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Biomedical subjects

A Pelaez

Publications and source records attributed to A Pelaez.

11 recordsLinked to original sources
PubMed2001

Unifying framework for synchronization of coupled dynamical systems.

A definition of synchronization of coupled dynamical systems is provided. We discuss how such a definition allows one to identify a unifying framework for synchronization of dynamical systems, and show how to encompass some of the different phenomena described so far in the context of synchronization of chaotic systems.

Journal Article↗
PubMed1996

Occupational allergy due to spider mites: Tetranychus urticae (Koch) and Panonychus citri (Koch).

BACKGROUND: Allergy to both house dust and storage mites is well established, but information about other species of mites is scant. OBJECTIVE: One hundred and fifty patients directly exposed to an occupational environment were studied to assess whether spider mites (Tetranychidae) caused their allergic symptoms. We also studied a group of 50 patients from an urban environment, who were not occupationally exposed to spider mites, with a strong sensitization to Dermatophagoides pteronyssinus (RAST class 4). METHODS: Case history (including questions about work-related symptoms), skin tests, RAST and conjunctival provocation tests were performed in both groups using Tetranychus urticae and Panonychus citri extracts as allergens. Cross-reactivity between spider mites and D. Pteronyssinus was determined by RAST inhibition. RESULTS: Fifty-four of 150 rural workers were positive to Tetranychidae and in all cases there was an associated sensitization to D. pteronyssinus. All individuals belonging to the urban group were positive to spider mites. RAST inhibition demonstrated a significant cross-reactivity between Tetranychidae and D. pteronyssinus. Five of fifty-four rural workers sensitized to spider mites developed symptoms only when they handled plants or fruits infested with spider mites and they became asymptomatic when exposure ceased. CONCLUSION: In the rural population studied, 36% of workers were found to be sensitized to spider mites and 10% had symptoms associated with occupational exposure. Since specific IgE antibodies to spider mites could not be detected in the absence of the specific IgE antibodies to D. pteronyssinus, and as all the affected workers were RAST positive to D. pteronyssinus, prior sensitization to house dust mites may be a risk factor for occupational allergy to spider mites.

Adult↗
PubMed1995

Immunological study of Melkersson-Rosenthal syndrome. Lack of response to food additive challenge.

A study was made of six patients with Melkersson-Rosenthal syndrome (MRS) to establish the aetiological role of foodstuffs and/or additives and the possible associated immunological alterations. In all cases Melkersson-Rosenthal syndrome (MRS) was diagnosed both clinically and histologically, excluding other causes of orofacial granulomatosis (OFG). A detailed study of possible triggering factors was performed in all patients. Blood analysis, x-rays and cultures, were always within normal limits, with the exception of the finding of circulating immune complexes (CICs) in three patients with facial palsy associated, and C-reactive protein positivity in two patients who presented persistent labial oedema. All patients were subjected to skin-prick tests with common inhalant allergens and with foods when sensitization to foods were suspected, and patch tests with European Standard Series and pastry components, organic dyes, perfumes and fragrances series. The results were negative in all cases. When asymptomatic, the patients were subjected to a double-blind oral challenge, under placebo control, with additives (monosodium glutamate, tartrazine, sulfites, erythrosine, paraoxybenzoate, sodium benzoate, lactose, aspirin, and annate), which was again negative. In no case did the patients refer the appearance of outbreaks with exposure to foods or contactants, and the course of the disease was unaffected by exclusion diets and the elimination of contactants. To conclude, we observed no sensitization to foods, additives or contactants in our patients. Likewise, there were no antecedents of atopy or hereditary predisposition related to the aetiopathogeny of MRS. The significance of the CIC encountered only in patients with facial paralysis remains to be established, due to the limited number of patients studied.

Adult↗
PubMed1994

Aluminium allergy in patients hyposensitized with aluminium-precipitated antigen extracts.

During hyposensitization therapy with aluminium-precipitated antigen solutions, a small % of patients develop persistent subcutaneous nodules at the injection site; the existence of delayed sensitivity to aluminium has been implicated in the pathogenesis of these nodules. We studied the prevalence of aluminium sensitivity (using patch, prick and intradermal tests) and common contact allergens (TRUE Test) in 20 healthy subjects, and in 40 patients treated with aluminium-containing extracts, 20 of whom had persistent subcutaneous nodules that remained for more than 2 months, the other half having no nodular reactions or nodules that remained for less than 2 months. Aluminium sensitivity was found only in those patients of the treated group who had persistent nodular reactions, 4 cases of positivity to an aluminium chloride patch test being found. All 4 cases were women, nodules remained for more than 6 months, and intracutaneous tests were negative. 3 of them also had contact sensitivity to nickel. In 2 cases, nodules were removed for histological and histochemical examination, showing non-specific inflammatory granulomas, and aluminium crystals being found in only 1 case. It is concluded that delayed sensitivity to aluminium appears to be implicated in the pathogenesis of persistent nodular reactions, but sensitivity to aluminium was not found in patients treated with aluminium-precipitated extracts without persistent nodular reactions.

Adolescent↗
PubMed1985

Challenge tests with tartrazine in patients with asthma associated with intolerance to analgesics (ASA-Triad). A comparative study with placebo.

In a study of the incidence of respiratory reaction to tartrazine, challenge tests were made with doses of 5, 25, 50, 100 and 200 mg of tartrazine and with a placebo, on forty-seven patients with asthma associated with intolerance to analgesics (ASA-Triad). The patient's clinical and spirographic condition was satisfactory when the test was made, and the administration of bronchodilators had been stopped 24 hr previously. In a total of 141 tests with tartrazine on forty-seven patients, only five tests were positive and occurred in only four patients. In three patients the test gave a negative result when repeated with an identical or larger dose of tartrazine. Only one patient had a respiratory reaction with 5 mg of tartrazine on two successive occasions, and this result is considered doubtful bearing in mind that the variation in FEV1 was at its limit. All the tests with placebo were negative except one. The clinical lability of the ASA-Triad patients could be the cause of some of the respiratory reactions attributed to tartrazine in some studies. The lability could, above all, be dependent on the suppression of the symptomatic treatment. The inconvenience associated with a colour-free diet and the small incidence of proven reactions to tartrazine, tend to invalidate the practice of recommending such diets unless evidence is available of a positive challenge test on at least two occasions. Even so, the risks induced are minimal.

Adolescent↗
PubMed1985

Cross-reactivity between Parietaria judaica and Parietaria officinalis.

The relative allergenicities of Parietaria judaica and Parietaria officinalis have been studied by in vivo and in vitro techniques and a strong resemblance has been shown, with common allergenic polypeptides, though they differ in a group of anodic proteins. In vivo activity was very similar and both pollen extracts reacted with sera from patients who were sensitive to P. judaica, thus demonstrating a high rate of cross-reactivity. Extracts from both species may therefore be used interchangeably in diagnosis and immunotherapy.

Allergens↗