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Biomedical subjects

J Ito

Publications and source records attributed to J Ito.

At least 19 recordsLinked to original sources
PubMed1995

Localization of trigeminal sensory innervation to the tongue and pharynx of the cat using horseradish peroxidase as tracer.

Trigeminal sensory innervation to the tongue and pharynx was investigated in the cat, using horseradish peroxidase (HRP) as a retrograde tracer. Following HRP application to the tongue, cells were labeled primarily in the posterolateral portion of the trigeminal ganglion. The pharynx was divided according to classical methodology into three regions: the epipharynx (nasopharynx), mesopharynx (oropharynx), and hypopharynx. When HRP was applied to the epipharynx and mesopharynx, HRP-labeled cells were found in the anteromedial and posterolateral portions of the trigeminal nerve, respectively. When HRP was applied to the hypopharynx, a single labeled cell was found in the trigeminal ganglion. These results indicate that trigeminal sensory nerve fibers in the cat branch to the tongue, epipharynx, and mesopharynx, but rarely to the hypopharynx.

Animals↗
PubMed1995

Rapid and gentle extraction, reconstitution and characterization of microfilament and glia filament from rat astrocytes.

We developed gentle and rapid methods for depolymerization and extraction of both microfilament and glia filament separately from a crude cytoskeletal fraction of rat astrocytes. Electron microscopy revealed that the filament reconstituted from the microfilament extract closely resembled F-actin that was formed from G-actin of rabbit skeletal muscle. It was found by immunoblotting analysis that even the reconstituted microfilament-like filaments, which had been purified by affinity chromatography with heavy meromyosin subfragment 1 (S1)-conjugated Sepharose, contained vimentin and glia fibrillary acidic protein (GFAP) besides actin, inferring the interaction between microfilament and glia filament. The filaments (9-10 nm thick) reconstituted from the glia filament extract were composed of actin and other minor components in addition to vimentin and GFAP. Actin, GFAP, 101, 34, 32.5, 30.5, 29.5 and 28 kDa proteins found in the reconstituted glia filament-like filaments were suggested to be glia filament-associated proteins.

Actin Cytoskeleton↗
PubMed1995

Effect of cholera toxin and pertussis toxin on the growth of A431 cells: kinetics of cyclic AMP and inositol trisphosphate in toxin-treated cells.

Cholera toxin and pertussis toxin were inhibitory to the incorporation of thymidine into A431 cells in serum-free culture. Cholera toxin enhanced the growth inhibitory effect of epidermal growth factor (EGF) on A431 cells, whereas pertussis toxin attenuated the effect. Cholera toxin increased the concentration of intracellular cyclic AMP (cAMP) to three-times the initial concentration at 120 minutes and it increased the concentration of intracellular inositol trisphosphate (IP3) rapidly but transiently. Pertussis toxin reduced the concentration of IP3 both in EGF treated and untreated A431 cells at 10 minutes. cAMP was not involved in pertussis toxin-mediated effects. In conclusion, the intracellular cAMP and IP3 concentrations in CT-treated A431 cells are compatible with previous reports regarding the growth inhibitory effects on A431 cells. The inhibitory effect of PTX on the EGF-induced increase of intracellular IP3 is thought to be compatible with the finding that PTX attenuated the EGF-induced growth inhibition.

Carcinoma, Squamous Cell↗
PubMed1995

In vitro and in vivo effects of somatostatin on the growth of A431 cells.

We previously reported that the octapeptide somatostatin (SS) analogue SMS 201-995 (SMS) unexpectedly stimulates the growth of A431 human epidermoid carcinoma cells in vitro. In the present study, we found that both SS-14 and SS-28 also stimulated the growth of A431 cells in vitro. The proliferative effect of SS-28 also stimulated the growth of A431 cells in vitro. The proliferative effect of SS-28 was greater than that of SS-14. In contrast, there was no difference in A431 cell tumor weight or area between the SMS-treated or untreated athymic, tumor-bearing mice. The serum epidermal growth factor (EGF) level of the SMS-treated mice was significantly lower than that of the untreated mice. Decreases in serum EGF may attenuate the proliferative effect of SMS in vivo.

Animals↗
PubMed1995

An early onset of hereditary progressive dystonia with marked diurnal fluctuation: determining clinical status using gait analysis.

We report on a 5 year old girl who has hereditary progressive dystonia with marked diurnal fluctuation that improved remarkably after treatment with L-dopa. A gait analysis of the patient was done and we compared her gait patterns with those of a normal child. The following results were obtained. Before L-dopa treatment: (i) knee extension time was prolonged with genu recurvatum; (ii) the flexors and the extensors were simultaneously activated in the stance phase, and reciprocity between them was impaired; and (iii) recorded sole contact was a toe-only pattern. After L-dopa treatment: (i) the step cycle was shorter mainly due to a shorter knee extension time; (ii) genu recurvatum improved; (iii) reciprocal activities of the flexors and the extensors were observed; and (iv) a normal sole contact pattern was also observed. The data from the gait analysis were useful in stabilizing the subject's clinical condition and in evaluating changes to it.

Age of Onset↗
PubMed1995

Studies of currently used and experimental cochlear implants.

Since 1987 we have inserted multichannel cochlear implants in 60 patients with severe hearing impairment. The surgical procedures were not very difficult, and few postoperative complications were encountered. Postoperative speech recognition by every patients was satisfactory. Nevertheless, some patients complained about their hearing in a noisy environment, or while listening to either TV or music. Consequently, cochlear implants needs further improvement. To improve speech recognition ability, a newly developed experimental system was constructed. Judging from the electrode activation pattern, the new system extracted the features of consonants more successfully than the present system. However, when this new system was installed in cochlear implant patients, no significant improvement in consonant recognition was obtained.

Adult↗
PubMed1995

Expression and activity-dependent changes of a novel limbic-serine protease gene in the hippocampus.

A novel murine cDNA which encodes a protein designated neuropsin was cloned. Northern and in situ hybridization analyses demonstrated that neuropsin mRNA is expressed specifically in the limbic system of mouse brain and is localized at highest concentration in pyramidal neurons of the hippocampal CA1-3 subfields. Direct hippocampal stimulation and kindling induced by amygdaloid stimulation caused a significant bilateral change in neuropsin mRNA level in the hippocampal pyramidal neurons. The activity-dependent changes and the specific localization indicate that neuropsin is involved in hippocampal plasticity.

Amino Acid Sequence↗
PubMed1995

Results with the currently used cochlear implant.

Over the past 7 years we have implanted the Nucleus multichannel cochlear implant in 60 patients with severe hearing impairment. The postoperative speech recognition of adult postlingually deaf patients was satisfactory. Adult prelingually deaf patients exhibited poorer speech perception than postlingually deaf patients. However, some patients showed better results than expected. The prelingually deaf patients needed a longer rehabilitation period than the postlingually deaf patients. There was considerable variation in performance among the prelingually deaf patients. As for juvenile deaf patients, some showed good speech perception ability, but postoperative rehabilitation took longer. The cooperation of doctors, audiologists, speech therapists, schoolteachers, and family members was essential, and the creation of a cochlear implant center for children is desirable to obtain better rehabilitation. On the questionnaire given to the cochlear implant patients, some complained about their hearing in a noisy environment or while listening to television or music. The present cochlear implant system obviously needs further improvement.

Adolescent↗
PubMed1995

Surgical difficulties and postoperative problems associated with cochlear implants.

Since 1987 we have implanted 60 severely hearing-impaired adults with the Nucleus Minisystem-22 cochlear implant. In most cases, the surgical procedures were performed with satisfactory results and very few postoperative problems. The complications associated with cochlear implant surgery include difficulty in drilling the ossified cochlea, electrode displacement, and insufficient insertion of the electrode. Postoperative problems include dizziness, tinnitus, facial nerve spasm, receiver-stimulator migration or extrusion, infection of the scalp flap, and facial nerve palsy. In most cases, these complaints did not develop into serious conditions.

Adult↗
PubMed1995

[Removal of infected pacemaker leads in the elderly under extracorporeal circulation: two case reports and review of Japanese literature].

Two elder cases in whom infected pacemaker leads were removed under extracorporeal circulation (ECC) are reported. The leads could not be with drawn without direct sharp dissection under ECC because they had become firmly encased with fibrous tissue within the right ventricle. Postoperative courses were uneventful and neither of these patients has experienced recurrent infection to date. Removal with ECC seems to be a safe and effective procedure even in the elderly, provided that cardiac function is good.

Age Factors↗
PubMed1994

Family A and family B DNA polymerases are structurally related: evolutionary implications.

In order to establish the evolutionary relationship between the family A and B DNA polymerases, we have closely compared the 3'-->5' exonuclease domains between the Klenow fragment of E.coli DNA polymerase I (a family A DNA polymerase) and the bacteriophage PRD1 DNA polymerase, the smallest member of the DNA polymerase family B. Although the PRD1 DNA polymerase has a smaller 3'-->5' exonuclease domain, its active sites appear to be very similar to those of the Klenow fragment. Site-directed mutagenesis studies revealed that the residues important for the 3'-->5' exonuclease activity, particularly metal binding ligands for the Klenow fragment, are all conserved in the PRD1 DNA polymerase as well. The metal binding ligands are also essential for the strand-displacement activity of the PRD1 DNA polymerase. Based on these results and the studies by others in various systems, we conclude that family A and B DNA polymerases, at least in the 3'-->5' exonuclease domain, are structurally as well as evolutionarily related.

Amino Acid Sequence↗
PubMed1994

Mutagenesis of a highly conserved lysine 340 of the PRD1 DNA polymerase.

All known family B DNA polymerases contain a conserved region of amino acids, KX6-7YG, which appears to be correspond to the 'finger' alpha helix O of the Klenow fragment of E. coli DNA polymerase I, a family A DNA polymerase. Toward the goal of establishing the evolutionary relationship between the family A and B DNA polymerases, we have employed site-directed mutagenesis to access the functional role of the invariant amino acid lysine-340 of the PRD1 DNA polymerase. We have replaced the lysine-340 with three amino acids: histidine, asparagine and glutamic acid, respectively. Mutant DNA polymerases were overexpressed and purified to near homogeneity. Our results showed that the modification of the lysine-340 of the PRD1 DNA polymerase abolishes the polymerase activity without affecting the 3' to 5' exonuclease activity. These results support the proposal that the KX6-7YG motif of the family B DNA polymerases may be analogous to the KX7YG motif of the family A DNA polymerases, suggesting that two family DNA polymerases share a common ancestor.

Amino Acid Sequence↗
PubMed1994

Purification and characterization of PRD1 DNA polymerase.

A small lipid-containing bacteriophage PRD1 encodes a DNA polymerase that utilizes a protein primer for the initiation of DNA replication. The purification of the PRD1 DNA polymerase has been hampered by the insolubility of the overexpressed enzyme in Escherichia coli cells. We have developed a simple and rapid procedure for purification of the overexpressed PRD1 DNA polymerase. This method is based on guanidine hydrochloride denaturation and renaturation of the insoluble PRD1 DNA polymerase overexpressed in E. coli containing the recombinant plasmid pEJG. The purified DNA polymerase was extensively characterized and found to be indistinguishable from the normal soluble PRD1 DNA polymerase as judged by enzymatic properties. These properties include: protein-primed initiation of PRD1 DNA replication, strand-displacement DNA synthesis, DNA polymerase processivity, 3' to 5' exonuclease activity and filling-in repair type DNA synthesis. Furthermore, the kinetic parameters determined for dNTPs and primer-terminus were of the same order of magnitude. The availability of a simple purification procedure for the PRD1 DNA polymerase should permit detailed structure-function analysis of this enzyme.

Cloning, Molecular↗
PubMed1994

Effect of caloric stimulation on primary vestibular fibers originating from otolith organs in the guinea pig.

The influence of caloric stimulation on the primary vestibular fibers originating from the otolith organ was investigated in the guinea pig. Firing rates were recorded from single vestibular neurons in the superior vestibular (Scarpa's) ganglion which were identified physiologically as originating from the otolith organs, mainly from the utricles. Eighty-six percent of the neurons responded to caloric stimulation. Neurons with a high coefficient of variation of firing regularity reacted more sensitively to tilting and also had a tendency to react more sensitively to caloric stimulation. There was a tendency for neurons with increased firing rates in response to ipsilateral tilting to have increased firing rates to warm stimulation, while neurons whose rates increased to contralateral tilting had increased firing rates to cold stimulation. These results indicate that the otolith organs have the same unidirectional tendency to caloric simulation with results comparable to optimal tilting directions.

Action Potentials↗
PubMed1994

Determination of the origin of autonomic nerves of the tongue using horseradish peroxidase as tracer.

Autonomic innervation of the tongue was investigated in cats using the horseradish peroxidase retrograde tracing method. The tongue was found to be innervated by sympathetic fibers originating in the ipsilateral superior cervical ganglion, but not by those originating in the middle cervical ganglion or stellate ganglion. The tongue was also innervated by fibers originating in the ipsilateral pterygopalatine ganglion, suggesting that this innervation is parasympathetic.

Animals↗