Y-27632, a Rho-associated protein kinase inhibitor,attenuates neuronal cell death after transient retinal ischemia

Purpose Transient retinal ischemia induces the death of retinal neuronal cells. Postischemic damage is associated with the infiltration of leukocytes into the neural tissue through vascular endothelia. The current study aimed to investigate whether this damage was attenuated by the inhibition of Rho/ROCK (Rho kinases) signaling, recently shown to play a critical role in the transendothelial migration of leukocytes. Methods Y-27632, a selective inhibitor of ROCK, was injected intravitreally into rat eyes with transient retinal ischemia. Cell loss of the ganglion cell layer (GCL) and thinning of the inner plexiform layer (IPL) with and without the administration of Y-27632 were evaluated by histological anaysis, TUNEL assay and retrograde labeling of retinal ganglion cells (RGCs). To examine the attenuation of leukocyte infiltration in postischemic retinas with the administration of Y-27632, silver nitrate staining and immunohistochemistry using an anti-LCA antibody were performed. Results Cell loss of the GCL and thinning of the IPL were significantly attenuated when 100 nmol Y-27632 was administered within three hours of the induction of ischemia. TUNEL assay and retrograde labeling of RGCs showed a decreased number of apoptotic cells and an increased number of RGCs in Y-27632-injected retinas. Moreover, silver nitrate staining and immunohistochemical analysis using an anti-LCA antibody showed that Y-27632 injection dramatically inhibited leukocyte infiltration and endothelial disarrangement. Conclusions Our data suggest that inhibition of Rho/ROCK signaling offers neuroprotective therapy against postischemic neural damage, by regulating leukocyte infiltration in the neural tissue.     

The mechanism of speech perception using multichannel cochlear implant

The mechanism of speech perception in patients with Australian multi-channel cochlear implant was investigated. 1) Vowel recognition abilities of patients were sufficient with this implant, whereas, consonant recognition abilities were insufficient. 2) Although the cochlear hair cells were functionally damaged, cochlear nerves had the ability to characterize frequency. 3) The signals from the implanted material were very simple compared to those from normal cochlea, however these patients could understand speech well, perhaps due to aid from the central nervous system.     

Effect of vestibular nerve section on cytochrome oxidase activity in the vestibular ganglion cells of the squirrel monkey

Cytochrome oxidase (CO) activity of the vestibular ganglion cells of the squirrel monkey was demonstrated histochemically under normal and experimental conditions. Under general anesthesia, right vestibular nerve section was performed on adult squirrel monkeys between the vestibular ganglion and brain stem. The left side was left intact and was used as a within-animal normal control. One squirrel monkey that did not undergo vestibular nerve section was also included in the normal group. Following a survival period of seven months, neurons in the vestibular ganglion of both sides were examined. In the normal control sides, a significant negative correlation between the size of the neuron and its optical density for CO stain was observed. Many neurons in the vestibular ganglion survived after vestibular nerve section, but their cell sizes and optical densities of CO stain decreased compared with those of the control side.     

Pumping and clearance function of the eustachian tube

The purpose of this study was to clarify the relationship between mucociliary and muscular clearance in the eustachian tube. Displacement of various viscosities and volumes of a colored fluid through the tube was observed endoscopically in cats. To test ciliary clearance, the fluid was placed in either the tympanum or the mastoid bulla. The interval between the instillation and beginning of discharge of the fluid from the pharyngeal orifice of tube was measured. Clearance time was prolonged with fluids having high viscosities, and the clearance time from the tympanum was shorter than that from the mastoid bulla. To test muscular clearance, the tensor veli palatini muscle was stimulated electrically to simulate swallowing, and the number of contractions necessary for massive discharge of the fluid was counted. Massive discharge occurred only with low viscosity fluid placed in the tympanum, whereas small amounts of highly viscous fluid were cleared by linear discharge. The authors concluded that when the volume of middle ear effusion was small, the fluid was cleared by mucociliary clearance. When the volume of fluid was large, the low viscosity fluid was cleared by muscular clearance only, while highly viscous fluid was cleared both by ciliary and muscular clearance.     

The origin of autonomic nerves of the Eustachian tube as studied by the horseradish peroxidase tracer method

Autonomic innervation of the Eustachian tube mucosa was investigated by the horseradish peroxidase retrograde tracing method. The Eustachian tube mucosa was found to be sympathetically innervated by fibres originating in the ipsilateral superior and middle cervical ganglia, but not by those originating in the stellate ganglion. The Eustachian tube mucosa was also innervated by fibres originating in the pterygopalatine ganglion, but not by those originating in the otic ganglion. The innervation from the pterygopalatine ganglion was considered to be parasympathetic.     

Respiratory Syncytial Virus Infection in Infants with Congenital Heart Disease and Treatment with Human Leukocyte lnterferone

Between 1980 and 1986, we observed lower respiratory-tract infection caused by respiratory syncytial virus (RSV) in 19 infants and young children with various forms of congenital heart disease. Of these, seven patients who presented with a severe illness were treated with intramuscular injections of 0.5 to 1 times 10⁶ IU per day of human leukocyte interferon (IFN) for three to five days. Intrinsic IFN activity developed before treatment in three subjects. Viral isolation studies showed active RSV infection prior to treatment, and no infectious RSV was recovered one to four days after treatment. Although there were no obvious changes in the clinical course after IFN therapy, no deaths related to RSV infection occurred. Analysis of the different types of congenital heart disease showed that ventricular septal defect and/or patent ductus arter-iosus with pulmonary hypertension were associated with the most severe RSV illness. The therapeutic value of IFN may improve in this group of subjects if it is given without delay.     

Eustachian tube patency detected by a photoelectric method

A method was developed to observe tubal orifice movement by fiberscope and detect patency of the eustachian tube by a photoelectric device (phototubometry). A highly sensitive photodiode in the external ear canal detected tube opening as increased luminosity in the tympanic cavity from a light source placed at the pharyngeal portion of the eustachian tube. The phototubometric record was superimposed on a TV screen to compare the opening in the pharyngeal portion of the eustachian tube to the tube opening during swallowing. The phototubometric records of 21 normal subjects examined by phototubometry showed the close relationship with the opened tubal lumen at the tensor veli palatini muscle (TVP) attached portion. This method is useful for examining tubal patency and observing changes in the pharyngeal portion of the eustachian tube.     

Magnetic resonance imaging of the eustachian tube. A correlative anatomical study

Magnetic resonance (MR) imaging of the eustachian tube (auditory tube) was performed in normal subjects and in a patient with nasopharyngeal carcinoma. The MR images obtained in an anteriorly tilted transaxial plane parallel to the eustachian tubes were compared with serial slices of a cadaver specimen. The eustachian tube cartilage, mucous lining of the eustachian tube, the lateral pharyngeal recess, the tensor veli palatini muscle, and the levator veli palatini muscle were identified in MR images using anatomical relationships. A patient with nasopharyngeal carcinoma is described to demonstrate an example of topographical morbid changes appearing around the eustachian tube.