The tightly coupled, one-for-one exchange of anions mediated by the human red blood cell AE1 anion-exchange protein involves a ping-pong mechanism, in which AE1 alternates between a state with the anion-binding site facing inward toward the cytoplasm (Ei) and a state with the site facing outward toward the external medium (Eo I t has long been known that energy-coupled transporters like the Na,K-ATPase are able to transport ions against their electrochemical gradients because the affinity of the ion-binding site changes when it is translocated from one side of the membrane to the other. For example, Na ϩ affinity is high for the inward-facing E 1 Na,K-ATPase form and low for the outwardfacing E 2 form, whereas K ϩ affinities have the opposite relationship (1). So far, no such asymmetry has been shown for ''passive'' transport systems in which ions move down their electrochemical gradients.The AE1 anion-exchange protein in human red blood cells seems to operate by a ping-pong mechanism, in which transport of Cl Ϫ or HCO 3 Ϫ across the membrane involves conversion of a form with the transport site facing inward (Ei) to a form with the site facing outward (Eo) or vice versa, a conversion that only occurs if a suitable anion is bound to the site (2-5). For both the unloaded (6, 7) and the Cl-loaded (8) forms of AE1, the free energies of the inward-facing forms are much lower than those for the outward-facing forms, so Ei Ͼ Ͼ Eo and ECli Ͼ Ͼ EClo.The possibility that AE1 might exhibit different asymmetric properties with respect to its two physiological substrates, Cl Ϫ and HCO 3 Ϫ , was first suggested by a brief report (9) that the rate of exchange of internal HCO 3 Ϫ (Bi) for external Cl Ϫ (Clo), Bi-Clo exchange, was faster than the reverse (Cli-Bo) exchange rate at 38°C. This finding was attributed to a differential inhibitory effect of these ions acting at an external ''modifier'' site, which later measurements failed to confirm (10, 11). Recently, we reinterpreted these data in light of a model (12) based on more complete kinetic information on Cl Ϫ -Cl Ϫ (10) and HCO 3 Ϫ -HCO 3 Ϫ (13) exchange, and hypothesized that at 38°C most of the HCO 3 -loaded transport sites face outward rather than inward as do the empty or Cl-loaded sites (13). This conclusion rested on only two data points at 38°C (9), where anion exchange is very fast (t 1/2 Ϸ 50 ms) and difficult to measure. To test the hypothetical asymmetry more rigorously, we have made far more extensive measurements of anion exchange under extremely asymmetric conditions and at 0°C where precise flux measurements are much easier to obtain. Materials and MethodsCell Preparation. Red blood cells were obtained from volunteers with informed consent and were washed three times in ice-cold 150 KH {150 mM KCl͞24 mM sucrose͞20 mM Hepes [4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid)], pH 6.9 at room temperature} to remove white cells and fibrin. Red cells were divided into two portions: one was washed three times at room temperature with 150 KH, pH 7.8 (at 0°C) an...

BACKGROUND. Currently, health professionals face the management of artificial airways in paediatric groups. This action requires delicate care and a lot of attention to detect, establish and manage pressing situations, in these cases being a greater risk of tracheo-pulmonary bacterial infections. OBJECTIVE. To identify and evaluate the scientific publications on infections in paediatric patients with tracheostomy tubes. MATERIAL AND METHODS. A systematic review of the years 2015-2020 was carried out, using the Elsevier, PubMed, Google Academic and Scielo databases, considering the population aged between 0-20 years who used a tracheostomy tube. RESULTS. From 322 articles distributed in the databases, 13 articles that met the inclusion criteria were selected. Comorbidities that were described as most frequently associated with infection of the tracheostomy tube in children were: neuromuscular disease, prematurity, ventilator use, congenital anomalies, chronic lung disease, obstruction airway, cystic fibrosis, and heart disease. The factors associated with length of stay (LOS) were the age from 30 days to 12 months, with a greater probability of re-entering the hospital and the presence of 4 or more complex chronic diseases. Regarding respiratory infections in patients with tracheostomy, P. aeruginosa was the most frequent bacteria present in cultures (90%), followed by Staphylococcus aureus. CONCLUSION. Although there are currently clinical criteria, risk factors and laboratory tests associated with infections of the post-tracheostomy tube in paediatric patients, further research is required to define clinical guidelines for the management in medical decision-making cases.

Pneumosinus dilatans is a rare disease characterized by air-filled expansion of a paranasal sinus. Approximately 134 cases are reported in the literature, but not only one associated with infantile cerebral palsy (ICP) and nasal polyposis. We herein present this case report aimed to further characterize this uncommon condition: a 28-year-old female diagnosed with infantile cerebral palsy and nasal polyposis, in whom the cranio-facial CT scan revealed the association of a pneumosinus dilatans involving the frontal sinus. The patient is currently undergoing a protocol for endoscopic surgery of the nose and paranasal sinuses.

BACKGROUND. Otosclerosis is a primary disease of the human otic capsule and stapes stage, being a frequent cause of conductive hearing loss in our country. The surgical treatment of choice is stapes surgery and prosthesis placement, performed in a conventional way, with a surgical microscope, for 30 years in our hospital. Recently, the option of performing stapes surgery endoscopically was introduced in our centre. OBJECTIVE. To evaluate the results in stapes surgery for otosclerosis between the conventional microscopic versus endoscopic procedure. MATERIAL AND METHODS. An observational, analytical and retrospective study on patients undergoing stapes surgery with microscopic and endoscopic technique was conducted. Data such as age, sex, state of origin, affected ear, as well as the technique used, duration of surgical intervention, hearing gain and postsurgical complications were taken. Data were taken from the records of patients admitted to the hospital. Descriptive statistics, Mann-Whitney U and Pearson’s Ji2, were used, considering a value of p≤ 0.05 as significant. RESULTS. No significant differences were found in surgical time or postoperative hearing between the two surgical techniques. The female sex was the most intervened. There was no significant difference between the post-surgical complications of both groups. CONCLUSION. Both procedures appear to be effective, with similar risks and postoperative results for the surgical treatment of otosclerosis.

Purpose To determine what influence our instagram account, @accigunbosque, can have on the spread of medical knowledge, as well as the impact it may have on the actual learning process, in order to describe the utility of these accounts on social media within the medical community. Methods A longitudinal, prospective, descriptive study and a narrative perception analysis. Interaction data was recollected for 26 weeks, and evaluations were carried out with 2 posts from the page, in order to assess the quality of interaction with educational material. The differences between before and after scores of the participants in the educational modules were calculated with the Wilcoxon signed-rank test for related samples. Finally, the texts of comments from publications were analyzed with NVivo11. Results The page generated 48 infographic posts and held 3 webinars throughout the study period. The maximum number of accounts reached was 15,368, the average number of visits to the profile was 380, the average amount likes received on posts was 316, and the maximum number of saves was 414. The median of comments per publication was 3, ranging from none to a maximum of 27. Participation in the quizzes was 16/568 and 3/502, and a significant difference was found (p = 0.024) in the first quiz. The content of 186 comments was reviewed and only 4% made additional contributions or left constructive remarks, with the rest being composed of emoticons and admiration. Conclusions For means of data sharing, Instagram can be a very useful tool as seen within our study. However, the actual learning process behind Instagram may prove to be deficient, considering the little participation in our two educational modules. This allows one to hypothesize that many Instagram users are likely to passively view and interact with educational Instagram posts, but may not actively retain information as expected.