Neurogenesis in the adult hippocampus declines with age, a process that has been implicated in cognitive and emotional impairments. However, the mechanisms underlying this decline have remained ...elusive. Here, we show that the age‐dependent downregulation of lamin B1, one of the nuclear lamins in adult neural stem/progenitor cells (ANSPCs), underlies age‐related alterations in adult hippocampal neurogenesis. Our results indicate that higher levels of lamin B1 in ANSPCs safeguard against premature differentiation and regulate the maintenance of ANSPCs. However, the level of lamin B1 in ANSPCs declines during aging. Precocious loss of lamin B1 in ANSPCs transiently promotes neurogenesis but eventually depletes it. Furthermore, the reduction of lamin B1 in ANSPCs recapitulates age‐related anxiety‐like behavior in mice. Our results indicate that the decline in lamin B1 underlies stem cell aging and impacts the homeostasis of adult neurogenesis and mood regulation.
SYNOPSIS
Mutations in the nuclear envelope protein lamin B1 are linked to cellular aging and senescence. Here, lamin B1 ablation in adult neural stem/progenitor cells (ANSPCs) in mice is shown to disrupt neurogenesis, leading to aging‐related behavioral changes.
Lamin B1 is highly expressed in ANSPCs, but selectively declines with age.
Conditional knockout of lamin B1 in ANSPCs leads to premature differentiation and reduction of adult hippocampal neurogenesis.
Lamin B1 knockout leads to age‐related anxiety‐like behaviours in mice.
Overexpression of lamin B1 suppresses ANSPC differentiation.
Ablation of the nuclear envelope protein lamin B1 in neural stem/progenitor cells disrupts neurogenesis and causes aging‐associated behavioral changes in mice.
Instituto de Ciencias Biomédicas and Centro de Estudios Moleculares de la Célula, Facultad de Medicina, Universidad de Chile, Santiago 653-0499, Chile
Submitted 22 January 2004
; accepted in final ...form 25 May 2004
In a previous work the involvement of a fenamate-sensitive Ca 2+ -activated nonselective cation channel (NSCC) in free radical-induced rat liver cell necrosis was demonstrated (5). Therefore, we studied the effect of radical oxygen species and oxidizing agents on the gating behavior of a NSCC in a liver-derived epithelial cell line (HTC). Single-channel currents were recorded in HTC cells by the excised inside-out configuration of the patch-clamp technique. In this cell line, we characterize a 19-pS Ca 2+ -activated, ATP- and fenamate-sensitive NSCC nearly equally permeable to monovalent cations. In the presence of Fe 2+ , exposure of the intracellular side of NSCC to H 2 O 2 increased their open probability ( P o ) by 40% without affecting the unitary conductance. Desferrioxamine as well as the hydroxyl radical (·OH) scavenger MCI-186 inhibited the effect of H 2 O 2 , indicating that the increase in P o was mediated by ·OH. Exposure of the patch membrane to the oxidizing agent 5,5'-dithio- bis -2-nitrobenzoic acid (DTNB) had a similar effect to ·OH. The increase in P o induced by ·OH or DTNB was not reverted by preventing formation or by DTNB washout, respectively. However, the reducing agent dithiothreitol completely reversed the effects on P o of both ·OH and DTNB. A similar increase in P o was observed by applying the physiological oxidizing molecule GSSG. Moreover, GSSG-oxidized channels showed enhanced sensitivity to Ca 2+ . The effect of GSSG was fully reversed by GSH. These results suggest an intracellular site(s) of action of oxidizing agents on cysteine targets on the fenamate-sensitive NSCC protein implicated in epithelial cell necrosis.
Ca 2+ -activated channels; radical oxygen species; oxidative stress
Address for reprint requests and other correspondence: A. Stutzin, Centro de Estudios Moleculares de la Célula, Facultad de Medicina, Universidad de Chile, 838-0453, Independencia, Santiago, Chile (E-mail: astutzin{at}bitmed.med.uchile.cl )
Abstract
Background
Given the problems generated by health care fragmentation, the coordinated provision of health care has become a priority, particularly in Latin America. This communication ...analyses the strategies for improving clinical coordination proposed by primary and secondary care doctors from public health service networks in six countries of the region (Argentina, Brazil, Chile, Colombia, Mexico and Uruguay), and their changes between 2015 and 2017.
Methods
Two cross-sectional survey-based studies (2015 and 2017) were analysed with application of the COORDENA questionnaire to a total of 4311 primary and secondary care doctors from two public health service networks in each country. A descriptive analysis was carried out, stratified by country and year, of the suggestions proposed in the open question ‘What do you propose to improve clinical coordination between primary and secondary care doctors in the network?
Results
In all countries, the introduction or improvement of strategies and mechanisms that facilitate interaction and mutual knowledge between professionals at different care levels were highlighted, especially joint meetings, direct communication mechanisms (such as telephone and/or e-mail) and strategies to strengthen the use of the referral and counter-referral sheet. Less frequently, other organisational strategies aimed at strengthening the primary care model, improving access to secondary care and coordinating the management level of the network, were also suggested.
Conclusions
The results contribute to generate recommendations for the improvement of clinical coordination in health systems, based on the suggestions of doctors, a perspective that is not usually considered in the design and implementation of interventions in health services. The need to promote strategies based on mutual feedback in the design of public health policies stands out.
Key messages
• The design of effective interventions aimed at improving coordination requires doctors’ participation.
• Strategies based on mutual feedback and communication should be promoted by healthcare organisations to improve clinical coordination.
Understanding cellular decisions due to receptor–ligand interactions at cell–cell interfaces has been hampered by the difficulty of independently varying the surface density of multiple different ...ligands. Here, we express the synthetic binder protein SpyCatcher, designed to form spontaneous covalent bonds with interactors carrying a Spytag, on the cell surface. Using this, we show that addition of different concentrations and combinations of native Spytag-fused ligands allows for the combinatorial display of ligands on cells within minutes. We use this combinatorial display of cell surface ligands—called CombiCells—to assess T cell antigen sensitivity and the impact of T cell co-stimulation and co-inhibition receptors. We find that the T cell receptor (TCR) displayed greater sensitivity to peptides on major-histocompatibility complexes (pMHC) than synthetic chimeric antigen receptor (CARs) and bi-specific T cell engager (BiTEs) display to their target antigen, CD19. While TCR sensitivity was greatly enhanced by CD2/CD58 interactions, CAR sensitivity was primarily but more modestly enhanced by LFA-1/ICAM-1 interactions. Lastly, we show that PD-1/PD-L1 engagement inhibited T cell activation triggered solely by TCR/pMHC interactions, as well as the amplified activation induced by CD2 and CD28 co-stimulation. The ability to easily produce cells with different concentrations and combinations of ligands should accelerate the study of receptor–ligand interactions at cell–cell interfaces.
Synopsis
The inherent difficulty in manipulating cell surface proteins limits our ability to study cell–cell recognition. This work develops a platform for the combinatorial display of cell surface ligands (CombiCells), and demonstrates its value for determining the sensitivity and costimulatory requirements for T cells recognizing antigens on target cells.
Proteins fused to SpyTag can be covalently coupled to the surfaces of cells expressing a membrane-anchored form of SpyCatcher.
This enables rapid production of cells expressing different concentrations and combinations of multiple proteins, including antigens and accessory receptor ligands.
Using CombiCells, the T cell receptor is found to be 10-fold more sensitive to its target ligand pMHC than CARs and BiTEs are to their target, CD19.
By presenting T cells with Spytag-pMHC, PD-1 engagement is shown to promiscuously inhibit T cell activation in the presence or absence of CD2 or CD28 co-stimulation.
Expression of SpyCatcher on the cell surface allows tritration and combinatorial display of purified ligands fused to Spytag, enabling controlled investigation of receptor–ligand interactions at immune cell interfaces.
OBJECTIVES: The effectiveness of community level interventions depends to a great extent on adherence. Currently, information on factors related to adherence in older adults from developing countries ...is scarce. Our aim was to identify factors associated to adherence to a physical activity intervention in older adults from a post-transitional middle income country. DESIGN, SETTING AND PARTICIPANTS: Using a combination of quantitative and qualitative methods we studied 996 older Chilean subjects (65–67.9 years at baseline) with low to medium socioeconomic status from 10 health centers randomized to receive a physical activity intervention as part of the CENEX cluster trial (ISRCTN48153354). MEASUREMENTS: Using a multilevel regression model, the relationship between adherence (defined a priori as attendance at a minimum of 24 physical activity classes spread over at least 12 months) and individual, intervention-related and contextual factors was evaluated. We also conducted 40 semi-structured interviews with older adults (n=36) and instructors (n=4). Transcripts of the interviews were analyzed using content analysis to identify barriers and facilitators to adherence. RESULTS: Adherence to physical activity intervention was 42.6% (CI 95% 39.5 to 45.6). Depression, diabetes mellitus, percentage of impoverished households and rate of arrests for violent crimes in the neighborhood predicted less adherence (p<0.05) while being retired, participation in physical activity prior to the intervention, and green areas per habitant were positively associated with adherence (p<0.05). The qualitative interviews identified three primary barriers to adherence: current health problems, lack of time due to commitments for caring for family members, and being employed, and two primary facilitators to adherence: the health benefits attributed to the intervention and the opportunity the classes provided for social interaction with others. CONCLUSION: In order to enhance effectiveness of community exercise interventions, strategies to improve participation should be targeted to older adults from deprived areas and those with psychological and medical conditions.
Fungal infections (FIs) are a major cause of morbi-mortality in immunocompromised patients. To date, there is little information about its burden in pediatric oncology centers in low- to ...middle-income countries. We aimed to compare clinical features and outcomes of fungal infection present on admission (POA) and healthcare-associated infections (HAI) in children with hematologic and malignant diseases at a pediatric oncology center in Quito, Ecuador.
Abstract
Background
Evaluation of interventions to improve continuity of care across care levels is scarce in Latin America. The
Aim
to analyse the impact of implemented interventions on the ...perception of continuity of care of chronic patients in public health care networks of five LA countries (Brazil, Chile, Colombia, Mexico, and Uruguay).
Methods
Quasi-experimental study (controlled before and after design). Comparable networks, one intervention (IN) and one control (CN) were selected in each country. Baseline (2015) and evaluation (2017) surveys were conducted applying CCAENA questionnaire® to a sample of patients with chronic conditions (392/network; 784/country/year). Result variables: information continuity (exchange of clinical information) and clinical management continuity (repetition of exams, accessibility of primary care (PC) and secondary care (SC), perception of agreement between PC and SC doctors and of collaboration between PC and SC doctors. Descriptive analysis were conducted, and chi-square test was calculated to determine significant changes.
Results
An increase in the perception of continuity of information between care levels was observed in the IN of all countries, but Colombia. Clinical management continuity: decrease in the repetition of exams and increase in accessibility of consultation with the specialist in all countries but Mexico. The accessibility of PC doctor decreased in the IN in all countries. No differences in the perception of agreement between PC and SC doctors regarding diagnosis, treatment and recommendations were found. The perception of collaboration between PC and SC doctors increased in the five countries.
Conclusions
Consistent with expected results, the level of perceived information continuity and clinical management continuity increased in the IN, with differences between countries. Further multivariate analyses will be conducted to explore the differences between the IN and CN.
Key messages
Provides a cross-country comparison of the perception of continuity of care in patients with chronic conditions. Contributes to fill the knowledge gap on the effectiveness of participatory interventions improving continuity of care.
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