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Anti-amphiphysin antibody is a rare paraneoplastic autoantibody. A case of a 74-year-old man with anti-amphiphysin antibody and multiple symptoms, including bulbar palsy along with cerebellar ataxia, who responded to treatment with intravenous cyclophosphamide is reported. The patient presented with progressive unsteady gait and difficulty in swallowing food and water for three months. On admission, he had severe ataxia, downbeat and horizontal nystagmus, dysarthria, dysphagia, loss of tendon reflexes, and dysuria. Anti-amphiphysin antibodies were detected in the serum, resulting in the diagnosis of non-stiff anti-amphiphysin syndrome. No significant abnormalities were observed in imaging studies of the brain and the whole body. The patient was treated with high-dose intravenous immunoglobulin and steroids, yielding only slight improvement. After two courses of intravenous cyclophosphamide pulse therapy, his neurological symptoms, notably dysphagia and cerebellar ataxia, improved. Follow-up computed tomography and fluorodeoxyglucose-positron emission tomography/computed tomography showed enlarged mediastinal lymph nodes and hypermetabolic uptake of F-18 fluorodeoxyglucose six months after the onset of the neurological symptoms. Histological examination of a lymph node showed metastatic small cell lung cancer. This case highlights the efficacy of cyclophosphamide as second-line immunotherapy for anti-amphiphysin syndrome.
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The management of oral mucosal pain in Stevens-Johnson syndrome (SJS), known for its severe mucocutaneous reactions, is a significant challenge due to the paucity of effective treatments reported in the literature. This case report aims to help fill this gap by describing the effective use of continuous intravenous fentanyl for the relief of severe oral mucosal pain in a patient with SJS. A patient with postoperative recurrence of cervical cancer developed SJS following chemotherapy. She had severe oral mucosal pain that was not relieved by 12.5 mcg/hour fentanyl transdermal patch, a regular medication. This pain was rated 10/10 on the Numerical Pain Rating Scale (NRS), and the patient had dysphagia and difficulty speaking. On admission, intravenous methylprednisolone (1000 mg/day), oral lip treatment with dexamethasone ointment, and oral rinses with azulene-lidocaine mixture were started. Analgesic treatment consisted of a 12.5 mcg/hour fentanyl transdermal patch of the regular medication and 1000 mg/dose of intravenous acetaminophen twice daily. Due to the inadequate efficacy of the transdermal patch, fentanyl was switched from the transdermal patch to a continuous intravenous fentanyl infusion at 20 mcg/hour on day three of admission. This adjustment significantly reduced pain intensity, which decreased to NRS 5/10 on day six of admission, and the patient was able to drink water and speak. Pain relief preceded clinical improvement of stomatitis. Grade 1 somnolence occurred after the start of intravenous fentanyl, but improved with follow-up. There were no other adverse effects such as respiratory depression. This case highlights the potential of intravenous fentanyl in the treatment of oral mucosal pain associated with SJS, although further studies are needed to confirm these findings and to develop comprehensive pain management protocols.
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Background/Purpose: This study aimed to evaluate how a two-week program using the in-phase mode of a balance adjustment system (the BASYS) affected postural control in participants with chronic ankle instability (CAI). It was hypothesized that the in-phase mode on the BASYS would lead to improved postural control compared with training on a balance disc. Study Design: Randomized control trial. Methods: Twenty participants with CAI were recruited. The participants were divided into two intervention groups: the BASYS (n = 10) and Balance Disc (BD; cushion type, n = 10). All participants underwent six supervised training sessions over a two-week period. Static postural control during single leg standing with closed eyes was assessed for the CAI limb. We collected COP data while participants balanced on the BASYS. The test was performed for 30 sec, and the total trajectory length and 95% ellipse area were calculated. In the assessment of dynamic postural stability, Y-Balance tests-anterior, posteromedial, and posterolateral directions were measured on the CAI limb for all participants and normalized to the individual's leg length. Participants were recorded at three instances: pretraining (Pre), post-training 1 (Post1: after the first training), and post-training 2 (Post2: after the last training). Results: There was an effect on time in the COP total trajectory length of the BASYS group, which was significantly decreased for Post 1 and Post 2 than for the Pre (p = 0.001, 0.0001). Group differences and time-by-group interactions were not observed for either of the Y-balance test reach distances. Conclusions: The study's primary finding was that two weeks of intervention in the in-phase mode on the BASYS improved static postural control in participants with CAI. Level of Evidence: Level â , randomized control trial.
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Patients with von Hippel-Lindau disease (vHL) are at risk of developing spatially and temporally multiple clear cell renal cell carcinomas (ccRCCs), which offers a valuable opportunity to analyze inter- and intra-tumor heterogeneity of genetic and immune profiles within the same patient. Here, we perform whole-exome and RNA sequencing, digital gene expression, and immunohistochemical analyses for 81 samples from 51 ccRCCs of 10 patients with vHL. Inherited ccRCCs are clonally independent and have less genomic alterations than sporadic ccRCCs. Hierarchical clustering of transcriptome profiles shows two clusters with distinct immune signatures: immune hot and cold clusters. Interestingly, not only samples from the same tumors but also different tumors from the same patients tend to show a similar immune signature, whereas samples from different patients frequently exhibit different signatures. Our findings reveal the genetic and immune landscape of inherited ccRCCs, demonstrating the relevance of host factors in shaping anti-tumor immunity.
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Carcinoma de Células Renais , Carcinoma , Neoplasias Renais , Doença de von Hippel-Lindau , Humanos , Carcinoma de Células Renais/genética , Carcinoma de Células Renais/patologia , Neoplasias Renais/genética , Neoplasias Renais/patologia , Proteína Supressora de Tumor Von Hippel-Lindau/genética , Proteína Supressora de Tumor Von Hippel-Lindau/metabolismo , Doença de von Hippel-Lindau/genética , Doença de von Hippel-Lindau/patologia , Sequência de Bases , Carcinoma/genética , MutaçãoRESUMO
OBJECTIVE: Cervical cancer is the fourth most common cause of cancer-related deaths in Asian women, due to its poor prognosis. This study aimed to decipher genomic alteration profiles of a cohort of Japanese cervical cancer patients to understand why certain patients benefited from molecular targeted therapies and their prognostic significance. METHODS: During 2008-2018, 154 cervical cancer patients underwent a potentially curative resection procedure at the National Cancer Center Hospital. Genomic DNA samples were analyzed using Ion AmpliSeq™ Cancer Hotspot Panel v2. Alterations in the copy number of PIK3CA, ERBB2, PTEN, and STK11 were detected using the TaqMan assay. HPV-positive results were confirmed by genomic testing and in situ hybridization assay. RESULTS: The frequency of genomic alterations in PIK3CA (36%), STK11 (16%), PTEN (11%), TP53 (11%), and KRAS (8%) was >5%. KRAS mutations were preferentially detected in patients with adenocarcinomas, and the frequency of PIK3CA mutations in patients with squamous cell carcinomas was higher than that in patients with other histological cancer types. HPV-positive results were observed in 139/154 (90.3%) patients, and TP53 mutants were detected in HPV-negative specimens. In this study, the overall survival of patients with genomic alterations in STK11 was worse than in patients with wild-type STK11 (hazard ratio = 10.6, P = 0.0079) and TCGA dataset (hazard ratio = 2.46, P = 0.029). CONCLUSIONS: More than one-third of Japanese cervical cancer patients exhibit mutations targeted by molecular targeted therapies. We have proposed the prognostic value of STK11 genomic alterations.
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Proteínas Serina-Treonina Quinases/genética , Neoplasias do Colo do Útero/genética , Quinases Proteína-Quinases Ativadas por AMP , Povo Asiático/genética , Análise Mutacional de DNA , DNA de Neoplasias/genética , DNA de Neoplasias/isolamento & purificação , Feminino , Humanos , Pessoa de Meia-Idade , Papillomaviridae/genética , Infecções por Papillomavirus/enzimologia , Infecções por Papillomavirus/genética , Infecções por Papillomavirus/patologia , Infecções por Papillomavirus/virologia , Valor Preditivo dos Testes , Proteínas Serina-Treonina Quinases/metabolismo , Neoplasias do Colo do Útero/enzimologia , Neoplasias do Colo do Útero/patologia , Neoplasias do Colo do Útero/virologiaRESUMO
BACKGROUND: Central nervous system (CNS) metastasis is a poor prognostic factor in patients with advanced non-small cell lung cancer (NSCLC) harboring epidermal growth factor receptor (EGFR) mutation EGFR-mutant NSCLC and is associated with a deteriorated quality of life (QOL). Some clinical studies have suggested a possible difference in the incidence of CNS metastasis between EGFR-mutant NSCLC patients treated with gefitinib and erlotinib, both of which are classified as first-generation EGFR tyrosine kinase inhibitors (TKIs). However, the difference in the incidence of CNS metastasis between patients receiving these two drugs has not yet been sufficiently well investigated. We analyzed the frequency of occurrence/progression of CNS metastasis in EGFR-mutant NSCLC patients treated with erlotinib and gefitinib as the first-line treatment. METHODS: We analyzed the incidence of CNS metastasis, frequency of progression of CNS metastasis and the treatment outcomes in EGFR-mutant patients who received gefitinib or erlotinib as the first-line EGFR-TKI treatment. CNS progressive disease (PD) was defined as progression of CNS metastasis during EGFR-TKI treatment. We also evaluated the progression-free survival (PFS), CNS-PFS, and overall survival (OS) of the patients who received each of the two drugs. RESULTS: A total of 170 patients were enrolled in the study, of which 144 had received gefitinib, and 26 had received erlotinib. The frequency of CNS PD in the erlotinib group tended to be lower than that in the gefitinib group (11.5% vs. 29.9%, P=0.06). In patients with no existing CNS metastasis at the start of the EGFR-TKI treatments, the incidence of CNS PD was significantly lower in the erlotinib group than that in the gefitinib group (4.8% vs. 24.5%, P=0.04). A re-biopsy after failure of EGFR-TKI treatment was performed in 48 patients. The incidence of EGFR T790M tended to be higher among patients with CNS PD than in those without CNS PD, although the difference was not statistically significant (66.7% vs. 40.4%; P=0.23). CONCLUSIONS: The incidence of progression of CNS metastasis during erlotinib treatment was lower than that during gefitinib treatment. In addition, the difference in the incidence in patients without existing CNS metastasis at the time of start of EGFR-TKI treatment was significantly lower in the patients treated with erlotinib than in those treated with gefitinib.
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Antígenos de Diferenciação de Linfócitos B/metabolismo , Antineoplásicos/uso terapêutico , Crizotinibe/uso terapêutico , Sequenciamento de Nucleotídeos em Larga Escala/métodos , Antígenos de Histocompatibilidade Classe II/metabolismo , Neoplasias Pulmonares/tratamento farmacológico , Neoplasias Pulmonares/genética , Antineoplásicos/farmacologia , Crizotinibe/farmacologia , Feminino , Humanos , Neoplasias Pulmonares/patologia , Pessoa de Meia-IdadeRESUMO
BACKGROUND: SMARCB1 (INI1) is a tumor-suppressor gene located at 22q11.2. Loss of SMARCB1 protein expression has been reported to be associated with atypical teratoid/rhabdoid tumors and malignant rhabdoid tumors of the kidney and extrarenal tissues. To date, however, SMARCB1-deficient carcinoma of the pleura has not been reported. We report the first case of SMARCB1- deficient squamous cell carcinoma of the pleura. CASE PRESENTATION: The case was a 33-year-old female. She was diagnosed squamous cell carcinoma of the pleura by thoracoscopy. The tumor cells were completely negative for SMARCB1 protein expression by immunohistochemistry. She received six cycles of cisplatin plus gemcitabine therapy and TS-1 monotherapy, however, her disease progressed rapidly with worsening chest pain and dyspnea, and she died at 10 months after diagnosis. CONCLUSIONS: This is the first report of SMARCB1-deficient squamous cell carcinoma of pleura. The tumor was highly aggressive and carried a poor prognosis with short survival. The clinical features and treatments of this tumor are not clear, and additional cases will assist the establishment of treatments.
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Biomarcadores Tumorais , Carcinoma de Células Escamosas/diagnóstico , Carcinoma de Células Escamosas/genética , Neoplasias Pleurais/diagnóstico , Neoplasias Pleurais/genética , Proteína SMARCB1/genética , Biópsia , Carcinoma de Células Escamosas/metabolismo , Carcinoma de Células Escamosas/terapia , Análise Mutacional de DNA , Evolução Fatal , Feminino , Expressão Gênica , Humanos , Imuno-Histoquímica , Mutação , Neoplasias Pleurais/metabolismo , Neoplasias Pleurais/terapia , Radiografia Torácica , Proteína SMARCB1/metabolismo , Tomografia Computadorizada por Raios XRESUMO
Purpose: DNA topoisomerase inhibitors are commonly used for treating small-cell lung cancer (SCLC). Tyrosyl-DNA phosphodiesterase (TDP1) repairs DNA damage caused by this class of drugs and may therefore influence treatment outcome. In this study, we investigated whether common TDP1 single-nucleotide polymorphisms (SNP) are associated with overall survival among SCLC patients.Experimental Design: Two TDP1 SNPs (rs942190 and rs2401863) were analyzed in 890 patients from 10 studies in the International Lung Cancer Consortium (ILCCO). The Kaplan-Meier method and Cox regression analyses were used to evaluate genotype associations with overall mortality at 36 months postdiagnosis, adjusting for age, sex, race, and tumor stage.Results: Patients homozygous for the minor allele (GG) of rs942190 had poorer survival compared with those carrying AA alleles, with a HR of 1.36 [95% confidence interval (CI): 1.08-1.72, P = 0.01), but no association with survival was observed for patients carrying the AG genotype (HR = 1.04, 95% CI, 0.84-1.29, P = 0.72). For rs2401863, patients homozygous for the minor allele (CC) tended to have better survival than patients carrying AA alleles (HR = 0.79; 95% CI, 0.61-1.02, P = 0.07). Results from the Genotype Tissue Expression (GTEx) Project, the Encyclopedia of DNA Elements (ENCODE), and the ePOSSUM web application support the potential function of rs942190.Conclusions: We found the rs942190 GG genotype to be associated with relatively poor survival among SCLC patients. Further investigation is needed to confirm the result and to determine whether this genotype may be a predictive marker for treatment efficacy of DNA topoisomerase inhibitors. Clin Cancer Res; 23(24); 7550-7. ©2017 AACR.
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Predisposição Genética para Doença , Diester Fosfórico Hidrolases/genética , Carcinoma de Pequenas Células do Pulmão/epidemiologia , Carcinoma de Pequenas Células do Pulmão/genética , Adulto , Idoso , Idoso de 80 Anos ou mais , Alelos , Biomarcadores Tumorais/genética , Reparo do DNA/genética , Feminino , Genótipo , Homozigoto , Humanos , Estimativa de Kaplan-Meier , Masculino , Pessoa de Meia-Idade , Polimorfismo de Nucleotídeo Único/genética , Carcinoma de Pequenas Células do Pulmão/patologia , Análise de Sobrevida , Resultado do TratamentoRESUMO
Some odorants have physiological and psychological effects on organisms. However, little is known about the effects of inhaling them, particularly on the central nervous system. Using DNA microarray analysis, we obtained gene expression profiles of the hypothalamus from restraint stressed rats exposed to racemic (R,S)-linalool. Hierarchical clustering across all probe sets showed that this inhalation of (R,S)-linalool influenced the expression levels of a wide range of genes in the hypothalamus. A comparison of transcription levels revealed that the inhalation of (R,S)-linalool restored the expression of 560 stress-induced probe sets to a normal status. Gene Ontology (GO) analysis showed that these genes were associated with synaptic transmission via neurotransmitters including anxiolytic neuropeptides such as oxytocin and neuropeptide Y. These genes also included several major histocompatibility complex (MHC) class I molecules necessary for neural development and plasticity. Moreover, Upstream Regulator Analysis predicted that the hormone prolactin would be activated by the inhalation of (R,S)-linalool under stress. Our results reveal some of the molecular mechanisms associated with odor inhalation in the hypothalamus in organisms under stress.
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Expressão Gênica/efeitos dos fármacos , Genes MHC Classe I/efeitos dos fármacos , Hipotálamo/efeitos dos fármacos , Monoterpenos/farmacologia , Neuropeptídeo Y/efeitos dos fármacos , Ocitocina/efeitos dos fármacos , Estresse Psicológico/metabolismo , Monoterpenos Acíclicos , Administração por Inalação , Animais , Masculino , Monoterpenos/administração & dosagem , Ratos , Ratos Wistar , Restrição Física , Regulação para CimaRESUMO
Personalized lung cancer therapy has progressed by targeting several oncogenic aberrations that drive lung carcinogenesis. Recent advances in gene analysis technologies, including next-generation sequencing that yields large amounts of genomic data, have greatly contributed to this progress. In addition, immune checkpoint blockade therapy has become available in Japan, and extensive searches for biomarkers predictive of therapeutic response have been carried out. "Clinical sequencing" which analyzes aberrations in a set of therapy-related genes in patient cancer specimens, has been actively conducted in Japan and other countries. This will help to establish more efficient and effective precision cancer medicine based on gene information. Herein, we summarize the recent progress in personalized lung cancer therapy research, including clinical sequencing.
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Antineoplásicos/uso terapêutico , Neoplasias Pulmonares/tratamento farmacológico , Neoplasias Pulmonares/genética , Biomarcadores Tumorais/genética , Ensaios Clínicos como Assunto , Sequenciamento de Nucleotídeos em Larga Escala , Humanos , Terapia de Alvo Molecular , Medicina de PrecisãoRESUMO
BACKGROUND: The Japan Guidelines of Lung Cancer Therapy recommend epidermal growth factor receptor-tyrosine kinase inhibitors as a first-line therapy for advanced/recurrent non-small cell lung cancer patients with epidermal growth factor receptor mutation. Although survival periods in recent reports of epidermal growth factor receptor-tyrosine kinase inhibitor treatment have been getting longer, the reasons why are unclear. We investigated the survival, prognostic factors and real-world treatment of non-small cell lung cancer patients with epidermal growth factor receptor mutation in clinical practice. METHODS: Non-small cell lung cancer patients (n = 1660) who started first-line treatment from January 2008 to December 2012 were enrolled. Patients were diagnosed with epidermal growth factor receptor mutation-positive advanced/recurrent non-small cell lung cancer by histology or cytology samples. The primary objective was to estimate overall survival. The secondary objectives were to determine prognostic factors, real-world treatment patterns and efficacy of gefitinib treatment. We calculated the treatment exposure rate for each treatment category using the following formula: exposure rate = person-years for the treatment category/total person-years × 100. RESULTS: The median overall survival was 30.8 months. Sex, age, histology, epidermal growth factor receptor mutation type, clinical stage and performance status affected overall survival. The exposure rates for all epidermal growth factor receptor-tyrosine kinase inhibitors, gefitinib and platinum-doublet chemotherapy were 62.1, 46.4 and 8.5% respectively. Overall 56.1% of patients were administered gefitinib as first-line therapy, and 39.0% were treated with ≥2 epidermal growth factor receptor-tyrosine kinase inhibitor regimens. The median progression-free survival in the first-line gefitinib group was 11.4 months. Factors affecting prognosis were sex, histology, clinical stage and performance status. CONCLUSION: Epidermal growth factor receptor-tyrosine kinase inhibitors, especially gefitinib, are major components of the treatment regimens for epidermal growth factor receptor mutation-positive non-small cell lung cancer. Switching and re-challenging with epidermal growth factor receptor-tyrosine kinase inhibitors were also practiced in Japan.
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Carcinoma Pulmonar de Células não Pequenas/tratamento farmacológico , Receptores ErbB/genética , Neoplasias Pulmonares/tratamento farmacológico , Inibidores de Proteínas Quinases/uso terapêutico , Adulto , Idoso , Idoso de 80 Anos ou mais , Povo Asiático , Carcinoma Pulmonar de Células não Pequenas/metabolismo , Carcinoma Pulmonar de Células não Pequenas/mortalidade , Carcinoma Pulmonar de Células não Pequenas/patologia , Intervalo Livre de Doença , Receptores ErbB/antagonistas & inibidores , Receptores ErbB/metabolismo , Feminino , Gefitinibe , Humanos , Japão , Neoplasias Pulmonares/metabolismo , Neoplasias Pulmonares/mortalidade , Neoplasias Pulmonares/patologia , Masculino , Pessoa de Meia-Idade , Mutação , Recidiva Local de Neoplasia/tratamento farmacológico , Estadiamento de Neoplasias , Prognóstico , Modelos de Riscos Proporcionais , Quinazolinas/uso terapêutico , Estudos Retrospectivos , Taxa de SobrevidaRESUMO
AIM: The aim of the study was to determine clinical and genetic characteristics of Japanese patients with hyperekplexia. METHOD: Clinical courses, responses to antiepileptic drugs, outcomes, and genetic testing were investigated in 17 Japanese patients (nine males, eight females, median age 1y, range birth-45y) with hyperekplexia. RESULTS: In all patients, muscle stiffness and startle responses appeared soon after birth. Only seven patients were diagnosed with hyperekplexia before 1 year of age. Seven patients had been misdiagnosed with other disorders such as epilepsy and adult-onset anxiety neurosis. Umbilical/inguinal hernias were seen in 10 patients. Life-threatening events were noted in four patients. Clonazepam was the most effective drug. Muscle stiffness completely disappeared in 12 patients before 5 years of age, whereas startle responses resolved in only three patients. Mutations in the GLRA1 and GLRB genes were identified in 16 patients and one patient respectively. In 14 patients, the mutation showed autosomal dominant inheritance; in the other three, inheritance was autosomal recessive. p.R271Q of GLRA1 was the most frequent mutation, found in 10 patients. Novel mutations, p.A272P and p.A384P of GLRA1, were detected. Clinical severity and outcome varied even in the same family. INTERPRETATION: Early correct diagnosis is essential for prevention of accidental injuries and to provide appropriate treatments for hyperekplexia. Clonazepam is effective, although the time taken for startle responses to resolve varied.
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Rigidez Muscular/fisiopatologia , Receptores de Glicina/genética , Reflexo de Sobressalto/fisiologia , Rigidez Muscular Espasmódica/diagnóstico , Rigidez Muscular Espasmódica/genética , Adolescente , Adulto , Criança , Progressão da Doença , Feminino , Hérnia Umbilical/fisiopatologia , Humanos , Lactente , Recém-Nascido , Japão , Masculino , Pessoa de Meia-Idade , Linhagem , Rigidez Muscular Espasmódica/tratamento farmacológicoRESUMO
Responses to environmental stimuli are mediated by the activation and inactivation of various signalling proteins. However, the temporal dynamics of these events in living animals are not well understood. Here we show real-time imaging of the activity of the key regulator of the MAP kinase pathway, Ras, in living Caenorhabditis elegans and that Ras is transiently activated within a few seconds in olfactory neurons in response to increase in the concentration of odorants. This fast activation of Ras is dependent on the olfactory signalling pathway and Ras guanyl nucleotide-releasing protein (RasGRP). A negative feedback loop then quickly leads to Ras inactivation despite the continued presence of the odorant. Phenotypes of Ras mutants suggest this rapid activation and inactivation of Ras is important for regulation of interneuron activities and olfactory behaviours. Our results reveal novel kinetics and biological implication of transient activation of Ras in olfactory systems.
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Caenorhabditis elegans/genética , Caenorhabditis elegans/metabolismo , Genes ras , Condutos Olfatórios/fisiologia , Ativação Transcricional , Animais , Proteínas de Caenorhabditis elegans/metabolismo , Retroalimentação Fisiológica , Guanilato Ciclase/metabolismo , Interneurônios/fisiologia , Proteínas de Membrana , Proteínas Quinases Ativadas por Mitógeno/metabolismo , Neurônios Receptores Olfatórios/fisiologia , Proteína Quinase C/metabolismo , Transdução de SinaisRESUMO
The same odorant can induce attractive or repulsive responses depending on its concentration in various animals including humans. However, little is understood about the neuronal basis of this behavioural phenomenon. Here we show that Caenorhabditis elegans avoids high concentrations of odorants that are attractive at low concentrations. Behavioural analyses and computer simulation reveal that the odour concentration-dependent behaviour is primarily generated by klinokinesis, a behavioural strategy in C. elegans. Genetic analyses and lesion experiments show that distinct combinations of sensory neurons function at different concentrations of the odorant; AWC and ASH sensory neurons have critical roles for attraction to or avoidance of the odorant, respectively. Moreover, we found that AWC neurons respond to only lower concentrations of the odorant, whereas ASH neurons respond to only higher concentrations of odorant. Hence, our study suggests that odour concentration coding in C. elegans mostly conforms to the labelled-line principle where distinct neurons respond to distinct stimuli.
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Caenorhabditis elegans/fisiologia , Células Quimiorreceptoras/fisiologia , Odorantes , Animais , Comportamento Animal , Proteínas de Caenorhabditis elegans/metabolismo , Cálcio/metabolismo , Quimiotaxia , Simulação por Computador , Subunidades alfa de Proteínas de Ligação ao GTP/metabolismo , Subunidades alfa Gi-Go de Proteínas de Ligação ao GTP/metabolismo , Pentanóis , Olfato/fisiologiaRESUMO
The locomotion of Caenorhabditis elegans exhibits complex patterns. In particular, the worm combines mildly curved runs and sharp turns to steer its course. Both runs and sharp turns of various types are important components of taxis behavior. The statistics of sharp turns have been intensively studied. However, there have been few studies on runs, except for those on klinotaxis (also called weathervane mechanism), in which the worm gradually curves toward the direction with a high concentration of chemicals; this phenomenon was discovered recently. We analyzed the data of runs by excluding sharp turns. We show that the curving rate obeys long-tail distributions, which implies that large curving rates are relatively frequent. This result holds true for locomotion in environments both with and without a gradient of NaCl concentration; it is independent of klinotaxis. We propose a phenomenological computational model on the basis of a random walk with multiplicative noise. The assumption of multiplicative noise posits that the fluctuation of the force is proportional to the force exerted. The model reproduces the long-tail property present in the experimental data.
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Comportamento Animal/fisiologia , Caenorhabditis elegans/fisiologia , Locomoção/fisiologia , Modelos Biológicos , Animais , Comportamento Animal/efeitos dos fármacos , Caenorhabditis elegans/efeitos dos fármacos , Quimiotaxia/efeitos dos fármacos , Simulação por Computador , Locomoção/efeitos dos fármacos , Cloreto de Sódio/farmacologia , CaudaRESUMO
Caenorhabditis elegans shows chemotaxis to various odorants and water-soluble chemoattractants such as NaCl. Previous studies described the pirouette mechanism for chemotaxis, in which C. elegans quickly changes the direction of locomotion by using a set of stereotyped behaviors, a pirouette, in response to a decrease in the concentration of the chemical. Here, we report the discovery of a second mechanism for chemotaxis, called the weathervane mechanism. In this strategy animals respond to a spatial gradient of chemoattractant and gradually curve toward higher concentration of the chemical. By computer simulation, we find that both of these mechanisms contribute to chemotaxis and both mechanisms need to act in parallel for efficient chemotaxis. Using laser ablation of individual neurons to examine the underlying neural circuit, we find the ASE sensory neurons and AIZ interneurons are essential for both the pirouette and weathervane mechanisms in chemotaxis to NaCl. Salt-conditioned animals show reversed responses in both of these behaviors, leading to avoidance of NaCl. These results provide a platform for detailed molecular and cellular analyses of chemotaxis and its plasticity in this model organism.