ECA-3: equine (CA) repeat polymorphism at chromosome 2p1.3-4.
Explore the source record for details and available documents.
Alleles↗
Biomedical subjects
M Sakagami
Publications and source records attributed to M Sakagami.
Vascular permeability of the stria vascularis and morphology of the endolymphatic sac in two types of experimental endolymphatic hydrops.
We produced two kinds of experimental endolymphatic hydrops. One was induced by obliteration of the endolymphatic sac (ES), and the other was induced by both systemic keyhole limpet hemocyanin immunization and secondary keyhole limpet hemocyanin challenge into the ES. The vascular permeability of the stria vascularis in acute and chronic phases was compared between both models by light and electron microscopy using the tracer method of horseradish peroxidase. Both models showed that the number of strial capillaries showing horseradish peroxidase leakage was significantly higher in the acute phase than in the chronic phase. In the acute phase, the ES showed acute inflammation in both models. In the chronic phase, extensive fibrosis occurred in the ES obliteration model, whereas the ES appeared to have a normal shape in the immunologically induced model. The mechanism of hydrops formation will be compared between the two models.
Acute Disease↗
Nystagmus measured by ENG after stapes surgery.
Much attention has been paid to hearing results after stapes surgery, but the risks of vestibular disturbance has not been extensively studied. Postoperative spontaneous nystagmus was measured daily at bedside by portable ENG in order to evaluate the vestibular damage from stapes surgery. Thirteen patients underwent primary stapedotomy or stapedectomy from August 1, 1992 to June 30, 1993. Nystagmus toward the operated ear was observed in 3 cases, that toward the opposite ear in 2 cases, that changing from toward the operated ear to toward the opposite ear in 2 cases, that changing from toward the opposite ear to toward the operated ear in 2 cases and no nystagmus in 4 cases. There was no relationship between duration of nystagmus and that of dizziness. Nystagmus was thought to be due to the following: i) inner ear damage by operation, ii) postoperative perilymphatic fistula, iii) floating footplate, and iv) stimulation of hair cells by high potassium ion in the perilymph due to blood flow into the inner ear.
Adolescent↗
A novel tRNA species as an origin of short interspersed repetitive elements (SINEs). Equine SINEs may have originated from tRNA(Ser).
Short interspersed repetitive elements (SINEs) were isolated from the equine genome and characterized. The equine SINE (ERE-1) family has several features characteristic of tRNA-derived retroposons. The five members of the equine family of SINEs are approximately 230 nucleotides in length and terminate with a sequence rich in oligo(A). They are all flanked by direct repeats at the 5' and 3' ends, and such repeats are the hallmarks of retroposons. In addition, the ERE-1 family has a tRNA-related region, which is similar to tRNA(Ser) of Drosophila (65% identity). tRNA(Ser) is a novel tRNA with respect to the origin of SINEs and has not previously been recognized among the twenty tRNA-derived SINEs characterized to date. The members of the ERE-1 family were found to be distributed among five species in the genus Equus, and their amplification may have contributed to the genetic variability of their hosts during evolution.
Animals↗
Spatial selectivity of go/no-go neurons in monkey prefrontal cortex.
We examined single-unit activity in the inferior prefrontal cortex during a visual go/no-go discrimination task under maintained visual fixation. The monkeys had to base their response on either the color, shape, or position of a discriminative cue, and the relevant task condition was indicated by the color of the fixation spot. We analyzed the spatial selectivity of 128 go/no-go neurons showing a marked differential cue-period activity that depended on whether the stimulus signaled a go or no-go response. Most of these neurons (n = 106, 83%) showed asymmetry between their responses to stimuli in the contralateral and ipsilateral visual fields. Seventy-seven of these neurons had a contralateral preferential field, and 29 had an ipsilateral preferential field. These results show that in many inferior prefrontal neurons a degree of differentiation in their responses to go and no-go stimuli depends on the cue positions, and that the coding of behavioral meaning is carried out mainly in the contralateral hemisphere.
Animals↗
Encoding of behavioral significance of visual stimuli by primate prefrontal neurons: relation to relevant task conditions.
Single-unit activity was recorded from the inferior dorsolateral prefrontal cortex of two monkeys while they performed a symmetrically rewarded go/no-go discrimination task. Three different task conditions were used in which the monkeys had to base their response on (1) the color, or (2) the shape, or (3) the position of a cue that was presented during fixation of a light spot. The colors of the fixation spot informed the monkeys which condition was relevant. The monkeys had to make an immediate release (go) or a delayed release (no-go) at the time of the fixation color change (imperative stimulus) depending on the currently relevant condition and the discriminative cue previously presented. The effect of changing the relevant condition on neuronal responses to the discriminative cue was analyzed. Out of 328 neurons tested in two or three conditions, 249 responded differentially at the cue period depending on the particular behavioral meaning of the stimulus (go or no-go) in at least one of the task conditions. This differential cue-period activity was examined across the different task conditions: the majority of neurons (111/154, 72%) showed such activity in all three conditions. In the remaining 43 neurons (28%) the differential activity was observed in two conditions (27/154, 18%) or in one condition (16/154, 10%). A few neurons (n = 7) showed feature-specific cue-period activity. In addition, 27 neurons displayed condition-dependent anticipatory activity prior to the cue onset. It is suggested that neurons in the inferior dorsolateral prefrontal cortex may participate in the conversion of sensory information from different visual channels into behavioral information (information on the upcoming response).
Animals↗
Failure of forskolin to elevate the endocochlear potential in kanamycin-poisoned animals.
The effect of forskolin (FSK) on the endocochlear potential (EP), K+ activity (AK), Na+ activity (ANa) and Cl- activity (ACl) in scala media (SM) was compared between normal and kanamycin (KM)-poisoned guinea pigs by means of double-barrelled ion-selective microelectrodes. The perfusion of the scala vestibuli (SV) with FSK (200 microM) produced EP elevation in normal animals whereas FSK failed to do it in KM-poisoned animals. FSK increased ACl of SM with no significant change in AK and ANa of SM in both groups of animals. Histological examination of KM-poisoned animals showed damaged outer and inner hair cells with an intact appearance of the stria vascularis. The mechanism underlying the failure of FSK to elevate the EP in KM-poisoned animals is discussed.
Animals↗
Localization of osteopontin in the otoconial organs of adult rats.
Although it is known that mammalian otoconia consist of calcium bicarbonate and organic materials, none of the protein components have been identified in mammals at the molecular level, and the mechanisms of morphogenesis and calcification of the otoconia is still unclear. In the present study, we demonstrated the presence of osteopontin (OPN) in rat otoconia by using immunohistochemistry, and detected OPN mRNA in the sensory hair cells by a non-radioisotopic in situ hybridization technique. These results indicate that OPN is one of the protein components in rat otoconia and suggest that sensory hair cells are involved in the production of otoconia.
Animals↗
Polymorphic sequence in the D-loop region of equine mitochondrial DNA.
The D-loop regions in equine mitochondrial DNA were cloned from three thoroughbred horses by polymerase chain reaction (PCR). The total number of bases in the D-loop region were 1114 bp, 1115 bp and 1146 bp. The equine D-loop region is A/T rich like many other mammalian D-loops. The large central conserved sequence block and small conserved sequence blocks 1, 2 and 3, that are common to other mammals, were observed. Between conserved sequence blocks 1 and 2 there were tandem repeats of an 8 bp equine-specific sequence TGTGCACC, and the number of tandem repeats differed among individual horses. The base composition in the unit of these repeats is G/C rich as are the short repeats in the D-loops of rabbit and pig. Comparing DNA sequences between horse and other mammals, the difference in the D-loop region length is mostly due to the difference in the number of DNA sequences at both extremities. The similarities of the DNA sequences are in the middle part of the D-loop. In comparison of the sequences among three thoroughbred horses, it was determined that the region between tRNA(Pro) and the large central conserved sequence block was the richest in variation. PCR primers in the D-loop region were designed and the expected maternal inheritance was confirmed by PCR-RFLP (restriction fragment length polymorphism).
Animals↗
Molecular cloning of an equine satellite-type DNA sequence and its chromosomal localization.
We have molecularly cloned portions of equine satellite-type DNA and investigated the organization of the DNA sequence of the cloned segments. Sequence analysis and dot-blot analysis, using the cloned sequence (ES200) as a probe, indicate that the satellite-type DNA sequence consists mainly of 221-bp tandem repeats and represents 3.7-11% of the equine genome. Southern blot analysis further shows that (1) no sequences homologous to ES200 exist in the human, swine, and bovine genomes and that (2) the fragment pattern of the satellite-type DNA produced by ApaI cleavage shows a slight difference among equine DNA samples, indicating a slight sequence variation between individual horses. To localize the satellite-type DNA in the horse genome, chromosome spreads on glass slides were first subjected to G-banding to identify each chromosome and then hybridized in situ with biotin-labeled ES200. The chromosome banding, together with the hybridization, demonstrates that the satellite sequences are preferentially localized on the centromeric regions of all chromosomes except chromosomes 2, 9, and 11.
Animals↗
Fine structural aspects on auditory hair cell degeneration in the budgerigar, Melopsittacus undulatus, as induced by kanamycin.
The effects of kanamycin, an antibiotic of the aminoglycoside group, on the auditory sensory epithelium of the budgerigar, Melopsittacus undulatus, were examined using both scanning and transmission electron microscopes. Results show that the threshold of the auditory brainstem response increased in birds treated with kanamycin 200 mg/kg for 49 days. While the auditory sensory epithelium of the normal budgerigar consists of short and tall hair cells, and supporting cells, following kanamycin administration, the middle to proximal region of the epithelium of the inner ear showed degenerative changes, with the other parts remaining apparently intact. In the damaged region, the short hair cells were flattened, and the tall ones became heterogeneous in shape. Both types of cells contained many dense bodies in their cytoplasm; they were rounded in shape and homogeneously dense. Severely degenerated tall hair cells also contained many large vacuoles with heterogeneous contents. Because the dense bodies and large vacuoles were positive for acid phosphatase reaction, they were respectively judged to be primary lysosomes and secondary lysosomes containing degenerating cell debris. Most supporting cells in the impaired region were lower in cytoplasmic electron density, and their apical surface became enlarged in area. Some flattened short hair cells were situated on the apical part of the swollen supporting cells. This finding suggests that the short hair cells are pressed toward the scala media by the supporting cells.
Animals↗
Strial dysfunction in a melanocyte deficient mutant rat (Ws/Ws rat).
A homozygous mutant rat at the white spotting (Ws) locus showing a deficiency of melanocytes has recently been found (4, 5). The function and morphology of the inner ear of the Ws/Ws rat were examined by auditory brainstem response (ABR), endocochlear DC potential (EP), and electron microscopy. The mean ABR threshold of the Ws/Ws rat was significantly higher than that of the control +/+ rat. Most Ws/Ws rats showed no or very little EP. In electron microscopy, the stria vascularis of the Ws/Ws rat proved to be very thin and flat with poor interdigitation of marginal cells, and absence of intermediate cells. The organ of Corti appeared to be intact in both the +/+ rat and the Ws/Ws rat. These electrophysiological and morphological findings suggest that the Ws/Ws rat suffered from severe hearing loss caused by strial dysfunction.
Acoustic Stimulation↗
Frequency characteristics of summating potential in Menière's disease.
SP iso-response functions in 9 patients with Menière's disease were examined for differences in the properties between +SP and -SP. The iso-response functions of +SP and -SP exhibited a large difference. The iso-response function for +SP was centered at high frequencies (around 9 kHz in most cases) with fairly steep slopes on both sides towards both higher and lower frequencies, whereas -SP showed a low-pass function. The tendency was found for patients with normal hearing at high frequencies to have a larger Q10dB than patients with a hearing loss. The difference in properties between +SP and -SP suggests the possibility that +SP may provide different information on the pathophysiology of Ménière's disease from that obtained from -SP.
Acoustic Stimulation↗
[Tympanoplasty in cholesteatoma otitis media with normal hearing].
Thirteen cholesteatomas, with hearing within 20dB, were operated on from 1985 to 1992. Their mean age was 22.1 years, and the mean follow-up period 1.8 years. Eleven cases were pars flaccid type, and 2 cases pars tensa type. Tympanoplasties were performed by the canal down method (4 cases), the canal up method (3 cases), both transmeatal atticotomy and scutumplasty (4 cases) and both the canal down method and mastoid obliteration (2 cases). Postoperative hearing results of three averaged speech frequencies were within 20dB in 11 cases and between 20 and 30dB in 2 cases. No recurrent cholesteatoma or extrusion of columella occurred during the follow-up period. One of the cases operated on by the canal down method showed postoperative mastoid cavity problems, and one of the cases operated on by the canal up method showed retraction of the pars flaccida. These findings prompted us to operate on cholesteatoma cases with normal hearing and to recommend tympanoplasty with transmeatal atticotomy and scutumplasty.
Adolescent↗
[Application of non-radioisotopic in situ hybridization to the inner ear--expression of osteopontin].
Osteopontin (OPN) is considered to be a non-collagenous bone matrix protein which is involved in the ossification process. However, OPN has recently been observed in ectopic sites such as the kidney and nervous tissues. In the present study, expression of OPN mRNA was examined in the rat inner ear by non-radioisotopic in situ hybridization. Signals of OPN mRNA were observed in the marginal cells of the stria vascularis, spiral ganglions, vestibular sensory hair cells and vestibular dark cells. OPN protein was detected only in otoliths by immunohistochemistry. The reasons for the presence of OPN mRNA in the cochlea and dark cells of the vestibulum were unclear. On the other hand, findings of the sacculus and utriculus suggest that OPN is one of the protein components of rat otoliths and that vestibular sensory hair cells are involved in the production of otoliths.
Animals↗
Regulation of the Escherichia coli rmf gene encoding the ribosome modulation factor: growth phase- and growth rate-dependent control.
Ribosome modulation factor (RMF) is a protein specifically associated with 100S ribosome dimers which start to accumulate in Escherichia coli cells upon growth transition from exponential to stationary phase. The structural gene, rmf, encoding the 55 amino acid residues RMF protein has been cloned from the 21.8 min region of the E. coli genome and sequenced. While rmf was silent in rapidly growing exponential phase cells, a high level of transcription took place concomitantly with the growth transition to stationary phase. Under slow growth conditions, rmf was expressed even in exponential phase and there was an inverse relationship between the expression of rmf and the cell growth rate. Thus, the expression profile of rmf is contrary to those of genes for ribosomal components and ribosome-associated proteins constituting the translational apparatus. The katF gene product, a stationary phase-specific sigma factor, was not required for the expression of rmf. Disruption of rmf resulted in loss of ribosome dimers and reduction of cell viability during stationary phase.
Amino Acid Sequence↗
An immunohistochemical and electrophysiological study on Isk protein in the stria vascularis of the guinea pig.
The reaction product against rat Isk protein antibody was demonstrated on the endolymphatic surface of the marginal cell of the guinea pig, using an immunohistochemical method. Clofilium, a potassium channel blocker which has been previously found to block rat kidney Isk channels, decreased the endocochlear potential (EP) when applied by perilymphatic perfusion and iontophoresis into endolymph. This finding of a decreased EP supports the presence of Isk protein on the endolymphatic surface of the marginal cell.
Action Potentials↗
Ultrastructure and barrier properties of the endolymphatic duct in the guinea pig.
The ultrastructure and barrier properties of the endolymphatic duct (ED) were examined by light and electron microscopy. ED epithelial cells were classified into two types: type I and type II duct cells. The type I duct cells were cuboidal or low columnar and were characterized by a convex apical surface and a few basal processes. The type II duct cells were squamous and were characterized by a flat apical and basal membrane, many small vesicles and a number of small pits along the basal membranes. After electrophoretic horseradish peroxidase (HRP) injection into the ED lumen, no HRP uptake into ED epithelial cells of either type was observed. There was no reaction product either in the lateral intercellular spaces beyond the tight junctions between ED epithelial cells or in ED subepithelial tissues. The ED epithelial cells were considered to play no active role in apical macromolecular absorption and to be impermeable to intraluminal macromolecules.
Absorption↗