RESUMO
To understand the nature of the brightest γ-ray binary system LS 5039, hard x-ray data of the object, taken with the Suzaku and NuSTAR observatories in 2007 and 2016, respectively, were analyzed. The two data sets jointly gave tentative evidence for a hard x-ray periodicity, with a period of â¼9 s and a period increase rate by â¼3×10^{-10} s s^{-1}. Therefore, the compact object in LS 5039 is inferred to be a rotating neutron star, rather than a black hole. Furthermore, several lines of arguments suggest that this object has a magnetic field of several times â¼10^{10} T, two orders of magnitude higher than those of typical neutron stars. The object is hence suggested to be a magnetar, which would be the first to be found in a binary. The results also suggest that the highly efficient particle acceleration process, known to be operating in LS 5039, emerges through interactions between dense stellar winds from the massive primary star, and ultrastrong magnetic fields of the magnetar.
RESUMO
During a winter thunderstorm on 24 November 2017, a strong burst of gamma rays with energies up to â¼10 MeV was detected coincident with a lightning discharge, by scintillation detectors installed at the Kashiwazaki-Kariwa Nuclear Power Station at sea level in Japan. The burst had a subsecond duration, which is suggestive of photoneutron production. The leading part of the burst was resolved into four intense gamma-ray bunches, each coincident with a low-frequency radio pulse. These bunches were separated by 0.7-1.5 ms, with a duration of âª1 ms each. Thus, the present burst may be considered as a "downward" terrestrial gamma-ray flash (TGF), which is analogous to upgoing TGFs observed from space. Although the scintillation detectors were heavily saturated by these bunches, the total dose associated with them was successfully measured by ionization chambers, employed by nine monitoring posts surrounding the power plant. From this information and Monte Carlo simulations, the present downward TGF is suggested to have taken place at an altitude of 2500±500 m, involving 8_{-4}^{+8}×10^{18} avalanche electrons with energies above 1 MeV. This number is comparable to those in upgoing TGFs.
RESUMO
Thunderclouds can produce bremsstrahlung gamma-ray emission, and sometimes even positrons. At 00:27:00 (UT) on 13 January 2012, an intense burst of gamma rays from a thundercloud was detected by the GROWTH experiment, located in Japan, facing the Sea of Japan. The event started with a sharp gamma-ray flash with a duration of <300 ms coincident with an intracloud discharge, followed by a decaying longer gamma-ray emission lasting for â¼60 s. The spectrum of this prolonged emission reached â¼10 MeV, and contained a distinct line emission at 508±3(stat.)±5(sys.) keV, to be identified with an electron-positron annihilation line. The line was narrow within the instrumental energy resolution (â¼80keV), and contained 520±50 photons which amounted to â¼10% of the total signal photons of 5340±190 detected over 0.1-10 MeV. As a result, the line equivalent width reached 280±40 keV, which implies a nontrivial result. The result suggests that a downward positron beam produced both the continuum and the line photons.
RESUMO
Magnetars are a special type of neutron stars, considered to have extreme dipole magnetic fields reaching â¼ 10(11) T. The magnetar 4 U 0142+61, one of the prototypes of this class, was studied in broadband x rays (0.5-70 keV) with the Suzaku observatory. In hard x rays (15-40 keV), its 8.69 sec pulsations suffered slow phase modulations by ± 0.7 sec, with a period of â¼ 15 h. When this effect is interpreted as free precession of the neutron star, the object is inferred to deviate from spherical symmetry by â¼ 1.6 × 10(-4) in its moments of inertia. This deformation, when ascribed to magnetic pressure, suggests a strong toroidal magnetic field, â¼ 10(12) T, residing inside the object. This provides one of the first observational approaches towards toroidal magnetic fields of magnetars.
RESUMO
We report the first observation of 3-30 MeV prolonged gamma-ray emission that was abruptly terminated by lightning. The gamma-ray detection was made during winter thunderstorms on December 30, 2010, by the Gamma-Ray Observation of Winter Thunderclouds experiment carried out in a coastal area along the Sea of Japan. The gamma-ray flux lasted for less than 3 min, continuously hardening closer to the lightning occurrence. The hardening at energies of 3-10 MeV energies was most prominent. The gamma-ray flux abruptly ceased less than 800 ms before the lightning flash that occurred over 5 km away from the experimental site. In addition, we observed a clear difference in the duration of the 3-10 MeV gamma rays and those >10 MeV, suggesting that the area of >10 MeV gamma-ray emission is considerably smaller than that of the lower-energy gamma rays. This work may give a manifestation that a local region emitting prolonged gamma rays connects with a distant region to initiate lightning.
RESUMO
During thunderstorms on 20 September 2008, a simultaneous detection of gamma rays and electrons was made at a mountain observatory in Japan located 2770 m above sea level. Both emissions, lasting 90 sec, were associated with thunderclouds rather than lightning. The photon spectrum, extending to 10 MeV, can be interpreted as consisting of bremsstrahlung gamma rays arriving from a source which is 60-130 m in distance at 90% confidence level. The observed electrons are likely to be dominated by a primary population escaping from an acceleration region in the clouds.
RESUMO
A report is made on a comprehensive observation of a burstlike gamma-ray emission from thunderclouds on the Sea of Japan, during strong thunderstorms on 6 January 2007. The detected emission, lasting for approximately 40 sec, preceded cloud-to-ground lightning discharges. The burst spectrum, extending to 10 MeV, can be interpreted as consisting of bremsstrahlung photons originating from relativistic electrons. This ground-based observation provides the first clear evidence that strong electric fields in thunderclouds can continuously accelerate electrons beyond 10 MeV prior to lightning discharges.
RESUMO
The number of airborne methicillin-resistant Staphylococcus aureus (MRSA) before, during and after bedmaking was investigated. Air was sampled with an Andersen air sampler in the rooms of 13 inpatients with MRSA infection or colonization. Sampling of surfaces, including floors and bedsheets, was performed by stamp methods. MRSA-containing particles were isolated on all the sampler stages-stage 1 (>7 microm diameter) to stage 6 (0.65-1.1 microm). The MRSA-containing particles were mostly 2-3 microm diameter before bedmaking and >5 microm during bedmaking. The number was significantly higher 15 min after bedmaking than during the resting period, but the differences in counts after 30 and 60 min were not significant. MRSA was detected on many surfaces. The results suggest that MRSA was recirculated in the air, especially after movement. To prevent airborne transmission, healthcare staff should exercise great care to disinfect inanimate environments. Further studies will be needed to confirm the level of MRSA contamination of air during bedmaking and establish measures for prevention of airborne transmission.
Assuntos
Microbiologia do Ar , Roupas de Cama, Mesa e Banho , Exposição Ambiental , Quartos de Pacientes , Staphylococcus aureus/isolamento & purificação , Infecção Hospitalar/epidemiologia , Zeladoria Hospitalar , Humanos , Resistência a Meticilina , Fatores de Risco , Infecções Estafilocócicas/epidemiologia , Staphylococcus aureus/efeitos dos fármacosRESUMO
The effects of salicylate and acoustic overstimulation on the electromotility of the cochlear outer hair cells (OHCs) were assessed in vivo using electrically-evoked otoacoustic emissions (EEOAEs). Alternating currents to evoke the EEOAE were delivered by means of an extracochlear electrode on the round window, with which the compound action potentials (CAPs) were also monitored before and after the manipulations. The EEOAE outputs were a linear function of the injected currents between 52 and 267 microA rms. Administration of salicylate (500 mg/kg) reduced the EEOAE outputs significantly at 5 and 8 kHz (p < 0.005). while no change in EEOAEs was observed at any frequency after exposure to a 4 kHz pure tone at 100 dB SPL for 10 min or at 120 dB SPL, for 30 min. These results indicate that administration of salicylate reduces the electromotility of the OHCs, and thus produces losses in neural sensitivity of the cochlea. In contrast, the electromotility of OHCs appears to be protected against short-term intense sound exposure.
Assuntos
Estimulação Acústica/efeitos adversos , Anti-Inflamatórios não Esteroides/farmacologia , Emissões Otoacústicas Espontâneas/efeitos dos fármacos , Salicilato de Sódio/farmacologia , Animais , Limiar Auditivo/efeitos dos fármacos , Movimento Celular/efeitos dos fármacos , Estimulação Elétrica , Cobaias , Células Ciliadas Auditivas Externas/efeitos dos fármacosRESUMO
Few researchers have microbiologically studied peritonsillar abscesses in detail, and their results have been conflicting. Although Streptococcus pyogenes (Group A beta-streptococcus) is commonly considered an important pathogen in this infection, recent studies have demonstrated the recovery of many other streptococci mainly consisting of alpha-streptococci. Few studies have identified these streptococci at the species level, however. We studied details of bacteriology in 31 cases of peritonsillar abscess treated between 1991 and 2000. The Streptococcus milleri group was most frequently isolated (25.8%), followed by Eikenella corrodens (9.7%), Staphylococcus aureus (6.5%), and S. pyogenes (3.2%). The S. milleri group, consisting of 3 species of Streptococcus constellatus, S. intermedius, and S. anginosus, forms part of the normal flora most commonly found in the mouth, throat, gastrointestinal tract, and genital tract. These species have become known as an important pathogen in abscess disease but little attention has been paid to their role in peritonsillar abscesses. To adequately culture the S. milleri group, incubation in air containing carbon dioxide or in an anaerobic condition is required, and then the differentiation of the 3 species requires the biochemical reactivity tests. Since hemolytic patterns of the S. milleri group vary, we studied the population of alpha-, beta-, and gamma-hemolytic strains among 36 strains of this group. We found 32 (88.8%) to be alpha-hemolytic. Although not all alpha-hemolytic strains belong to the S. milleri group, a considerable number of this group could be missed among alpha-streptococci isolated from the peritonsillar abscess. As antibiotics began being used widely, normal flora such as the S. milleri group may have become an important pathogen in peritonsillar abscesses due to an imbalance between organisms and host defense.
Assuntos
Abscesso Peritonsilar/microbiologia , Streptococcus/isolamento & purificação , Adolescente , Adulto , Idoso , Feminino , Hemólise , Humanos , Masculino , Pessoa de Meia-Idade , Streptococcus/patogenicidadeRESUMO
We investigated the localization of histidine decarboxylase (HDC), which is the rate-limiting enzyme that generates histamine from histidine, in human aorta/coronary artery. RT-PCR and immunohistochemical staining revealed that the HDC gene was expressed in monocytes/macrophages and T cells in the arterial intima but not in smooth muscle cells in either the arterial intima or the media. A luciferase promoter assay with U937 and Jurkat cells demonstrated that interleukin-4 (IL-4) inhibited the expression of the HDC gene. In contrast, among a scavenger receptor family, IL-4 as well as histamine up-regulated U937 cells to express the LOX-1 gene but not the SR-A gene, which genes encode receptors that scavenge oxidized lipids. These findings suggest that histamine synthesized in the arterial wall participates in the initiation and progression of atherosclerosis and that IL-4 can act as an important inhibitory and/or stimulatory factor in the function of monocytes/macrophages modulated by histamine in relation to the process of atherosclerosis.
Assuntos
Arteriosclerose/metabolismo , Histamina/farmacologia , Histidina Descarboxilase/metabolismo , Interleucina-4/farmacologia , Macrófagos/metabolismo , Monócitos/metabolismo , Fagocitose , Túnica Íntima/metabolismo , Northern Blotting , Clonagem Molecular , Genes Reporter , Humanos , Imuno-Histoquímica , Interleucina-4/metabolismo , Células Jurkat , Luciferases/metabolismo , Oxigênio/metabolismo , Regiões Promotoras Genéticas , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Fatores de Tempo , Transfecção , Células U937 , Regulação para CimaRESUMO
OBJECTIVES: To quantitatively investigate the existence of airborne methicillin-resistant Staphylococcus aureus (MRSA) in a hospital environment and to perform phenotyping and genotyping of MRSA isolates to study MRSA epidemiology. DESIGN: Prospective surveillance of patients with MRSA infections or colonizations was performed, as was an observational study of environmental airAirborne samples were taken by an air sampler; samples were obtained from object surfaces by stamping or swabbing. Epidemiological study of MRSA isolates was performed with an antibiotic susceptibility test, coagulase typing, and pulsed-field gel electrophoresis. SETTING: Three single-patient rooms in a 37-bed otolaryngology-head and neck surgery unit. PATIENTS: Three patients with squamous cell head and neck cancer were observed to have been colonized or infected with MRSA after surgery. RESULTS: The MRSA samples were collected from the air in single-patient rooms during both a period of rest and when bedsheets were being changed. Isolates of MRSA were detected in all stages (from stage 1 [>7 microm] to stage 6 [0.65-1.1 microm]). About 20% of the MRSA particles were within a respirable range of less than 4 microm. Methicillin-resistant S aureus was also isolated from inanimate environments, such as sinks, floors, and bedsheets, in the rooms of the patients with MRSA infections as well as from the patients' hands. An epidemiological study demonstrated that clinical isolates of MRSA in our ward were of one origin and that the isolates from the air and from inanimate environments were identical to the MRSA strains that caused infection or colonization in the inpatients. CONCLUSIONS: Methicillin-resistant S aureus was recirculated among the patients, the air, and the inamimate environments, especially when there was movement in the rooms. Airborne MRSA may play a role in MRSA colonization in the nasal cavity or in respiratory tract MRSA infections. Measures should be taken to prevent the spread of airborne MRSA to control nosocomial MRSA infection in hospitals.
Assuntos
Infecção Hospitalar/etiologia , Resistência a Meticilina , Infecções Estafilocócicas/etiologia , Staphylococcus aureus/isolamento & purificação , Carcinoma de Células Escamosas/microbiologia , Carcinoma de Células Escamosas/cirurgia , Contagem de Colônia Microbiana , Infecção Hospitalar/prevenção & controle , Eletroforese em Gel de Campo Pulsado , Genótipo , Neoplasias de Cabeça e Pescoço/microbiologia , Neoplasias de Cabeça e Pescoço/cirurgia , Humanos , Testes de Sensibilidade Microbiana , Fenótipo , Estudos Prospectivos , Infecções Estafilocócicas/tratamento farmacológico , Infecções Estafilocócicas/prevenção & controleRESUMO
The nonhistone chromosomal protein, high mobility group 1 (HMG1), which is ubiquitously expressed in higher eukaryotic cells, preferentially binds to cisplatin-modified DNA. The observation that HMG1 is overexpressed in cisplatin-resistant human cancer cells suggests that cisplatin resistance may be closely associated with HMG1. To decipher the mechanism of HMG1 overexpression in cisplatin-resistant cells, we isolated two overlapping genomic DNA clones containing the entire human HMG1 gene. These clones, which span approximately 15 kb of contiguous DNA, include 5 kb of the 5' flanking region as well as the entire coding sequence. We sequenced 1500 bp upstream of the first exon. The segment proximal to the transcription initiation site did not contain a TATA box but did possess an activating transcription factor site, an activator protein-2 site, one CCAAT box, and two CCAAT-binding transcription factor/nuclear factor-1 (CTF/NF-1) sites. HMG1 promoter activity was 3-10-fold higher in cisplatin-resistant KB-CP20 cells than in parental KB cells. An in vivo footprint experiment showed several differences of dimethyl sulfate modifications between KB and KB-CP20 cells in the area around the CTF/NF-1 sites. In addition, electrophoretic gel mobility shift assays showed that binding of a nuclear factor from cisplatin-resistant cells to the CTF/NF-1 site was significantly higher than the binding of the same factor from parental cells. Semiquantitative reverse transcription-PCR and Western blot analysis also showed that expression of CTF/NF-1 was 3-20-fold higher in the resistant cell line than in its parental counterpart. These findings suggest that, in cisplatin-resistant cells, the expression of HMG1 gene product is enhanced at the transcriptional level and that this probably occurs through the enhanced expression of the CCAAT binding factor, CTF/NF-1.
Assuntos
Antineoplásicos/farmacologia , Cisplatino/farmacologia , Regulação Neoplásica da Expressão Gênica , Proteínas de Grupo de Alta Mobilidade/genética , Ativação Transcricional , Sequência de Bases , Proteínas Estimuladoras de Ligação a CCAAT/metabolismo , Clonagem Molecular , Sequência Consenso , Pegada de DNA , DNA de Neoplasias/genética , DNA de Neoplasias/metabolismo , Resistencia a Medicamentos Antineoplásicos/genética , Proteínas de Grupo de Alta Mobilidade/biossíntese , Humanos , Células KB , Dados de Sequência Molecular , Fatores de Transcrição NFI , Regiões Promotoras Genéticas/genética , RNA Mensageiro/biossíntese , RNA Mensageiro/genética , Análise de Sequência de DNA , Fatores de Transcrição/metabolismo , Regulação para CimaRESUMO
Streptococcus constellatus, S. intermedius, and S. anginosus, the three species of the S. milleri group, form part of the normal flora most commonly found in the mouth, throat, gastrointenstinal tract, and genital tract. The S. milleri group has become known as an important pathogen in abscess disease, but little attention has been paid to their role in deep neck abscesses. We have treated 9 patients with deep neck abscesses relating to the S. milleri group since 1991, and regarded this group as an important pathogen also in these abscesses. We studied the frequency of the S. milleri group isolated from deep neck abscesses in our cases and from the literature and discuss clinical significance and bacteriological pathogenesis. Cases numbered 27 treated at our facility since 1991 and 200 cases reported in the Japanese literature since 1990. Of our 9 cases, 4 originated from acute pharyngitis, 3 from peritonsillar abscesses, and 2 from odontogenic infection. Serious complications such as mediastinitis, cervical necrotizing fasciitis, sepsis accompanied by disseminated intravascular coagulation, and spondylitis of the cervical vertebrae were seen in 4 cases. Among organisms isolated, the S. milleri group appeared to be a pathogen contributing to abscess formation and to serious complications. The genus Streptococcus was most frequently isolated both in our 27 cases (66.7%) and the 200 in the literature (45.5%). Among species of the genus Streptococcus, the S. milleri group numbered the highest in our cases at 33.3% but only 8.5% in the literature. Cases in the literature, however, contained many unknown species of Streptococci--31.5% vs. 18.5% in our cases. alpha-streptococcus was frequently reported in the literature among unknown species of Streptococci--36 of 63. Culture-negative cases were also numbered more in the literature than in our case--29.0% vs. 18.5%. Special conditions and procedures are required to suitably isolate and detect the S. milleri group. Since not all facilities use identical techniques in routine bacteriological examination, a considerable number of the S. milleri group could be missed in unknown species of Streptococci or alpha-streptococcus and culture-negative cases. The detailed pathogenesis of the S. milleri group remains to be clarified. Infection by normal flora on mucosa is thought to occur due to an imbalance between organisms and host defense in deep neck abscesses. Some strains of the S. milleri group have been reported to produce many tissue-destroying enzymes such as collagenase and hyaluronidase. The co-existence of the S. milleri group with some anaerobe strains has also been suggested to accelerate inflammation. We discuss the mechanism inducing the massive release of cytokines through T cell response to certain exotoxins produced by S. milleri group, as reported in toxic shock-like syndrome due to the group A beta-streptococcus and in alpha-streptococcal shock syndrome due to viridans streptococci (alpha-streptococci).
Assuntos
Abscesso/microbiologia , Pescoço , Streptococcus/isolamento & purificação , Abscesso/etiologia , Adulto , Idoso , Idoso de 80 Anos ou mais , Feminino , Humanos , Lactente , Masculino , Pessoa de Meia-Idade , Abscesso Peritonsilar/complicações , Faringite/complicaçõesRESUMO
Different neoplasms and infections are known to involve the masticator space, but pathological diagnosis and treatment of these lesions are not always simple due to anatomical complexity. We treated a 66-year-old man with an abscess in the nasopharyngeal masticator space. Physical and CT findings resembled those of neoplastic lesion because the onset dated back 5 years and the patient was lacking in notable signs of infection. Surgery through the maxillary sinus to the lesion enabled us to confirm its pathology and drain pus, with subsequent cure. We noted periodontal infection of the mandibular molars accompanied with osteomyelitis as a cause of this abscess, so infected molars were extracted 13 days after surgery. The infection had spread upward along the mastication muscles, resulting in an abscess in both the upper masseter muscle and the lower temporalis muscle. Based on a review of the literature, most abscesses in the masticator space originate from the mandibular molar, while the most impressive physical finding varied between the submandibular region and temporal fossa, as did its acute or chronic clinical course. Such clinical manifestations appear to reflect the pattern of infection spread along the muscles of mastication and a pattern involving adjacent spaces. We emphasize diagnostic significance when assessing findings for each mastication muscle and mandibular bone depicted using computed tomography, magnetic resonance imaging, and bone-scan technetium.
Assuntos
Abscesso/diagnóstico , Doenças Mandibulares/diagnóstico , Músculos da Mastigação/patologia , Doenças Nasofaríngeas/diagnóstico , Idoso , Doença Crônica , Humanos , Imageamento por Ressonância Magnética , Masculino , Tomografia Computadorizada por Raios XRESUMO
Changing the sleep position from supine to non-supine is a simple but effective treatment for some patients with sleep apnea syndrome. In the present study, we compared the clinical data for good responders (GRs), those who responded well to the sleep position change, with those for poor responders (PRs), and also evaluated the effect of surgical treatment on the positional improvement of ventilation in the PR group. Forty-one adult patients with sleep apnea syndrome (mean age: 47.1 years, mean obesity index: 125.8%) were divided into two groups based on their polysomnographic responses to sleep position change. Thirty-two patients were classified as the GR group, whose apnea-hypopnea index (AHI) in the non-supine position declined to less than half of their AHI in the supine position, and nine whose non-supine AHI remained greater than half of their supine AHI were classified as the PR group. The AHI and the desaturation index (DI) for the PR group were significantly higher than those for the GR group, and the obesity index was also higher in the PR group. For the eight PRs who had surgical therapy, their polysomnographic data improved much more in the non-supine position than in the supine position. Of six patients whose total AHI was still 10 or more after surgery, four changed into GRs. The combination of surgery and sleep position change seemed to be an effective treatment even for patients with a little improvement before surgery.
Assuntos
Postura/fisiologia , Síndromes da Apneia do Sono/terapia , Sono/fisiologia , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Polissonografia , Síndromes da Apneia do Sono/fisiopatologia , Síndromes da Apneia do Sono/cirurgiaRESUMO
BACKGROUND: Several studies have previously shown some factors that modify the pathogenesis of perennial allergic rhinitis (PAR). However, the association between bacterial colonization and PAR has not been well understood. OBJECTIVE: We sought to study the association between superantigen-producing Staphylococcus aureus and PAR. METHODS: S aureus colonization in the nasal cavity and its superantigen production were studied in 65 patients with PAR and 45 nonallergic control subjects. The nasal symptom scores of the patients were evaluated. Furthermore, we examined the response to staphylococcal enterotoxin B or toxic shock syndrome toxin 1 of peripheral blood lymphocytes from both patients and control subjects by measuring proliferative responses and production of cytokines (IFN-gamma, IL-4, and IL-5). RESULTS: The rate of nasal carriage of S aureus in the patients (44%) was significantly higher than that of the control subjects (20%, P <.01). Moreover, the rate of nasal carriage of superantigen-producing S aureus in the patients (22%) was significantly higher than that of the control subjects (6.7%, P <.05). The nasal symptom scores of the S aureus -positive patients were significantly higher than those of the S aureus -negative patients (P <.05), although there was no significant association between symptom scores and superantigen production. Peripheral blood lymphocytes from the patients showed significantly higher proliferative responses and were more likely to produce T(H2 )type cytokines in response to superantigens (P <.01), but the responses were not different among the patients with S aureus carriage and superantigen production. CONCLUSION: This study suggests that PAR leads to a higher carriage rate of S aureus, and nasal carriage of S aureus may aggravate PAR.
Assuntos
Toxinas Bacterianas , Cavidade Nasal/microbiologia , Staphylococcus aureus/imunologia , Adolescente , Adulto , Idoso , Criança , Enterotoxinas/farmacologia , Humanos , Interferon gama/metabolismo , Interleucina-4/metabolismo , Interleucina-5/metabolismo , Ativação Linfocitária , Linfócitos/metabolismo , Pessoa de Meia-Idade , Rinite Alérgica Perene/imunologia , Superantígenos/imunologiaRESUMO
Clinically, salicylates have been known to have a ototoxic side effect of reversible hearing loss and to reduce the voltage-dependent length change (electromotility) in experiments on isolated outer hair cells (OHC). In order to clarify how the reduction of OHC electromotility due to salicylates contributes to cochlear dysfunction in vivo, we observed compound action potentials (CAP) threshold as well as the outputs of the electrically evoked otoacoustic emissions (EEOAE) before and after intravenous administration of 500 mg/kg sodium salicylate in a guinea pig model. A silver ball electrode placed on the round window membrane of the animal was used for both recording of the CAP and stimulation to elicit the EEOAE. The CAP threshold to tone bursts with frequencies from 2 to 10 kHz elevated by 13 to 22 dB, and outputs of the EEOAE decreased approximately 4 dB for 5 kHz stimulation, and 12 dB for 8 kHz after salicylate administration. These results suggested that systemically administered salicylate also reduced the electromotility of the OHC, and caused the hearing impairment in vivo.
Assuntos
Emissões Otoacústicas Espontâneas/efeitos dos fármacos , Salicilato de Sódio/efeitos adversos , Potenciais de Ação/efeitos dos fármacos , Animais , Movimento Celular/efeitos dos fármacos , Surdez/induzido quimicamente , Estimulação Elétrica , Cobaias , Células Ciliadas Auditivas Externas/efeitos dos fármacosRESUMO
Immunoreactivities of endothelin-1, endothelin-3, endothelin receptor type A, and Na,K-ATPase were investigated in the stria vascularis of adult male WBB6F1 +/+ mice and in that of W/Wv mutants lacking strial intermediate cells. In the +/+ mice, electron microscopic immunoreactivity for the endothelins was seen on the rough endoplasmic reticulum, Golgi apparatus, cytoplasmic vesicles and lysosomes exclusively in the strial intermediate cells by the postembedment method. Immunoreactive endothelin receptor A was localized along the plasma membrane of strial marginal cells of both wild and mutant types although the immunoreactivity of the latter was much less than that of the former by the preembedment method. These findings suggest that the endothelins, which are produced in the strial intermediate cells, may play a role in the maintenance of the stria vascularis function in the +/+ mice. Since the plasma membrane of the marginal cells of the W/Wv mice, which do not generate a high positive endocochlear potential, also showed immunoreactivity for Na,K-ATPase, it seems likely that the endothelins are involved in the activation of sodium pump of the strial marginal cells by mediation of endothelin receptor A. In addition, the role of lysosomes in the crinophagy of the endothelins in the strial intermediate cells is proposed in the +/+ mice.