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2.
J Gastrointest Surg ; 27(10): 2057-2067, 2023 10.
Artículo en Inglés | MEDLINE | ID: mdl-37464143

RESUMEN

BACKGROUND: Laparoscopic gastrectomy could reduce pain and opioid consumption, compared to open gastrectomy. However, it is difficult to judge the clinical relevance of this reduction, since these outcomes are reported in few randomized trials and in limited detail. METHODS: This secondary analysis of a multicenter randomized trial compared laparoscopic versus open gastrectomy for resectable gastric adenocarcinoma (cT1-4aN0-3bM0). Postoperative pain was analyzed by opioid consumption in oral morphine equivalents (OME, mg/day) at postoperative day (POD) 1-5, WHO analgesic steps, and Numeric Rating Scales (NRS, 0-10) at POD 1-10 and discharge. Regression and mixed model analyses were performed, with and without correction for epidural analgesia. RESULTS: Between 2015 and 2018, 115 patients in the laparoscopic group and 110 in the open group underwent surgery. Some 16 patients (14%) in the laparoscopic group and 73 patients (66%) in the open group received epidural analgesia. At POD 1-3, mean opioid consumption was 131, 118, and 53 mg OME lower in the laparoscopic group, compared to the open group, respectively (all p < 0.001). After correcting for epidural analgesia, these differences remained significant at POD 1-2 (47 mg OME, p = 0.002 and 69 mg OME, p < 0.001, respectively). At discharge, 27% of patients in the laparoscopic group and 43% patients in the open group used oral opioids (p = 0.006). Mean highest daily pain scores were between 2 and 4 at all PODs, < 2 at discharge, and did not relevantly differ between treatment arms. CONCLUSION: In this multicenter randomized trial, postoperative pain was comparable between laparoscopic and open gastrectomy. After laparoscopic gastrectomy, this was generally achieved without epidural analgesia and with fewer opioids. TRIAL REGISTRATION: NCT02248519.


Asunto(s)
Laparoscopía , Neoplasias Gástricas , Humanos , Analgésicos Opioides/uso terapéutico , Neoplasias Gástricas/cirugía , Neoplasias Gástricas/tratamiento farmacológico , Dolor Postoperatorio/tratamiento farmacológico , Dolor Postoperatorio/etiología , Gastrectomía/efectos adversos
4.
BMJ Open ; 13(4): e068970, 2023 04 19.
Artículo en Inglés | MEDLINE | ID: mdl-37076142

RESUMEN

PURPOSE: Although elective surgery is generally safe, some procedures remain associated with an increased risk of complications. Improved preoperative risk stratification and earlier recognition of these complications may ameliorate postoperative recovery and improve long-term outcomes. The perioperative longitudinal study of complications and long-term outcomes (PLUTO) cohort aims to establish a comprehensive biorepository that will facilitate research in this field. In this profile paper, we will discuss its design rationale and opportunities for future studies. PARTICIPANTS: Patients undergoing elective intermediate to high-risk non-cardiac surgery are eligible for enrolment. For the first seven postoperative days, participants are subjected to daily bedside visits by dedicated observers, who adjudicate clinical events and perform non-invasive physiological measurements (including handheld spirometry and single-channel electroencephalography). Blood samples and microbiome specimens are collected at preselected time points. Primary study outcomes are the postoperative occurrence of nosocomial infections, major adverse cardiac events, pulmonary complications, acute kidney injury and delirium/acute encephalopathy. Secondary outcomes include mortality and quality of life, as well as the long-term occurrence of psychopathology, cognitive dysfunction and chronic pain. FINDINGS TO DATE: Enrolment of the first participant occurred early 2020. During the inception phase of the project (first 2 years), 431 patients were eligible of whom 297 patients consented to participate (69%). Observed event rate was 42% overall, with the most frequent complication being infection. FUTURE PLANS: The main purpose of the PLUTO biorepository is to provide a framework for research in the field of perioperative medicine and anaesthesiology, by storing high-quality clinical data and biomaterials for future studies. In addition, PLUTO aims to establish a logistical platform for conducting embedded clinical trials. TRIAL REGISTRATION NUMBER: NCT05331118.


Asunto(s)
Bancos de Muestras Biológicas , Calidad de Vida , Humanos , Diagnóstico Precoz , Estudios Longitudinales , Complicaciones Posoperatorias/diagnóstico , Complicaciones Posoperatorias/epidemiología
5.
JAMA Surg ; 158(3): 254-263, 2023 03 01.
Artículo en Inglés | MEDLINE | ID: mdl-36598762

RESUMEN

Importance: Current fasting guidelines for procedures under anesthesia are poorly implemented, leading to negative metabolic sequelae. Recent studies in children showed support of liberal clear fluid intake; adult physiology can support clear fluid intake, but implementation studies are lacking. Objective: To evaluate the successfulness of implementation of a liberal clear fluid policy with regard to fasting duration, well-being, and safety in adults scheduled for anesthesia. Design, Setting, and Participants: This was a quality improvement study conducted from January 2016 to July 2021 at a tertiary referral hospital in the Netherlands. Adults scheduled for nonemergency procedures under anesthesia were included in the study. Patients undergoing obstetrics procedures or those who were intubated preoperatively were excluded. Interventions: Stepwise introduction of a liberal fluid fasting policy, allowing for ingestion of clear fluids until arrival at the operating room. Main Outcomes and Measures: The primary outcome was change in fasting duration. Secondary outcomes were patient well-being, measured as preoperative thirst, amount of fluid ingested, postoperative nausea and vomiting (PONV), and administration of antiemetics. Safety was measured as incidence of regurgitation and aspiration (pneumonia). Results: Of the 76 451 patients (mean [SD] age, 56 [17] years; 39 530 male individuals [52%] 36 921) included in the study, 59 036 (78%) followed the standard policy, and 16 815 (22%) followed the liberal policy. Time series analysis showed an estimated fasting duration decrease of 3:07 hours (IQR, 1:36-7:22; P < .001) after implementation of the liberal policy. Postimplementation median (IQR) fasting duration was 1:20 (0:48-2:24) hours. The incidence of regurgitation changed from 18 (95% CI, 14-21) to 24 (95% CI, 17-32) in 10 000 patients, and the incidence of aspiration changed from 1.7 (95% CI, 0.6-2.7) to 2.4 (95% CI, 0.5-4.7) in 10 000 patients. In the liberal policy, thirst feelings decreased (37% [4982 of 8615] vs 46% [3373 of 7362]; P < .001). PONV incidence decreased from 10.6% (6339 of 59 636) to 9.4% (1587 of 16 815; P < .001) and antiemetic administration decreased from 11.0% (6538 of 59 636) to 9.5% (1592 of 16 815; P < .001). Conclusions and Relevance: Results of this quality improvement study suggest that a liberal fasting policy was associated with a clinically relevant reduction in fasting duration and improved patient well-being with regard to preoperative thirst and PONV. Although a slightly higher incidence of regurgitation could not be ruled out, wider implementation of such a policy may be advocated as results are still within the clinically accepted risks margins. Results suggest that surgical procedures in patients who drink clear fluids within 2 hours before anticipated anesthesia should not be postponed or canceled.


Asunto(s)
Anestesia , Neumonía por Aspiración , Niño , Adulto , Humanos , Masculino , Persona de Mediana Edad , Náusea y Vómito Posoperatorios , Cuidados Preoperatorios/métodos , Ayuno
6.
Ned Tijdschr Geneeskd ; 1662022 10 20.
Artículo en Holandés | MEDLINE | ID: mdl-36300494

RESUMEN

INTRODUCTION: Patients with a history of chronic obstructive pulmonary disease (COPD) or asthma undergoing surgery are at risk for developing postoperative pulmonary complications, associated with morbidity and mortality. A national guideline was composed on preventive strategies in non-thoracic surgery, in which perioperative administration of corticosteroids are a cornerstone. We investigated the implementation in our hospital. METHOD: Patients with a history of asthma and/or COPD who underwent non-thoracic surgery between January 2017 and July 2018 in our hospital, were included. Primary outcome was perioperative administration of intravenous prednisolone or oral prednisone as preventative treatment. The reasons for (non)adherence were investigated as secondary outcome. RESULTS: 1,623 patients qualified for a preventative treatment. Overall, 653 patients (40%) received treatment according to protocol. The other 970 patients received no treatment (79%), another corticosteroid (12%) or received the other strategy (9%). Based on interviews and surveys, several barriers were found: fear of side effects of corticosteroids, indications for other types of corticosteroids, and lack of confidence in the literature. CONCLUSION: The current guideline for prevention of postoperative pulmonary complications has not been implemented thoroughly at our hospital. The lack of adherence appears to be caused by lack in clarity in clinical practice, lack of confidence in the evidence on which the protocol is based, and fear of side effects of corticosteroids. There are also notable differences between the vision of pulmonologists and the anesthesiologists. Further research is needed to solidify the guideline, anticipating aforementioned compliance barriers to achieve better implementation.


Asunto(s)
Asma , Enfermedad Pulmonar Obstructiva Crónica , Humanos , Prednisona/uso terapéutico , Enfermedad Pulmonar Obstructiva Crónica/complicaciones , Enfermedad Pulmonar Obstructiva Crónica/tratamiento farmacológico , Corticoesteroides/uso terapéutico , Prednisolona , Adhesión a Directriz
7.
BJA Open ; 3: 100022, 2022 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-37588577

RESUMEN

Background: Informed consent for anaesthesia is mandatory and requires provision of information and subsequent consent during consultation between anaesthesiologist and patient. Although information can be provided in an electronic format, it is unknown whether this a valid substitute for a consultation. We explored whether provision of digital information is equivalent to oral consultation and whether it enables patients to give electronic informed consent (e-consent) for anaesthesia. Methods: Qualitative feasibility study using semi-structured interviews in 20 low-risk adults scheduled for minor surgery under general anaesthesia or procedural sedation at a university hospital. Data were analysed using a thematic content analysis approach. During the interviews, patients followed an application that provides information and subsequent e-consenting. Results: The mean age was 50 yr and patients had good digital skills. Fifteen patients (75%) had previous experience of anaesthesia. The digital application provided enough information for all patients, but eight (40%) preferred consultation with an anaesthesiologist, mainly for personal contact. Patients had different information needs, with previous experiences leading to lower information needs. Nineteen patients had sufficient information to consent autonomously. Most patients considered separate anaesthesia consent superfluous to the surgical consent. Conclusion: The digital application provided sufficient information and patients valued the information offered and the advantage of processing information at their own pace. This information made patients feel empowered to autonomously consent to anaesthesia without consultation. Remarkably, consent for anaesthesia was considered unimportant, because patients felt they had 'no choice' if they wanted to undergo surgery.

9.
Eur J Prev Cardiol ; 28(3): 262-269, 2021 04 23.
Artículo en Inglés | MEDLINE | ID: mdl-33891688

RESUMEN

BACKGROUND: Functional capacity is used as an indicator for cardiac testing before non-cardiac surgery and is often performed subjectively. However, the value of subjectively estimated functional capacity in predicting cardiac complications is under debate. We determined the predictive value of subjectively assessed functional capacity on postoperative cardiac complications and mortality. DESIGN: An observational cohort study in patients aged 60 years and over undergoing elective inpatient non-cardiac surgery in a tertiary referral hospital. METHODS: Subjective functional capacity was determined by anaesthesiologists. The primary outcome was postoperative myocardial injury. Secondary outcomes were postoperative inhospital myocardial infarction and one year mortality. Logistic regression analysis and area under the receiver operating curves were used to determine the added value of functional capacity. RESULTS: A total of 4879 patients was included; 824 (17%) patients had a poor subjective functional capacity. Postoperative myocardial injury occurred in 718 patients (15%). Poor functional capacity was associated with myocardial injury (relative risk (RR) 1.7, 95% confidence interval (CI) 1.5-2.0; P < 0.001), postoperative myocardial infarction (RR 2.9, 95% CI 1.9-4.2; P < 0.001) and one year mortality (RR 1.7, 95% CI 1.4-2.0; P < 0.001). After adjustment for other predictors, functional capacity was still a significant predictor for myocardial injury (odds ratio (OR) 1.3, 95% CI 1.0-1.7; P = 0.023), postoperative myocardial infarction (OR 2.0, 95% CI 1.3-3.0; P = 0.002) and one year mortality (OR 1.4, 95% CI 1.1-1.8; P = 0.003), but had no added value on top of other predictors. CONCLUSIONS: Subjectively assessed functional capacity is a predictor of postoperative myocardial injury and death, but had no added value on top of other preoperative predictors.


Asunto(s)
Cardiopatías , Infarto del Miocardio , Anciano , Humanos , Persona de Mediana Edad , Infarto del Miocardio/diagnóstico , Infarto del Miocardio/epidemiología , Infarto del Miocardio/etiología , Oportunidad Relativa , Complicaciones Posoperatorias/diagnóstico , Complicaciones Posoperatorias/epidemiología , Periodo Posoperatorio
10.
JMIR Mhealth Uhealth ; 9(1): e23402, 2021 01 07.
Artículo en Inglés | MEDLINE | ID: mdl-33410758

RESUMEN

BACKGROUND: Major surgery is associated with negative postoperative outcomes such as complications and delayed or poor recovery. Multimodal prehabilitation can help to reduce the negative effects of major surgery. Offering prehabilitation by means of mobile health (mHealth) could be an effective new approach. OBJECTIVE: The objectives of this pilot study were to (1) evaluate the usability of the Be Prepared mHealth app prototype for people undergoing major surgery, (2) explore whether the app was capable of bringing about a change in risk behaviors, and (3) estimate a preliminary effect of the app on functional recovery after major surgery. METHODS: A mixed-methods pilot randomized controlled trial was conducted in two Dutch academic hospitals. In total, 86 people undergoing major surgery participated. Participants in the intervention group received access to the Be Prepared app, a smartphone app using behavior change techniques to address risk behavior prior to surgery. Both groups received care as usual. Usability (System Usability Scale), change in risk behaviors 3 days prior to surgery, and functional recovery 30 days after discharge from hospital (Patient-Reported Outcomes Measurement Information System physical functioning 8-item short form) were assessed using online questionnaires. Quantitative data were analyzed using descriptive statistics, chi-square tests, and multivariable linear regression. Semistructured interviews about the usability of the app were conducted with 12 participants in the intervention group. Thematic analysis was used to analyze qualitative data. RESULTS: Seventy-nine people-40 in the intervention group and 39 in the control group-were available for further analysis. Participants had a median age of 61 (interquartile range 51.0-68.0) years. The System Usability Scale showed that patients considered the Be Prepared app to have acceptable usability (mean 68.2 [SD 18.4]). Interviews supported the usability of the app. The major point of improvement identified was further personalization of the app. Compared with the control group, the intervention group showed an increase in self-reported physical activity and muscle strengthening activities prior to surgery. Also, 2 of 2 frequent alcohol users in the intervention group versus 1 of 9 in the control group drank less alcohol in the run-up to surgery. No difference was found in change of smoking cessation. Between-group analysis showed no meaningful differences in functional recovery after correction for baseline values (ß=-2.4 [95% CI -5.9 to 1.1]). CONCLUSIONS: The Be Prepared app prototype shows potential in terms of usability and changing risk behavior prior to major surgery. No preliminary effect of the app on functional recovery was found. Points of improvement have been identified with which the app and future research can be optimized. TRIAL REGISTRATION: Netherlands Trial Registry NL8623; https://www.trialregister.nl/trial/8623.


Asunto(s)
Aplicaciones Móviles , Ejercicios de Estiramiento Muscular , Ejercicio Preoperatorio , Telemedicina , Anciano , Femenino , Humanos , Persona de Mediana Edad , Países Bajos , Medición de Resultados Informados por el Paciente , Proyectos Piloto , Cuidados Preoperatorios , Periodo Preoperatorio
11.
Crit Care Res Pract ; 2019: 4837591, 2019.
Artículo en Inglés | MEDLINE | ID: mdl-31016043

RESUMEN

BACKGROUND: Adequate pain control is essential in the treatment of patients with traumatic rib fractures. Although epidural analgesia is recommended in international guidelines, the use remains debatable and is not undisputed. The aim of this study was to describe the efficacy and safety of epidural analgesia in patients with multiple traumatic rib fractures. METHODS: A retrospective cohort study was performed. Patients with ≥3 rib fractures following blunt chest trauma who received epidural analgesia between January 2015 and January 2018 were included. The main outcome parameters were the success rate of epidural analgesia and the incidence of medication-related side effects and catheter-related complications. RESULTS: A total of 76 patients were included. Epidural analgesia was successful in a total of 45 patients (59%), including 22 patients without and in 23 patients with an additional analgesic intervention. In 14 patients (18%), epidural analgesia was terminated early without intervention due to insufficient sensory blockade (n=4), medication-related side effects (n=4), and catheter-related complications (n=6). In 17 patients (22%), the epidural catheter was removed after one or multiple additional interventions due to insufficient pain control. Minor epidural-related complications or side effects were encountered in 36 patients (47%). One patient had a major complication (opioid intoxication). CONCLUSION: Epidural analgesia was successful in 59% of patients; however, 30% needed additional analgesic interventions. As about half of the patients had epidural-related complications, it remains debatable whether epidural analgesia is a sufficient treatment modality in patients with multiple rib fractures.

12.
Eur J Trauma Emerg Surg ; 45(4): 597-622, 2019 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-29411048

RESUMEN

PURPOSE: Many studies report on outcomes of analgesic therapy for (suspected) traumatic rib fractures. However, the literature is inconclusive and diverse regarding the management of pain and its effect on pain relief and associated complications. This systematic review and meta-analysis summarizes and compares reduction of pain for the different treatment modalities and as secondary outcome mortality during hospitalization, length of mechanical ventilation, length of hospital stay, length of intensive care unit stay (ICU) and complications such as respiratory, cardiovascular, and/or analgesia-related complications, for four different types of analgesic therapy: epidural analgesia, intravenous analgesia, paravertebral blocks and intercostal blocks. METHODS: PubMed, EMBASE and CENTRAL databases were searched to identify comparative studies investigating epidural, intravenous, paravertebral and intercostal interventions for traumatic rib fractures, without restriction for study type. The search strategy included keywords and MeSH or Emtree terms relating blunt chest trauma (including rib fractures), analgesic interventions, pain management and complications. RESULTS: A total of 19 papers met our inclusion criteria and were finally included in this systematic review. Significant differences were found in favor of epidural analgesia for the reduction of pain. No significant differences were observed between epidural analgesia, intravenous analgesia, paravertebral blocks and intercostal blocks, for the secondary outcomes. CONCLUSIONS: Results of this study show that epidural analgesia provides better pain relief than the other modalities. No differences were observed for secondary endpoints like length of ICU stay, length of mechanical ventilation or pulmonary complications. However, the quality of the available evidence is low, and therefore, preclude strong recommendations.


Asunto(s)
Analgésicos/uso terapéutico , Dolor Musculoesquelético/prevención & control , Fracturas de las Costillas/complicaciones , Administración Intravenosa , Adolescente , Adulto , Anciano , Analgesia Epidural/estadística & datos numéricos , Cuidados Críticos/estadística & datos numéricos , Métodos Epidemiológicos , Humanos , Tiempo de Internación/estadística & datos numéricos , Persona de Mediana Edad , Bloqueo Nervioso/estadística & datos numéricos , Dimensión del Dolor , Adulto Joven
13.
Ned Tijdschr Geneeskd ; 157(25): A6068, 2013.
Artículo en Holandés | MEDLINE | ID: mdl-23777966

RESUMEN

Here we report two cases in which healthy young patients died during surgery because ventilation was impossible by a clinical picture of massive subcutaneous emphysema. The probable diagnosis was tracheal rupture. This diagnosis was not confirmed during coroner's autopsy, but there had been no systematic search for a puncture in the trachea or the main bronchial tubes. Immediate recognition of this situation, and implementation of ventilation of one lung by pushing a narrower endobronchial tube beyond the tracheal rupture, is potentially life-saving.


Asunto(s)
Intubación Intratraqueal/efectos adversos , Enfisema Subcutáneo/etiología , Tráquea/lesiones , Resultado Fatal , Femenino , Humanos , Masculino , Periodo Perioperatorio , Rotura/etiología , Enfisema Subcutáneo/mortalidad , Tráquea/cirugía , Adulto Joven
14.
Nature ; 450(7170): 725-30, 2007 Nov 29.
Artículo en Inglés | MEDLINE | ID: mdl-18046412

RESUMEN

With the emergence of multidrug resistant (MDR) bacteria, it is imperative to develop new intervention strategies. Current antibiotics typically target pathogen rather than host-specific biochemical pathways. Here we have developed kinase inhibitors that prevent intracellular growth of unrelated pathogens such as Salmonella typhimurium and Mycobacterium tuberculosis. An RNA interference screen of the human kinome using automated microscopy revealed several host kinases capable of inhibiting intracellular growth of S. typhimurium. The kinases identified clustered in one network around AKT1 (also known as PKB). Inhibitors of AKT1 prevent intracellular growth of various bacteria including MDR-M. tuberculosis. AKT1 is activated by the S. typhimurium effector SopB, which promotes intracellular survival by controlling actin dynamics through PAK4, and phagosome-lysosome fusion through the AS160 (also known as TBC1D4)-RAB14 pathway. AKT1 inhibitors counteract the bacterial manipulation of host signalling processes, thus controlling intracellular growth of bacteria. By using a reciprocal chemical genetics approach, we identified kinase inhibitors with antibiotic properties and their host targets, and we determined host signalling networks that are activated by intracellular bacteria for survival.


Asunto(s)
Espacio Intracelular/microbiología , Proteínas Proto-Oncogénicas c-akt/metabolismo , Salmonella typhimurium/crecimiento & desarrollo , Animales , Antibacterianos/química , Antibacterianos/farmacología , Línea Celular Tumoral , Humanos , Espacio Intracelular/efectos de los fármacos , Isoquinolinas/química , Isoquinolinas/farmacología , Macrófagos/efectos de los fármacos , Macrófagos/microbiología , Redes y Vías Metabólicas , Ratones , Inhibidores de Proteínas Quinasas/farmacología , Proteínas Proto-Oncogénicas c-akt/antagonistas & inhibidores , Interferencia de ARN , Salmonella typhimurium/efectos de los fármacos , Sulfonamidas/química , Sulfonamidas/farmacología
15.
Proc Natl Acad Sci U S A ; 104(14): 5989-94, 2007 Apr 03.
Artículo en Inglés | MEDLINE | ID: mdl-17389361

RESUMEN

TNF family member CD70 is the ligand of CD27, a costimulatory receptor that shapes effector and memory T cell pools. Tight control of CD70 expression is required to prevent lethal immunodeficiency. By selective transcription, CD70 is largely confined to activated lymphocytes and dendritic cells (DC). We show here that, in addition, specific intracellular routing controls its plasma membrane deposition. In professional antigen-presenting cells, such as DC, CD70 is sorted to late endocytic vesicles, defined as MHC class II compartments (MIIC). In cells lacking the machinery for antigen presentation by MHC class II, CD70 travels by default to the plasma membrane. Introduction of class II transactivator sufficed to reroute CD70 to MIIC. Vesicular trafficking of CD70 and MHC class II is coordinately regulated by the microtubule-associated dynein motor complex. We show that when maturing DC make contact with T cells in a cognate fashion, newly synthesized CD70 is specifically delivered via MIIC to the immunological synapse. Therefore, we propose that routing of CD70 to MIIC serves to coordinate delivery of the T cell costimulatory signal in time and space with antigen recognition.


Asunto(s)
Células Presentadoras de Antígenos/inmunología , Ligando CD27/inmunología , Células Dendríticas/inmunología , Antígenos de Histocompatibilidad Clase II/inmunología , Animales , Células Presentadoras de Antígenos/ultraestructura , Células de la Médula Ósea/citología , Ligando CD27/ultraestructura , Membrana Celular/inmunología , Membrana Celular/ultraestructura , Células Cultivadas , Técnicas de Cocultivo , Células Dendríticas/ultraestructura , Técnica del Anticuerpo Fluorescente Indirecta , Técnicas de Transferencia de Gen , Vectores Genéticos , Células HeLa , Antígenos de Histocompatibilidad Clase II/ultraestructura , Humanos , Ligandos , Lipopolisacáridos/farmacología , Activación de Linfocitos/inmunología , Melanoma/inmunología , Melanoma/ultraestructura , Ratones , Ratones Endogámicos C57BL , Microscopía Fluorescente
16.
Pigment Cell Res ; 19(5): 412-23, 2006 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-16965270

RESUMEN

Melanosomes are lysosome-related organelles that synthesize, store and transport melanin. In epidermal melanocytes, melanosomes mature and are transferred to surrounding keratinocytes, which is essential for skin and coat colour. Mouse coat colour mutants reveal a critical role for the small GTPase Rab27a, which recruits myosin Va through its effector protein melanophilin/Slac2a. Here we have studied how two different Rab GTPases control two motor proteins during subsequent phases in transport of melanosomes. We show that the small GTPase Rab7 mainly associates with early and intermediate stage melanosomes and Rab27a to intermediate and mature melanosomes. Rab27a is found in an active state on mature melanosomes in the tips of the dendrites. The Rab7-Rab7-interacting lysosomal protein-dynein pathway only controls early and intermediate stage melanosomes because the mature melanosomes lack Rab7 and associate with the actin network through Rab27a recruited MyoVa. Thus two Rab proteins regulate two different motor proteins, thereby controlling complementary phases in melanosome biogenesis: Rab7 controls microtubule-mediated transport of early and Rab27a the subsequent actin-dependent transport of mature melanosomes.


Asunto(s)
Citoesqueleto/metabolismo , Melanosomas/metabolismo , Proteínas de Unión al GTP rab/metabolismo , Animales , Transporte Biológico/fisiología , Citoesqueleto/ultraestructura , Humanos , Melanosomas/genética , Melanosomas/ultraestructura , Ratones , Pigmentación/genética , Proteínas rab27 de Unión a GTP , Proteínas de Unión a GTP rab7
17.
Biochem Biophys Res Commun ; 344(3): 747-56, 2006 Jun 09.
Artículo en Inglés | MEDLINE | ID: mdl-16631113

RESUMEN

The small GTPase Rab7 controls fusion and transport of late endocytic compartments. A critical mediator is the Rab7 effector RILP that recruits the minus-end dynein-dynactin motor complex to these compartments. We identified a natural occurring splice variant of RILP (RILPsv) lacking only 27 amino acids encoded by exon VII. Both variants bind Rab7, prolong its GTP-bound state, and induce clustering of late endocytic compartments. However, RILPsv does not recruit the dynein-dynactin complex, implicating exon VII in motor recruitment. Clustering might still occur via dimerization, since both RILP and RILPsv are able to form hetero- and homo-dimers. Moreover, both effectors compete for Rab7 binding but with different outcome for dynein-dynactin recruitment and transport. Hence, RILPsv provides an extra dimension to the control of vesicle fusion and transport by the small GTPase Rab7.


Asunto(s)
Proteínas Portadoras/metabolismo , Dineínas/metabolismo , Endocitosis , Lisosomas/metabolismo , Lisosomas/ultraestructura , Melanoma/metabolismo , Proteínas Motoras Moleculares/metabolismo , Proteínas Adaptadoras Transductoras de Señales , Sitios de Unión , Línea Celular Tumoral , Variación Genética/genética , Humanos , Melanoma/ultraestructura , Proteínas Motoras Moleculares/ultraestructura , Unión Proteica , Empalme de Proteína/genética , Relación Estructura-Actividad , Proteínas de Unión al GTP rab/metabolismo , Proteínas de Unión a GTP rab7
18.
Traffic ; 6(12): 1070-7, 2005 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-16262719

RESUMEN

Small GTPases of the Rab family control timing of vesicle fusion. Fusion of two vesicles can only occur when they have been brought into close contact. Transport by microtubule- or actin-based motor proteins will facilitate this process in vivo. Ideally, transport and vesicle fusion are linked activities. Active, GTP-bound Rab proteins dock on specific compartments and are therefore perfect candidates to control transport of the different compartments. Recently, a number of Rab proteins were identified that control motor protein recruitment to their specific target membranes. By cycling through inactive and active states, Rab proteins are able to control motor protein-mediated transport and subsequent fusion of intracellular structures in both spatial and timed manners.


Asunto(s)
Vesículas Citoplasmáticas/fisiología , Fusión de Membrana/fisiología , Proteínas de Unión al GTP rab/fisiología , Animales , Transporte Biológico Activo/fisiología , Humanos , Transporte de Proteínas/fisiología
19.
Adv Cancer Res ; 93: 129-58, 2005.
Artículo en Inglés | MEDLINE | ID: mdl-15797446

RESUMEN

Tumor vaccine development aimed at stimulating the cellular immune response focuses mainly on MHC class I molecules. This is not surprising since most tumors do not express MHC class II or CD1 molecules. Nevertheless, the most successful targets for cancer immunotherapy, leukemia and melanoma, often do express MHC class II molecules, which leaves no obvious reason to ignore MHC class II molecules as a mediator in anticancer immune therapy. We review the current state of knowledge on the process of MHC class II-restricted antigen presentation and subsequently discuss the consequences of MHC class II expression on tumor surveillance and the induction of an efficient MHC class II mediated antitumor response in vivo and after vaccination.


Asunto(s)
Presentación de Antígeno/inmunología , Transformación Celular Neoplásica/inmunología , Antígenos de Histocompatibilidad Clase II/inmunología , Chaperonas Moleculares/inmunología , Vacunas contra el Cáncer , Vigilancia Inmunológica , Inmunoterapia/métodos
20.
Immunity ; 22(2): 221-33, 2005 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-15723810

RESUMEN

Major Histocompatibility Complex (MHC) class II molecules, including Human Leukocyte Antigen (HLA)-DR, present peptide fragments from proteins degraded in the endocytic pathway. HLA-DR is targeted to late-endocytic structures named MHC class II-containing Compartments (MIIC), where it interacts with HLA-DM. This chaperone stabilizes HLA-DR during peptide exchange and is critical for successful peptide loading. To follow this process in living cells, we have generated cells containing HLA-DR3/Cyan Fluorescent Protein (CFP), HLA-DM/Yellow Fluorescent Protein (YFP), and invariant chain. HLA-DR/DM interactions were observed by Fluorescence Resonance Energy Transfer (FRET). These interactions were pH insensitive, yet occurred only in internal structures and not at the limiting membrane of MIIC. In a cellular model of infection, phagosomes formed a limiting membrane surrounding internalized Salmonella. HLA-DR and HLA-DM did not interact in Salmonella-induced vacuoles, and HLA-DR was not loaded with antigens. The absence of HLA-DR/DM interactions at the limiting membrane prevents local loading of MHC class II molecules in phagosomes. This may allow these bacteria to successfully evade the immune system.


Asunto(s)
Antígenos HLA-D/inmunología , Antígenos HLA-DR/inmunología , Antígenos de Histocompatibilidad Clase II/inmunología , Tolerancia Inmunológica/inmunología , Orgánulos/metabolismo , Fagosomas/inmunología , Línea Celular , Endocitosis , Transferencia Resonante de Energía de Fluorescencia , Antígenos HLA-D/química , Antígenos HLA-D/ultraestructura , Antígenos HLA-DR/química , Antígenos HLA-DR/ultraestructura , Humanos , Concentración de Iones de Hidrógeno , Membranas Intracelulares/inmunología , Membranas Intracelulares/metabolismo , Microscopía Electrónica , Modelos Moleculares , Orgánulos/inmunología , Estructura Terciaria de Proteína
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