Polysaccharides as scaffolds for bone regeneration

This review is concerned with the use of polysaccharides for bone regeneration. Cellulose, alginate and chitosan have been chosen as examples of the formidable potential of this class of materials. Many others could be cited but our experience and research interests dictated the choice. As in many areas of research we know how they started but we cannot see how and if they will end. Modification of cellulose was our entrance to the world of polysaccharides and a lot of what we know we owe to Charles Baquey, to whom we would like to express our immense gratitude. This chapter is dedicated to him, for his cooperation, unlimited enthusiasm and friendship.

Résumé

Cette revue s'inscrit dans l'utilisation de polysaccharides pour la régénération osseuse. La cellulose, l'alginate et le chitosan ont été choisis comme exemple compte tenu du formidable potentiel de cette classe de matériaux. Beaucoup d'autres auraient pu être cités mais notre expérience et nos intérêts en recherche ont guidé ce choix. La modification de cellulose a été notre introduction dans le monde des « polysaccharides » et la plupart de nos connaissances sont dues à Charles Baquey à qui nous voulons ici exprimer notre immense gratitude. Ce chapitre lui est dédié pour son implication, son enthousiasme illimité et son amitié.     

An Optimization based on Simulation Approach to the Patient Admission Scheduling Problem: Diagnostic Imaging Department Case Study

The growing influx of patients in healthcare providers is the result of an aging population and emerging self-consciousness about health. In order to guarantee the welfare of all the healthcare stakeholders, it is mandatory to implement methodologies that optimize the healthcare providers' efficiency while increasing patient throughput and reducing patient's total waiting time. This paper presents a case study of a conventional radiology workflow analysis in a Portuguese healthcare provider. Modeling tools were applied to define the existing workflow. Re-engineered workflows were analyzed using the developed simulation tool. The integration of modeling and simulation tools allowed the identification of system bottlenecks. The new workflow of an imaging department entails a reduction of 41 % of the total completion time.     

Flexibility of emerging face categorization at different levels of abstraction

Categorization of visual stimuli at different levels of abstraction relies on the encoding of relevant diagnostic features present at different spatial scales. We used the Eidolon Factory, an image-manipulation algorithm that introduces random disarray fields across spatial scales, to study how such a process flexibly combines perceptual information to perform successful categorization depending on task demands. Images of animal faces, human faces, and everyday objects were disarrayed coherently (random fields correlated) or incoherently (random fields randomized) to create a family of 50 eidolons per stimulus image with increasing disarray. Participants (N = 243) viewed each family of eidolons in a smooth sequence from maximum disarray to no disarray and performed a category verification task either at the superordinate (any face type) or basic (human face only) levels at two levels of uncertainty: participants in one group used their gut feeling to respond, whereas another group had to be sure of their decision. When participants used their gut feeling to respond, we observed a superordinate-level advantage. When they were sure of their response, we observed a basic-level advantage. Coherently disarrayed sequences impaired target detection compared to incoherently disarrayed sequences for both levels of response certainty. Furthermore, participants’ sensitivity in the Any Face condition increased when they observed coherently disarrayed sequences and had to be sure of their response. These results suggest that the visual system does not strictly adhere to feedforward processing but flexibly adjusts to the relevant perceptual information depending on task context.     

Diazepam enhancement of GABA-gated currents in binary and ternary GABAA receptors

Although the predominant GABA_A receptor isoform in the adult rodent central nervous system is a ternary complex composed of α₁β_2/3γ₂-subunits, small populations of binary receptors lacking β-subunits (i.e., complexes containing αγ-subunits) have also been identified. When expressed in HEK 293 cells, recombinant GABA_A receptors composed of either α₁β_2/3γ₂- or α₁γ₂-subunits form benzodiazepine-responsive, GABA-gated chloride channels. The objective of this study was to compare the ability of a prototypic benzodiazepine (diazepam) to augment GABA-gated chloride currents in these binary and ternary receptor isoforms. The potency of GABA was characteristically increased by diazepam (1μM) in both receptor isoforms, but this increase was significantly greater (p<0.05) in receptors composed of α₁β₂γ₂-subunits (approximately five-to sixfold) compared to α₁γ₂-subunits (∼2.2-fold). At GABA concentrations approximating its EC₅₀ value (5 μM), the greater augmentation observed in ternary receptors was attributable to a higher efficacy of diazepam. Radioligand binding studies revealed that theB _max of [³H]flunitrazepam was increased ∼1.8- and 3.5-fold in cells expressing α₁β₂γ₂- and α₁β₃γ₂-subunits, respectively, compared to cells expressing α₁γ₂-subunits. A similar increase (∼3.8-fold) in theB _max of [³H]Ro 15-4513 was observed in HEK 293 cells transiently transfected with cDNAs encodign α₆β₃γ₂- compared to α₆γ₂-subunits. TheK _d values of these radioligands were not different in binary and ternary receptor isoforms. It is hypothesized that the greater efficacy of diazepam in α₁β₂γ₂ compared to α₁γ₂ GABA_A receptors results from the higher benzodiazepine binding site density produced by the formation of a ternary complex.     

Attitudes towards do-not-resuscitate decisions: differences among health professionals in a Portuguese hospital

OBJECTIVES: Implementation of an in-hospital cardiopulmonary resuscitation (CPR) program stresses the need to discuss do-not-resuscitate (DNR) orders, as CPR may not be desirable in some terminally ill patients. Ethical, social, educational, and professional issues may influence these decisions. This study was designed to evaluate attitudes among four categories of healthcare professionals. DESIGN AND SETTING: Survey in a tertiary hospital in Portugal. METHODS: An anonymous self-completed questionnaire was distributed to 825 staff members, 527 of whom responded (20% physicians, 44% nurses, 20% health technicians, 16% healthcare domestic staff). Responses were compared between the various health professional groups. RESULTS: The level of medical/health training was positively related to the frequency of DNR decisions (physicians and nurses could foresee more circumstances warranting DNR decisions than technical/administrator or domestic staff) and negatively related to the willingness to include the patient's family in the DNR decision (physicians and nurses saw less need for the family's participation than technical/administrator or domestic staff). Significant differences were also found between professional groups regarding the physician's responsibility and the nurses' participation in DNR decisions. There was no difference between the professional groups regarding the need to note the DNR decision in clinical charts. CONCLUSION: Health professionals differ in their attitudes concerning DNR decisions. In particular, the level of medical/health training and/or degree of involvement with the patient's daily care may play an important role in DNR decisions.     

The sensitivity of room-air pulse oximetry in the detection of hypercapnia

OBJECTIVE: To estimate the sensitivity of room-air pulse oximetry in the detection of moderate hypercapnia. METHODS: In this retrospective case-control study, charts were reviewed from patients with and without moderate hypercapnia (Pa co 2 >50 mm Hg), as determined by analysis of arterial blood gas samples obtained in the ED. Test characteristics (sensitivity, specificity, and likelihood ratios [LR) for room-air pulse oximetry < or = 96% to detect hypercapnia were calculated, as were confidence intervals. RESULTS: A total of 349 charts were eligible for abstraction-92 cases and 257 controls. A room-air pulse oximetry reading < or = 96% detected 88 of 92 cases of hypercapnia. Test characteristics were as follows (with 95% confidence interval): sensitivity, 0.96 (0.89-0.99); specificity, 0.39 (0.33-0.45), LR of a room-air pulse oximetry value >96%, 0.1 (0.04-0.3); and LR of a room-air pulse oximetry value < or = 96%, 1.6 (1.4-1.7). CONCLUSION: Room-air pulse oximetry detects moderate hypercapnia with high sensitivity.