Célia M. Antunes

Airborne olive pollen counts are not representative of exposure to the major olive allergen Ole e 1

Pollen is routinely monitored, but it is unknown whether pollen counts represent allergen exposure. We therefore simultaneously determined olive pollen and Ole e 1 in ambient air in Córdoba, Spain, and Évora, Portugal, using Hirst‐type traps for pollen and high‐volume cascade impactors for allergen.

Variation of the group 5 grass pollen allergen content of airborne pollen in relation to geographic location and time in season

BACKGROUND Allergies to grass pollen are the number one cause of outdoor hay fever. The human immune system reacts with symptoms to allergen from pollen. OBJECTIVE We investigated the natural variability in release of the major group 5 allergen from grass pollen across Europe. METHODS Airborne pollen and allergens were simultaneously collected daily with a volumetric spore trap and a high-volume cascade impactor at 10 sites across Europe for 3 consecutive years. Group 5 allergen levels were determined with a Phl p 5-specific ELISA in 2 fractions of ambient air: particulate matter of greater than 10 μm in diameter and particulate matter greater than 2.5 μm and less than 10 μm in diameter. Mediator release by ambient air was determined in FcεRI-humanized basophils. The origin of pollen was modeled and condensed to pollen potency maps. RESULTS On average, grass pollen released 2.3 pg of Phl p 5 per pollen. Allergen release per pollen (potency) varied substantially, ranging from less than 1 to 9 pg of Phl p 5 per pollen (5% to 95% percentile). The main variation was locally day to day. Average potency maps across Europe varied between years. Mediator release from basophilic granulocytes correlated better with allergen levels per cubic meter (r(2) = 0.80, P < .001) than with pollen grains per cubic meter (r(2) = 0.61, P < .001). In addition, pollen released different amounts of allergen in the non-pollen-bearing fraction of ambient air, depending on humidity. CONCLUSION Across Europe, the same amount of pollen released substantially different amounts of group 5 grass pollen allergen. This variation in allergen release is in addition to variations in pollen counts. Molecular aerobiology (ie, determining allergen in ambient air) might be a valuable addition to pollen counting.

Bursting electrical activity in pancreatic β-cells: evidence that the channel underlying the burst is sensitive to Ca2+ influx through L-type Ca2+ channels

In glucose-stimulated pancreatic β-cells, the membrane potential alternates between a hyperpolarized silent phase and a depolarized phase with Ca2+ action potentials. The molecular and ionic mechanisms underlying these bursts of electrical activity remain unknown. We have observed that 10.2–12.8 mM Ca2+, 1 μM Bay K 8644 and 2 mM tetraethylammonium (TEA) trigger bursts of electrical activity and oscillations of intracellular free Ca2+ concentration ([Ca2+]i) in the presence of 100 μM tolbutamide. The [Ca2+]i was monitored from single islets of Langerhans using fura-2 microfluorescence techniques. Both the high-Ca2+ and Bay-K-8644 evoked [Ca2+]i oscillations overshot the [Ca2+]i recorded in tolbutamide. Nifedipine (10–20 μM) caused an immediate membrane hyperpolarization, which was followed by a slow depolarization to a level close to the burst active phase potential. The latter depolarization was accompanied by suppression of spiking activity. Exposure to high Ca2+ in the presence of nifedipine caused a steady depolarization of approximately 8 mV. Ionomycin (10 μM) caused membrane hyperpolarization in the presence of 7.7 mM Ca2+, which was not abolished by nifedipine. Charybdotoxin (CTX, 40–80 nM), TEA (2 mM) and quinine (200 μM) did not suppress the high-Ca2+-evoked bursts. It is concluded that: (1) the channel underlying the burst is sensitive to [Ca2+]i rises mediated by Ca2+ influx through L-type Ca2+ channels, (2) both the ATP-dependent K+ channel and the CTX and TEA-sensitive Ca2+-dependent K+ channel are highly unlikely to provide the pacemaker current underlying the burst. We propose that the burst is mediated by a distinct Ca2+-dependent K+ channel and/or by [Ca2+]idependent slow processes of inactivation of Ca2+ currents.

Changes in the salivary protein profile of morbidly obese women either previously subjected to bariatric surgery or not

Saliva is a non-invasive source of biomarkers useful in the study of physiological mechanisms. Moreover, this fluid has diverse functions, among which food perception and ingestion, making it particularly suitable for the study of obesity. The aims of this study were to assess changes in salivary proteome among morbidly obese women, with a view to provide information about mechanisms potentially related to the development of obesity, and to evaluate whether these changes persist after weight loss. Mixed saliva samples from morbidly obese women (N = 18) who had been either subjected (group O-BS) or not (group O) to bariatric surgery and women with normal weight (N = 14; group C) were compared for protein profiles, alpha-amylase abundance and enzymatic activity, and carbonic anhydrase (CA) VI abundance. Differences in salivary obese profiles were observed for 23 different spots. Zinc-alpha-2 glycoprotein-containing spots showed higher abundance in group O only, whereas cystatin S-containing spots presented higher abundance in the two groups of obese subjects. Most of the spots identified as salivary amylase were present at lower levels in group O-BS. With regard to the amylase enzymatic activity, increases were observed for group O and decreases for group O-BS. One interesting finding was the high correlation between levels of CA VI and body mass index in group O, which was not observed for groups O-BS or C. The differences between groups, mainly regarding salivary proteins involved in taste sensitivity and metabolism, point to the potential of using saliva in the study of obesity development.

Effects of high-fat diet on salivary α-amylase, serum parameters and food consumption in rats

Salivary α-amylase, a major protein in saliva, has been described as a marker of sympathetic nervous system activity, hence for metabolic energy balance. In this context, its expression in overweight and obesity is of interest. Rats fed with a diet enriched with sunflower oil differentially gained weight yielding two subgroups according to their susceptibility (OP) or resistance (OR) to obesity. Elevated plasmatic levels of leptin in the OP subgroup and altered plasmatic lipid profiles (lower triglycerides and higher total cholesterol/high-density lipoprotein (HDL) ratio compared to controls) in the OR subgroup were observed. Animals from the OP subgroup presented higher α-amylase expression and activity even prior to the dietary treatment, suggesting that this salivary protein may constitute a putative indicator of susceptibility for fat tissue accumulation. After 18 weeks of high-fat diet consumption, salivary α-amylase levels did not significantly change in the OP subgroup, but increased 3-fold in the OR subgroup. The increase in α-amylase levels for the latter might represent an adaptation to lower starch intake. These results suggest that salivary α-amylase secretion might be useful to predict susceptibility for weight gain induced by high-fat diet consumption.

The Effect of Tannins on Mediterranean Ruminant Ingestive Behavior: The Role of the Oral Cavity

Sheep, cattle and goat are domestic ruminants of significant economic interest in the Mediterranean region. Although sharing the same pasture ranges, they ingest different plants and plant parts and, consequently different levels of tannins. This suggests an ability to detect and adapt ingestion according to animal physiological limits of tolerance for plant secondary metabolites. This review will detail the effects of dietary tannins on feeding behavior, and the role of the oral cavity in this process, with focus on such ruminant species. The role of salivary protein profile in tannin perception in the oral cavity, and as a defense mechanism, will be discussed.

3-Hydroxypyrrolidine and (3,4)-dihydroxypyrrolidine derivatives: inhibition of rat intestinal α-glucosidase.

Thirteen pyrrolidine-based iminosugar derivatives have been synthesized and evaluated for inhibition of α-glucosidase from rat intestine. The compounds studied were the non-hydroxy, mono-hydroxy and dihydroxypyrrolidines. All the compounds were N-benzylated apart from one. Four of the compounds had a carbonyl group in the 2,5-position of the pyrrolidine ring. The most promising iminosugar was the trans-3,4-dihydroxypyrrolidine 5 giving an IC50 of 2.97±0.046 and a KI of 1.18 mM. Kinetic studies showed that the inhibition was of the mixed type, but predominantly competitive for all the compounds tested. Toxicological assay results showed that the compounds have low toxicity. Docking studies showed that all the compounds occupy the same region as the DNJ inhibitor on the enzyme binding site with the most active compounds establishing similar interactions with key residues. Our studies suggest that a rotation of ∼90° of some compounds inside the binding pocket is responsible for the complete loss of inhibitory activity. Despite the fact that activity was found only in the mM range, these compounds have served as simple molecular tools for probing the structural features of the enzyme, so that inhibition can be improved in further studies.

High external Ca2+ levels trigger membrane potential oscillations in mouse pancreatic β-cells during blockade of K(ATP) channels

Glucose depolarizes the pancreatic beta-cell and induces membrane potential oscillations, but the nature of the underlying oscillatory conductance remains unknown. We have now investigated the effects of the Ca2+ ionophore ionomycin and high external Ca2+ concentration ([Ca2+]o) on glucose-induced electrical activity and whole islet intracellular free Ca2+ concentration ([Ca2+]i), under conditions where the K(ATP) channel was blocked (100 microM tolbutamide or 4 microM glibenclamide). Raising [Ca2+]o to 10.2 or 12.8 mM, but not to 5.1 or 7.7 mM, turned continuous electrical activity into bursting activity. High [Ca2+]o (12.8 mM) regenerated a pattern of fast [Ca2+]i oscillations overshooting the levels recorded in tolbutamide. Ionomycin (10 microM) raised the [Ca2+]i and synergized with 5.1 mM Ca2+ to hyperpolarize the beta-cell membrane. The data indicate that a [Ca2+]i-sensitive and sulphonylurea-insensitive oscillatory conductance underlies the beta-cell bursting activity.

Association between Salivary Leptin Levels and Taste Perception in Children

The satiety inducing hormone leptin acts not only at central nervous system but also at peripheral level. Leptin receptors are found in several sense related organs, including the mouth. A role of leptin in sweet taste response has been suggested but, until now, studies have been based on in vitro experiments, or in assessing the levels of the hormone in circulation. The present study investigated whether the levels of leptin in saliva are related to taste perception in children and whether Body Mass Index (BMI) affects such relationship. Sweet and bitter taste sensitivity was assessed for 121 children aged 9-10 years and unstimulated whole saliva was collected for leptin quantification, using ELISA technique. Children females with lower sweet taste sensitivity presented higher salivary leptin levels, but this is only in the normal weight ones. For bitter taste, association between salivary leptin and caffeine threshold detection was observed only in preobese boys, with higher levels of salivary hormone in low sensitive individuals. This study is the first presenting evidences of a relationship between salivary leptin levels and taste perception, which is sex and BMI dependent. The mode of action of salivary leptin at taste receptor level should be elucidated in future studies.

Protein Electrophoresis in Saliva Study

Saliva started for been less studied than other body fluids, but in the last years it has being receiving an increased attention. Until now, more than 2000 different proteins and peptides have been identified in whole saliva and salivary glandular secretions [1]. From these, more than 90% derive from the secretion of the three pairs of “major” salivary glands (parotid, submandibular and sublingual glands). The remaining 10% derives from “minor” salivary glands and from extra-glandular sources, namely gingival crevicular fluid, mucosal transudations, bacteria and bacterial products, viruses and fungi, desquamated epithelial cells, and food debris [2].