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Biomedical subjects

J Ito

Publications and source records attributed to J Ito.

At least 217 records · Page 12Linked to original sources
PubMed1991

The influence of middle ear pressure on the lateral vestibulospinal tract neurons in cats.

The influence of changes in middle ear pressure on the lateral vestibulospinal tract (LVST) neurons was investigated in anesthetized cats. The activities of some LVST neurons increased with negative pressure and decreased with positive pressure. This tendency was stronger when pressure changes were applied to the contralateral middle ear than to the ipsilateral side. The influence of changes in middle ear pressure on LVST neurons was opposite to that on the vestibular nerve, suggesting the existence of inhibitory inter- and commissural neurons.

Animals↗
PubMed1991

The prevalence of anti-HCV antibodies in hemodialysis patients.

The prevalence of antibodies to hepatitis C virus (anti-HCV) was assessed in 489 hemodialysis patients and 152 members of the staff of dialysis units, using an Ortho HCV Ab ELISA Test. Of the 489 patients, 100 (20.4%) had anti-HCV, a significantly greater rate than was found in either staff members (0.7%, P less than 0.01) or local healthy blood donors (1.1%, P less than 0.001). Anti-HCV positivity was apparently related to the duration of hemodialysis.

Adult↗
PubMed1991

Deoxyspergualin in lethal murine graft-versus-host disease.

The beneficial effect of deoxyspergualin (DSG, NKT-01) on lethal graft-versus-host disease in mice has been studied in a major histoincompatible donor-recipient combination. Suppression of the effector mechanisms responsible for the lethal outcome in this GVHD model is also noted. This study reveals: (1) DSG has a marked potential for treatment of lethal GVHD; (2) DSG and methotrexate in combination yield longer survival times than DSG or MTX alone; (3) long-term survivors, following DSG treatment, become stable chimeras as evidenced by cell-surface analysis of spleen cells; and (4) high activity of H-2-reactive cytotoxic T lymphocytes is detected in spleens of the mice with lethal GVHD, whereas natural killer activity is only slightly increased. DSG inhibits CTL activity not only in the induction stage but also in the advanced stage of the disease. These findings indicate that DSG might be beneficial in clinical bone marrow transplantation either alone or in combination with MTX.

Animals↗
PubMed1991

Responses and anatomical connections of peripheral vestibular neurons innervating otolith organs.

The response patterns of the Scarpa's neurons and lateral vestibular nucleus (LVN) neurons that respond to lateral and antero-posterior tilting were investigated using cats. The following observations were made: 1) The Scarpa's neurons that respond to lateral tilting have directional sensitivity physiologically and may innervate the utricular macula; 2) The LVN neurons that respond to lateral tilting are found mostly in the ventral part of the LVN and also have directional sensitivity. They project toward the spinal cord into the lateral vestibulo-spinal tract.

Acoustic Maculae↗
PubMed1991

[Auditory event-related potentials (ERPs) in healthy subjects and patients with dementia].

To study the effects of aging and gender differences of ERP components, auditory ERPs were recorded in 106 healthy subjects. Forty-three patients with dementia of the Alzheimer type and 24 patients with vascular dementia were also studied. In healthy subjects, there was a significant positive linear correlation between P300 latency and age, with P300 latency increasing at the rate of 1.5 msec/year. Neither N100 nor P200 component was correlated with age. The amplitudes of N100, P200 and P300 components in females were slightly larger than those in males, but the differences were not significant. Not only P300 latencies but also P200 latencies were significantly different in healthy subjects, patients with dementia of the Alzheimer type and those with vascular dementia. In 74.4% of patients with dementia of the Alzheimer type and 62.5% of those with vascular dementia, the P300 latency was over 2 SE above the age-estimated regression line. The difference of the P300 latency prolongation may have resulted from the severity of dementia but not from the etiology of dementia.

Adult↗
PubMed1990

[The MR findings on the corpus callosum of normal young volunteers].

The size and shape of the corpus callosum of twenty-seven normal young volunteers (age 18-31 years, 17 men and 10 women) were investigated using a superconducting high field (1.5 T) MRI unit. The length of the corpus callosum was 71.1 +/- 5.1 mm (mean +/- S.D.) and the height was 24.9 +/- 2.1 mm. The length ratio of the corpus callosum to the brain was 43.9 +/- 2.3% with the ratio of the height 25.0 +/- 2.3%. The callosal index (height/length) was 35.4 +/- 2.9%. The area of the corpus callosum in the midsagittal plane was 681.4 +/- 93.6 mm2 (min. 563 mm2 to max. 902 mm2). We divided the corpus callosum into three segments: rostrum and genu; anterior and posterior trunks; splenium. Each part accounts for one third of the total area of the corpus callosum. The genu and splenium were generally equal in thickness. The minimal thickness of the trunk was 3 mm with the maximal one 9 mm. The posterior trunk was never thicker than the anterior one. The posterior part of the posterior trunk showed thinning and concavity in almost all cases. So-called impressio corporis callosi was observed in 12 cases (44.4%). Thirteen cases (48.1%) showed a shallow concave configuration at the anterior dorsal surface of the corpus callosum. Six cases of these were thought to be due to compression by the pericallosal artery. This finding was not detected in the posterior portion of the corpus callosum. This concavity was also seen in infants. The thinning of the posterior part of the posterior trunk was seen after the development of the splenium, but the concave configuration at the anterior dorsal surface of the corpus callosum may be encountered before the full development of the genu and splenium.

Adult↗
PubMed1990

Site-specific mutagenesis of PRD1 DNA polymerase: mutations in highly conserved regions of the family B DNA polymerase.

The PRD1 DNA polymerase is a small multifunctional enzyme containing three major conserved amino acid sequences shared by family B DNA polymerases. Thus, the PRD1 DNA polymerase provides an useful model system with which to study structure-function relationships of DNA polymerase molecules. In order to investigate the functional and structural roles of the highly conserved amino acid sequences, we have introduced mutations into each of the 3 conserved regions of the PRD1 DNA polymerase. Genetic complementation study as well as DNA polymerase assay indicated that each mutation inactivated DNA polymerase catalytic activity, but not the 3' to 5' exonuclease activity.

Amino Acid Sequence↗
PubMed1990

Positron emission tomographic study of auditory sensation in a patient with a cochlear implant.

The speech comprehension ability of patients with a cochlear implant is fairly good even when information from the implant device is insufficient. It is presumed that the higher brain system has important roles in discriminating speech. The purpose of the present study was to investigate the function of the auditory cortices of a patient with a cochlear implant before and after sound signal inputs. In this study, we used positron emission computed tomography, which can detect brain activity by providing quantitative measurements of the metabolic rates of oxygen and glucose. Without sound signals, the auditory cortices of the patient showed remarkably low metabolic rates. However, with the cochlear implant device, the activity returned to near normal levels. These findings suggest that the activation of the speech comprehension mechanism of the higher brain system can be initiated by sound signals from the implant device.

Acoustic Stimulation↗
PubMed1990

The influence of caloric stimulation on the otolith organs in the cat.

The influence of caloric stimulation on the otolith organs was investigated in cats by recording the firing rate of the single vestibular nerve fiber originating from each otolith organ. Sixty-six percent of the vestibular nerve fibers originating from the otolith organs responded to the caloric stimulation. The caloric nystagmus occurred not only by the activities of the semicircular canal system but also by those of the otolith system.

Action Potentials↗
PubMed1990

Autoradiographic study of tissue distribution of [3H]ubenimex in IMC carcinoma-bearing mice.

[3H]Ubenimex was administered to IMC carcinoma-bearing mice, and the tissue distribution of the radioactivity was examined at various times after drug injection by autoradiography of glutaraldehyde-fixed tissues. Silver grains were concentrated on some of the macrophages present around the solid tumor and in thymic medulla, splenic red pulp, and mesenteric lymph node medulla. The grains were also seen at a similar concentration on some nurse cell-like cells in the thymic cortex and on some reticular cells in splenic red pulp. In the liver, grains were concentrated on the hepatocytes and bile duct epithelium. The grains were most densely concentrated on kidney proximal straight tubules, in which strong leucine aminopeptidase activity was also observed.

Animals↗
PubMed1990

An essential arginine residue for initiation of protein-primed DNA replication.

A group of proteins that act as primers for initiation of linear DNA replication are called DNA-terminal proteins (terminal proteins). We have found a short stretch of conserved amino acid sequence among the terminal proteins from six different sources. The location of this sequence motif is also similar among the different terminal-proteins. To determine the functional role of this terminal-protein domain in DNA replication, we have studied the bacteriophage PRD1 system. The PRD1 terminal protein and DNA polymerase genes were cloned into expression vectors, and the recombinant plasmids were used for constructing PRD1 terminal protein mutants. Site-directed mutagenesis and functional analysis showed that one of the two arginines (Arg-174) in the conserved sequence is critical for the initiation complex-forming activity of the PRD1 terminal protein. Replacement of Arg-174 by noncharged amino acids resulted in nonfunctional terminal protein. Phenylglyoxal, an alpha-dicarbonyl compound that reacts with the guanidino group of arginine, inhibits initiation complex formation between PRD1 terminal protein and dGMP. On the basis of these results, we propose that Arg-174 represents, at least in part, the binding site for phosphate groups of dGTP.

Amino Acid Sequence↗
PubMed1990

HLA class II (DR, DQ) in Japanese patients with type 1 diabetes mellitus.

DNA restriction fragment length polymorphism (RFLP) typing of HLA-DR and DQ alleles of 60 Japanese type 1 (insulin dependent) diabetic patients and 115 controls was performed. RFLP typing of DRB1 showed increased frequency of DR9 and decreased frequencies of DR2 and DRW6 among patients compared to controls. In the RFLP typing of BamHI-digested DNA to DQ beta probe (BamHI-DQB1), the incidence of the 10.26 kb fragment, which represents either DQW4, DQW8 or DQW9, was markedly elevated in the patients, whereas the incidence of DQW6 was reduced. The predicted DR-DQ haplotype study revealed that DR4-DQW4 or DQW8, DRW8-DQW4 or DQW8 and DR9-DQW9 may contribute to susceptibility to type 1 diabetes. When serological typing of the 13 DRW8 patients was performed, all the 11 DRW8 patients carrying DQW4 or DQW8 (BamHI-10.26 kb) were positive for DQW3. These results indicated that the HLA-DQ locus may play an important role in the development of type 1 diabetes in the Japanese as well as other ethnic groups and that the DRW8-DQW8 haplotype may predispose to the disease in Japan.

Alleles↗
PubMed1990

Clinical usefulness of urinary growth hormone measurement in short children.

Growth hormone (GH) levels in nocturnal urine were measured in 96 short children and 73 children of normal height in order to investigate whether urinary GH levels reflect spontaneous GH secretion and whether they might be used to screen short children for GH treatment. GH levels in 24-hour urine samples were significantly correlated with urinary albumin and beta 2-microglobulin levels in normal children, demonstrating an influence of renal function on urinary GH measurements. Nocturnal urinary GH levels showed significant positive correlations with mean serum GH levels during 3 hours of sleep (r = 0.26, p less than 0.05) and plasma insulin-like growth factor I (IGF-I) levels, reflecting physiological GH secretion. Urinary GH levels were significantly lower in the eight children with complete GH deficiency (3.1 +/- 2.3 ng/g creatinine) than in the normal children (13.8 +/- 11.2 ng/g creatinine). Urinary GH levels in three other groups of short children, partial GH deficiency (11.1 +/- 16.9 ng/g creatinine), impaired GH secretion during sleep (10.4 +/- 12.6 ng/g creatinine) and non-endocrine short stature (18.8 +/- 19.5 ng/g creatinine), were not significantly different from those in the normal children. However, when the cut-off point for defining GH insufficiency was set at 5 ng/g creatinine, 87.5% (21 out of 24) of the short children with low urinary GH levels were suitable subjects for GH treatment (i.e. had complete GH deficiency, partial GH deficiency or impaired GH secretion during sleep).(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1990

Nucleotide sequence and transcription of the right early region of bacteriophage PRD1.

We have sequenced the rightmost 1,700 base pairs of bacteriophage PRD1. This region encompasses the right early region and completes the sequence of all PRD1 early functions. We have also mapped the 5' initiation site of right early transcripts in vivo and in vitro. This has allowed us to assign gene XII to an open reading frame and suggests that another open reading frame may also be expressed. Gene XII, which has been implicated in the replication process and the regulation of gene expression, is predicted to encode a protein with a molecular mass of 16.7 kilodaltons. Data base searches have revealed no significant homology between the product of this gene and other proteins. Transcription mapping studies have revealed that right early transcripts elongate from right to left and have enabled us to identify the right early promoter. This promoter behaves identically in vivo and in vitro. We also demonstrate that this promoter directs the transcription of two RNAs of different sizes in vitro.

Amino Acid Sequence↗
PubMed1990

The trigeminal sensory innervation to the middle ear, eustachian tube, and pharynx: a study by the horseradish peroxidase tracer method.

The trigeminal sensory innervations to the middle ear, the eustachian tube, and the pharynx were examined using the horseradish peroxidase (HRP) method in cats. After HRP application to the middle ear and the eustachian tube, HRP-labeled cells were found mainly in the posterolateral portion and the anteromedial portion of the trigeminal ganglion, respectively. In the case of injection into the epipharynx and the mesopharynx, HRP-labeled cells were found in the anteromedial portion and the posterolateral portion, respectively. HRP-labeled cells were hardly observed when HRP was applied to the hypopharynx. These results indicate that trigeminal nerve sensory fibers branch to the middle ear, including the eustachian tube, epipharynx, and mesopharynx.

Animals↗
PubMed1990

Acute megakaryoblastic leukemia in Down syndrome, following thrombocytopenia with antiplatelet antibody.

We report a case of acute megakaryoblastic leukemia (AMKL) with antiplatelet antibody in a boy with Down syndrome. When the patient was admitted, his platelet count was 1.3 X 10(4)/mm3 and antiplatelet antibody in the plasma was detected. Two months after admission, blasts, which showed positive reaction to both antiplatelet monoclonal antibody and platelet peroxidase, increased.

Autoantibodies↗
PubMed1990

[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.

Adult↗