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Biomedical subjects

J Ito

Publications and source records attributed to J Ito.

At least 73 records · Page 4Linked to original sources
PubMed2000

Cholesterol-sphingomyelin interaction in membrane and apolipoprotein-mediated cellular cholesterol efflux.

Helical apolipoproteins interact with cellular surface and generate high density lipoprotein (HDL) by removing phospholipid and cholesterol from cells. We have reported that the HDL is generated by this reaction with the fetal rat astrocytes and meningeal fibroblasts but cholesterol is poorly available to this reaction with the astrocytes (Ito et al. 1999. J. Neurochem. 72: 2362;-2369). Partial digestion of the membrane by extracellular sphingomyelinase increased the incorporation of cholesterol into thus-generated HDL from both types of cell. This increase was diminished by supplement of endogenous or exogenous sphingomyelin to the cells. The sphingomyelinase treatment decreased cholesterol in the membrane mainly in the detergent-resisting domain. The intracellular cholesterol used by acylCoA:cholesterol acyltransferase increased by the sphingomyelinase treatment in the absence of apoA-I, more remarkably in the fibroblast than in the astrocytes. ApoA-I suppressed this increase completely in the astrocytes, but only partially in the fibroblast. The effect of the sphingomyelin digestion was more prominent for the apolipoprotein-mediated reaction than the diffusion-mediated cellular cholesterol efflux. Thus, cholesterol molecules restricted by sphingomyelin in the domain of the plasma membrane appear to be primarily used for the HDL assembly upon the apolipoprotein;-cell interaction.

Animals↗
PubMed1999

Effects of ortho-substituent groups of sulochrin on inhibitory activity to eosinophil degranulation.

Sulochrin, a metabolite of fungi, has been shown to have an inhibitory activity to eosinophil degranulation. A series of sulochrin derivatives substituted at ortho-positions to the 10-carbonyl group was examined the activity. The importance of alkylester at C-6 position and several chemical properties of substituted groups at ortho-positions to exhibit activity are described.

Anti-Allergic Agents↗
PubMed1999

Regeneration of the lateral vestibulospinal tract in adult rats by transplants of embryonic brain tissue.

We transected the lateral vestibulospinal tract in the spinal cord of adult rats. In one group we performed simple transection, and in other group we transplanted the lesion with embryonic tissue. In rats receiving simple transection, there was no regeneration, but in 22% of the rats receiving transplants of embryonic tissue, the axon regrew beyond the transected site, regenerated on the denervated side, terminating in the normal targets. The present findings are contrary to the widely held view that the adult mammalian central vestibular system cannot be restored following damage.

Animals↗
PubMed1999

DNA polymerase C of the thermophilic bacterium Thermus aquaticus: classification and phylogenetic analysis of the family C DNA polymerases.

Bacterial family C DNA polymerases (DNA pol IIIs), the major chromosomal replicative enzymes, have been provisionally classified based on primary sequences and domain structures into three classes: class I (Escherichia coli DNA pol C-type), class II (Bacillus subtilis DNA pol C-type), and class III (cyanobacterial DNA pol C-type), respectively. We have sequenced the structural gene encoding the DNA pol C catalytic subunit of the thermophilic bacterium Thermus aquaticus. This gene, designated the Taq DNA pol C gene, contains a 3660-bp open reading frame which specifies a polypeptide of molecular weight of 137,388 daltons. Comparative sequence analyses revealed that Taq DNA pol C is a class I family C DNA polymerase. The Taq DNA pol C is most closely related to the Deinococcus radiodurans DNA pol C. Although a phylogenetic tree based on the class I family C DNA pols is still in the provisional stage, some important conclusion can be drawn. First, the high-G+C and the low-G+C Gram-positive bacteria are not monophyletic. Second, the low-G+C Gram-positive bacteria contain multigenes of family C DNA pols (classes I and II). Third, the cyanobacterial family C DNA pol, classified as class III because it is encoded by a split gene, forms a group with the high-G+C Gram-positive bacteria.

Amino Acid Sequence↗
PubMed1999

Primary structure of the DNA polymerase I gene of an alpha-proteobacterium, Rhizobium leguminosarum, and comparison with other family A DNA polymerases.

The structural gene for DNA polymerase I of Rhizobium leguminosarum was determined. The rhizobium DNA polymerase I consists of 1016 amino acid residues with a calculated molecular weight of 111,491 Dalton. The amino acid sequence comparison with E. coli DNA polymerase I, Thermus aquaticus DNA polymerase I, and Rickettsia prowazekii DNA polymerase I showed that, although 5'-nuclease and DNA polymerase domains are highly conserved, 3' to 5' exonuclease domains are much less conserved. While both R. leguminosarum and R. prowazekii belong to the alpha subdivision of the Proteobacteria on the basis of 16S ribosomal RNA phylogeny, the primary structure of the DNA polymerase I is quite different; the rhizobium DNA polymerase I has 3' to 5' proofreading exonuclease, but the rickettsia DNA polymerase I does not.

Amino Acid Motifs↗
PubMed1999

Imaging of calvarial eosinophil granuloma.

We reviewed the imaging of four pathologically proven calvarial eosinophil granulomas. The diameter of the lesions ranged from 13 to 40 mm; three were biconvex, but the other had a collar-stud appearance. Two lesions were in the frontal and two in the parietal bone. On bone-window CT, a bevelled edge was seen in three cases and button sequestration in one, but no sclerotic rim was shown. Although one lesion had a low-density area, the lesions were slightly denser than grey matter. They were isointense with grey or white matter on T1-weighted MRI and gave heterogeneous high signal on proton-density and T2-weighted images. All enhanced markedly, with a less strongly enhancing portion within them. A tail of dural enhancement and reactive change in the overlying galea or temporal muscle were seen in all cases.

Bone Diseases↗
PubMed1999

Bilateral optic neuritis in a child diagnosed with Gd-enhanced MR imaging using fat-suppression technique.

A 4-year-old boy developed bilateral optic neuritis. Although precise neuro-ophthalmological evaluation was difficult, the diagnosis was made with gadolinium-enhanced MR imaging using fat-suppression technique in the initial stage of the disease. Enhancement and enlargement of the intraorbital and intracanalicular optic nerve were demonstrated bilaterally as well as protrusion of the optic nerve head. The disease responded dramatically to intravenous steroid therapy. The etiologies in children usually differ from those in adolescent and adult patients.

Adipose Tissue↗
PubMed1999

Regeneration of the mammalian central vestibular pathway using the rat as animal model.

Regeneration of the mammalian central vestibular system was examined in rat. The lateral vestibulospinal tract (LVST) of infant rat was transected unilaterally at the level of C1-3. After a postoperative interval of several weeks, the LVST was examined by injecting an anterograde tracer (wheat germ agglutinin-conjugated horseradish peroxidase) into the lateral vestibular nucleus (LVN) and a retrograde tracer (Fast Blue) into the lumbar enlargement. More than half of the rats showed successful regeneration, indicating definite plasticity in the mammalian central vestibular system.

Animals↗
PubMed1999

Surgical considerations regarding cochlear implantation in the congenitally malformed cochlea.

A 4-year-old girl with congenital profound deafness underwent cochlear implant surgery. Preoperative CT and MRI revealed that her inner ears had common-cavity or aplasia-type malformation. The bilateral internal auditory meatus were markedly narrowed. Audiometric examination demonstrated that only slight residual hearing remained in the low-frequency range and that a hearing aid would be of no benefit. Cochlear implantation was performed in her left ear. Because of the abnormal position of the facial nerve, the routine facial recess approach could not be performed. A canal-wall-down mastoidectomy was performed, and multichannel cochlear implant electrodes were inserted by careful drilling of the bony wall of the semicircular canal area. All 22 electrodes were completely inserted into the cavity. The patient can perceive sounds and her hearing ability is progressively improving.

Child, Preschool↗
PubMed1999

Detectability of anterior displacement of the articular disk in the temporomandibular joint on helical computed tomography: the value of open mouth position.

OBJECTIVE: The purpose of this study was to establish the diagnostic reliability of anterior displacement of the articular disk in the temporomandibular joint on helical computed tomography. STUDY DESIGN: Ninety-four consecutive patients were examined through use of both computed tomography and magnetic resonance imaging. On axial computed tomography, anterior disk displacement was defined as the presence of an area of soft tissue density that was semilunar in shape and located in front of the mandibular condyle. RESULTS: With magnetic resonance imaging taken as the diagnostic gold standard in evaluation of articular disk position, the sensitivity, specificity, and accuracy for computed tomography were 91%, 100%, and 97%, respectively, in the closed mouth position and 96%, 99%, and 98%, respectively, in the open mouth position. CONCLUSIONS: The detectability on axial helical computed tomography of anterior displacement of the articular disk in the temporomandibular joint in the open mouth position was almost equal to that on magnetic resonance imaging. It is recommended that the open mouth position be added when helical computed tomography is used to evaluate patients with temporomandibular joint disease.

Absorptiometry, Photon↗
PubMed1999

Intracortical hemangioma of the mandible. Case report.

We describe the first reported case of an intracortical hemangioma of the mandible in a 13-year-old Japanese girl. Panoramic radiography and CT demonstrated a small osteolytic lesion which had expanded and thinned the cortex at the inferior border of the left mandible. The lesion enhanced on post-contrast T1-weighted MRI. The diagnosis was confirmed by histopathology following block excision. Intracortical hemangioma should be considered in the differential diagnosis of radiolucent lesions orf the mandible

Adolescent↗
PubMed1999

Differential generation of high-density lipoprotein by endogenous and exogenous apolipoproteins in cultured fetal rat astrocytes.

Most peripheral cells generate cholesterol-rich high-density lipoprotein (HDL) with exogenous apolipoprotein as one of the mechanisms for the maintenance of cellular cholesterol homeostasis. Astrocytes isolated from fetal rat brain showed a unique behavior in this reaction. Consistent with previous findings, the astrocytes synthesized apolipoprotein (apo) E and generated cholesterol-rich pre-beta-HDL-like lipoprotein with this apoE, and cellular cholesterol and phospholipids. When exogenous apoA-I and E were added to the medium, they caused generation of additional HDL with cellular phospholipid. It is interesting that this additional part was very poor in cholesterol except for the generation of relatively cholesterol-rich HDL only in the initial few hours of the incubation. The mobilization of intracellular cholesterol for this reaction was also very limited, reflecting the poor cholesterol incorporation into the HDL. Thus, the results demonstrated a unique profile of HDL generation and cholesterol efflux by apolipoproteins in rat astrocytes, with endogenous apoE producing cholesterol-rich HDL and exogenous apolipoproteins producing cholesterol-poor HDL. These lipoproteins may play differential roles in cholesterol transport in the CNS.

Animals↗
PubMed1999

Hearing ability by telephone of patients with cochlear implants.

We investigated the telephone communication ability of patients with cochlear implants who could understand conversations in natural voice without difficulty. The hearing ability of those patients with telephone adapters, which usually are used to reduce noise level in the telephone and to record into a tape recorder, was also investigated. Vowel-confusion, consonant-confusion, and speech-tracking test results of patients listening to voices by telephone and by telephone adapter were compared with those of patients listening to natural, nontelephone voices. The average score of the speech-tracking test with natural voice was 111.5 phrases per 5 minutes. This score dropped to 62.4 by telephone. However, with a telephone adapter, the score of the speech-tracking test was 109.3 phrases per 5 minutes. This was almost the same score as that of the natural voice. So, generally speaking, the telephone communication ability of cochlear implant patients was not good enough. However, hearing ability with a telephone adapter came close to hearing ability during natural speech.

Cochlear Implants↗
PubMed1999

Regeneration of the central auditory pathway in adult rats.

Regeneration of the auditory pathway in the central nervous system, which has not been reported previously, was investigated in adult rats. The ventral cochlear tract (VCT) in the medulla oblongata of adult rats was completely transected unilaterally by a ventral approach through an opening in the basioccipital bone. After postoperative intervals of 1 day to 3 months, the cochlear tract was examined by an anterograde tracing method using wheat germ aggulutinin-conjugated horseradish peroxidase (WGA-HRP) injected unilaterally in the ventral cochlear nucleus (VCN) ipsilateral to the lesion. In this simple transection experiment no regeneration was observed. However, when embryo brainstem tissue was transplanted on the transected site, regeneration occurred in about 30% of the rats examined. These results indicate the occurrence of obvious regeneration in the central auditory pathway, which was previously thought not to be restored once damaged, and they raise hope for future treatment of humans.

Animals↗
PubMed1999

mRNA expression of complement components and regulators in rat arterial smooth muscle cells.

The presence of C5b-9 complexes, some complement regulators, and abundant cytokines in atherosclerotic lesions has been reported. However, it is unclear whether these complement-associated proteins are produced by vascular smooth muscle cells (SMCs) and how they are influenced by the cytokines. In the present study, we demonstrated, by the reverse transcription-polymerase chain reaction method, the mRNA expression of complement components (C3, C4, and C5) and membrane regulators (decay-accelerating factor, membrane cofactor protein, Crry, and CD59) in cultured SMCs derived from the rat carotid artery. The expression of C9 mRNA was also induced upon stimulation by interferon-gamma (IFN-gamma), tumor necrosis factor-alpha (TNF-alpha) and/or lipopolysaccharide (LPS). Northern blot analysis showed that the mRNA expression of C3, C4, DAF and Crry was up-regulated, but that of CD59 was down-regulated by IFN-gamma, TNF-alpha and/or LPS alone or by synergy. The increase of C3 mRNA by TNF-alpha or LPS and that of C4 mRNA by IFN-gamma was induced in a dose-dependent manner. The results indicate that the arterial SMCs of rat have the ability to produce complement components and regulators, which is affected by cytokines and/or LPS. Since atherosclerosis is characterized by the intimal proliferation of SMCs, the complement system including its regulators may be involved in the pathogenesis of the disease.

Animals↗