Risk of stroke in chronic heart failure patients with preserved ejection fraction, but without atrial fibrillation: analysis of the CHARM-Preserved and I-Preserve trials.

AIMS: The incidence and predictors of stroke in patients with heart failure and preserved ejection fraction (HF-PEF), but without atrial fibrillation (AF), are unknown. We described the incidence of stroke in HF-PEF patients with and without AF and predictors of stroke in those without AF. METHODS AND RESULTS: We pooled data from the CHARM-Preserved and I-Preserve trials. Using Cox regression, we derived a model for stroke in patients without AF in this cohort and compared its performance with a published model in heart failure patients with reduced ejection fraction (HF-REF)-predictive variables: age, body mass index, New York Heart Association class, history of stroke, and insulin-treated diabetes. The two stroke models were compared and Kaplan-Meier curves for stroke estimated. The risk model was validated in a third HF-PEF trial. Of the 6701 patients, 4676 did not have AF. Stroke occurred in 124 (6.1%) with AF and in 171 (3.7%) without AF (rates 1.80 and 1.00 per 100 patient-years, respectively). There was no difference in performance of the stroke model derived in the HF-PEF cohort and the published HF-REF model (c-index 0.71, 95% confidence interval 0.57-0.84 vs. 0.73, 0.59-0.85, respectively) as the predictive variables overlapped. The model performed well in the validation cohort (0.86, 0.62-0.99). The rate of stroke in patients in the upper third of risk approximated to that in patients with AF (1.60 and 1.80 per 100 patient-years, respectively). CONCLUSIONS: A small number of clinical variables identify a subset of patients with HF-PEF, but without AF, at elevated risk of stroke.

Risk of Stroke in Chronic Heart Failure Patients Without Atrial Fibrillation: Analysis of the Controlled Rosuvastatin in Multinational Trial Heart Failure (CORONA) and the Gruppo Italiano per lo Studio della Sopravvivenza nell'Insufficienza Cardiaca-Heart Failure (GISSI-HF) Trials.

BACKGROUND: Our aim was to describe the incidence and predictors of stroke in patients who have heart failure without atrial fibrillation (AF). METHODS AND RESULTS: We pooled 2 contemporary heart failure trials, the Controlled Rosuvastatin in Multinational Trial Heart Failure (CORONA) and the Gruppo Italiano per lo Studio della Sopravvivenza nell'Insufficienza cardiaca-Heart Failure trial (GISSI-HF). Of the 9585 total patients, 6054 did not have AF. Stroke occurred in 165 patients (4.7%) with AF and in 206 patients (3.4%) without AF (rates 16.8/1000 patient-years and 11.1/1000 patient-years, respectively). Using Cox proportional-hazards models, we identified the following independent predictors of stroke in patients without AF (ranked by χ(2) value): age (hazard ratio, 1.34; 95% confidence interval, 1.18-1.63 per 10 years), New York Heart Association class (1.60, 1.21-2.12 class III/IV versus II), diabetes mellitus treated with insulin (1.87, 1.22-2.88), body mass index (0.74, 0.60-0.91 per 5 kg/m(2) up to 30), and previous stroke (1.81, 1.19-2.74). N-terminal pro B-type natriuretic peptide (available in 2632 patients) was also an independent predictor of stroke (hazard ratio, 1.31; 1.11-1.57 per log unit) when added to this model. With the use of a risk score formulated from these predictors, we found that patients in the upper third of risk had a rate of stroke that approximated the risk in patients with AF. CONCLUSIONS: A small number of demographic and clinical variables identified a subset of patients who have heart failure without AF at a high risk of stroke.

Allosteric activation of Bordetella pertussis adenylyl cyclase by calmodulin: molecular dynamics and mutagenesis studies.

Adenylyl cyclase (AC) toxin is an essential toxin that allows Bordetella pertussis to invade eukaryotic cells, where it is activated after binding to calmodulin (CaM). Based on the crystal structure of the AC catalytic domain in complex with the C-terminal half of CaM (C-CaM), our previous molecular dynamics simulations (Selwa, E., Laine, E., and Malliavin, T. (2012) Differential role of calmodulin and calcium ions in the stabilization of the catalytic domain of adenyl cyclase CyaA from Bordetella pertussis. Proteins 80, 1028­1040) suggested that three residues (i.e. Arg(338), Asn(347), and Asp(360)) might be important for stabilizing the AC/CaM interaction. These residues belong to a loop-helix-loop motif at the C-terminal end of AC, which is located at the interface between CaM and the AC catalytic loop. In the present study, we conducted the in silico and in vitro characterization of three AC variants, where one (Asn(347); ACm1A), two (Arg(338) and Asp(360); ACm2A), or three residues (Arg(338), Asn(347), and Asp(360); ACm3A) were substituted with Ala. Biochemical studies showed that the affinities of ACm1A and ACm2A for CaM were not affected significantly, whereas that of ACm3A was reduced dramatically. To understand the effects of these modifications, molecular dynamics simulations were performed based on the modified proteins. The molecular dynamics trajectories recorded for the ACm3AC-CaM complex showed that the calcium-binding loops of C-CaM exhibited large fluctuations, which could be related to the weakened interaction between ACm3A and its activator. Overall, our results suggest that the loop-helix-loop motif at the C-terminal end of AC is crucial during CaM binding for stabilizing the AC catalytic loop in an active configuration.

Characterization of a membrane-active peptide from the Bordetella pertussis CyaA toxin.

Bordetella pertussis, the pathogenic bacteria responsible for whooping cough, secretes several virulence factors, among which is the adenylate cyclase toxin (CyaA) that plays a crucial role in the early stages of human respiratory tract colonization. CyaA invades target cells by translocating its catalytic domain directly across the plasma membrane and overproduces cAMP, leading to cell death. The molecular process leading to the translocation of the catalytic domain remains largely unknown. We have previously shown that the catalytic domain per se, AC384, encompassing residues 1-384 of CyaA, did not interact with lipid bilayer, whereas a longer polypeptide, AC489, spanning residues 1-489, binds to membranes and permeabilizes vesicles. Moreover, deletion of residues 375-485 within CyaA abrogated the translocation of the catalytic domain into target cells. Here, we further identified within this region a peptidic segment that exhibits membrane interaction properties. A synthetic peptide, P454, corresponding to this sequence (residues 454-485 of CyaA) was characterized by various biophysical approaches. We found that P454 (i) binds to membranes containing anionic lipids, (ii) adopts an α-helical structure oriented in plane with respect to the lipid bilayer, and (iii) permeabilizes vesicles. We propose that the region encompassing the helix 454-485 of CyaA may insert into target cell membrane and induce a local destabilization of the lipid bilayer, thus favoring the translocation of the catalytic domain across the plasma membrane.

Supportive care needs among older Mexican adults with metastatic cancer.

INTRODUCTION: Supportive care needs may vary according to age. The purpose of this research is to describe and compare supportive care needs between older adults with metastatic cancer (age ≥ 65 years) and their younger counterparts. MATERIALS AND METHODS: We conducted a retrospective secondary analysis of a cohort of patients with newly diagnosed metastatic solid tumors. Supportive care needs were assessed at baseline and at a three-month follow-up. Patients were divided into two groups (aged ≥65/<65 years). Differences in clinical characteristics and supportive care needs were compared utilizing descriptive statistics. Multivariate logistic regression models were employed to identify patient characteristics associated with specific supportive care needs. RESULTS: Between 2018 and 2022, 375 patients were enrolled. Median age was 66 years (interquartile range 19-94). At baseline, older adults had a higher number of supportive care needs (4.8 vs. 4.2, p = 0.01) and were at higher risk of malnutrition (75 vs. 65%, p = 0.05). Increasing age (odds ratio [OR] 1.02 (95% confidence interval [CI] 1.0-1.04, p = 0.03) and an estimated life expectancy <6 months (OR 3.0, 95%CI 1.5-6.1; p < 0.01) were associated with higher odds of malnutrition, while a higher educational level was associated with decreased odds (OR 0.68, 95%CI 0.5-0.8; p < 0.01). At three-month follow-up, older adults still had a higher number of supportive care needs (3.8 vs.2.6, p < 0.01) and were more likely to have fatigue (62 vs. 47%, p = 0.02). An estimated life expectancy of <6 months was associated with increased odds of fatigue (OR 3.0, 95%CI 1.5-6.3; p < 0.01). DISCUSSION: Older adults reported significantly more supportive care needs, particularly risk of malnutrition and fatigue. This information can help in the creation of supportive care services tailored to the needs of older individuals.

Molecular crowding stabilizes both the intrinsically disordered calcium-free state and the folded calcium-bound state of a repeat in toxin (RTX) protein.

Macromolecular crowding affects most chemical equilibria in living cells, as the presence of high concentrations of macromolecules sterically restricts the available space. Here, we characterized the influence of crowding on a prototypical RTX protein, RC(L). RTX (Repeat in ToXin) motifs are calcium-binding nonapeptide sequences that are found in many virulence factors produced by Gram-negative bacteria and secreted by dedicated type 1 secretion systems. RC(L) is an attractive model to investigate the effect of molecular crowding on ligand-induced protein folding, as it shifts from intrinsically disordered conformations (apo-form) to a stable structure upon calcium binding (holo-form). It thus offers the rare opportunity to characterize the crowding effects on the same polypeptide chain under two drastically distinct folding states. We showed that the crowding agent Ficoll70 did not affect the structural content of the apo-state and holo-state of RC(L) but increased the protein affinity for calcium. Moreover, Ficoll70 strongly stabilized both states of RC(L), increasing their half-melting temperature, without affecting enthalpy changes. The power law dependence of the melting temperature increase (ΔT(m)) on the volume fraction (φ) followed theoretical excluded volume predictions and allowed the estimation of the Flory exponent (ν) of the thermally unfolded polypeptide chain in both states. Altogether, our data suggest that, in the apo-state as found in the crowded bacterial cytosol, RTX proteins adopt extended unfolded conformations that may facilitate protein export by the type I secretion machinery. Subsequently, crowding also enhances the calcium-dependent folding and stability of RTX proteins once secreted in the extracellular milieu.

Delivering Palliative and Supportive Care for Older Adults with Cancer: Interactions between Palliative Medicine and Geriatrics.

The world's population is aging rapidly, with projections indicating that by 2050 one in six people will be aged ≥65 years. As a result, the number of cancer cases in older people is expected to increase significantly. Palliative care is an essential component of cancer care with a direct impact on quality of life. However, older adults with cancer often suffer from multiple comorbidities, cognitive impairment, and frailty, posing unique challenges in the delivery of palliative care. The complex healthcare needs of older patients with cancer therefore require a comprehensive assessment, including a geriatric evaluation. Collaboration between geriatrics and palliative care can offer a solution to the challenges faced by older people with cancer, since this is a population with overlapping concerns for both disciplines. This review highlights the importance of palliative care for older adults with cancer and the benefits of a multidisciplinary approach. It also addresses the coordination of palliative care and geriatrics for specific symptom management and decision making.

Calcium-induced folding of intrinsically disordered repeat-in-toxin (RTX) motifs via changes of protein charges and oligomerization states.

Ligand-induced disorder-to-order transition plays a key role in the biological functions of many proteins that contain intrinsically disordered regions. This trait is exhibited by so-called RTX (repeat-in-toxin) motifs found in many virulence factors secreted by numerous gram-negative pathogenic bacteria: RTX proteins are natively disordered in the absence of calcium but fold upon calcium binding. The adenylate cyclase toxin (CyaA) produced by Bordetella pertussis, the causative agent of whooping cough, contains ∼40 RTX motifs organized in five successive blocks separated by non-RTX flanking regions. This RTX domain mediates toxin binding to its eukaryotic cell receptor. We previously showed that the last block of the RTX domain, block V, which is critical for CyaA toxicity, exhibits the hallmarks of intrinsically disordered proteins in the absence of calcium. Moreover, the C-terminal flanking region of CyaA block V is required for its calcium-induced folding. Here, we describe a comprehensive analysis of the hydrodynamic and electrophoretic properties of several block V RTX polypeptides that differ in the presence and/or length of the flanking regions. Our results indicate that the length of the C-terminal flanking region not only controls the calcium-induced folding but also the calcium-induced multimerization of the RTX polypeptides. Moreover, we showed that calcium binding is accompanied by a strong reduction of the net charge of the RTX polypeptides. These data indicate that the disorder-to-order transition in RTX proteins is controlled by a calcium-induced change of the polypeptide charges and stabilized by multimerization.

Anal cancer in older adults: A Young International Society of Geriatric Oncology review paper.

Anal cancer is an uncommon malignancy, however, its incidence has been increasing worldwide, including among older adults. The care of older patients with anal cancer requires a multidisciplinary and comprehensive team approach to ensure improved outcomes and maintenance of quality of life, and the geriatric assessment should be a key component in the evaluation of every older patient with anal cancer. Despite older adults representing a large proportion of patients with anal cancer, they were underrepresented in trials that defined currently accepted standard therapies, including definitive chemoradiotherapy. Nonetheless, data from retrospective studies suggest that fit older patients with anal cancer should receive standard treatment similarly to their younger counterparts. This review describes the current knowledge regarding the management of anal cancer in older adults, including geriatric assessment, localized, recurrent/persistent, and metastatic disease.

The Zinc Finger Antiviral Protein ZAP Restricts Human Cytomegalovirus and Selectively Binds and Destabilizes Viral UL4/UL5 Transcripts.

Interferon-stimulated gene products (ISGs) play a crucial role in early infection control. The ISG zinc finger CCCH-type antiviral protein 1 (ZAP/ZC3HAV1) antagonizes several RNA viruses by binding to CG-rich RNA sequences, whereas its effect on DNA viruses is less well understood. Here, we decipher the role of ZAP in the context of human cytomegalovirus (HCMV) infection, a ß-herpesvirus that is associated with high morbidity in immunosuppressed individuals and newborns. We show that expression of the two major isoforms of ZAP, ZAP-S and ZAP-L, is induced during HCMV infection and that both negatively affect HCMV replication. Transcriptome and proteome analyses demonstrated that the expression of ZAP results in reduced viral mRNA and protein levels and decelerates the progression of HCMV infection. Metabolic RNA labeling combined with high-throughput sequencing (SLAM-seq) revealed that most of the gene expression changes late in infection result from the general attenuation of HCMV. Furthermore, at early stages of infection, ZAP restricts HCMV by destabilizing a distinct subset of viral mRNAs, particularly those from the previously uncharacterized UL4-UL6 HCMV gene locus. Through enhanced cross-linking immunoprecipitation and sequencing analysis (eCLIP-seq), we identified the transcripts expressed from this HCMV locus as the direct targets of ZAP. Moreover, our data show that ZAP preferentially recognizes not only CG, but also other cytosine-rich sequences, thereby expanding its target specificity. In summary, this report is the first to reveal direct targets of ZAP during HCMV infection, which strongly indicates that transcripts from the UL4-UL6 locus may play an important role for HCMV replication.IMPORTANCE Viral infections have a large impact on society, leading to major human and economic losses and even global instability. So far, many viral infections, including human cytomegalovirus (HCMV) infection, are treated with a small repertoire of drugs, often accompanied by the occurrence of resistant mutants. There is no licensed HCMV vaccine in sight to protect those most at risk, particularly immunocompromised individuals or pregnant women who might otherwise transmit the virus to the fetus. Thus, the identification of novel intervention strategies is urgently required. In this study, we show that ZAP decelerates the viral gene expression cascade, presumably by selectively handpicking a distinct set of viral transcripts for degradation. Our study illustrates the potent role of ZAP as an HCMV restriction factor and sheds light on a possible role for UL4 and/or UL5 early during infection, paving a new avenue for the exploration of potential targets for novel therapies.

Calcium-induced folding and stabilization of the intrinsically disordered RTX domain of the CyaA toxin.

The adenylate cyclase toxin (CyaA) is one of the major virulence factors of Bordetella pertussis, the causative agent of whooping cough. Its C-terminal region, the receptor-binding domain (RD), contains ∼40 calcium-binding Repeat in ToXin (RTX) motifs, which are characteristic of many virulence factors of pathogenic bacteria. We previously showed that RD is intrinsically disordered in the absence of calcium and acquires its functional three-dimensional structure upon calcium binding. To gain further insight into the physicochemical properties of RD, we characterized its calcium-induced conformational and stability changes by combining spectroscopic approaches. We show that RD, in the absence of calcium, adopts premolten globule conformations, due in part to the strong internal electrostatic repulsions between the negative charges of the aspartate-rich polypeptide sequence. Accordingly, sodium is able to screen these electrostatic repulsions, allowing a partial compaction of the polypeptide, whereas calcium triggers a strong compaction as well as the acquisition of secondary and tertiary structures in a highly cooperative manner. The differential sensitivity of the calcium-loaded state to guanidinium- and urea-induced denaturations provides further evidence that electrostatic interactions play a critical role in the folding and stability of RD. These results provide new insights into the folding/function relationship of the RTX motifs.

Calmodulin-induced conformational and hydrodynamic changes in the catalytic domain of Bordetella pertussis adenylate cyclase toxin.

Bordetella pertussis, the causative agent of whooping cough, secretes among various toxins an adenylate cyclase (CyaA) that displays a unique mechanism of cell invasion, which involves a direct translocation of its N-terminal catalytic domain (AC, 400 residues) across the plasma membrane of the eukaryotic targeted cells. Once into the cytosol, AC is activated by endogenous calmodulin and produces toxic amounts of cAMP. The structure of AC in complex with the C-terminal part of calmodulin has recently been determined. However, as the structure of the catalytic domain in the absence of calmodulin is still lacking, the molecular basis of AC activation by calmodulin remains largely unknown. To characterize this activation mechanism, we investigated here the biophysical properties of the isolated catalytic domain in solution with or without calmodulin. We found that calmodulin triggered only minor modifications of the protein secondary and tertiary structure but had a pronounced effect on the hydrodynamic properties of AC. Indeed, while the isolated catalytic domain was spherical and hydrated, it underwent a significant elongation as well as compaction and dehydration upon calmodulin interaction. On the basis of these data, we propose a model for the structural transition between the calmodulin-free and calmodulin-bound AC.

Evaluation of a Mobile Health Intervention to Improve Wellness Outcomes for Breast Cancer Survivors.

PURPOSE: Breast cancer survivors are at increased risk of cancer recurrence, second malignancies, and other comorbid conditions. This study examined if use of a convenient, commercially available, $65 per month app that gives breast cancer survivors access to a health and wellness coach is more effective than a self-guided toolkit and one-time health education session at achieving the following goals: 1) improving adherence to a plant-based diet, 2) increasing physical activity, 3) assisting with weight loss and reduction in body mass index, 4) reducing elevated depression and fatigue scores, and 5) leading to sustained adherence to lifestyle and wellness plan at and beyond 6 months. METHODS: A nonrandomized 2-group control study design with pre-post repeated measures (N=127 subjects) was utilized. Women 18 years of age or older, with curative-intent breast cancer, were included in the study. App users received a survivorship care plan and enrolled in a 6-month subscription to the health app. A control group received the same information but, instead of access to the app, were given a self-guided toolkit. RESULTS: At 6 months, more patients in the app group experienced weight loss and had a significantly greater reduction in overall body mass index (P<0.01). The app group also demonstrated statistically significant improvements in "strenuous" physical activity (P=0.04) and had significant improvement in their dietary patterns (P<0.001), as compared to the self-guided group. The app group had greater reduction in fatigue and improvement in depression, but these changes were not statistically significant. At 12 months, none of the app users were still using the app, but many were still following their wellness plan and had maintained their weight loss. Outliers in both groups and low rate of response made evaluation of results difficult. CONCLUSIONS: The results of this advanced practice provider-led study demonstrated that a live health coaching app that provides wellness coaching can offer motivated breast cancer survivors and cancer programs a modality that offers convenient, effective support at a reasonable cost.

Copper-Doped Cobalt Spinel Electrocatalysts Supported on Activated Carbon for Hydrogen Evolution Reaction.

The development of electrocatalysts based on the doping of copper over cobalt spinel supported on a microporous activated carbon has been studied. Both copper-cobalt and cobalt spinel nanoparticles were synthesized using a silica-template method. Hybrid materials consisting of an activated carbon (AC), cobalt oxide (Co3O4), and copper-doped cobalt oxide (CuCo2O4) nanoparticles, were obtained by dry mixing technique and evaluated as electrocatalysts in alkaline media for hydrogen evolution reaction. Physical mixtures containing 5, 10, and 20 wt.% of Co3O4 or CuCo2O4 with a highly microporous activated carbon were prepared and characterized by XRD, TEM, XPS, physical adsorption of gases, and electrochemical techniques. The electrochemical tests revealed that the electrodes containing copper as the dopant cation result in a lower overpotential and higher current density for the hydrogen evolution reaction.

Translocation and calmodulin-activation of the adenylate cyclase toxin (CyaA) of Bordetella pertussis.

The adenylate cyclase toxin (CyaA) is a multi-domain protein secreted by Bordetella pertussis, the causative agent of whooping cough. CyaA is involved in the early stages of respiratory tract colonization by Bordetella pertussis. CyaA is produced and acylated in the bacteria, and secreted via a dedicated secretion system. The cell intoxication process involves a unique mechanism of transport of the CyaA toxin catalytic domain (ACD) across the plasma membrane of eukaryotic cells. Once translocated, ACD binds to and is activated by calmodulin and produces high amounts of cAMP, subverting the physiology of eukaryotic cells. Here, we review our work on the identification and characterization of a critical region of CyaA, the translocation region, required to deliver ACD into the cytosol of target cells. The translocation region contains a segment that exhibits membrane-active properties, i.e. is able to fold upon membrane interaction and permeabilize lipid bilayers. We proposed that this region is required to locally destabilize the membrane, decreasing the energy required for ACD translocation. To further study the translocation process, we developed a tethered bilayer lipid membrane (tBLM) design that recapitulate the ACD transport across a membrane separating two hermetic compartments. We showed that ACD translocation is critically dependent on calcium, membrane potential, CyaA acylation and on the presence of calmodulin in the trans compartment. Finally, we describe how calmodulin-binding triggers key conformational changes in ACD, leading to its activation and production of supraphysiological concentrations of cAMP.

Calcium-dependent disorder-to-order transitions are central to the secretion and folding of the CyaA toxin of Bordetella pertussis, the causative agent of whooping cough.

The adenylate cyclase toxin (CyaA) plays an essential role in the early stages of respiratory tract colonization by Bordetella pertussis, the causative agent of whooping cough. Once secreted, CyaA invades eukaryotic cells, leading to cell death. The cell intoxication process involves a unique mechanism of translocation of the CyaA catalytic domain directly across the plasma membrane of the target cell. Herein, we review our recent results describing how calcium is involved in several steps of this intoxication process. In conditions mimicking the low calcium environment of the crowded bacterial cytosol, we show that the C-terminal, calcium-binding Repeat-in-ToXin (RTX) domain of CyaA, RD, is an extended, intrinsically disordered polypeptide chain with a significant level of local, secondary structure elements, appropriately sized for transport through the narrow channel of the secretion system. Upon secretion, the high calcium concentration in the extracellular milieu induces the refolding of RD, which likely acts as a scaffold to favor the refolding of the upstream domains of the full-length protein. Due to the presence of hydrophobic regions, CyaA is prone to aggregate into multimeric forms in vitro, in the absence of a chaotropic agent. We have recently defined the experimental conditions required for CyaA folding, comprising both calcium binding and molecular confinement. These parameters are critical for CyaA folding into a stable, monomeric and functional form. The monomeric, calcium-loaded (holo) toxin exhibits efficient liposome permeabilization and hemolytic activities in vitro, even in a fully calcium-free environment. By contrast, the toxin requires sub-millimolar calcium concentrations in solution to translocate its catalytic domain across the plasma membrane, indicating that free calcium in solution is actively involved in the CyaA toxin translocation process. Overall, this data demonstrates the remarkable adaptation of bacterial RTX toxins to the diversity of calcium concentrations it is exposed to in the successive environments encountered in the course of the intoxication process.

Reevaluation of ATR signaling in primary resting chronic lymphocytic leukemia cells: evidence for pro-survival or pro-apoptotic function.

ATM, primarily activated by DNA double-strand breaks, and ATR, activated by single-stranded DNA, are master regulators of the cellular response to DNA damage. In primary chronic lymphocytic leukemia (CLL) cells, ATR signaling is considered to be switched off due to ATR downregulation. Here, we hypothesized that ATR, though expressed at low protein level, could play a role in primary resting CLL cells after genotoxic stress. By investigating the response of CLL cells to UV-C irradiation, a prototypical activator of ATR, we could detect phosphorylation of ATR at Thr-1989, a marker for ATR activation, and also observed that selective ATR inhibitors markedly decreased UV-C-induced phosphorylation of ATR targets, including H2AX and p53. Similar results were obtained with the purine analogs fludarabine and cladribine that were also shown to activate ATR and induce ATR-dependent phosphorylation of H2AX and p53. In addition, ATR inhibition was found to sensitize primary CLL cells to UV-C by decreasing DNA repair synthesis. Conversely, ATR inhibition rescued CLL cells against purine analogs by reducing expression of the pro-apoptotic genes PUMA and BAX. Collectively, our study indicates that ATR signaling can be activated in resting CLL cells and play a pro-survival or pro-apoptotic role, depending on the genotoxic context.

Stability, structural and functional properties of a monomeric, calcium-loaded adenylate cyclase toxin, CyaA, from Bordetella pertussis.

Bordetella pertussis, the causative agent of whooping cough, secretes an adenylate cyclase toxin, CyaA, which invades eukaryotic cells and alters their physiology by cAMP overproduction. Calcium is an essential cofactor of CyaA, as it is the case for most members of the Repeat-in-ToXins (RTX) family. We show that the calcium-bound, monomeric form of CyaA, hCyaAm, conserves its permeabilization and haemolytic activities, even in a fully calcium-free environment. In contrast, hCyaAm requires sub-millimolar calcium in solution for cell invasion, indicating that free calcium in solution is involved in the CyaA toxin translocation process. We further report the first in solution structural characterization of hCyaAm, as deduced from SAXS, mass spectrometry and hydrodynamic studies. We show that hCyaAm adopts a compact and stable state that can transiently conserve its conformation even in a fully calcium-free environment. Our results therefore suggest that in hCyaAm, the C-terminal RTX-domain is stabilized in a high-affinity calcium-binding state by the N-terminal domains while, conversely, calcium binding to the C-terminal RTX-domain strongly stabilizes the N-terminal regions. Hence, the different regions of hCyaAm appear tightly connected, leading to stabilization effects between domains. The hysteretic behaviour of CyaA in response to calcium is likely shared by other RTX cytolysins.

Aprendizaje y servicio: percepciones de estudiantes de Terapia Ocupacional de la Universidad de La Frontera / Learning and service: perceptions students of Occupational Therapy of the Universidad de La Frontera

RESUMEN Fundamento: la formación de Terapeutas Ocupacionales de la Universidad de La Frontera se realiza a través de currículos innovadores, por ello se apuesta por estrategias metodológicas para desarrollar pensamiento crítico y reflexivo, trabajo en equipo con responsabilidad social, al surgir así aprendizaje y servicio. Objetivo: conocer la percepción en relación con aprendizaje y servicio, en estudiantes de quinto nivel en el módulo de Intervención Psicosocial de la carrera de Terapia Ocupacional de la Universidad de La Frontera. Métodos: se realizó un estudio cualitativo, descriptivo, exploratorio, mediante estudio intrínseco de caso, muestra: no probabilística, intencionada, de casos por criterios y por conveniencia, conformada por 20 estudiantes, previa firma del consentimiento informado, se formaron dos grupos focales. Para el análisis de datos se utilizó reducción progresiva y agrupación en categorías descriptivas. Se utilizaron los criterios de rigor de Guba y aspectos éticos de Emanuel. Resultados: del Nivel I emergieron 332 unidades de significado, agrupadas en cuatro categorías descriptivas codificadas en función del objetivo del estudio: significado del concepto, desarrollo de competencias genéricas, factores facilitadores y obstaculizadores, destacan resolución de conflictos y aprendizaje continuo para la primera como competencias; para la segunda aprender haciendo y aprendizaje significativo; para la tercera apoyo docente y comunicación comunitaria; para la cuarta aspectos personales y relaciones interpersonales. Conclusiones: los estudiantes atribuyen un gran valor a la metodología aprendizaje y servicio, les permite desarrollar competencias relevantes para el uso profesional esenciales para el vínculo terapéutico, competencias genéricas visualizadas: resolución de conflicto, aprendizaje continuo y sentido crítico y reflexivo.

ABSTRACT Background: the training of Occupational Therapists of the Universidad de La Frontera is carried out through innovative curricula; therefore, it is committed to methodological strategies to develop critical and reflective thinking, teamwork with social responsibility, Learning and Service arises. Objective: to know the perception in relation to learning and service, in 5th level students in the psychosocial intervention module of the Occupational Therapy course at the University of La Frontera. Methods: qualitative, descriptive, exploratory study was carried out through an intrinsic case study. The non-probabilistic, intentional sample of cases by criteria and for convenience, made up of 20 students, after signing the informed consent, formed two focus groups. For data analysis, progressive reduction and grouping into descriptive categories was used. Guba's criteria of rigor and Emanuel's ethical aspects were used. Results: from Level I, 332 units of meaning emerged, grouped into 4 descriptive categories coded according to the objective of the study: meaning of the concept, development of generic competences, facilitating factors and impeding factors, conflict resolution and continuous learning for the first as competences; for the second, learning by doing and meaningful learning; for the third teaching aid and community communication; for the fourth personal aspects and interpersonal relationships. Conclusions: the students attribute great value to this Learning and Service methodology; it allows them to develop relevant competencies for essential professional use for the therapeutic bond, visualized generic competences: conflict resolution, continuous learning, and critical and reflective sense.