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PURPOSE: To determine the recurrence rate of exudative age-related macular degeneration (wet AMD) in patients on 12-week dosing interval anti-vascular endothelial growth factor (anti-VEGF) bevacizumab therapy. METHODS: A retrospective chart review was performed on wet AMD patients treated with anti-VEGF therapy using a "treat-and-extend" methodology at one physician's practice site over 2 years (2012-2014). Charts were evaluated for visual acuity, anti-VEGF agent used, treatment interval, duration of treatment, trials off of anti-VEGF therapy, evidence of exudation, and wet AMD recurrence characteristics. RESULTS: Three hundred and twenty-one wet AMD patients were treated. Fifty-seven eyes were without active exudation by clinical examination or optical coherence tomography (OCT) and were maintained on repeating 12-week interval suppressive anti-VEGF therapy. Sixteen percent (8/49) showed exudation recurrence with an average 10% cumulative recurrence rate per year for eyes on bevacizumab. Eight eyes without active exudation were discontinued off of bevacizumab therapy. Sixty-three percent (5/8) demonstrated recurrence on average 4 months after stopping therapy. CONCLUSION: The findings in this study suggest that if a patient can be extended to 12-week interval bevacizumab therapy, there is on average a 10% chance of recurrence with each successive year. If anti-VEGF therapy is discontinued in these patients, there is an increased chance of recurrence by 4 months.
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Bevacizumab/administración & dosificación , Agudeza Visual , Degeneración Macular Húmeda/epidemiología , Anciano de 80 o más Años , Inhibidores de la Angiogénesis/administración & dosificación , Colorado/epidemiología , Relación Dosis-Respuesta a Droga , Femenino , Angiografía con Fluoresceína/métodos , Estudios de Seguimiento , Fondo de Ojo , Humanos , Incidencia , Inyecciones Intravítreas , Masculino , Receptores de Factores de Crecimiento Endotelial Vascular/antagonistas & inhibidores , Recurrencia , Estudios Retrospectivos , Factores de Tiempo , Tomografía de Coherencia Óptica/métodos , Degeneración Macular Húmeda/diagnóstico , Degeneración Macular Húmeda/tratamiento farmacológicoRESUMEN
BACKGROUND/PURPOSE: To report a case of simultaneous endophthalmitis and anterior segment ischemia (ASI) that occurred in a patient after strabismus surgery. This is the first known case of both complications occurring at the same time. METHODS: Case report. RESULTS: A 60-year-old woman presented with eye pain and loss of vision 6 days after uncomplicated strabismus surgery for thyroid eye disease. On examination, she had corneal edema, anterior segment fibrin, an atonic iris, and no view to the posterior segment. On fluorescein angiography of the anterior segment, a large portion of the iris was nonperfused. Posterior segment ultrasound showed dense vitritis and a choroidal abscess. Intraoperative cultures grew methicillin-resistant Staphylococcus aureus. CONCLUSIONS: Endophthalmitis and anterior segment ischemia are both exceedingly rare complications of strabismus surgery. It is possible that each one occurred independently, but more likely one process potentiated the other. One possible mechanism is inflammation-induced thrombosis.
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Segmento Anterior del Ojo/irrigación sanguínea , Endoftalmitis/etiología , Isquemia/etiología , Procedimientos Quirúrgicos Oftalmológicos/efectos adversos , Estrabismo/cirugía , Enfermedades de la Coroides/etiología , Femenino , Humanos , Enfermedades del Iris/etiología , Isquemia/patología , Persona de Mediana EdadRESUMEN
PURPOSE: To determine whether preoperative medical testing reduces the risk of postoperative systemic adverse events after vitreoretinal surgery. METHODS: Retrospective cohort study at a single academic university hospital involving a total of 2,215 patients undergoing vitreoretinal surgery. Medical charts of 2,215 patients who underwent vitreoretinal surgery between January 2002 and November 2011 at Vanderbilt University were reviewed for baseline comorbidities, preoperative testing, type of anesthesia during surgery, and systemic adverse events occurring within 30 days after surgery. Main outcome measures were the association of baseline characteristics and preoperative testing with postoperative systemic adverse events. RESULTS: Approximately a half of patients had electrolyte, renal function, and electrocardiogram evaluation. The most common comorbidities were hypertension (53%), diabetes mellitus (37%), and coronary artery disease (18%). The most common preoperative testing performed was blood glucose (58%). A total of 102 systemic adverse events occurred in 89 of 2,215 patients (4%) within the first 30 days after surgery with the majority (72%) occurring within the first 24 hours. The most common adverse event was bradycardia (34%) followed by desaturation (25%). Patients with a history of coronary artery disease, asthma, chronic renal disease, or receiving general anesthesia had a 2.04 (P = 0.01), 2.18 (P = 0.03), 2.76 (P < 0.01), and 3.72 (P < 0.001) increased odds of developing postoperative systemic adverse events, respectively. Multivariate logistic regression analysis demonstrated no significant correlation between preoperative testing and postoperative adverse events. CONCLUSION: Incidence of postoperative systemic adverse events after vitreoretinal surgery was 4% and was significantly increased in patients with coronary artery disease, asthma, chronic renal disease, or receiving general anesthesia. In this series, preoperative testing did not measurably influence rates of postoperative systemic complications.
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Pruebas Diagnósticas de Rutina , Atención Perioperativa , Complicaciones Posoperatorias , Cirugía Vitreorretiniana , Glucemia , Estudios de Cohortes , Comorbilidad , Femenino , Estado de Salud , Hospitales de Enseñanza , Humanos , Masculino , Persona de Mediana Edad , Estudios Retrospectivos , Factores de RiesgoRESUMEN
The Drosophila gene pickpocket (ppk) encodes an ion channel subunit of the degenerin/epithelial sodium channel (DEG/ENaC) family. PPK is specifically expressed in nociceptive, class IV multidendritic (md) neurons and is functionally required for mechanical nociception responses. In this study, in a genome-wide genetic screen for other ion channel subunits required for mechanical nociception, we identify a gene that we name balboa (also known as CG8546, ppk26). Interestingly, the balboa locus encodes a DEG/ENaC ion channel subunit highly similar in amino acid sequence to PPK. Moreover, laser-capture isolation of RNA from larval neurons and microarray analyses reveal that balboa is also highly enriched in nociceptive neurons. The requirement for Balboa and PPK in mechanical nociception behaviors and their specific expression in larval nociceptors led us to hypothesize that these DEG/ENaC subunits form an ion channel complex in vivo. In nociceptive neurons, Balboa::GFP proteins distribute uniformly throughout dendrites but remarkably localize to discrete foci when ectopically expressed in other neuron subtypes (where PPK is not expressed). Indeed, ectopically coexpressing ppk transforms this punctate Balboa::GFP expression pattern to the uniform distribution observed in its native cell type. Furthermore, ppk-RNAi in class IV neurons alters the broad Balboa::GFP pattern to a punctate distribution. Interestingly, this interaction is mutually codependent as balboa-RNAi eliminates Venus::PPK from the sensory dendrites of nociceptors. Finally, using a GFP-reconstitution approach in transgenic larvae, we directly detect in vivo physical interactions among PPK and Balboa subunits. Combined, our results indicate a critical mechanical nociception function for heteromeric PPK and Balboa channels in vivo.
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Proteínas de Drosophila/genética , Drosophila melanogaster/fisiología , Canales Epiteliales de Sodio/genética , Nocicepción , Canales de Sodio/genética , Animales , Animales Modificados Genéticamente/genética , Animales Modificados Genéticamente/crecimiento & desarrollo , Animales Modificados Genéticamente/fisiología , Canales de Sodio Degenerina/genética , Canales de Sodio Degenerina/metabolismo , Dendritas/metabolismo , Proteínas de Drosophila/metabolismo , Drosophila melanogaster/genética , Drosophila melanogaster/crecimiento & desarrollo , Canales Epiteliales de Sodio/metabolismo , Larva/fisiología , Análisis de Secuencia por Matrices de Oligonucleótidos , Análisis de Secuencia de Proteína , Canales de Sodio/metabolismoRESUMEN
An 11-year-old girl with no significant medical or ocular history presented to the emergency department with asymmetrical eyelid swelling for 2 days. She was noted to have eyelid crepitus on examination. The patient reported a prolonged episode of crying followed by chest pain and dyspnea that resolved prior to her presentation. Both face and chest CT showed extensive air tracking in the subcutaneous tissues of the neck and face and pneumomediastinum without pneumothorax. The patient was discharged home without further intervention. On follow-up 1 to 2 weeks later, she had complete resolution of her symptoms. While pneumomediastinum is extremely rare in the pediatric population, it can be considered in the differential diagnoses of eyelid swelling and crepitus in the appropriate context. To this author's knowledge, this is the first pediatric case of pneumomediastinum with an initial presentation of eyelid swelling.
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Edema/diagnóstico , Enfermedades de los Párpados/diagnóstico , Enfisema Mediastínico/diagnóstico por imagen , Dolor en el Pecho/diagnóstico , Niño , Disnea/diagnóstico , Femenino , Humanos , Tomografía Computarizada por Rayos XRESUMEN
BACKGROUND: Hematoma expansion, the leading cause of neurologic deterioration after intracerebral hemorrhage (ICH), remains one of the few modifiable risk factors for poor outcome. In the present study, we explored whether common genetic variants within the hemostasis pathway were related to hematoma expansion during the acute period after ICH. METHODS: Patients with spontaneous ICH who were admitted to the institutional Neuro-ICU between 2009 and 2011 were enrolled in the study, and clinical data were collected prospectively. Hematoma size was measured in patients admitted on or before postbleed day 2. Baseline models for hematoma growth were constructed using backwards stepwise logistic regression. Genotyping of single-nucleotide polymorphisms for 13 genes involved in hemostasis was performed, and the results were individually included in the above baseline models to test for independent association of hematoma expansion. RESULTS: During the study period, 82 patients were enrolled in the study and had complete data. The mean age was 65.9 ± 14.9 years, and 38% were female. Only von Willebrand factor was associated with absolute and relative hematoma growth in univariate analysis (P < .001 and P = .007, respectively); von Willebrand factor genotype was independently predictive of relative hematoma growth but only approached significance for absolute hematoma growth (P = .002 and P = .097, respectively). CONCLUSIONS: Our genomic analysis of various hemostatic factors identified von Willebrand factor as a potential predictor of hematoma expansion in patients with ICH. The identification of von Willebrand factor single-nucleotide polymorphisms may allow us to better identify patients who are at risk for hematoma enlargement and will benefit the most from treatment. The relationship of von Willebrand factor with regard to hematoma enlargement in a larger population warrants further study.
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Hemorragia Cerebral/genética , Hematoma/genética , Hemostasis/genética , Polimorfismo de Nucleótido Simple , Factor de von Willebrand/genética , Anciano , Anciano de 80 o más Años , Pruebas de Coagulación Sanguínea , Angiografía Cerebral/métodos , Hemorragia Cerebral/sangre , Hemorragia Cerebral/diagnóstico por imagen , Progresión de la Enfermedad , Femenino , Estudios de Asociación Genética , Predisposición Genética a la Enfermedad , Hematoma/sangre , Hematoma/diagnóstico por imagen , Humanos , Modelos Lineales , Modelos Logísticos , Masculino , Persona de Mediana Edad , Análisis Multivariante , Fenotipo , Estudios Prospectivos , Factores de Riesgo , Factores de Tiempo , Tomografía Computarizada por Rayos XRESUMEN
Intracerebral hemorrhage (ICH) is a devastating form of stroke associated with a high rate of morbidity and mortality. It is now believed that much of this damage occurs in the subacute period following the initial insult via a cascade of complex pathophysiologic pathways that continues to be investigated. Increased levels of certain serum proteins have been identified as biomarkers that may reflect or directly participate in the inflammation, blood brain barrier disruption, endothelial dysfunction, and neuronal and glial toxicity that occur during this secondary period of cerebral injury. Some of these biomarkers have the potential to serve as therapeutic targets or surrogate endpoints for future research or clinical trials. Others may someday augment current clinical techniques in diagnosis, risk-stratification, prognostication, treatment decision and measurement of therapeutic efficacy. While much work remains to be done, biomarkers show significant potential to expand clinical options and improve clinical management, thereby reducing mortality and improving functional outcomes in ICH patients.
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Biomarcadores/sangre , Lesiones Encefálicas/sangre , Lesiones Encefálicas/etiología , Hemorragia Cerebral/complicaciones , Animales , HumanosRESUMEN
Optogenetics is a powerful tool that enables the spatiotemporal control of neuronal activity and circuits in behaving animals. Here, we describe our protocol for optical activation of neurons in Drosophila larvae. As an example, we discuss the use of optogenetics to activate larval nociceptors and nociception behaviors in the third-larval instar. We have previously shown that, using spatially defined GAL4 drivers and potent UAS (upstream activation sequence)-channelrhodopsin-2â·YFP transgenic strains developed in our laboratory, it is possible to manipulate neuronal populations in response to illumination by blue light and to test whether the activation of defined neural circuits is sufficient to shape behaviors of interest. Although we have only used the protocol described here in larval stages, the procedure can be adapted to study neurons in adult flies--with the caveat that blue light may not sufficiently penetrate the adult cuticle to stimulate neurons deep in the brain. This procedure takes 1 week to culture optogenetic flies and ~1 h per group for the behavioral assays.
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Conducta Animal/fisiología , Drosophila/fisiología , Neuronas/fisiología , Óptica y Fotónica/métodos , Animales , Animales Modificados Genéticamente , Encéfalo/fisiología , Proteínas de Drosophila/genética , Larva/fisiología , Proteínas del Tejido Nervioso/genética , Nocicepción , Estimulación Luminosa/métodos , Rodopsina/genéticaRESUMEN
BACKGROUND AND PURPOSE: The restoration of blood-flow following cerebral ischemia incites a series of deleterious cascades that exacerbate neuronal injury. Pharmacologic inhibition of the C3a-receptor ameliorates cerebral injury by attenuating post-ischemic inflammation. Recent reports also implicate C3a in the modulation of tissue repair, suggesting that complement may influence both injury and recovery at later post-ischemic time-points. METHODS: To evaluate the effect of C3a-receptor antagonism on post-ischemic neurogenesis and neurological outcome in the subacute period of stroke, transient focal cerebral ischemia was induced in adult male C57BL/6 mice treated with multiple regimens of a C3a receptor antagonist (C3aRA). RESULTS: Low-dose C3aRA administration during the acute phase of stroke promotes neuroblast proliferation in the subventricular zone at 7 days. Additionally, the C3a receptor is expressed on T-lymphocytes within the ischemic territory at 7 days, and this cellular infiltrate is abrogated by C3aRA administration. Finally, C3aRA treatment confers robust histologic and functional neuroprotection at this delayed time-point. CONCLUSIONS: Targeted complement inhibition through low-dose antagonism of the C3a receptor promotes post-ischemic neuroblast proliferation in the SVZ. Furthermore, C3aRA administration suppresses T-lymphocyte infiltration and improves delayed functional and histologic outcome following reperfused stroke. Post-ischemic complement activation may be pharmacologically manipulated to yield an effective therapy for stroke.
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Antiinflamatorios/farmacología , Complemento C3a/antagonistas & inhibidores , Inflamación/prevención & control , Neurogénesis/efectos de los fármacos , Fármacos Neuroprotectores/farmacología , Receptores de Complemento/antagonistas & inhibidores , Accidente Cerebrovascular/prevención & control , Animales , Isquemia Encefálica/complicaciones , Isquemia Encefálica/patología , Complemento C3a/metabolismo , Modelos Animales de Enfermedad , Inflamación/etiología , Inflamación/metabolismo , Masculino , Ratones , Ratones Endogámicos C57BL , Neurogénesis/fisiología , Receptores de Complemento/metabolismo , Daño por Reperfusión/etiología , Daño por Reperfusión/mortalidad , Daño por Reperfusión/prevención & control , Accidente Cerebrovascular/etiología , Accidente Cerebrovascular/mortalidad , Tasa de Supervivencia , Linfocitos T/inmunología , Linfocitos T/metabolismo , Linfocitos T/patologíaRESUMEN
OBJECTIVE: Alteration in platelet aggregation has been shown to promote bleeding and affect outcome after intracerebral hemorrhage (ICH).We investigated the influence of genetic variants of platelet aggregation, and their effects on admission ICH volume and clinical outcome. METHODS: Our prospective study analyzed selected candidate single-nucleotide polymorphisms (SNPs) previously associated with platelet aggregation phenotype in previous genome-wide association studies, with regards to outcome and ICH volume. Patients were assessed at the Columbia University Medical Center Neuro-Intensive Care Unit. Exclusion criteria included age <18 years, ICH following trauma, hemorrhagic transformation, or tumor, no consent for genetic analysis, or incomplete data. Radiological variables (location and volume of acute ICH, presence of intraventricular extension, midline shift, and hydrocephalus) and clinical variables (mortality and modified Rankin score at discharge) were prospectively recorded. RESULTS: One hundred and twenty-two patients with spontaneous ICH between February 2009 and May 2011 diagnosed via clinical assessment and admission computed tomography scan were included. The median admission Glasgow coma scale score (GCS) was 11·5. Univariate predictors of mortality at discharge included systolic blood pressure, presence of intraventricular hemorrhage, anticoagulant use, and GCS, the only independent predictor of discharge mortality (P<0·001). Age, intraventricular hemorrhage, and GCS were associated with poor functional outcome; age (P = 0·001) and GCS (P<0·001) were significant in the multivariate model. Admission GCS (P<0·01), antiplatelet use, and rs342286 (PIK3CG; P = 0·04; R(2) = 0·247) had univariate associations with hematoma volume. DISCUSSION: We identified SNP rs342286 as an independent predictor of admission hematoma volume. Our findings suggest that PIK3CG function, which is previously linked to this SNP and affects platelet aggregation, impacts the severity of the intraparenchymal bleed.
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Hemorragia Cerebral/genética , Hemorragia Cerebral/patología , Fosfatidilinositol 3-Quinasa Clase Ib/genética , Agregación Plaquetaria/genética , Recuperación de la Función/genética , Hemorragia Cerebral/mortalidad , Femenino , Predisposición Genética a la Enfermedad , Genotipo , Escala de Coma de Glasgow , Humanos , Masculino , Persona de Mediana Edad , Fenotipo , Reacción en Cadena de la Polimerasa , Polimorfismo de Nucleótido Simple , PronósticoRESUMEN
Specialized somatosensory neurons detect temperatures ranging from pleasantly cool or warm to burning hot and painful (nociceptive). The precise temperature ranges sensed by thermally sensitive neurons is determined by tissue-specific expression of ion channels of the transient receptor potential(TRP) family.We show here that in Drosophila, TRPA1 is required for the sensing of nociceptive heat. We identify two previously unidentified protein isoforms of dTRPA1, named dTRPA1-C and dTRPA1-D, that explain this requirement. A dTRPA1-C/D reporter was exclusively expressed in nociceptors, and dTRPA1-C rescued thermal nociception phenotypes when restored to mutant nociceptors. However,surprisingly, we find that dTRPA1-C is not a direct heat sensor. Alternative splicing generates at least four isoforms of dTRPA1. Our analysis of these isoforms reveals a 37-amino-acid-long intracellular region (encoded by a single exon) that is critical for dTRPA1 temperature responses. The identification of these amino acids opens the door to a biophysical understanding of a molecular thermosensor.
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Proteínas de Drosophila/química , Proteínas de Drosophila/metabolismo , Drosophila melanogaster/metabolismo , Calor , Canales Catiónicos TRPC/química , Canales Catiónicos TRPC/metabolismo , Sensación Térmica , Alelos , Secuencia de Aminoácidos , Animales , Secuencia de Bases , Clonación Molecular , Técnicas de Silenciamiento del Gen , Pruebas Genéticas , Activación del Canal Iónico , Canales Iónicos , Datos de Secuencia Molecular , Mutación/genética , Neuronas/metabolismo , Nocicepción , Nociceptores/metabolismo , Técnicas de Placa-Clamp , Isoformas de Proteínas/química , Isoformas de Proteínas/metabolismo , Estructura Terciaria de Proteína , Interferencia de ARN , Relación Estructura-Actividad , Canal Catiónico TRPA1RESUMEN
The Drosophila TRPA channel Painless is required for the function of polymodal nociceptors which detect noxious heat and noxious mechanical stimuli. These functions of Painless are reminiscent of mammalian TRPA channels that have also been implicated in thermal and mechanical nociception. A popular hypothesis to explain the mechanosensory functions of certain TRP channels proposes that a string of ankyrin repeats at the amino termini of these channels acts as an intracellular spring that senses force. Here, we describe the identification of two previously unknown Painless protein isoforms which have fewer ankyrin repeats than the canonical Painless protein. We show that one of these Painless isoforms, that essentially lacks ankyrin repeats, is sufficient to rescue mechanical nociception phenotypes of painless mutant animals but does not rescue thermal nociception phenotypes. In contrast, canonical Painless, which contains Ankyrin repeats, is sufficient to largely rescue thermal nociception but is not capable of rescuing mechanical nociception. Thus, we propose that in the case of Painless, ankryin repeats are important for thermal nociception but not for mechanical nociception.
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Repetición de Anquirina , Proteínas de Drosophila/química , Proteínas de Drosophila/metabolismo , Canales Iónicos/química , Canales Iónicos/metabolismo , Fenómenos Mecánicos , Nocicepción , Temperatura , Alelos , Animales , Animales Modificados Genéticamente , Proteínas de Drosophila/genética , Drosophila melanogaster/genética , Canales Iónicos/genética , Isoformas de Proteínas/química , Isoformas de Proteínas/genética , Isoformas de Proteínas/metabolismoRESUMEN
PURPOSE: To develop a mathematical model that can predict refractive changes after Descemet stripping endothelial keratoplasty (DSEK). METHODS: A mathematical formula based on the Gullstrand eye model was generated to estimate the change in refractive power of the eye after DSEK. This model was applied to four DSEK cases retrospectively, to compare measured and predicted refractive changes after DSEK. RESULTS: The refractive change after DSEK is determined by calculating the difference in the power of the eye before and after DSEK surgery. The power of the eye post-DSEK surgery can be calculated with modified Gullstrand eye model equations that incorporate the change in the posterior radius of curvature and change in the distance between the principal planes of the cornea and lens after DSEK. Analysis of this model suggests that the ratio of central to peripheral graft thickness (CP ratio) and central thickness can have significant effect on refractive change where smaller CP ratios and larger graft thicknesses result in larger hyperopic shifts. This model was applied to four patients, and the average predicted hyperopic shift in the overall power of the eye was calculated to be 0.83 D. This change reflected in a mean of 93% (range, 75%-110%) of patients' measured refractive shifts. CONCLUSIONS: This simplified DSEK mathematical model can be used as a first step for estimating the hyperopic shift after DSEK. Further studies are necessary to refine the validity of this model.
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Córnea/fisiopatología , Queratoplastia Endotelial de la Lámina Limitante Posterior , Distrofia Endotelial de Fuchs/cirugía , Hiperopía/fisiopatología , Modelos Teóricos , Refracción Ocular/fisiología , Distrofia Endotelial de Fuchs/fisiopatología , Humanos , Estudios RetrospectivosRESUMEN
Highly branched class IV multidendritic sensory neurons of the Drosophila larva function as polymodal nociceptors that are necessary for behavioral responses to noxious heat (>39 degrees C) or noxious mechanical (>30 mN) stimuli. However, the molecular mechanisms that allow these cells to detect both heat and force are unknown. Here, we report that the pickpocket (ppk) gene, which encodes a Degenerin/Epithelial Sodium Channel (DEG/ENaC) subunit, is required for mechanical nociception but not thermal nociception in these sensory cells. Larvae mutant for pickpocket show greatly reduced nociception behaviors in response to harsh mechanical stimuli. However, pickpocket mutants display normal behavioral responses to gentle touch. Tissue-specific knockdown of pickpocket in nociceptors phenocopies the mechanical nociception impairment without causing defects in thermal nociception behavior. Finally, optogenetically triggered nociception behavior is unaffected by pickpocket RNAi, which indicates that ppk is not generally required for the excitability of the nociceptors. Interestingly, DEG/ENaCs are known to play a critical role in detecting gentle touch stimuli in Caenorhabditis elegans and have also been implicated in some aspects of harsh touch sensation in mammals. Our results suggest that neurons that detect harsh touch in Drosophila utilize similar mechanosensory molecules.
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Proteínas de Drosophila/metabolismo , Drosophila melanogaster/metabolismo , Canales de Sodio/metabolismo , Animales , Proteínas de Drosophila/genética , Drosophila melanogaster/genética , Drosophila melanogaster/crecimiento & desarrollo , Regulación de la Expresión Génica/fisiología , Calor/efectos adversos , Larva/genética , Larva/metabolismo , Mecanotransducción Celular/fisiología , Dimensión del Dolor , Interferencia de ARN , Células Receptoras Sensoriales/citología , Células Receptoras Sensoriales/fisiología , Canales de Sodio/genética , TactoRESUMEN
BACKGROUND: Natural selection has resulted in a complex and fascinating repertoire of innate behaviors that are produced by insects. One puzzling example occurs in fruit fly larvae that have been subjected to a noxious mechanical or thermal sensory input. In response, the larvae "roll" with a motor pattern that is completely distinct from the style of locomotion that is used for foraging. RESULTS: We have precisely mapped the sensory neurons that are used by the Drosophila larvae to detect nociceptive stimuli. By using complementary optogenetic activation and targeted silencing of sensory neurons, we have demonstrated that a single class of neuron (class IV multidendritic neuron) is sufficient and necessary for triggering the unusual rolling behavior. In addition, we find that larvae have an innately encoded preference in the directionality of rolling. Surprisingly, the initial direction of rolling locomotion is toward the side of the body that has been stimulated. We propose that directional rolling might provide a selective advantage in escape from parasitoid wasps that are ubiquitously present in the natural environment of Drosophila. Consistent with this hypothesis, we have documented that larvae can escape the attack of Leptopilina boulardi parasitoid wasps by rolling, occasionally flipping the attacker onto its back. CONCLUSIONS: The class IV multidendritic neurons of Drosophila larvae are nociceptive. The nociception behavior of Drosophila melanagaster larvae includes an innately encoded directional preference. Nociception behavior is elicited by the ecologically relevant sensory stimulus of parasitoid wasp attack.