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Biomedical subjects

M Pena

Publications and source records attributed to M Pena.

30 records · Page 2Linked to original sources
PubMed1977

Failure of lactose and glucose to influence in vivo intestinal calcium transport in normal rats.

The influence of luminal lactose and glucose on intestinal calcium transport was examined in vivo in normal post-weaned young rats. In situ segments of duodenum, midgut and ileum were perfused through the lumen for 1 h with an isotonic solution of 3.4 mM calcium containing radioactive isotopic 45Ca as tracer and additionally either 10 mM lactose or 10 mM glucose, or, for the control group, no saccharide. Net absorption was measured by disappearance of luminal calcium; lumen-to-plasma flux was determined from the disappearance of tracer 45Ca. This concentration of luminal lactose or glucose had no direct effect on calcium transport under these steady state conditions.

Animals↗
PubMed1975

Calcium-binding activity of rat intestinal mucosa after massive small bowel resection.

Male Sprague-Dawley rats underwent resection of 50 cm of either proximal or distal small intestine or sham-operation. 6-7 weeks after operation mucosal calcium-binding activity was measured in segments of duodenum ileum and remaining 'midgut'. Similar measurements were obtained from weight and age-matched unoperated rats. There was no difference in calcium-binding activity between unoperated and sham-operated animals. After proximal resection the binding activity increased significantly in duodenum and midgut but did not change in ileum. After distal resection the binding activity decreased in duodenum but was unchanged in midgut and ileum. These studies show that mucosal calcium-binding activity undergoes changes but alteration of the binding activity in remaining gut varies with the location of the small bowel resection.

Animals↗
PubMedDate not supplied

Prevalence of allergy to latex in the pediatric population.

Latex is a substance that is extracted from the plant Hevea Brasiliensis, and world production is 6 million metric tons per year. After gathering it undergoes a series of processes in which ammonia, vulcanization-accelerating additives or anti-oxidants are added. All of this may constitute the antigenic load that latex contains. It is used in medicine for gloves, drainage tubes, dental implants and a growing number of products from condoms to sport products or automobile components. Over fifteen different allergenic bands have been described, with molecular weights of between 2 and 100 kDa. In a joint study, USA-Finland identified three antigenic bands that predominate according to the population type studied (2). In children with spina bifida, congenital urogenital abnormalities or those submitted to multiple surgical interventions, the band of 27 kDa is predominant. This antigen has not been detected in adult serum, which suggests that contact with the antigen is through the mucous membranes and the sensitization is triggered from here. The incidence of allergy to latex in the general population is not known, but it seems to be lower than 1%. Turjanmaa (1) establishes a frequency of 0.125% (1/800) in patients submitted to general surgery. The incidence of sensitization to latex varies according to the population studied. Among the population considered to be at risk are the workers of the health environment, where the incidence is between 2.6 and 16.9%, whereas in the general population the percentage is around 1%. Sensitivity to latex is of great importance in patients suffering from spina bifida, in whom an incidence of between 28 and 67% has been found. We present our experience in a group of children attending our service for the first time for diverse reasons of supposed allergic etiology. The objective is to determine the incidence of sensitization to latex according to the diagnostic methodology [cutaneous test or by determination of specific IgE (CAP)]; according to the type of patient (atopic or non-atopic), the direct relationship with latex material and the role that can be played by a history of surgical intervention. In our experience with 282 children studied in our pediatric allergology service using diverse methods, the incidence of allergy to latex is 3.19%. Nevertheless, if we analyze this percentage we observe that if the diagnosis is based exclusively on cutaneous tests, it is only 1.08%; if to establish a diagnosis we used exclusively the determination of specific IgE (CAP) we would label 7. 2% of our children as allergic. Atopy is a factor that facilitates sensitization. In our sample, the incidence among the atopic population is 4.4%, though this percentage may vary between 1.69% and 9.5% depending on the methodology used. There are several hypotheses for explaining these discrepancies in the diagnostic tests. Although there do not seem to be differences regarding the ammonia content of the different lots, it seems that the differential factor could lie in the type of extract and in whether it is commercial or a natural latex extract. It could be a consequence of the existence of a prophyllin, so it has not been ruled out that a part of the IgE is an antiprophyllin. The presence of different epitopes would mean that each of them has the ability to produce its own specific IgE, though the RAST/CAP was not able to differentiate them and identified them as whole. The rate of allergy to latex in a group of children suffering from myelomeningocele is 80%. At a paediatric level, sensitization to latex is influenced by the means of contact, the duration of the exposure to the antigen and the fact that the exposure occurs early, which in the case of children with myelomeningocele is associated with the immaturity of the defence mechanism of the mucous membranes.

Child↗
PubMedDate not supplied

Allergy to pomegranate (Punica granatum).

We present the case of a 7-year-old IgE-dependent asthmatic child who, moments after ingesting several pomegranate seeds, showed a clinical condition of bronchospasm which responded to treatment with inhaled salbutamol. Cutaneous tests using the prick-by-prick techniques with extract of the fresh fruit were positive and the RAST for pomegranate was 0.8 PRU/ml. In the literature studied, we have found few specific references to allergy to pomegranate.

Asthma↗
PubMedDate not supplied

The prick test and specific IgE (RAST and MAST-CLA) compared with the oral challenge test with milk, eggs and nuts.

In spite of the development of numerous in vivo and in vitro diagnostic techniques for food allergy, the oral challenge test (OCT) is still the "gold standard". Consequently, we have compared it with some of the more recent techniques. We studied 36 patients with a medical history compatible with food allergy (to milk, eggs or nuts) and 11 patients without food allergy (6 nonatopic and 5 with acarid allergy). A prick test, specific IgE (RAST and MAST-CLA) and an OCT with the suspected food were performed in all patients. The following parameters were calculated for all patients overall and for each of the three allergic groups separately: sensitivity, specificity and match with the OCT. We also studied the RAST-MAST-CLA correlation and the variability of the MAST-CLA. The prick test was the most sensitive (95%) and the MAST-CLA (13% divergence in two measurements) the most specific (92%). The RAST and the MAST-CLA (68% match) gave similar results, with an acceptable match (75% and 77%, respectively) with the OCT. The medical history could only suggest the diagnosis (39% false-positives). After comparing the results with those in the literature, it is suggested that greater attention should be paid to the limitations of these techniques compared with the OCT.

Adolescent↗
PubMedDate not supplied

The value of specific IgG4 determination in childhood allergy to egg in relation to specific IgE and the provocation test.

The value of IgG4 determination in food allergy shows conflicting results in the medical literature. Our pediatric study was carried out in two phases. The first compared the percentage of detection and agreement of specific IgE (RAST) and IgG4 (FAST) for egg white and egg yolk in 104 patients with possible hypersensitivity to egg and positive skin tests. The second, in 22 new patients, compared IgG4 determination with the oral provocation test (OPT; the diagnostic "gold standard"). In the first phase, the percentage of positive cases for both antibodies was almost identical, but little agreement was observed between them. In the second phase, the sensitivity, specificity and agreement with the OPT were higher for IgE than for IgG4. Thus, we conclude that IgG4 levels may be high in food allergy, but their detection seems to have little diagnostic value in allergy to egg proteins in children.

Administration, Oral↗
PubMedDate not supplied

Study of the sensitization to storage mites in a pediatric population in Barcelona.

We performed the following study in order to determine the prevalence and characteristics of sensitization to storage mites in children mostly from the city of Barcelona. All children over 3 years of age attending our unit for the first time due to respiratory problems were given cutaneous tests using the prick test for the house dust mites Dermatophagoides pteronyssinus and D. farinae, and the storage mites Acarus siro, Lepidoglyphus destructor and Tyrophagus putrescentiae. We carried out a RAST and conjunctival test when it was considered appropriate. Of a total of 356 children studied, 39 showed cutaneous sensitization to storage mites, which represented 11% of the population studied, and 20% of the total sensitized to mites. However, only 3 of these children were only sensitized to storage mites, the remaining 36 (92%) also showing sensitization to house dust mites. Of the storage mites studied, L. destructor was the most significant. A history of immunotherapy to mites was associated with a greater percentage of positive cutaneous tests to storage mites, although this was not the case with the RAST test.

Animals↗