/mg protein) and catalase (CAT) (15.5+/-1.0 mmol/min/mg protein) activities than flounder (SOD: 7.9+/-0.9 U/mg protein; CAT: 11.1+/-0.8 mmol/min/mg protein). After 1 month in captivity the antioxidant enzymes activities in liver decreased in mullets, while for flounders the responses were not consistent because during the experimental period flounders did not ate and responses of antioxidant enzymes and oxidative damages were dependent on the fasting condition. The liver oxidative damages were evaluated by estimating oxidised lipids and proteins. Both species showed similar levels for these two parameters. The hepatic lipid peroxidation in flounder increased after 1 month in captivity, while in mullet an increase was observed only in summer and autumn. The oxidised protein content increased for both species after the depuration period. This study reveals differences between species under oxidative stress when exposed to pollutants. In a clean environment, the mullet's primary antioxidant defences decreased indicating that the animals living in Douro estuary were facing an oxidative stress. The data indicate that, namely in mullet, the presence of pollutants induce oxidative stress responses.

Animals↗
PubMed2004

Organochlorine contaminants in flounder (Platichthys flesus) and mullet (Mugil cephalus) from Douro estuary, and their use as sentinel species for environmental monitoring.

In order to monitor the presence of organic pollutants in Douro estuary (NW Portugal), two sentinel fish species, grey mullet (Mugil cephalus) and flounder (Platichthys flesus), were periodically sampled from May 2001 to April 2002. At all sampling periods, several specimens of both species were allowed to depurate in clean sea water. Levels of PCBs and DDTs were quantified in liver and muscle of both species. The accumulation of PCBs was higher in muscle of mullet, with a maximum of 345 ng/g dw, than in flounder, with a maximum 52ng/g dw. In the liver, flounder showed the highest levels (811 ng/g dw). Of the 18 congeners analysed, CBs 180 (hepta), 153 and 138 (hexachlorobiphenyls) were predominant in the tissue of both species. The maximum concentration of tDDT was measured in flounder liver (301ng/g dw). In contrast, a 10-fold higher tDDT was recorded in mullet muscle (63-69 ng/g dw and 8-16 ng/g dw for mullet and flounder, respectively). The hepatic ethoxyresorufin O-deethylase (EROD) activity was periodically determined. Consistently, a 10-fold higher enzymatic activity was present in mullet in comparison with flounder (1536 pmol/min/mg protein in mullet and 156 pmol/min/mg protein in flounder). In mullet, no correlation could be found between EROD activity and gonado-somatic index (GSI) or hepato-somatic index (HSI). On the contrary, during the reproductive season, female flounder showed a negative correlation between EROD activity and GSI. Despite being in clean sea water for 1 month period, no significant decrease in the tissue content of PCBs and tDDT was found. However, mullet's EROD activity followed a clear pattern, with a decrease enzymatic activity after being in captivity. Female flounder displayed a similar trend during the resting season. Yet, during the reproductive season, an increased EROD activity was recorded after being in captivity for 1 month, which may be associated with a modulation effect of steroids on CYP 1A1. Histological analyses of gonad revealed that 21% of male mullet displayed testis-ova, while no male flounder was found to show gonadal abnormalities. Overall, the study reports the accumulation of significant levels of PCBs and DDTs in the tissues of the studied species. It also provides important evidences supporting the use of grey mullet as a sentinel species for monitoring the presence of organic contaminants and xeno-estrogenic pollution in southern European estuaries.

Analysis of Variance↗
PubMed2004

Cytoprotection by Achyrocline satureioides (Lam) D.C. and some of its main flavonoids against oxidative stress.

Epidemiological studies indicate that dietary antioxidants can influence the incidence of neurodegenerative diseases. Among them flavonoids have been proposed to be effective cytoprotectors. Consequently, herbs with a high concentration of these compounds such as Achyrocline satureioides, Ginkgo biloba and Epilobium parviflorum are of special interest. In this context a comparative study of the cytoprotective capacity of infusions from the three plants against an oxidative insult was performed. Hence, the cytoprotective activity of each infusion against H2O2 injury to PC12 cells was tested and the antioxidant capacity was assessed by the ABTS*+ radical bleaching assay. Free and glycosylated flavonoids contained in the infusions were identified by HPLC and the cytoprotective effect of some of these individual flavonoids was tested. The analysis of the flavonoid content of the infusions revealed different profiles. Epilobium parviflorum infusion showed the highest antioxidant capacity but only Achyrocline satureioides infusion proved to be cytoprotective. Moreover, the free flavonoids quercetin and luteolin contained in this infusion were also cytoprotective. In conclusion, the free radical scavenger capacity did not correlate with the cytoprotective profile of the infusions. The special mixture of unglycosylated Achyrocline satureioides flavonoids could be a clue to explain the unique effect of this plant.

Achyrocline↗
PubMed2004

Dieulafoy's lesion: management and long-term outcome.

BACKGROUND AND STUDY AIMS: Dieulafoy's lesion is usually considered to be a rare cause of gastrointestinal bleeding and little information is available about the long-term follow-up of this condition. We studied the clinical pattern and long-term outcome in patients with Dieulafoy's lesion who were managed in a gastrointestinal intensive care unit. PATIENTS AND METHODS: We reviewed the data on the diagnosis, treatment, and outcome of 70 patients admitted to our unit for acute upper gastrointestinal bleeding due to Dieulafoy's lesion. Endoscopic hemostasis was performed in 69 cases. Patients underwent surgery if endoscopic therapy failed. A phone interview was carried out to assess the long-term clinical outcome. RESULTS: Dieulafoy's lesion accounted for 4 % of cases of upper gastrointestinal bleeding in patients admitted during the period studied. The mean number +/- SD of endoscopies required to establish the diagnosis was 1.4 +/- 0.75. Endoscopic hemostasis was initially successful in 91.3 % of patients, while nearly 16 % of patients required surgery because endoscopic therapy failed. The overall mortality rate was 8.6 %. None of the 52 patients who were followed up by phone reported recurrent bleeding after discharge from hospital, in a mean follow-up period of 69 months. CONCLUSIONS: Dieulafoy's lesion is a not uncommon cause of severe recurrent gastrointestinal bleeding. Endoscopic therapy is safe and effective in achieving permanent hemostasis. The long-term prognosis for Dieulafoy's lesion is excellent, even when patients are treated using endoscopic methods alone.

Adult↗
PubMed2003

Neuroprotection by flavonoids.

The high morbidity, high socioeconomic costs and lack of specific treatments are key factors that define the relevance of brain pathology for human health and the importance of research on neuronal protective agents. Epidemiological studies have shown beneficial effects of flavonoids on arteriosclerosis-related pathology in general and neurodegeneration in particular. Flavonoids can protect the brain by their ability to modulate intracellular signals promoting cellular survival. Quercetin and structurally related flavonoids (myricetin, fisetin, luteolin) showed a marked cytoprotective capacity in in vitro experimental conditions in models of predominantly apoptotic death such as that induced by medium concentrations (200 M) of H2O2 added to PC12 cells in culture. Nevertheless, quercetin did not protect substantia nigra neurons in vivo from an oxidative insult (6-hydroxydopamine), probably due to difficulties in crossing the blood-brain barrier. On the other hand, treatment of permanent focal ischemia with a lecithin/quercetin preparation decreased lesion volume, showing that preparations that help to cross the blood-brain barrier may be critical for the expression of the effects of flavonoids on the brain. The hypothesis is advanced that a group of quercetin-related flavonoids could become lead molecules for the development of neuroprotective compounds with multitarget anti-ischemic effects.

Arteriosclerosis↗
PubMed2003

Pesticides in Portuguese surface and ground waters.

Pesticides used in Portuguese agricultural areas have been found in surface and ground waters. In the surface water collected in three river basins from 1983 to 1999, insecticides and herbicides were detected from the monitored pesticides, particularly atrazine, chlorfenvinphos (Z+E), alpha- and beta-endosulfan, lindane, molinate and simazine, reaching the maximum values, respectively, of 0.63, 31.6, 0.18 microg/L (alpha-endosulfan), 0.18 microg/L (beta-endosulfan), 0.24, 48 and 0.3 microg/L. In the ground water collected from the wells of seven agricultural areas from 1991 to 1998, several monitored herbicides were detected: alachlor, atrazine, metolachlor, metribuzine and simazine, reaching the maximum concentration values of 13, 30, 56, 1.4 and 0.4 microg/L, respectively. The herbicides more frequently detected were atrazine (64%), simazine (45%) and alachlor (25%). Other than these, the monitored pesticides can be present in Portuguese surface and ground waters. Therefore, to improve the analytical conditions, the use of multiresidue methods and automated techniques are desirable in future work.

Agriculture↗
PubMed2003

Screening of antioxidant activity of three Indian medicinal plants, traditionally used for the management of neurodegenerative diseases.

A number of Indian medicinal plants have been used for thousands of years in the traditional system of medicine (Ayurveda). Amongst these are plants used for the management of neurodegenerative diseases such as Parkinson's, Alzheimer's, loss of memory, degeneration of nerves and other neuronal disorders by the Ayurvedic practitioners. Though the etiology of neurodegenerative diseases remains enigmatic, there is evidence, which indicates that defective energy metabolism, excitotoxicity and oxidative damage may be crucial factors (Ann. Neurol. 38 (3) (1995) 357). The part of the Ayurvedic system that provides an approach to prevention and treatment of degenerative diseases is known as Rasayana, and plants used for this purpose are classed as rejuvenators. This group of plants generally possesses strong antioxidant activity (Pharmacol. Biochem. Behav. 43 (1992) 1175), but only a few have been investigated in detail. In the present study, three such rasayana plants were tested for the first time for their toxicity and free radical scavenging activity both in vitro and ex vivo. All the three plant infusions (up to 1 mg/ml) showed no toxic effects on the viability of PC12 cell line as judged by MTT-test. Both ethanolic extracts and water infusions of the plants were tested for their antioxidant activity in the 2,2'-azinobis-3-ethyl-benzothiazoline-6-sulfonic acid (ABTS*(+)) radical cation decolorization assay; inhibition of lipid peroxidation by plant infusions was carried out using spontaneous lipid peroxidation of rat brain homogenate, and IC50 values were determined. The results from the ABTS assay showed that the ethanolic extract of Sida cordifolia was found to be most potent (IC50 16.07 microg/ml), followed by Evolvulus alsinoides (IC50 33.39 microg/ml) and Cynodon dactylon (IC50 78.62 microg/ml). The relative antioxidant capacity for the water infusions was observed in the following order: E. alsinoides (IC50 172.25 microg/ml)>C. dactylon (IC50 273.64 microg/ml)>S. cordifolia (IC50 342.82 microg/ml). The results of water infusions of the plants on lipid peroxidation were as follows: E. alsinoides (IC50 89.23 microg/ml)>S. cordifolia) (IC50 126.78 microg/ml)>C. dactylon (IC50 608.31 microg/ml).

Animals↗
PubMed2001

Glucose effects on gastric motility and tone evoked from the rat dorsal vagal complex.

1. To examine the effects of glucose on the central components of the vago-vagal reflex control of gastric function, we performed both in vivo and in vitro experiments on neurones in the medial nucleus of the tractus solitarius (mNTS) and in the dorsal motor nucleus of the vagus (DMV). 2. In the in vivo anaesthetized rat preparation, unilateral microinjection of D-glucose (10 or 50 mM (60 nl)(-1)) in mNTS produced inhibition of gastric motility and an increase in intragastric pressure. D-glucose had no effect in the DMV. 3. In the in vitro rat brainstem slice preparation, whole-cell recordings of DMV neurones showed that increasing the glucose concentration of the perfusion solution from 5 mM to 15 or 30 mM produced outward currents of 35 +/- 5 pA (n = 7) and 51 +/- 10 pA (n = 11), respectively. These were blocked by tetrodotoxin and picrotoxin, indicating that glucose was acting indirectly to cause the release of GABA. Decreasing the glucose concentration of the perfusing solution by one-half produced an inward current of 36 +/- 5 pA (n = 7). 4. Stimulation of the NTS evoked inhibitory postsynaptic currents (IPSCs) in DMV neurones. The amplitude of the evoked IPSCs was positively correlated with glucose concentration. Perfusion with the ATP-sensitive K(+) (K(ATP)) channel opener diazoxide mimicked the effect of reduced glucose, while perfusion with the K(ATP) channel blocker glibenclamide mimicked the effects of increased glucose. 5. Our data indicate that glucose had no direct excitatory effect on DMV neurones, but DMV neurones appear to be affected by an action of glucose on cell bodies of mNTS neurones via effects on an ATP-sensitive potassium channel.

Animals↗
PubMed2001

Cooperativity of phospholipid reorganization upon interaction of dipyridamole with surface monolayers on water.

Results from various surface sensitive characterization techniques suggest a model for the interaction of the piperidinopyrimidine dipyridamole (DIP)--known as a vasodilator and inhibitor of P-glycoprotein associated multidrug resistance of tumor cells--with phospholipid monolayers in which the drug is peripherally associated with the membrane, binding (up to) five phospholipids at a time. These multiple interactions are responsible for a very strong association of the drug with the lipid monolayer even at exceedingly low concentrations (approximately 0.2 mol%). Electrostatic interactions and hydrogen bonding are likely involved in the binding of DIP to DPPC. Cooperative effects among the lipids are invoked to explain the macroscopically measurable changes of lipid monolayer properties even when only one out of 100 DPPC molecules is directly associated with a DIP molecule. A reversal of the observed changes upon drug association with the membrane as the DIP concentration surpasses a threshold concentration (c(crit)approximately 0.5 mol%) may be explained by cooperativity in a different context, the self-aggregation of drug molecules. With its implications for the interaction of DIP with phospholipid films, this work provides a first approach to the explanation of the high sensitivity of cell membranes to piperidinopyrimidine drugs on a molecular level.

Dipyridamole↗
PubMed2001

Suicide attempts and the tryptophan hydroxylase gene.

Tryptophan hydroxylase (TPH) is the rate-limiting enzyme of serotonin synthesis. In this case-control study, we investigated whether the TPH gene was a susceptibility factor for suicidal behavior. Seven polymorphisms spanning the entire gene were studied in a case-control study including 231 individuals who had attempted suicide and 281 controls. Significant associations were found between variants in introns 7, 8 and 9 (chi(2) = 11.2, df = 1, P< 0.0008 for the allele distribution; these loci are in complete linkage disequilibrium) and in the 3' noncoding region (chi(2) = 30.94, P = 0.0014) and suicide attempt. The association was strongest for subjects who had attempted suicide by violent means and who had a history of major depression. No significant association was observed between suicide attempts and polymorphisms in the promoter, intron 1 and intron 3. The results presented here, and those of previous studies, suggest that a genetic variant of the 3' part of the TPH gene may be a susceptibility factor for a phenotype combining suicidal behavior, mood disorder and impulsive aggression.

Adult↗
PubMed2001

Axotomy and nerve growth factor regulate levels of neuronal nicotinic acetylcholine receptor alpha3 subunit protein in the rat superior cervical ganglion.

Neuronal nicotinic acetylcholine receptors (nAChRs) play a significant role in sympathetic transmission in the superior cervical ganglia (SCG), with most of the signal carried by a nAChR containing an alpha3 subunit. Work has shown that transection of the postganglionic nerves (axotomy) of the SCG results in a decrease in mRNA transcripts for alpha3, alpha5, alpha7 and beta4 and in protein expression of alpha7 and beta4. To evaluate effects of axotomy on alpha3 protein in the SCG, quantitative immunoblotting was used to demonstrate a dramatic decrease (> 80%) in the levels of this subunit 4 days after axotomy. Similarly, immunocytochemistry showed a marked decline in the number and the intensity of stained neurons for the alpha3 subunit as well as tyrosine hydroxylase. Ganglia explanted into culture for 4 days also showed a substantial decrease in alpha3 subunit protein. This decrease was partially prevented by the addition of nerve growth factor (NGF) to the culture medium at the time of explantation. Additionally, this decrease was reversed by the addition of NGF to the culture medium following 4 days in culture in the absence of NGF. These findings suggest that the loss of alpha3 subunit contributes to the reported decrease in ganglionic synaptic transmission that follows axotomy, and that NGF plays an important role in regulating the expression of alpha3-containing nAChRs in the SCG.

Animals↗
PubMed2001

A pilot investigation to subjectively measure treatment effect and side-effect profile of non-ablative skin remodeling using a 532 nm, 2 ms pulse-duration laser.

BACKGROUND AND OBJECTIVE: Carbon dioxide laser skin resurfacing has become a standard treatment for wrinkles and sun-damaged skin. This ablative treatment, however, is associated with undesirable complications and long recovery times. A growing body of evidence suggests that dermal inflammation and subsequent collagen formation can be stimulated without removal of the epidermis, raising the possibility of effective non-ablative skin remodeling for mild to moderately photodamaged skin. MATERIALS AND METHODS: This preliminary study was performed to evaluate the safety and subject satisfaction of non-ablative skin remodeling using a 532 nm, 2 ms pulse-duration, frequency-doubled Nd:YAG laser. Subjects with mild-to-deep lip wrinkles and mild-moderate acne scarring were treated one half of their lip (wrinkles) or cheek (acne scarring), leaving the other side as an untreated control. Subjects were treated at 3-6 week intervals for an average of three treatments. Subjective assessment of improvement was estimated by subject self-evaluation of the percentage improvement over baseline, and a blinded observer attempted to identify the treated side on physical examination. RESULTS: Subjective assessment revealed an average improvement of 51.4% and 53.6% for upper lip wrinkles and facial acne scarring, respectively. Side effects were limited to transient erythema that resolved over 0.25-2 hours following treatment. CONCLUSIONS: These results demonstrate that non-ablative treatment with the 532 nm, 2 ms pulse-duration Nd:YAG laser results in subjective improvement of rhytides and acne scarring, with a high safety profile.

Acne Vulgaris↗