In-Hospital Mortality and Risk Prediction in Minimally Invasive Sutureless versus Conventional Aortic Valve Replacement.

Objective. Available evidence suggests that a minimally invasive approach with the use of sutureless bioprostheses has a favorable impact on the outcome of patients undergoing aortic valve replacement (AVR). Methods. From 2010 to 2019, 2732 patients underwent conventional AVR through median sternotomy with a stented bioprosthesis (n = 2048) or minimally invasive AVR with a sutureless bioprosthesis (n = 684). Results. Using the propensity score, 206 patients in each group were matched, and the matched groups were well balanced regarding preoperative risk factors. Both unmatched and matched patients of the sutureless + minimally invasive group showed significantly shorter cross-clamp times and longer ICU stay. In-hospital mortality was the only outcome measure that was confirmed in both analyses, and was higher in the stented + conventional group (2.54% and 2.43% in unmatched and matched patients, respectively) compared with the sutureless + minimally invasive group (0.88% and 0.97% in unmatched and matched patients, respectively) (p = 0.0047 and p < 0.0001, respectively). No differences in postoperative pacemaker implantation were recorded in matched patients of both groups (n = 2 [1%] in the stented + conventional group vs. n = 4 [2%] in the sutureless + minimally invasive group; p = 0.41). The discrimination power of EuroSCORE II was not confirmed in the sutureless + minimally invasive group, yielding an area under the ROC curve of 0.568. Conclusions. Minimally invasive sutureless AVR has a favorable impact on the immediate outcome and is associated with significantly lower in-hospital mortality rates compared with conventional AVR, resulting in the absence of the discrimination power of EuroSCORE II for predicting AVR outcomes.

Convalescent or standard plasma versus standard of care in the treatment of COVID-19 patients with respiratory impairment: short and long-term effects. A three-arm randomized controlled clinical trial.

BACKGROUND: The efficacy of early treatment with convalescent plasma in patients with COVID-19 is debated. Nothing is known about the potential effect of other plasma components other than anti-SARS-CoV-2 antibodies. METHODS: To determine whether convalescent or standard plasma would improve outcomes for adults in early phase of Covid19 respiratory impairment we designed this randomized, three-arms, clinical trial (PLACO COVID) blinded on interventional arms that was conducted from June 2020 to August 2021. It was a multicentric trial at 19 Italian hospitals. We enrolled 180 hospitalized adult patients with COVID-19 pneumonia within 5 days from the onset of respiratory distress. Patients were randomly assigned in a 1:1:1 ratio to standard of care (n = 60) or standard of care + three units of standard plasma (n = 60) or standard of care + three units of high-titre convalescent plasma (n = 60) administered on days 1, 3, 5 after randomization. Primary outcome was 30-days mortality. Secondary outcomes were: incidence of mechanical ventilation or death at day 30, 6-month mortality, proportion of days with mechanical ventilation on total length of hospital stay, IgG anti-SARS-CoV-2 seroconversion, viral clearance from plasma and respiratory tract samples, and variations in Sequential Organ Failure Assessment score. The trial was analysed according to the intention-to-treat principle. RESULTS: 180 patients (133/180 [73.9%] males, mean age 66.6 years [IQR 57-73]) were enrolled a median of 8 days from onset of symptoms. At enrollment, 88.9% of patients showed moderate/severe respiratory failure. 30-days mortality was 20% in Control arm, 23% in Convalescent (risk ratio [RR] 1.13; 95% confidence interval [CI], 0.61-2.13, P = 0.694) and 25% in Standard plasma (RR 1.23; 95%CI, 0.63-2.37, P = 0.544). Time to viral clearance from respiratory tract was 21 days for Convalescent, 28 for Standard plasma and 23 in Control arm but differences were not statistically significant. No differences for other secondary endpoints were seen in the three arms. Serious adverse events were reported in 1.7%, 3.3% and 5% of patients in Control, Standard and Convalescent plasma arms respectively. CONCLUSIONS: Neither high-titer Convalescent nor Standard plasma improve outcomes of COVID-19 patients with acute respiratory failure. Trial Registration Clinicaltrials.gov Identifier: NCT04428021. First posted: 11/06/2020.

Comparison between the age, creatinine and ejection fraction II score and the European System for Cardiac Operative Risk Evaluation II: which score for which patient?

OBJECTIVES: Each surgical risk prediction model requires a validation analysis within a large 'real-life' sample. The aim of this study is to validate the age, creatinine and ejection fraction (ACEF) II risk score compared with the European System for Cardiac Operative Risk Evaluation (EuroSCORE) II. METHODS: All patients operated on at 8 Italian cardiac surgery centres in the period 2009-2019 with available data for the calculation of EuroSCORE II and ACEF II were included in the study. Mortality was recorded and receiver operating characteristic curves were plotted for the overall study population and for different patient subgroups according to the type of surgery. RESULTS: A total of 14 804 patients were enrolled [median age of 70 (62-77) years, 35.4% female], and among these, 3.1% underwent emergency surgery. Thirty-day mortality was 2.84% (n = 420). In the total population, the area under the curve with EurosCORE II was significantly higher than that recorded with ACEF II [0.792, 95% confidence interval (CI) 0.79-0.8 vs 0.73, 95% CI 0.73-0.74; P < 0.001]. This finding was also confirmed in the patient subgroups undergoing isolated valve surgery (EuroSCORE II versus ACEF II: 0.80, 95% CI 0.79-0.814 vs 0.74, 95% CI 0.724-0.754; P = 0.045) or isolated aortic surgery (0.754, 95% CI 0.70-0.79 vs 0.53, 95% CI 0.48-0.58; P = 0.002). In contrast, the 2 scores did not differ significantly in patients undergoing isolated bypass surgery (0.8, 95% CI 0.78-0.81 vs 0.77, 95% CI 0.75-0.78; P = 1). CONCLUSIONS: In both the overall population and patient subgroups, EuroSCORE II proved to be more accurate than ACEF II. However, in patients undergoing bypass surgery, ACEF II proved to be an easy and simple to use risk score, demonstrating comparable risk prediction performance with the more complex EuroSCORE II.

Sutureless versus transcatheter aortic valve replacement: A multicenter analysis of "real-world" data.

BACKGROUND: Recent data suggested that transcatheter aortic valve replacement (TAVR) may be indicated also for low-risk patients. However, robust evidence is still lacking, particularly regarding valve performance at follow-up that confers a limitation to its use in young patients. Moreover, a literature gap exists in terms of 'real-world' data analysis. The aim of this study is to compare the cost-effectiveness of sutureless aortic valve replacement (SuAVR) versus transfemoral TAVR. METHODS: Prospectively collected data were retrieved from a centralized database of nine cardiac surgery centers between 2010 and 2018. Follow-up was completed in June 2019. A propensity score matching (PSM) analysis was performed. RESULTS: Patients in the TAVR group (n=1002) were older and with more comorbidities than SuAVR patients (n=443). The PSM analysis generated 172 pairs. No differences were recorded between groups in 30-day mortality [SuAVR vs TAVR: n=7 (4%) vs n=5 (2.9%); p=0.7] and need for pacemaker implant [n=10 (5.8%) vs n=20 (11.6%); p=0.1], but costs were lower in the SuAVR group (20486.6±4188€ vs 24181.5±3632€; p<0.01). Mean follow-up was 1304±660 days. SuAVR patients had a significantly higher probability of survival than TAVR patients (no. of fatal events: 22 vs 74; p<0.014). Median follow-up was 2231 days and 2394 days in the SuAVR and TAVR group, respectively. CONCLUSION: The treatment of aortic valve stenosis with surgical sutureless or transcatheter prostheses is safe and effective. By comparing the two approaches, patients who can undergo surgery after heart team evaluation show longer lasting results and a more favorable cost ratio.

Treatment with eltrombopag of severe immune thrombocytopenia and hemolytic anemia associated with COVID-19 pneumonia: a case report.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the causative agent of coronavirus disease 2019 (COVID-19). Whether SARS-CoV-2 can trigger an autoimmune reaction against platelets and red blood cells remains unclear. Herein, we report a case of COVID-19 pneumonia associated with severe immune thrombocytopenia and hemolytic anemia. An 83-year-old woman was admitted to the hospital because of both dyspnea and diffuse mucocutaneous bleeding. Exams revealed hemolytic anemia (HA), severe immune thrombocytopenia (ITP), and bilateral pneumonia. Molecular testing confirmed a diagnosis of COVID-19 pneumonia. Thrombocytopenia did not respond to first-line treatment with immunoglobulin, corticosteroids, and platelet transfusions. Addition to therapy of the thrombopoietin receptor agonist, eltrombopag, resulted in full recovery. COVID-19 can be associated with ITP and HA. There are neither guidelines nor clinical experience on the treatment of COVID-19-associated ITP and our case, showing complete response to eltrombopag, may help clinicians in their practice during the COVID-19 pandemic. PLAIN LANGUAGE SUMMARY: The case of an 83-year-old woman with COVID-19 pneumonia associated with two severe blood diseases that cause platelet and red cell destruction Coronavirus disease 2019 (COVID-19) is caused by a virus called severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). We do not know exactly whether this virus can stimulate our immune system to react against platelets and red blood cells. Herein, we report a case of COVID-19 pneumonia associated with two severe blood diseases, immune thrombocytopenia, which causes platelet destruction, and hemolytic anemia, which causes red cell destruction. An 83-year-old woman was admitted to the hospital because of both difficulty in breathing and diffuse bleeding in mucosae and skin. Exams revealed hemolytic anemia, severe immune thrombocytopenia, and pneumonia in both lungs. Molecular testing confirmed a diagnosis of COVID-19 pneumonia. The first treatment with immunoglobulin, corticosteroids, and platelet transfusions was not enough to cure thrombocytopenia; the addition of eltrombopag which acts on the thrombopoietin receptor agonist resulted in full recovery. COVID-19 can be present together with immune thrombocytopenia and hemolytic anemia. As there are no guidelines on the treatment of immune thrombocytopenia in patients with COVID-19 and the clinical experience is limited, the complete response achieved with eltrombopag may help clinicians in their practice during the COVID-19 pandemic.

Lung Ultrasonography for the Diagnosis of SARS-CoV-2 Pneumonia in the Emergency Department.

STUDY OBJECTIVE: Accurate diagnostic testing to identify severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection is critical. Although highly specific, SARS-CoV-2 reverse transcriptase-polymerase chain reaction (RT-PCR) has been shown in clinical practice to be affected by a noninsignificant proportion of false-negative results. This study seeks to explore whether the integration of lung ultrasonography with clinical evaluation is associated with increased sensitivity for the diagnosis of coronavirus disease 2019 pneumonia, and therefore may facilitate the identification of false-negative SARS-CoV-2 RT-PCR results. METHODS: This prospective cohort study enrolled consecutive adult patients with symptoms potentially related to SARS-CoV-2 infection who were admitted to the emergency department (ED) of an Italian academic hospital. Immediately after the initial assessment, a lung ultrasonographic evaluation was performed and the likelihood of SARS-CoV-2 infection, based on both clinical and lung ultrasonographic findings ("integrated" assessment), was recorded. RT-PCR SARS-CoV-2 detection was subsequently performed. RESULTS: We enrolled 228 patients; 107 (46.9%) had SARS-CoV-2 infection. Sensitivity and negative predictive value of the clinical-lung ultrasonographic integrated assessment were higher than first RT-PCR result (94.4% [95% confidence interval {CI} 88.2% to 97.9%] versus 80.4% [95% CI 71.6% to 87.4%] and 95% [95% CI 89.5% to 98.2%] versus 85.2% [95% CI 78.3% to 90.6%], respectively). Among the 142 patients who initially had negative RT-PCR results, 21 tested positive at a subsequent molecular test performed within 72 hours. All these false-negative cases were correctly identified by the integrated assessment. CONCLUSION: This study suggests that, in patients presenting to the ED with symptoms commonly associated with SARS-CoV-2 infection, the integration of lung ultrasonography with clinical evaluation has high sensitivity and specificity for coronavirus disease 2019 pneumonia and it may help to identify false-negative results occurring with RT-PCR.

Minimally invasive surgical versus transcatheter aortic valve replacement: A multicenter study.

OBJECTIVES: Treatment of aortic valve stenosis is evolving, indications for transcatheter approach (TAVI) have increased but also surgical valve replacement has changed with the use of minimally invasive approaches. Comparisons between TAVI and surgery have rarely been done with minimally invasive techniques (mini-SAVR) in the surgical arm. Aim of the present study is to compare mini-SAVR and TAVI in a multicenter recent cohort. METHODS: Evaluated were 2904 patients undergone mini-SAVR (2407) or TAVI (497) in 10 different centers in the period 2011-2016. The Heart Team approved treatment for complex cases. The primary outcome is the incidence of 30-day mortality following mini-SAVR and TAVI. Secondary outcomes are the occurrence of major complications following both procedures. Propensity matched comparisons was performed based on multivariable logistic regression model. RESULTS: In the overall population TAVI patients had increased surgical risk (median EuroSCORE II 3.3% vs. 1.7%, p ≤ 0.001) and 30-day mortality was higher (1.5% and 2.8% in mini-SAVR and TAVI respectively, p = 0.048). Propensity score identified 386 patients per group with similar baseline profile (median EuroSCORE II ~3.0%). There was no difference in 30-day mortality (3.4% in mini-SAVR and 2.3% in TAVI; p = 0.396) and stroke, surgical patients had more blood transfusion, kidney dysfunction and required longer ICU and hospital length of stay while TAVI patients had more permanent pace maker insertion. CONCLUSIONS: Mini-SAVR and TAVI are both safe and effective to treat aortic stenosis in elderly patients with comorbidities. A joint evaluation by the heart-team is essential to direct patients to the proper approach.

"Wind of change": the role of human centered healthcare factors in the implementation of clinical governance in an Italian University teaching hospital.

BACKGROUND: Clinical governance (CG) is an approach to quality improvement in healthcare aimed at achieving a patient-centered health care system. The main objective of this study was to highlight human centered healthcare latent factors underlying the results of a CG assessment performed in the teaching hospital "A. Gemelli" of Rome, Italy. MATERIALS AND METHODS: CG implementation levels were assessed through OPTIGOV© (OPTimizing healthcare GOVernance), a CG scorecard methodology. In order to identify the variables generating latent factors that can influence the governance of the Hospital, the multiple correspondence analysis (MCA) was applied. RESULTS: The application of OPTIGOV© showed a good CG implementation level in the Gemelli Hospital. By applying MCA, the variables aggregated so as to define 3 latent factors (F1: assessment for people oriented improvement strategy; F2: assessment for people targeted management; F3: tracking for timely accountable people) explaining as a whole 82.68% of the total variance and respectively 48.09% (F1), 24.95% (F2) and 9.64% (F3). CONCLUSIONS: The heuristic interpretation of the three latent factors could bring back to the concept of humanization in healthcare. This study shows that in the teaching hospital "A. Gemelli" humanization in healthcare is the driver of health care quality improvement.

Defining needs and goals of post-ICU care for trauma patients: preliminary study.

BACKGROUND: The aim of this study was to assess the long-term physical and psychological disabilities and their economic impact in severe trauma survivors. METHODS: Adult patients with Injury Severity Score >15 and Abbreviated Injury Scale ≤3 admitted to the ICU of a Level 1 trauma centre in the Lazio Region and discharged alive from hospital underwent a structured interview 12-24 months after the event. Self-reported somatic symptoms, autonomy, anxiety and depression were evaluated using a Likert-type Scale, Barthel Index and Hospital Anxiety and Depression Score (HADS), respectively. Patients' working and economic status were also investigated. RESULTS: A total of 32/58 patients matching the inclusion criteria were included in the final analysis. Eighteen patients (56%) reported at least a partial restriction in daily activities. Most common symptoms included muscle or joint pain, fatigue, and headache. All patients were receiving rehabilitation 1-2 years after the event. Fifty-eight percent of the patients spent more than €3600/year from their family budget for rehabilitation and medical care, however only 25% were receiving financial support from regional social services and 44% were unemployed at the time of the interview. Thirty patients (94%) had HADS Depression Score≥11. CONCLUSION: Survivors of severe trauma in our cohort had limited autonomy and need long-term rehabilitation. Most of them rely on private healthcare services with a significant financial impact on their family budget. Almost all patients had moderate to severe depression. Future post-ICU counseling services should facilitate access to rehabilitation and psychological support for these patients.

Wait watchers: the application of a waiting list active management program in ambulatory care.

OBJECTIVE: This study describes and evaluates the application of a waiting list management program in ambulatory care. DESIGN: Waiting list active management survey (telephone call and further contact); before and after controlled trial. SETTING: Local Health Trust in Veneto Region (North-East of Italy) in 2008-09. PARTICIPANTS: Five hundred and one people on a 554 waiting list for C Class ambulatory care diagnostic and/or clinical investigations (electrocardiography plus cardiology ambulatory consultation, eye ambulatory consultation, carotid vessels Eco-color-Doppler, legs Eco-color-Doppler or colonoscopy, respectively). INTERVENTION: Active list management program consisting of a telephonic interview on 21 items to evaluate socioeconomic features, self-perceived health status, social support, referral physician, accessibility and patients' satisfaction. A controlled before-and-after study was performed to evaluate anonymously the overall impact on patients' self-perceived quality of care. MAIN OUTCOME MEASURES: The rate of patients with deteriorating healthcare conditions; rate of dropout; interviewed degree of satisfaction about the initiative; overall impact on citizens' perceived quality of care. RESULTS: 95.4% patients evaluated the initiative as useful. After the intervention, patients more likely to have been targeted with the program showed a statistically significant increase in self-reported quality of care. CONCLUSIONS: Positive impact of the program on some dimensions of ambulatory care quality (health status, satisfaction, willingness to remain in the queue), thus confirming the outstanding value of 'not to leave people alone' and 'not to leave them feeling themselves alone' in healthcare delivery.

Interventions to evaluate fitness to drive among people with chronic conditions: Systematic review of literature.

When an health condition has been identified, the question of whether to continue driving depends not on a medical diagnosis, but on the functional consequences of the illness. The complex nature of physical and mental impairments and their relationship with safe driving make the availability of evidence based tools necessary for health professionals. The review aims at identifying and summarizing scientific findings concerning the relationship between neuropsychological and clinical screening tests and fitness to drive among people with chronic conditions. Studies were searched for driving ability evaluation by road test or simulator, clinical/neuropsychological examinations of participants with chronic diseases or permanent disablement impairing driving performance, primary outcomes as fatal/non-fatal traffic injuries and secondary outcomes as fitness to drive assessment. Twenty-seven studies fulfilled the inclusion criteria. Some studies included more than one clinical condition. The illness investigated were Alzheimer Disease (n=6), Parkinson Disease (n=8), Cardiovascular Accident (n=4), Traumatic Brain Injuries (n=3), Sleep Apnea Syndrome (n=2), Narcolepsy (n=1), Multiple Sclerosis (n=1) and Hepatic Encephalopathy (n=1), comorbidities (n=3). No studies match inclusion criteria about Myasthenia Gravis, Diabetes Mellitus, Renal Diseases, Hearing Disorders and Sight Diseases. No studies referred to primary outcomes. The selected studies provided opposite evidences. It would be reasonable to argue that some clinical and neuropsychological tests are effective in predicting fitness to drive even if contrasting results support that driving performance decreases as a function of clinical and neuropsychological decline in some chronic diseases. Nevertheless we found no evidence that clinical and neuropsychological screening tests would lead to a reduction in motor vehicle crashes involving chronic disabled drivers. It seems necessary to develop tests with proven validity for identifying high-risk drivers so that physicians can provide guidance to their patients in chronic conditions, and also to medical advisory boards working with licensing offices.

Mutation analysis of CCM1, CCM2 and CCM3 genes in a cohort of Italian patients with cerebral cavernous malformation.

Cerebral cavernous malformations (CCMs) are vascular lesions of the CNS characterized by abnormally enlarged capillary cavities. CCMs can occur as sporadic or familial autosomal dominant form. Familial cases are associated with mutations in CCM1[K-Rev interaction trapped 1 (KRIT1)], CCM2 (MGC4607) and CCM3 (PDCD10) genes. In this study, a three-gene mutation screening was performed by direct exon sequencing, in a cohort of 95 Italian patients either sporadic or familial, as well as on their at-risk relatives. Sixteen mutations in 16 unrelated CCM patients were identified,nine mutations are novel: c.413T > C; c.601C > T; c.846 + 2T > G; c.1254delA; c.1255-4delGTA; c.1682-1683 delTA in CCM1; c.48A > G; c.82-83dupAG in CCM2; and c.395 + 1G > A in CCM3 genes [corrected].The samples, negative to direct exon sequencing, were investigated by MLPA to search for intragenic deletions or duplications. One deletion in CCM1 exon 18 was detected in a sporadic patient. Among familial cases 67% had a mutation in CCM1, 5.5% in CCM2, and 5.5% in CCM3, whereas in the remaining 22% no mutations were detected, suggesting the existence of either undetectable mutations or other CCM genes. This study represents the first extensive research program for a comprehensive molecular screening of the three known genes in an Italian cohort of CCM patients and their at-risk relatives.

Structural and functional differences between KRIT1A and KRIT1B isoforms: a framework for understanding CCM pathogenesis.

KRIT1 is a disease gene responsible for Cerebral Cavernous Malformations (CCM). It encodes for a protein containing distinct protein-protein interaction domains, including three NPXY/F motifs and a FERM domain. Previously, we isolated KRIT1B, an isoform characterized by the alternative splicing of the 15th coding exon and suspected to cause CCM when abnormally expressed. Combining homology modeling and docking methods of protein-structure and ligand binding prediction with the yeast two-hybrid assay of in vivo protein-protein interaction and cellular biology analyses we identified both structural and functional differences between KRIT1A and KRIT1B isoforms. We found that the 15th exon encodes for the distal beta-sheet of the F3/PTB-like subdomain of KRIT1A FERM domain, demonstrating that KRIT1B is devoid of a functional PTB binding pocket. As major functional consequence, KRIT1B is unable to bind Rap1A, while the FERM domain of KRIT1A is even sufficient for this function. Furthermore, we found that a functional PTB subdomain enables the nucleocytoplasmic shuttling of KRIT1A, while its alteration confers a restricted cytoplasmic localization and a dominant negative role to KRIT1B. Importantly, we also demonstrated that KRIT1A, but not KRIT1B, may adopt a closed conformation through an intramolecular interaction involving the third NPXY/F motif at the N-terminus and the PTB subdomain of the FERM domain, and proposed a mechanism whereby an open/closed conformation switch regulates KRIT1A nuclear translocation and interaction with Rap1A in a mutually exclusive manner. As most mutations found in CCM patients affect the KRIT1 FERM domain, the new insights into the structure-function relationship of this domain may constitute a useful framework for understanding molecular mechanisms underlying CCM pathogenesis.

Social relationships and HRQL: a cross-sectional survey among older Italian adults.

BACKGROUND: The aim of this study is to investigate the association between social relationships and Health Related Quality of Life (HRQL) among the elderly in Italy. METHODS: A sample of 33,744 Italian residents, representing the non-institutionalised population aged 60 years and over was extracted from the national ISTAT cross-sectional survey during 1999-2000. HRQL was measured with the SF-12, from which the Physical Component Score (PCS) and Mental Component Score (MCS) were obtained. Data were subjected to descriptive analysis and multiple logistic regression models with adjustment for the main confounders. RESULTS: Our analysis shows a gradient in PCS and MCS among the terziles in seeing/meeting "friends" and "family" and, for PCS, a North-South gradient among the Italian regions. Females, the elderly who reported a lower household income, those who spent less time in recreational and religious activities, who lived too far from their relatives and had few relationships with friends and relatives, were significantly less likely to have an MCS above the median value. For PCS, an increase in HRQL was likely to be associated with a higher educational level, while lower PCS scores were associated with: age 75+, inadequate household income, unmarried status, infrequency of seeing/meeting friends, too high a mean distance from own home to relatives' homes, lack of leisure time spent in recreational activities, living in the Centre-South of Italy, chronic diseases, reduced autonomy, and use of drugs during the previous two days. Significant interactions between suffering from one chronic disease and the use of drugs were also found for both MCS and PCS. CONCLUSION: Some dimensions of social relationships were significantly associated with HRQL. These findings are crucial for devising welfare strategies at both the regional and the European level, i.e. in countries such as Italy where the primacy of family support of the elderly has declined in recent years.

Rap1: a turnabout for the crosstalk between cadherins and integrins.

The coordinate modulation of the cellular functions of cadherins and integrins plays an essential role in fundamental physiological and pathological processes, including morphogenesis, tissue differentiation and renewal, wound healing, immune surveillance, inflammatory response, tumour progression, and metastasis. However, the molecular mechanisms underlying the fine-balanced relationship between cadherin and integrin functions are still elusive. This review focuses on recent findings on the involvement of the small GTPase Rap1 in the regulation of cadherin- and integrin-dependent cell adhesion and signal transduction. In particular, it highlights some of the novel results recently obtained that raise the possibility of a pivotal role for Rap1 in the functional crosstalk between cadherins and integrins, suggesting interesting new regulatory mechanisms.

E-cadherin endocytosis regulates the activity of Rap1: a traffic light GTPase at the crossroads between cadherin and integrin function.

The coordinate modulation of cadherin and integrin functions plays an essential role in fundamental physiological and pathological processes, including morphogenesis and cancer. However, the molecular mechanisms underlying the functional crosstalk between cadherins and integrins are still elusive. Here, we demonstrate that the small GTPase Rap1, a crucial regulator of the inside-out activation of integrins, is a target for E-cadherin-mediated outside-in signaling. In particular, we show that a strong activation of Rap1 occurs upon adherens junction disassembly that is triggered by E-cadherin internalization and trafficking along the endocytic pathway. By contrast, Rap1 activity is not influenced by integrin outside-in signaling. Furthermore, we demonstrate that the E-cadherin endocytosis-dependent activation of Rap1 is associated with and controlled by an increased Src kinase activity, and is paralleled by the colocalization of Rap1 and E-cadherin at the perinuclear Rab11-positive recycling endosome compartment, and the association of Rap1 with a subset of E-cadherin-catenin complexes that does not contain p120ctn. Conversely, Rap1 activity is suppressed by the formation of E-cadherin-dependent cell-cell junctions as well as by agents that inhibit either Src activity or E-cadherin internalization and intracellular trafficking. Finally, we demonstrate that the E-cadherin endocytosis-dependent activation of Rap1 is associated with and is required for the formation of integrin-based focal adhesions. Our findings provide the first evidence of an E-cadherin-modulated endosomal signaling pathway involving Rap1, and suggest that cadherins may have a novel modulatory role in integrin adhesive functions by fine-tuning Rap1 activation.

Identification of Krit1B: a novel alternative splicing isoform of cerebral cavernous malformation gene-1.

Cerebral cavernous malformations (CCM) are vascular malformations, mostly located in the central nervous system, which occur in 0.1-0.5% of the population. They are characterized by abnormally enlarged and often leaking capillary cavities without intervening neural parenchyma. Some are clinically silent, whereas others cause seizures, intracerebral haemorrhage or focal neurological deficits. These vascular malformations can arise sporadically or may be inherited as an autosomal dominant condition with incomplete penetrance. At least 45% of families affected with cerebral cavernous malformations harbour a mutation in Krev interaction trapped-1 (Krit1) gene (cerebral cavernous malformation gene-1, CCM1). This gene contains 16 coding exons which encode a 736-amino acid protein containing three ankyrin repeats and a FERM domain. Neither the CCM1 pathogenetic mechanisms nor the function of the Krit1 protein are understood so far, although several hypotheses have been inferred from the predicted consequences of Krit1 mutations as well as from the identification of Krit1 as a binding partner of Rap1A, ICAP1A and microtubules. Here, we report the identification of Krit1B, a novel Krit1 isoform characterized by the alternative splicing of the 15th coding exon. We show that the Krit1B splice isoform is widely expressed in mouse cell lines and tissues, whereas its expression is highly restricted in human. In addition, we developed a real-time PCR strategy to accurately quantify the relative ratio of the two Krit1 alternative transcripts in different tissues, demonstrating a Krit1B/Krit1A ratio up to 20% in mouse thymus, but significantly lower ratios in other tissues. Bioinformatic analysis using exon/gene-prediction, comparative alignment and structure analysis programs supported the existence of Krit1 alternative transcripts lacking the 15th coding exon and showed that the splicing out of this exon occurs outside of potentially important Krit1 structural domains but in a region required for association with Rap1A, suggesting a subtle, yet important effect on the protein function. Our results indicate that maintenance of a proper ratio between Krit1A and Krit1B could be functionally relevant and suggest that the novel Krit1B isoform might expand our understanding of the role of Krit1 in CCM1 pathogenesis.