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Biomedical subjects

T Yagi

Publications and source records attributed to T Yagi.

At least 325 records · Page 18Linked to original sources
PubMed1996

Impairment of suckling response, trigeminal neuronal pattern formation, and hippocampal LTD in NMDA receptor epsilon 2 subunit mutant mice.

Multiple epsilon subunits are major determinants of the NMDA receptor channel diversity. Based on their functional properties in vitro and distributions, we have proposed that the epsilon 1 and epsilon 2 subunits play a role in synaptic plasticity. To investigate the physiological significance of the NMDA receptor channel diversity, we generated mutant mice defective in the epsilon 2 subunit. These mice showed no suckling response and died shortly after birth but could survive by hand feeding. The mutation hindered the formation of the whisker-related neuronal barrelette structure and the clustering of primary sensory afferent terminals in the brainstem trigeminal nucleus. In the hippocampus of the mutant mice, synaptic NMDA responses and longterm depression were abolished. These results suggest that the epsilon 2 subunit plays an essential role in both neuronal pattern formation and synaptic plasticity.

Animals↗
PubMed1996

Involvement of Fyn tyrosine kinase in progression of cytokinesis of B lymphocyte progenitor.

We analyzed the role of Fyn tyrosine kinase in cell cycle progression of B lymphocyte progenitor (pro B cell). Whereas there were no substantial defects in the intramarrow B cell genesis in the fyn(-) mouse, and long-term proliferation of fyn(-) pro B cells was maintained in vitro under a serum containing culture condition, the cell cycle was arrested at G2/M upon serum deprivation. Morphological analyses demonstrated that the cytokinesis of fyn(-) pro B cells was retarded in the presence of serum and that the entry of fyn(-) pro B cells into late telophase was completely blocked under the serum-free condition. In contrast, the earlier phases of mitosis of fyn(-) pro B cells proceeded normally without FCS. This failure to initiate late telophase resulted in the accumulation of elliptical binucleated cells that might be the outcome of the nuclear division without cytokinesis. Consistent with this defect in the progression of cytokinesis, Fyn was localized in the midspace of dividing pro B cells at anaphase. These results suggested that Fyn localizes at the midspace of dividing pro B cells and regulates the progression of cytokinesis.

Animals↗
PubMed1996

Sites and types of UV-induced mutations leading to inactivation of the growth-arresting activity in p21 (sdi1/cip1/waf1) cDNA.

The p53-regulated gene product p21 (sdi1,cip1,waf1) negatively regulates cell growth and has been suggested to be a potential tumour-suppressor gene. To determine the sites and types of mutations which inactivate the growth-arresting activity in sdi1 cDNA, plasmids containing sdi1 cDNA and the neomycin-resistant gene were irradiated with UV light and transfected into CHO cells. The UV irradiation increased number of the geneticin-resistant colonies which should have the UV-mutated sdi1 cDNA. Sdi1 mRNA was expressed in 23 out of 36 colonies (64%). In 13 sdi1 cDNA sequences analysed, mutations were found at codon 46 in nine cDNAs, and one each at codons 34, 54, 66 and 73. All the mutation sites are in the CDK-binding region. Ten mutations (77%) (codons 46 and 66) are C to T transition mutation at the dipyrimidine sequences, which is the major type of the UV-induced mutation.

Animals↗
PubMed1996

Effect of intraatrial reentry on initiation of atrioventricular reentrant tachycardia.

We studied the effect of intraatrial reentry (IAR) on initiation of orthodromic reentrant tachycardia (ORT) in 150 patients with Wolff-Parkinson-White syndrome using His-bundle recording and the atrial extrastimulus technique. IAR was initiated by premature atrial stimulation in 44 patients (29%), and it was followed by ORT in 16 patients (11%). In 8 patients (5%), IAR promoted the initiation of ORT, whereas in 5 patients (3%), IAR inhibited the initiation of ORT. These findings suggest that ORT is frequently induced following IAR. IAR, which was frequently observed during electrophysiological studies, seems to play an important role in the initiation of ORT.

Adult↗
PubMed1996

Active transport activities of free B-6 vitamers in various yeast strains.

Active transport activities of free B-6 vitamers in 35 strains of 8 genera of yeast were measured by isocratic reverse-phase HPLC. Many but not all strains transported pyridoxamine and/or pyridoxine. The active transport activities in some yeast strains tested were completely inhibited by amiloride (0.5 mM). In contrast to cells so far studied, yeast cells showed a novel character in metabolism of accumulated B-6 vitamers: the phosphorylation of the free B-6 vitamers was regulated at a low level. There was no apparent correlation between the presence of the active transport activity in yeasts and the requirement of vitamin B-6 for their growth.

Amiloride↗
PubMed1996

Three-dimensional analysis of nystagmus induced by neck vibration.

The role of dorsal neck proprioceptive inputs to vestibular compensation was investigated in 11 patients with unilateral vestibular dysfunction. Subjects had neither spontaneous nystagmus nor disequilibrium, indicating that they were well compensated. Vibratory stimulation to the dorsal neck produced marked nystagmus. All subjects showed horizontal component directed towards the contralateral side of the lesion. Vertical and torsional components of the nystagmus were exhibited by 10 and 7 subjects, respectively. These results indicate that the neck vibration caused a discompensation in vestibularly well compensated subjects after unilateral dysfunction. In addition, the influence of neck afferent on the vestibulo-ocular reflex pathways, not only of the horizontal, but also the vertical systems, is discussed.

Eye Movements↗
PubMed1996

[Evaluation of left ventricular volume and ejection fraction using three-dimensional transesophageal echocardiography].

Left ventricular (LV) volume and ejection fraction (EF) derived from three-dimensional echocardiography using a multiplane transesophageal probe (3D-TEE) were compared with LV volume and EF obtained from left ventriculography (LVG) in 14 patients (mean age: 61 years). Left ventricular volumes were calculated using a summation of disks algorithm based on multiple reconstructed short-axis cross-sections from 3D data. Left ventricular volume (end-diastole and end-systole) and EF from 3D-TEE were compared with those from LVG using linear regression analysis. Three-dimensional TEE demonstrated excellent correlations with LVG for measuring LV volume (r = 0.97, SEE = 11 ml) and EF (r = 0.95, SEE-4%), respectively. Three-dimensional TEE is useful for the measurement of LV volume and EF in the clinical setting.

Echocardiography, Transesophageal↗
PubMed1996

[A case of abdominal tuberculous lymphadenitis diagnosed by percutaneous needle biopsy under ultrasound control and followed up by ultrasound imaging].

A case of abdominal tuberculous lymphadenitis diagnosed by percutaneous needle biopsy under ultrasound control and followed up by ultrasound imaging was reported. A 63 years-old male was admitted to a certain hospital complaining of dizziness and diplopia. Chest roentgenogram showed bilateral infiltrative shadows in the upper lung fields and Mycobacterium tuberculosis was detected in cultures from specimens of gastric aspiration. Abdominal ultrasound examination and computed tomography showed abdominal lymph nodes swelling. Needle biopsy under ultrasound control was performed, and the specimens showed necrosis and Mycobacterium tuberculosis was positive by culture. He was diagnosed as lung tuberculosis with abdominal tuberculous lymphadenitis and admitted to our hospital for anti-tuberculous chemotherapy. Ultrasound examination done every two weeks showed diminution in size of the lymph nodes after a month of anti-tuberculous therapy. For the diagnosis of abdominal lymph node swelling, a needle biopsy under ultrasound control is safe and useful technique, and a ultrasound examination is also valuable to follow up the course of abdominal tuberculous lymphadenitis.

Abdomen↗
PubMed1996

[The cases of acute spontaneous subdural hematoma].

In this paper, 10 cases of acute spontaneous subdural hematoma (ASSDH) among 149 cases of all acute subdural hematoma (ASDH) were reported with a review of 36 cases in the literature. The age of the patients with ASSDH ranged from 48 to 90 years (mean age of 71.9 years), and the average age of ASDH patients was 52.4 years. The male to female ratio of ASSDH and ASDH was 3:7 and 5:2, respectively. ASSDH patients were older than ASDH patients, and ASSDH patient tended to be female. Four cases of ASSDH patients had the past history of dementia. The outcome of 5 cases of ASSDH with general complications was fatal. During operation in all cases except one, spurting arterial rupture from a branch of the cortical artery adjacent to the Sylvian fissure was observed. It was presumed in the literature that the mechanism of the arterial rupture is gliding movement of the brain, tearing an arterial twig with dural attachment, or the existence of the junction of an arterial twig as an anatomically weak point. Hypertension, alcoholism, dementia, past history of subdural hematoma or subarachnoid hemorrhage may be important influencing factors in this mechanism.

Acute Disease↗
PubMed1996

Pseudoaneurysm and ventricular septal rupture complicated with inferior myocardial infarction diagnosed by two-dimensional and Doppler echocardiography: case report.

A 72-year-old woman with inferior myocardial infarction presented with both a pseudoaneurysm and a ventricular septal rupture detected by two-dimensional and Doppler echocardiography. The pseudoaneurysm originated from the junctional area between the inferior portion of the ventricular septum and posterior left ventricular wall. The short-axis view of two-dimensional echocardiography revealed an abrupt discontinuity of the junctional area and an echo-free space behind the left ventricular cavity. The communication orifice was 5 mm wide. Color Doppler echocardiography showed a left-to-right shunt flow from the pseudoaneurysm to the right ventricle was visualized. Combined use of two-dimensional and color Doppler echocardiography was useful for detecting a pseudoaneurysm resulting in rupture of the ventricular septum.

Aged↗
PubMed1996

[Automatic assessment of left ventricular cavity area by the automated contour tracking method].

Measurements of left ventricular cavity area by the manual tracing method from apical four-chamber views were compared with those using the automated contour tracking (ACT) method. Nine consecutive patients in whom clear images were obtained by two-dimensional echocardiography were studied, and left ventricular end-diastolic, end-systolic areas an fractional area changes were calculated using the ACT method. The ACT method slightly underestimated left ventricular cavity areas, but excellent correlations were obtained with left ventricular end-diastolic and end-systolic areas between the ACT and manual methods (r = 0.99, SEE = 1.5 cm2; r = 0.99, SEE = 1.2 cm2; respectively). Manual tracing fractional area change correlated well with that by the ACT method (r = 0.95, SEE = 3.4%). The ACT method provides accurate estimates of the area of the left ventricular cavity.

Cardiac Volume↗