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T Shimazaki

Publications and source records attributed to T Shimazaki.

At least 55 records · Page 3Linked to original sources
PubMed1993

Hybrid cell extinction and re-expression of Oct-3 function correlates with differentiation potential.

The Oct-3 gene is expressed in highly undifferentiated cells and is implicated in mammalian early embryogenesis. We have generated a series of hybrid cells between pluripotent embryonal carcinoma cells (Oct-3+) and fibroblasts (Oct-3-), and have studied the regulation and function of Oct-3. Upon fusion, the hybrid cells differentiated to nestin+/Brn-2+ cells resembling neuroepithelial stem cells. Expression of Oct-3 was extinguished at the transcriptional level in all the hybrid cells examined. The Oct-3 modulating activity required for the Oct-3-mediated enhancer activation was also extinguished. When the Oct-3 transactivating function was introduced into the hybrid cells, they transformed into morphologically distinct nestin-/Brn-2- cells ('revertants'). When the 'revertant' cells subsequently lost Oct-3 expression, they differentiated back to nestin+/Brn-2+ cells. The close correlation between the phenotypic changes and the gain/loss of Oct-3 function indicates that Oct-3 can induce dedifferentiation of the neural cells.

Animals↗
PubMed1993

Murine chromosomal location of four class III POU transcription factors.

A family of mouse genes encoding class III POU transcription factors consists of four members: Oct-6, Brn-2, Brn-1, and Brn-4. In accordance with mouse nomenclature, these loci have been designated Otf-6, Otf-7, Otf-8, and Otf-9, respectively. While the four genes share a highly conserved class III POU domain, the remaining regions are considerably diverged from each other. The POU domains of these transcription factors recognize the octamer-motif sequence and possess a similar DNA-binding specificity. Chromosomal mapping has demonstrated that the four genes are unlinked: Otf-6 is located on the distal region of chromosome 4, Otf-7 on the proximal region of chromosome 4, Otf-8 on chromosome 1, and Otf-9 on the X chromosome.

Animals↗
PubMed1993

12(R)-methyl-leukotriene B3: a stable leukotriene B analogue toward the reductase metabolism.

Biological potencies of 12(R)-methyl-LTB3 [12(R)-Me-LTB3] and 12(S)-Me-LTB3 and their stability toward reductase metabolism are described. 12(R)- and 12(S)-Me-LTB3 of more than 95% chemical purity were synthesized highly stereoselectively via the palladium catalyzed coupling reaction of the vinylborane derived from the enzyme 1 and Sia2BH with the iodide 2 of R and S configuration. To assess biological activity of 12-Me-LTB3, cytosolic free calcium ([Ca2+]i) rise in rat PMNLs and binding affinity to the LTB4 receptors were compared with those of natural LTB4. The potency of 12(R)-Me-LTB3 was found to be almost equal to LTB4, while, by complete contrast, 12(S) isomer showed very low activity of 1/200-1/400. These results indicate that the C(12) hydroxyl group of R configuration is essential to elicit the biological activity and that [Ca2+]i rise elicited by 12-Me-LTB3 is mediated through interaction with the LTB4 receptors. Stability of 12(R)-Me-LTB3 toward the reductase metabolism was evaluated by using rat PMNLs. Thus, rat PMNLs were incubated at 37 degrees C with 12(R)-Me-LTB3 and LTB4, respectively. The amount of 12(R)-Me-LTB3 was almost unchanged up to 30 min under these conditions, though LTB4 was rapidly consumed in a time-dependent manner, thus strongly indicating that 12(R)-Me-LTB3 is not metabolized via the reductase pathway.

Animals↗
PubMed1993

Ganglions and ganglionic neurons in the cat's larynx.

Localization, projections and role of ganglia and ganglionic neurons in the laryngeal framework were demonstrated in cats. Six to 8 large size ganglia containing 50 to 80 ganglionic neurons per ganglion in the paraglottic space, 4 to 6 small ganglia involving 5 to 25 cells in each ganglion dorsal to the posterior cricoarytenoid muscle, and 1 to 3 small ganglia including 15 to 25 perikarya per ganglion around the inferior laryngeal nerve were observed. Each ganglion showed spindle shaped covering fibrous capsule. Ganglionic neurons totaling 600 to 800 were oval shaped with an average diameter of 25 microns. Projections of the ganglionic neurons to the superior cervical ganglion (SCG) and nodose ganglion (NG) through the ipsilateral internal branch of the superior laryngeal nerve and to periphery were detected. From the dorsal motor nucleus of vagus, SCG and NG, the ganglionic cells received projections ipsilaterally. On immunocytochemistry many vasoactive intestinal polypeptide (VIP)-immunoreactive (ir) neurons, some neuropeptide Y (NPY)- and tyrosine hydroxylase (TH)-ir neurons and a few substance P (SP)-ir cells were recognized in ganglions. VIP-, NPY-, TH-, SP-, and calcitonin gene-related peptide (CGRP)-ir fibers were also observed in and around vessels and glands. Following denervation, VIP-, NPY- and TH-ir neurons and fibers did not change. These results prove that laryngeal ganglionic neurons have endogenic autonomic, especially cholinergic nature and innervate vessels and glands.

Animals↗
PubMed1993

[Morphological study of intra-laryngeal ganglia and their neurons in the cat].

The distribution, number, projections and nature of ganglia and ganglionic neurons in the feline larynx were investigated morphologically. Six to eight large oval or spindle-shaped ganglia (including 50-80 ganglionic neurons per ganglion) in rostral portions of the paraglottic spaces, four to six small spindle-shaped ganglions (containing 5-25 ganglionic perikarya in each ganglion) dorsal to the posterior cricoarytenoid muscles and one to three small elliptical ganglia (having 15-25 ganglionic cells in each ganglion) around the inferior laryngeal nerves were observed in the larynx. Each ganglion was covered with a fibrous capsule and ganglionic neurons with a diameter of 25-30 microns totaled 600 to 800. Ganglionic neurons received projections from the dorsal motor nucleus of vagus, the superior cervical ganglion (SCG) and the nodose ganglion (NG) ipsilaterally. On the other hand, ganglionic neurons projected to SCG, NG, ipsilaterally and the laryngeal mucosa bilaterally with ipsilateral predominance. Ganglionic neurons showed acetylcholinesterase positive reactions, presumably parasympathetic. On immunocytochemistry, many vasoactive intestinal polypeptide (VIP)-immunoreactive (ir) neurons, and a few tyrosine hydroxylase (TH)-ir and substance P (SP)-ir cells were recognized in ganglions, but no calcitonin gene-related peptide (CGRP)-ir neurons were found. These VIP, TH, SP-ir neurons did not change after denervation of the ipsilateral superior and recurrent laryngeal nerves. Many VIP- and some TH-, SP-, CGRP-ir fibers were also observed around vessels and glandular cells. The present findings show that intra-laryngeal ganglionic neurons not only have an endogenic cholinergic nature, but are also involved in local sympathetic and sensory nervous systems.

Animals↗
PubMed1993

[A case of hypertrophic obstructive cardiomyopathy using intraoperative trans-esophageal echocardiography].

A 45-year-old man underwent trans-aortic myectomy for hypertrophic obstructive cardiomyopathy (HOCM). Although two mounds of hypertrophic septal muscle were resected, Brockenbrough phenomena proved unsatisfactory myectomy. Intraoperative trans-esophageal echocardiogram (TEE) revealed a residual mound at the apical septum. After the additional myectomy, Brockenbrough phenomena was disappeared. Intraoperative TEE is an useful supplement in the operation of transaortic myectomy for HOCM.

Cardiomyopathy, Hypertrophic↗
PubMed1992

Peripheral nervous system in the larynx. An anatomical study of the motor, sensory and autonomic nerve fibers.

The laryngeal peripheral nervous system is presented on the basis of our results in the cat, following 10 years of investigation using mainly tracer techniques. The present paper focused on the localization of each laryngeal motoneuron, the myotopical arrangements of motoneurons innervating the pharyngeal and esophageal striated muscles within the nucleus ambiguus in the motor nerve supply, and also on the location of neurons, the distribution and density of nerve fibers, the area and laterality of the innervation, and the pathway to the larynx in the sensory and sympathetic nerve supplies. Regarding the parasympathetic nerve supply, the neural ganglia and the ganglionic cells in and around the laryngeal nerves and in the laryngeal framework are demonstrated. Most of this innervation, however, is still unclear. Discussions from the literature are also reported.

Animals↗
PubMed1991

Strategy changes in human contingency judgments as a function of contingency tables.

Judgment strategies of 169 undergraduate students on problems to judge the contingency between two binary events were identified by the method of rule-based analysis to clarify whether or not the strategies the subjects used would be affected by the concrete nature of the contingency table. Problems were constructed along two factors: total cell frequency and width of range of objective contingencies. Although the factor of total cell frequency had no effect on subjects' strategies, the number of subjects who changed strategies corresponding with problem instances increased when the objective contingencies were set closer to zero or when problems became more difficult. These results are discussed in the context of previous studies of this issue in the literature.

Adolescent↗
PubMed1990

Some newly synthesized leukotriene B4 analogs inhibit LTB4-induced lysozyme release from rat polymorphonuclear leukocytes.

Antagonistic activities of newly synthesized LTB4 analogs, which possess the same olefinic geometry and the same hydroxyl group stereochemistry as natural LTB4, were investigated by studying lysozyme release from rat polymorphonuclear leukocytes (PMNLs). 14,15-Dihydro LTB4(LTB3) induced lysozyme release from PMNLs as well as LTB4, while 14,15-dehydro LTB4 did not cause lysozyme release but instead clearly inhibit LTB4-induced lysozyme release. Compounds containing aminocarbonyl groups partially retained lysozyme releasing activity. A displacement of the hydrocarbon chain at C13-20 by cyclohexenyl and beta-cyclohexylethyl groups had little effect on lysozyme release, but did strongly inhibit release induced by LTB4. These results may be useful in developing LTB4 antagonists.

Animals↗
PubMed1990

Analysis of breathing pattern in children with asthma.

The breathing pattern in children with asthma was studied, using respiratory inductive plethysmography. The subjects were 31 children with mild to moderate asthma (15 males, 16 females; aged 6-15 years, average 11 years). The respiratory rate was 25.5 +/- 10.7/min. (mean +/- S.D.) during asthma attacks and 18.4 +/- 5.0/min. between attacks with a significant increase during attacks (P less than 0.001). The expiratory time was 1.774 +/- 0.833 second during attacks, and 2.125 +/- 0.602 seconds between attacks. The expiratory time to total respiratory time ratio (TE/TTOT) was 0.631 +/- 0.056 during attacks and 0.608 +/- 0.035 between attacks. Thus there was a slight prolongation at the time of attack, but the difference was not significant. The tidal volume was increased slightly during mild and moderate attacks. VT/TI (mean inspiratory flow) was increased during attacks. The respiratory pattern was thoracic during attacks and changed to the abdominal pattern with improvement.

Adolescent↗
PubMed1990

[Influence of change in dental chair position on circulation kinetics. 1. Effects on rate x pressure product].

The rate x pressure product is a product of the systolic blood pressure and heart rate and is widely used in clinical medicine as an index of the cardiac oxygen supply-demand balance. Employing 20 healthy male subjects, we studied the changes in the rate x pressure product due to a body position change from the sitting position to the supine position in a dental chair. The following results were obtained: 1. The change from the sitting position caused a 10% decrease in the rate x pressure product, and this value did not return to the initial sitting position value even after 5 min in the supine position. 2. The heart rate tended to decrease due to the position change. 3. Immediately after the position change, the systolic blood pressure decreased significantly (p less than 0.05), but it tended to return to the initial value with the lapse of time. The lower rate x pressure product in the supine position suggests that the supine position is more advantageous than the sitting one in treatment of the elderly and patients with cardiovascular diseases from the viewpoint of the systemic cardiovascular kinetics.

Blood Pressure↗
PubMed1990

[Epidermoid cyst of the oral floor with massive deposition of melanin in the cystic epithelium].

Dermoid cyst or epidermoid cyst of the oral cavity usually occurs in the floor of the mouth. We encountered a 21-year-old woman who had developed epidermoid cyst in the oral floor. Since infancy she had been aware of a swelling in the oral floor. Recently, the swelling began to grow larger gradually. The lesion was excised under general anesthesia by intraoral approach. The swelling was spherical in shape, measured 50 x 45 x 40 mm in size, and weighed 40 g. Histopathological examination revealed keratinized, stratified squamous epithelium on the cyst wall and marked deposition of melanin at the base of the epithelium.

Adult↗
PubMed1990

[Reconstruction of occlusal function with osseointegrated implant following mandibular resection].

We succeeded satisfactorily to restore the occlusal function by use of an osseointegrated implant following iliac bone grafting and partial mandibulectomy in 4 patients who underwent surgical resection of odontgenic cyst and benign or malignant tumor of the oral cavity. Case 1: The patient was a 19-year-old man. Partial resection of the mandible was carried out under the diagnosis of odontgenic keratocyst of the left lateral incisor to the 1st premolar region. Iliac bone grafting was performed as secondary surgery. After confirmation of the fusion of the grafted bone, the occlusal function was restored by use of an osseointegrated implant. Case 2: The patient was a 36-year-old man. After segmental resection of the mandible under the diagnosis of ameloblastoma of the left 2nd premolar to the right 2nd premolar region, mandibular reconstruction was carried out with an A-O plate. Iliac bone grafting was performed as secondary surgery. After fusion of the grafted bone had been confirmed, the A-O plate was remounted and the fixture was immediately implanted. Five months later, vestibuloplasty by free skin grafting and attachment of the abutment were carried out. A superstructure was mounted. Case 3: The patient was a 22-year-old woman. The histopathologically confirmed odontogenic myxoma in the right mandible posteriorly from the second premolar was resected. Immediate reconstruction of the mandible was carried out by use of an iliac bone graft. After confirmation of the fusion of the grafted bone, the occlusal function was restored by use of an osseointegrated implant. Case 4: The patient was a 57-year-old woman with carcinoma of the right lingual margin and mouth floor. The tumor was resected with the mandibular margin. Immediate reconstruction of the tongue and mouth floor with a major pectoral muscle skin flap was carried out. In the absence of evidence of recurrence, restoration of the occlusal function was attempted with an osseointegrated implant.

Adult↗
PubMed1989

Syndrome of generalized (peripheral tissue and pituitary) resistance to thyroid hormone.

Generalized resistance to thyroid hormone (GRTH), or Refetoff syndrome, is a disease in which peripheral tissues show resistance to thyroid hormone. Three patients with this disease were investigated. Cases 1 and 2 involved identical 7-year-old female twins and case 3, a 5-year-old girl. All three patients had goiters, and cases 1 and 2 had sensorineural deafness. In all three, the blood levels of T4, free T4, and T3 were high, while the blood levels of TSH were normal or slightly elevated. The responses shown by blood levels of the thyroid hormone and TSH to administration of propylthiouracil and T3 suggest that the regulating mechanism in the hypothalamic-pituitary-thyroid system was functional. Upon administration of T3, no sign of hyperthyroidism was observed.

Child↗
PubMed1989

[Measurement of oral and facial blood flow with a laser Doppler flowmeter. 4. Alteration of oral blood flow by position change].

The laser doppler flowmeter was developed by Stern in 1975 and applied for practical use by Nilsson et al. in 1980. Since then, it has been used in various fields of medicine. The primary advantages of this device an that it is noninvasive and can monitor the blood flow continuously and rapidly. We used a Laser doppler flowmeter to continuously monitor the change in the oral peripheral blood flow due to changes in the body position of patients in a dental chair, since such changes are unavoidable during the course of dental treatment. A change from the sitting position to the supine position caused an increase in oral blood flow in 19 of 20 patients. In terms of the mean value per minute, oral blood flow was 23% greater in the supine position.

Blood Flow Velocity↗
PubMed1989

[Five cases referred to the First Department of Oral Surgery due to failure of impacted mandibular third molar extraction].

Of patients referred to our department over the post two years due to failure of tooth extraction 5 with impacated mandibular third molars were treated. We found that extraction had been hindered by the narrow operative field due to inadequate incision of the overlying mucosal tissue, insufficient bone resection and inadequate separation of the crown and root.

Humans↗