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Biomedical subjects

L Almeida

Publications and source records attributed to L Almeida.

At least 37 records · Page 2Linked to original sources
PubMed1997

Alarm pheromone induces stress analgesia via an opioid system in the honeybee.

Changes of the stinging response threshold of Apis mellifera scutellata were measured on foragers fixed on a holder and stimulated with an electric shock as a noxious stimulus. The threshold of responsiveness to the noxious stimulus increased when bees were previously stimulated with isopentyl acetate, which is a main component of the alarm pheromone of the sting chamber. This effect is antagonised by previous injection of naloxone-hydrochloride (Endo Laboratories Inc.). Results suggest that in the honeybee an endogenous opioid system activated by isopentyl acetate is responsible for modulation of perception for nociceptive stimuli. The resulting stress-induced analgesia in the defender bee would reduce its probability of withdrawal thus increasing its efficiency against enemies.

Analgesia↗
PubMed1997

[Prevalence of several cardiovascular risk factors in a population in the municipality of Viseu].

STUDY OBJECTIVE: To assess the prevalence of the main changeable cardiovascular risk factors (hypertension, hypercholesterolemia and smoking) in the population of the Viseu municipality. MATERIAL AND METHODS: The population was obtained through a publicity campaign in local radios and on lighted placards in the town of Viseu. We chose a set of volunteers above 20 years of age, who answered a questionnaire about smoking habits, academic qualifications, profession and residence. After the inquiry, the total cholesterol and blood pressure were determined. We considered hypertension (HBP) values > or = 140/90 mmHg and hypercholesterolemia > 200 mg/dl. RESULTS: 1852 persons were inquired (3.2% of the population of the Viseu municipality) 1173 of which were females. According to the age groups, we verified that the ages between 50 and 69 years represented 47.9% of the total amount of volunteers. In what concerns smoking habits, we found a prevalence of 9.1% (15.9% in males and 5.2% in females). In the study of the prevalence of HBP we found a value of 38.5%, higher in males (42.8%) than in females (35.9%). The prevalence of hypercholesterolemia found was 34.9% (no significant differences between the sexes). CONCLUSION: In comparison with other studies carried out in the Portuguese population, a low prevalence of smoking habits, high hypertension and similar hypercholesterolemia were found.

Adult↗
PubMed1996

Inhibition of metmyoglobin/H2O2-dependent low density lipoprotein lipid peroxidation by naturally occurring phenolic acids.

The ferrylmyoglobin <==> metmyoglobin redox transitions promoted by hydrogen peroxide and dietary phenolic acids and their potential role in the oxidation of LDL were studied. The use of parinaric acid incorporated in LDL as a probe for radicals (detected by fluorescence quenching of the probe) revealed an oxidative stress inside LDL shortly ( < 1 min) after addition of hydrogen peroxide to metmyoglobin in the aqueous phase outside the particle, reflecting an efficient access of the oxidant to LDL lipids. However, the propagation step of peroxidation only occurs after a lag phase, as detected by the kinetics of oxygen consumption. Triton X-100 decreases but does not suppress the lag phase of oxidation. Addition of metmyoglobin (without peroxide) to LDL was not followed by significant oxidation during the time of the experiment, unless Triton X-100 was present in the medium. When dietary phenolic acids were present in the medium before peroxide addition, an inhibition of parinaric acid fluorescence quenching and oxygen consumption was recorded as a function of concentration and substitution pattern on the phenol ring of the phenolic acids. This was associated with a conversion of ferrylmyoglobin to metmyoglobin. The results indicate that the naturally occurring phenolic acids prevent ferrylmyoglobin-dependent LDL oxidation in a way strongly dependent on the substitution pattern on the phenol ring. Among the phenolic compounds studied, the o-dihydroxy derivatives of cinnamic and benzoic acids (caffeic, chlorogenic, and protocatechuic acids), in a molar ratio of 1 to metmyoglobin, efficiently blocked LDL oxidation initiated by ferrylmyoglobin. Replacement of one OH group from catecholic structure with an H (p-coumaric acid) or methoxy group (ferulic acid) decreased the antioxidant activity. Also, the catechol structure fused in heterocyclic rings with adjacent carbonyl groups (ellagic acid) resulted in decreased antioxidant activity. These observations correlate with the efficiency of phenolic acids to reduce ferrylmyoglobin to metmyoglobin. Therefore, the protection of LDL against oxidation is assigned to the reduction of the oxoferryl moiety of the hemoprotein to the ferric form. Additionally, it is suggested that an access constraint of oxidants plays a minor role in the ferrylmyoglobin-induced oxidation against LDL.

Animals↗
PubMed1996

A randomised study on the impact of peroral amoxicillin in women with prelabour rupture of membranes preterm.

One hundred and six third trimester pregnant women with prelabour rupture of membranes preterm were randomised to either peroral amoxicillin 0.75 g 3 times daily (n = 50) or placebo (n = 56) in a blinded way. The patients were hospitalised in bed for 7 days unless contractions started and delivery ensued. Only 1 patient was discharged after 7 days of treatment, while the remaining ones delivered within 1 week after admission. The average rupture-to-expulsion interval was 68.4 h in the placebo group and 91.7 h in the amoxicillin group, implying a significantly prolonged stay by 43% in the amoxicillin group (p = 0.03). The other outcome variables registered (birth weight, stillbirth prevalence, vaginal haemorrhage and postpartum endometritis-myometritis) did not differ significantly in the two treatment groups. There was a trend towards a longer duration of stay in the neonatal ward among newborns in the amoxicillin group suffering neonatal death (p = 0.06). It is concluded that antibiotic treatment of this group of women may be justified in settings were sexually transmitted diseases and other genital infections are prevalent, whereas such treatment is less likely to have an effect when genital infection is rare.

Adult↗
PubMed1995

Two related phenolic antioxidants with opposite effects on vitamin E content in low density lipoproteins oxidized by ferrylmyoglobin: consumption vs regeneration.

Endogenous alpha-tocopherol of low density lipoprotein (LDL) particles exposed to ferrylmyoglobin (iron in the form of FeIV = O) vanishes as a function of myoglobin concentration. After alpha-tocopherol depletion, subsequent heavy lipid peroxidation is prevented by caffeic and p-coumaric acids, i.e., phenolic acids present in foods and beverages, by a mechanism involving the one-electron transfer reaction between the phenols and the ferrylmyoglobin, with formation of metmyoglobin and the corresponding phenoxyl radicals from caffeic and p-coumaric acids, as previously discussed. Caffeic acid delays alpha-tocopherol consumption when present before oxidation challenging and restores alpha-tocopherol when added halfway during the reaction. Conversely, p-coumaric acid accelerates the rate of alpha-tocopherol consumption when added either before or during the oxidation reaction. In LDL enriched with alpha-tocopherol, caffeic acid induces an inhibition period of oxidation longer than that expected from the sum of discrete periods characteristic of the phenolic acid and alpha-tocopherol. Surprisingly, p-coumaric acid decreases the peroxidation chain rate. Similar effects of these phenolic acids on alpha-tocopherol consumption were observed in a Triton X-100 micellar system, i.e., in the absence of a peroxidation chain reaction. Results suggest that caffeic acid acts synergistically with alpha-tocopherol, extending the antioxidant capacity of LDL by recycling alpha-tocopherol from the alpha-tocopherol radical (i.e., alpha-tocopheroxyl radical). By contrast, the phenoxyl radical from p-coumaric acid (produced by electron-transfer reaction between phenolic acid and ferrylmyoglobin) oxidizes alpha-tocopherol. However, in spite of alpha-tocopherol consumption, the exchange reaction recycling p-coumaric acid can still afford an antioxidant protection to LDL on basis of the chain-breaking activity of p-coumaric acid. These results emphasize the biological relevance of small structural modifications of phenols on the interaction with alpha-tocopherol in LDL. The significance of these results in the context of atherosclerosis is discussed.

Antioxidants↗
PubMed1995

Reduction of ferrylmyoglobin by dietary phenolic acid derivatives of cinnamic acid.

The reaction of dietary phenolic acid derivatives of cinnamic acid with high valence states of horse myoglobin was studied. When metmyoglobin was oxidized by hydrogen peroxide (H2O2) in the presence of the phenolic acids, ferrylmyoglobin was reduced to metmyoglobin. However, addition of the phenolic acids to a ferrylmyoglobin solution resulted in a modified metmyoglobin spectrum characterized mainly by a blue shift of the 631 nm peak and a new isosbestic point at 613 nm suggesting an irreversible modification of the hemeprotein. The efficiency and the kinetic profile of ferrylmyoglobin reduction were dependent on both the concentration and the structure of the phenolic acid. Electron-donating substituent groups in the phenol ring increased the efficiency of ferrylmyoglobin reduction whereas electron-withdrawing groups decreased it. The phenolic acids exhibiting a catechol structure were the most efficient in reducing ferrylmyoglobin. Caffeic and chlorogenic acids react faster than trolox, and caffeic acid faster than ascorbate. During the electron-transfer reactions, the phenolic acids were oxidized to quinoid forms and, in some cases, to polymer products as indicated by comparison of the ultraviolet (UV) spectra obtained in the presence of metmyoglobin/H2O2 with those recorded after oxidation of phenolic acids by horseradish peroxidase/H2O2 and catechol oxidase. The results suggest that dietary phenolic derivatives of cinnamic acid may counteract deleterious oxidations initiated by ferrylmyoglobin.

Animals↗
PubMed1994

[Pulse wave velocity as initial marker of atherosclerosis].

OBJECTIVE: To evaluate the influence of hypercholesterolaemia on arterial distensibility. MATERIAL AND METHODS: 43 male New Zealand White rabbits, with similar ages and weights, were included in the present study. The animals were divided in two groups: Group A (n = 15) was fed a normal diet; Group B (n = 28) was fed normal diet plus 0.1% cholesterol. at the beginning and after 6 and 9 months, blood samples were obtained for determination of serum cholesterol (total, esterified, LDL) and Triglyceride levels. Pulse wave velocity (PWV) was also evaluated, by mecanography, after 6 and 9 months of the beginning of the experiment. After 6 months (Group A = 4 and Group B = 7) and 9 months (Group A = 6 and Group B = 7) of the experiment, some animals were killed for anatomopathological studies. RESULTS: Major differences were obtained between the two groups, specially in what concerns to LDL and cholesterol levels (p < 0.001). There was also a remarkable difference in PWV between the two groups (6.078 +/- 0.162/9.002 +/- 0.196 m/s at 6 months and 7.639 +/- 0.590/9.557 +/- 0.543 m/s at 9 months) from the rabbits fed normal or cholesterol diet, respectively. The anatomical lesions were only significant after 9 months. However there was a decrease in aorta internal diameters at thoracic and renal levels at 6 months (34% and 53%) and at 9 months (29% and 33%), without significant changes in their thickness. In the heart, the left ventricle (LV) had a significant thickness increase after 6 months (about 43%). CONCLUSIONS: These data indicate that even before anatomical lesions had occurred, important functional changes are present, in the arterial wall. Then, the evaluation of the PWV could be a promising non-invasive diagnostic method of early atherosclerosis, with obvious implications concerning its prophylaxis and therapy.

Animals↗
PubMed1994

Application of vaginal misoprostol before cervical dilatation to facilitate first-trimester pregnancy interruption.

OBJECTIVE: To study the capacity of vaginal misoprostol to soften the cervix and facilitate cervical dilatation in women undergoing first-trimester pregnancy interruption. METHODS: We performed a double-blind, placebo-controlled study in 100 women opting for voluntary pregnancy interruption. The subjects were randomly allocated to two treatment groups, receiving either 200 micrograms misoprostol or placebo in the posterior vaginal fornix 6 hours before cervical dilatation. We noted the number of women with vaginal bleeding, with chorionic tissue in the vagina, or with no resistance to a Hegar 8 dilator, and recorded the total time in minutes for pregnancy interruption. RESULTS: Vaginal bleeding from the cervix occurred in 70% of the misoprostol group and in 8% of the placebo group (odds ratio 26.83; 95% confidence interval [CI] 9.73-74.00). Almost one-fourth (22%) of the misoprostol-treated women had chorionic tissue in the vagina, compared to one woman (2%) in the placebo group (odds ratio 13.82; 95% CI 2.59-73.61). Cervical dilatation was achieved in 74 and 10% of the misoprostol- and placebo-treated women, respectively (odds ratio 25.62; 95% CI 9.61-68.28). The time required for pregnancy interruption was significantly shorter with misoprostol (P < .004). CONCLUSION: Misoprostol is significantly more effective in facilitating cervical dilatation than is placebo. The average intervention time for pregnancy interruption was reduced by 35%.

Abortion, Induced↗
PubMed1993

Pregnancy interruption by vaginal misoprostol.

A total of 132 pregnant women with average gestational age of 14.2 weeks (range 11-22 weeks) undergoing legal abortion volunteered for a trial utilizing vaginal administration of misoprostol. In 106 women a dose of 800 micrograms was utilized, whilst in 26 women 1,200-1,600 micrograms were given. Nonsurgical expulsion of the fetus was successful in 117 cases (88.6%). Four cases had to be excluded for various social reasons. A total of 11 did not achieve fetal expulsion within 56 h after application of misoprostol. These cases (11/132; 8.3%) were considered failures. Previous reports in the literature of toxicity trials on animals reporting no fetotoxic nor teratogenic effects of misoprostol at doses up to 10,000 micrograms/kg body weight seem to be of no validity in the human since we could demonstrate that almost 80% of pregnancies were interrupted at a dose of 10-15 micrograms/kg body weight. The conclusion is that vaginal administration of this prostaglandin analogue, not requiring cool temperature for storage, is remarkably effective in achieving safe interruption of pregnancy without any significant complications.

Abortion, Legal↗
PubMed1990

Widespread dermatophyte infections that mimic collagen vascular disease.

This article reports the cases of two patients in whom a widespread dermatophyte infection mimicked the cutaneous lesions of their underlying collagen vascular disease. Griseofulvin may be associated with an increased incidence of adverse cutaneous reactions in patients with systemic lupus erythematosus. One patient with systemic lupus erythematosus developed erythema multiforme after taking griseofulvin.

Adult↗
PubMed1990

Mechanism of action of doxepin in the treatment of chronic urticaria.

The present study examined 15 patients previously resistant to conventional antihistamines, in which doxepin at doses in the range of 50-75 mg/day was shown to be effective in treatment of chronic urticaria and without significant adverse side effects. However, some controversy remains about its mechanism of action in this particular disease. The aim of the present study was to examine the muscarinic, H1 and H2 blocking activity of doxepin. The following methods were used: a) gastric acid hypersecretion induced by histamine and carbachol in the pylorus-ligated rat preparation; b) contractile dose-response curves to histamine and carbachol in the guinea pig ileum; c) dimaprit-stimulated guinea pig atrium in vitro. pA2 values were determined for atropine, mepyramine, cimetidine and doxepin. As regards histamine, doxepin (50 mg/kg, po) increased gastric pH and decreased secretion volume, gastric acid concentration and total acid output; with carbachol, doxepin weakly antagonized those values. In the ileum, doxepin competitively antagonized carbachol (pA2 = 7.08) and histamine (pA2 = 9.72); pA2 values for atropine and mepyramine against carbachol and histamine were 9.11 and 8.82, respectively. In the atria, the dose-response curve to dimaprit was also competitively displaced by cimetidine (pA2 = 6.69) and doxepin (pA2 = 6.00). Doxepin displayed a very high affinity for H1 histamine receptor, being 8-fold more potent than mepyramine. Doxepin showed significant H2 blocking activity which was 5 times less potent than that of cimetidine. Doxepin competitively antagonized carbachol in the guinea pig ileum, and was 107 times less potent than atropine. The combined H1, H2 and muscarinic blocking activities of doxepin may contribute towards explaining its clinical efficacy in the treatment of chronic urticaria.

Adult↗
PubMed1989

Tripe palms and malignancy.

Tripe palms are characterized clinically by thickened velvety palms with pronounced dermatoglyphics. We describe two patients with triple palms and pulmonary tumors, and review the 77 patients with idiopathic- and malignancy-associated tripe palms reported in the world literature. The majority (94%) of published cases of tripe palms occurred in patients with cancer; only five patients showed no evidence of an associated malignancy. Tripe palms were frequently seen in conjunction with acanthosis nigricans (77% of cases), although they can occur alone (23% of cases). In cancer patients with tripe palms alone, the most common underlying neoplasm was pulmonary carcinoma (53% of cases), whereas patients with both tripe palms and acanthosis nigricans frequently had gastric (35% of cases) or pulmonary (11% of cases) carcinomas. A wide variety of other solid tumors have also been observed. Importantly, in over 40% of patients, tripe palms were the presenting feature of a previously undiagnosed malignancy. Therefore, all patients with tripe palms should be evaluated with a full diagnostic work-up for an associated malignancy, particularly lung or gastric carcinoma.

Aged↗
PubMed1989

Acute febrile neutrophilic dermatosis.

Acute febrile neutrophilic dermatosis, or Sweet's syndrome, usually occurs in middle-aged women with a preceding upper respiratory tract infection. In about 20 percent of reported cases, the syndrome is associated with an underlying malignancy, most frequently acute myelogenous leukemia. A dense infiltrate of mature neutrophils is seen in the middle and upper portions of the dermis. Corticosteroid therapy produces rapid improvement of all manifestations of the syndrome.

Acute Disease↗
PubMed1989

Photoallergy to benzophenone.

Incorrect diagnosis of photoallergy to sunscreen products represents a unique clinical dilemma. Increasing sunscreen usage for suspected idiopathic photosensitivity or a change to a sunscreen containing the same photoallergen only worsens the problem. While photoallergy to p-aminobenzoic acid and its esters is well known by dermatologists and the lay public, benzophenone photoallergy is not well appreciated. We report herein the cases of four individuals with photoallergy to oxybenzone in sunscreens. It is likely that such reactions will become more commonplace since oxybenzone is by far the most frequently used agent in modern, high sun protection factor sunscreens (greater than 8 sun protection factor) being marketed today.

4-Aminobenzoic Acid↗
PubMed1989

Benign familial pemphigus complicated by herpes simplex virus.

Herpes simplex should be recognized as a precipitating factor, a secondary invader, or an imitator of chronic benign familial pemphigus. Results of Tzanck smear and viral culture can confirm the presence of the pathogen so that acyclovir therapy can be instituted.

Acyclovir↗
PubMedDate not supplied

Cellular and clinical pharmacokinetic/pharmacodynamic basis for lack of efficacy of 21-day continuous topotecan in patients with untreated advanced adenocarcinoma of the pancreas.

BACKGROUND: In a phase II study, topotecan was evaluated for response and toxicity in patients with advanced pancreatic carcinoma at the schedule of 0.7 mg/m2/day q 21 days q 28 days. METHODS: Responses were assessed after at least 2 courses using WHO criteria, and toxicity was evaluated after each course according to the CTC-NCI standards. Between December 1995 and September 1997, 15 assessable patients (median age, 55 years; range, 36-74; median ECOG performance, 1; range, 0-3) were included in the study. All had biopsy-proven and measurable disease, a life-expectancy of at least 3 months, and normal bone marrow, liver, and renal function. None of the patients had undergone prior cytotoxic or radiation therapy, and 10 were initially treated by surgery. Twenty-five cycles were assessable for toxicity. Plasma was collected from 7 patients who had received a total of 10 cycles and was, after extraction with methanol at -20 degrees C, analyzed for total topotecan by an HPLC method. The thus determined steady-state concentrations were assessed for their capacity to affect growth and DNA integrity in the BxPC-3 human pancreatic carcinoma cell line after 21 days of continuous exposure. For these purposes, we used a sulforhodamine B staining assay, and agarose gel electrophoresis, respectively. RESULTS: Grades 3-4 leukopenia, thrombocytopenia, granulocytopenia, and anemia occurred in 8, 6, 8 and 8 cycles, respectively. Other mild to moderate side effects (grades 1-2) included malaise, nausea and vomiting, anorexia, and alopecia. No objective tumor response was documented. HPLC analysis of patients' plasma showed the attainment of constant steady-state levels of 1.0+/-0.1 ng/mL during the entire infusion period. At such a concentration, topotecan did not significantly affect growth or DNA integrity in the BxPC-3 cells. Fifty percent cell growth inhibition and appreciable oligonucleosomal DNA fragmentation were only evident with 21 days topotecan > or = 50 ng/mL. CONCLUSIONS: Our data suggest that the lack of clinical activity of 0.7 mg/m2 daily topotecan for 21 days q 28 days in patients with advanced pancreatic carcinoma might be partially attributed to the achievement of non-tumoricidal plasma drug concentrations.

Adenocarcinoma↗