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Biomedical subjects

T Tabata

Publications and source records attributed to T Tabata.

At least 235 records · Page 13Linked to original sources
PubMed1992

Properties of an albumin inhibiting lysosomal acid cholesteryl ester hydrolase in rat liver.

Lysosomal acid cholesteryl ester hydrolase (acid CEH, EC. 1.1.1.13) activity was inhibited by addition of an increasing amount of d = 1.21 bottom fraction from rat serum (Lipids in press). To clarify the mechanism of this inhibition, rat native and modified albumin were added to the assay mixture and their effects on acid CEH activity were examined. The inhibitory effect on acid CEH activity was dependent on the concentration of rat albumin. Albumin of various mammalian species, including human, bovine and rabbit, also inhibited acid CEH activity. This inhibitory activity was markedly increased by heat treatment, the effect increasing in parallel with the prolongation of the treatment. Moreover, this albumin-dependent inhibition of acid CEH activity was also markedly increased by methylation of albumin. In contrast, the inhibition of acid CEH activity by modified albumins, such as acetyl albumin, succinyl albumin and glycine methyl ester albumin, was much lower than that of albumin, and no stimulatory effect of heat treatment on the albumins was observed. The heat-treated albumin-dependent inhibition of acid CEH activity was not abolished in the presence of sodium deoxycholate. The values of Vmax obtained were similar with or without heat-treated albumin. These results suggest that the inhibitory effects of heat-treated albumin may be due to an intrinsic and characteristic property of the lipid/water interface, and that the stimulatory effects of heat treatment on albumin-dependent inhibition may be due to heat-induced changes in the affinity and conformation of albumin.

Albumins↗
PubMed1992

Response field of cat trigeminal sensory complex neurons responsive to mechanical stimulation of the canine tooth.

Response fields of periodontal mechanoreceptive (PM) neurons in the cat's trigeminal sensory complex were examined while mechanical stimulation was applied to the canine tooth in 12 directions on the horizontal plane. Almost all the slowly adapting PM neurons were directionally selective to stimulation, and their response fields had response angles greater than 180 degrees, i.e. broad type.

Afferent Pathways↗
PubMed1992

Examination of human bone surrounded by a dense hydroxyapatite dental implant after long-term use.

A high-density hydroxyapatite (D-HAP) ceramic dental implant that had functioned for more than 5 years was studied, using light and electron transmission microscopy, after it was retrieved from a human mandible. The D-HAP implant had come in contact with thick bone trabeculae; in the nontrabecular area, a thick bone addition was formed on the implant. The lamellar arrangement of the added bone was basically parallel to the implant's surface and continuously connected with the lamellar surface layer of the trabeculae at the added bone-trabeculae connection. Also, bone remodeling around the implant had occurred, especially in the area contacting the thickened trabeculae, wherein remodeling units were formed parallel to the implant surface. Moreover, positive results of chemical bonding existed and were recognized between the D-HAP and the bone. No structural changes were observed in the D-HAP ceramics. From this study, the characteristics of biological affinity, functional adaptability, and material stability suggested that D-HAP is a suitable material for dental implants.

Animals↗
PubMed1992

A two-site immunochemiluminometric assay for intact parathyroid hormone and its clinical utility in hemodialysis patients.

Measurement of serum parathyroid hormone (PTH) concentrations is complicated by the fact that there are several fragments of the hormone in the circulating as a result of the metabolism of PTH. The best way to study the secretory activity of the parathyroid glands directly may be to measure the biologically active intact PTH molecule. Recently, it has become possible to overcome these limitations by application of the two-site immunoradiometric assay (IRMA) to the measurement of intact PTH. The two-site immunometric technique has been applied to the two-site immunochemiluminescent assay (ICMA) for the measurement of circulating intact PTH. To evaluate the utility of measurements of serum intact PTH by two-site ICMA in hemodialysis patients, two-site ICMA and IRMA were compared in 104 hemodialysis patients. We found a good correlation (r = 0.93) between values obtained by ICMA and by IRMA. Although serum intact PTH by ICMA was significantly suppressed by rising plasma ionized calcium after a session of hemodialysis in 29 patients, mid-region PTH did not show a significant change. This result suggests the intact PTH assay is more suitable for the earlier detection of secondary hyperparathyroidism than the mid-region assay and may be useful for precise assessment of clinical status and response to therapeutic intervention designed to correct the progressive bone disease in hemodialysis patients. We conclude that two-site ICMA for serum intact PTH which could be measured without radioisotopes nor scintillation counter is as useful as IRMA in hemodialysis patients.

Humans↗
PubMed1992

[Clinical significance of the click intervals for the diagnosis of dysfunction of the Medtronic-Hall prosthetic valve].

To investigate the clinical significance of click interval for evaluation of prosthetic valve dysfunction, 20 patients underwent Medtronic-Hall (MH) valve replacement (14 in the mitral position and 6 in the aortic position) were studied by simultaneous high-speed recordings of phonocardiogram, echocardiogram and/or Doppler echocardiogram. Two of the 20 patients, one in the mitral and the other in the aortic position, showed MH valve dysfunction. Eleven patients with normally functioning Björk-Shiley (BS) valve in the mitral position served as controls. Results were as follows: 1. There were usually 3 opening clicks (OC1, OC2, OC3) in patients with normally functioning MH valve in the mitral position. These 3 clicks coincided in timing with the beginning of opening, maximum opening and the end of sliding motion, respectively. Both OC1 and OC2 of the MH valve occurred in similar timing with those of the BS valve (A2-OC1 interval: MH = 65.4 +/- 11.8 msec vs BS = 72.3 +/- 17.2 msec; OC1-OC2 interval: MH = 31.2 +/- 7.7 msec vs BS = 27.3 +/- 6.1 msec). However, OC3 occurred significantly later in MH valve than in the BS valve (OC2-OC3 interval: MH = 32.3 +/- 7.5 msec vs BS = 16.4 +/- 3.8 msec, p < 0.01). 2. There were 2 closing clicks (CC1, CC2) in normally functioning the MH valve in the aortic position. These 2 clicks coincided in timing with the beginning and the end of the closing motion, respectively. Mean value of CC1-CC2 interval in 5 prosthetic patients with normal function was 31.0 +/- 9.6 msec. 3. A patient with malfunctioning MH valve in the mitral position showed a markedly prolonged OC1-OC2 interval, ranging from 66 to 140 msec, and she had multiple diastolic clicks after the OC2 phase. Prolonged OC1-OC2 interval was mainly caused by the delay of appearance of OC2, and it was thought to be due to temporary limitation of opening motion of the valve by valve thrombosis. 4. A patient with malfunctioning MH valve in the aortic position showed a markedly prolonged CC1-CC2 interval (100 msec), and he had a significant severe aortic regurgitation during this phase. At operation, fibrinoid thrombus was attached to the aortic annulus at the side of minor orifice of the valve. Closing motion of the valve was disturbed by this thrombus, and the completion of valve closure was markedly delayed.(ABSTRACT TRUNCATED AT 400 WORDS)

Adult↗
PubMed1992

[Mitral valve prolapse associated with partial absence of commissural chordal insertion: report of two cases].

We reported 2 cases of mitral valve prolapse (MVP) associated with partial absence of the chordae tendineae. Case 1 was a 25-year-old man who was admitted to our hospital for further examinations of an apical pansystolic murmur (Levine 4/6) and the abnormal shadow on his chest radiograph. He was diagnosed as having grade 3 + mitral regurgitation (MR) by the Sellers classification and pulmonary varix by cardiac catheterization. Transesophageal echocardiography revealed MVP of the rough zone of the anterior mitral leaflet and MR blowing into the pulmonary varix. Case 2 was a 60-year-old man who was admitted to our hospital because of congestive heart failure and apical pansystolic murmur (Levine 4/6). Parasternal echocardiography revealed prolapse of both the anterior and posterior mitral leaflets and moderate MR. In both cases, absence of insertion of anterolateral commissural chordae was confirmed after surgery, and the abnormalities of chordal arrangement and insertion were considered as causes of MVP in these cases.

Adult↗
PubMed1991

Distribution of trigeminal sensory nucleus neurons projecting to the mesencephalic parabrachial area of the cat.

Horseradish peroxidase (HRP) retrograde tracing experiments in the cat demonstrated projections from the trigeminal sensory nuclei to the mesencephalic parabrachial area (PBA), which is located ventral to the inferior colliculus and dorsal to the brachium conjunctivum and includes the nucleus cuneiformis and the most lateral part of the periaqueductal gray. After HRP injection into the mesencephalic PBA, HRP-labeled neuronal cell bodies in the trigeminal sensory nuclei were mainly distributed in the interpolar and caudal spinal trigeminal nuclei (Vi and Vc) bilaterally with a clear-cut contralateral dominance. In Vi, HRP-labeled neurons were mainly distributed in the lateral and medial border regions. In Vc, labeled neurons were located mainly in laminae I and V.

Animals↗
PubMed1991

HBP-1a and HBP-1b: leucine zipper-type transcription factors of wheat.

Wheat transcription factors HBP-1a and HBP-1b bind to the hexamer motif, ACGTCA, of wheat histone gene promoters. HBP-1b also binds to the hexamer motif in the promoter of the 35S RNA gene of cauliflower mosaic virus, whereas HBP-1a does not. A cDNA clone encoding HBP-1b was isolated on the basis of its binding specificity to the hexamer motif. The deduced amino acid sequence indicates that HBP-1b, like HBP-1a, belongs to a leucine zipper class of transcription factors. Mutational analyses of the HBP-1a and -1b encoded cDNAs revealed that truncated polypeptides containing the leucine zipper and basic regions are sufficient for DNA binding. HBP-1a and -1b form homodimers, as expected from earlier studies on this class of transcription factors, but did not form heterodimers. Although the hexamer motif or its homologs exist in several plant genes, HBP-1a and -1b exhibited the highest binding affinity to the hexamer motif in the histone promoters, suggesting that both DNA binding proteins are involved in transcriptional regulation of wheat histone genes.

Amino Acid Sequence↗
PubMed1991

Response properties of periodontal mechanosensitive units in the cat's thalamus.

1) The response characteristics of periodontal mechanosensitive neurons in the thalamic nucleus were studied by using 15 adult cats anesthetized with alpha-chloralose (40 mg/kg, i.v.). 2) 468 periodontal mechanosensitive units (PM units) responsive to light mechanical stimulation of the teeth were recorded from a medioventral aspect of the nucleus ventralis posteromedialis (VPM). Of these neurons, 213 units (45.5%) were slowly adapting, and 255 units (54.5%) were rapidly adapting. 3) The receptive field of the PM units was represented by the number of receptive quadrants on the dental arches of both jaws. About half of the PM units (279, 59.6%) were one-quadrant units. Of these neurons, 69 (14.7%) were single tooth units. Two-quadrant, three-quadrant and four-quadrant units numbered 123 (26.3%), 3 (0.6%) and 63 (13.5%) respectively. Of the PM units detected, 246 units (52.6%), 124 units (26.4%) and 98 units (20.9%) responded to mechanical stimulation of the teeth on only the contralateral side, on only the ipsilateral side and on both sides, respectively. 4) One-quadrant units were distributed mainly in the rostral part of the PM area, and four-quadrant units were found in the caudal part of the PM area. A somatotopic organization for each tooth was not found. 5) The incidence of single tooth units in the thalamus was extremely low, compared with those in the primary afferents and in the trigeminal nuclear complex. Most of the thalamic neurons had larger receptive fields than both the primary afferents and the trigeminal nuclear complex neurons. 6) The high incidence of four-quadrant units at the caudal part of the PM area suggests that many PM fibers converge there. However, it is still unclear whether these fibers come through the intrathalamic neurons or directly from the trigeminal nuclear complex.

Animals↗
PubMed1991

Response properties of the periodontal mechanosensitive neurons in the trigeminal main sensory nucleus of the cat.

Periodontal mechanosensitive units (PM units) were recorded from the trigeminal main sensory nucleus (Vms) of the cat. The receptive fields of PM units were arranged from mandibular to maxillary divisions dorso-ventrally. The majority of PM units were single tooth units responsive to the canine tooth. They were directionally selective and had sustained responses to pressure applied to the tooth. The optimal stimulus direction of maxillary and mandibular PM units when the canine tooth was stimulated was single and it was oriented predominantly in the caudio-medial or rostrolateral direction. The threshold intensity of canine tooth stimulation was less than 0.05 N in most of the units. These findings indicate that the response properties of PM units in the Vms resemble fairly closely those of the primary afferent nerves arising from the periodontal mechanoreceptors.

Adaptation, Physiological↗
PubMed1991

Facilitatory effect of jaw opening on somatosensory (SI) cortical neurones sensitive to tooth pressure in the cat.

In anaesthetized cats, an upper canine tooth was stimulated mechanically at two different levels of jaw opening, the resting position and an open position with 20 +/- 2 mm between the upper and lower canines. The evoked field potentials and neuronal discharges were recorded from the caudal part of the contralateral coronal gyrus (SI cortex). The waveforms of the evoked potentials appeared in a positive-negative sequence. There were no significant changes in them when the jaws were open. Discharge patterns elicited in the cortical neurones by mechanical stimulation of the teeth consisted of initial 'burst' discharges, inhibitory pauses and/or large after-discharges. Jaw opening did not influence any phases of these responses to suprathreshold stimulation, spontaneous activities, or the sizes of the receptive fields. However, jaw opening did affect the initial 'burst' phase of the response to threshold stimulation, i.e. that which caused the neurones to fire with a probability of 30-50% with the jaw closed. Jaw opening enhanced this response probability in half (6/12) of the units that had very small receptive fields restricted to the canine tooth, but did not influence it in the majority (21/24) of the units that had larger receptive fields including the oral mucosa and the facial skin. There was no difference in distribution in the coronal gyrus between the two groups of neurones categorized by whether or not they were influenced by jaw position.

Animals↗
PubMed1991

Local administration trials of interleukin-2 for head and neck cancer.

Recombinant interleukin-2 (rIL-2) has been administered locally in 20 patients with head and neck cancer. Two complete responses in lower lip cancer and 1 partial response in lingual cancer have been obtained. Immunohistological study reveals that tumor infiltrating lymphocytes (TILs), including activated T lymphocytes and natural killer cells, are increased after rIL-2 use. Intraarterial chemotherapy, performed subsequently to the local use of rIL-2 results in a dramatic decrease in tumor size within a short time, and a high frequency of CR cases is observed. Local use of rIL-2 is beneficial for treatment of head and neck cancers, and induction immunochemotherapy combining locally used rIL-2 and arterially infused anticancer drugs plays an important role in a multidisciplinary treatment for these cancers.

Administration, Topical↗
PubMed1991

Circulating bone Gla protein in end-stage renal disease determined by newly developed two-site immunoradiometric assay.

As a marker for bone formation, bone Gla protein (BGP) levels in the circulation have been measured in clinical research and management for metabolic bone diseases. We evaluated the clinical availability of a newly developed two-site immunoradiometric assay (IRMA) for human BGP and determined the serum BGP concentrations using this methodology in patients with abnormal calcium metabolism including those with end-stage renal disease undergoing maintenance dialysis. A cross-reactivity test revealed that this assay system specifically recognizes intact molecules (1-49) of BGP and excludes fragments of the molecules (1-19, 12-33, 23-33). Serum BGP levels in dialysis patients were positively correlated with those by conventional radioimmunoassay (RIA) (r = 0.918, p less than 0.00001, n = 37) as well as normal individuals (r = 0.935, p less than 0.0001, n = 16). However, the levels of BGP determined by IRMA were estimated to be significantly lower than those by RIA (23.6 +/- 9.8 vs. 29.6 +/- 9.1 ng/ml, p less than 0.00001). These results suggest that this IRMA system, with a rapid and easy procedure, excludes fragment forms of BGP in the circulation, which are found in uremic sera and probably attributed to increased bone resorption. Further studies are needed to ensure that serum intact BGP levels mainly reflect BGP production in osteoblasts, particularly in end-stage renal disease.

Female↗
PubMed1991

Effect of intermittent oral 1,25(OH)2D3 therapy on bone Gla protein in dialysis patients.

Serum Bone Gla Protein (BGP) levels were measured by both immunoradiometric assay (IRMA) and radioimmunoassay (RIA) to investigate the effect of intermittent 1,25(OH)2D3 administration to dialysis patients who could not tolerate an increase in an active vitamin D3 dose and/or calcium to control secondary hyperparathyroidism due to hypercalcemia. The administration of active vitamin D3 gradually increased the serum BGP to more than 3 times the original level by the 8th week. At the 12th week after starting the active vitamin D3 therapy, mean BGP was about twice the original level, which was about half the maximum level at the 8th week. The BGP (IRMA)/BGP (RIA) ratio was increased significantly at 4th and 8th weeks compared to the original level. During this period, serum calcium, phosphorous, or intact molecule PTH (I-PTH) levels showed insignificant changes, with a slight reduction in the mid molecule PTH (m-PTH) level, and a significant reduction in ALP. Serum BUN and creatinine levels were not changed significantly. These data suggest that BGP was increased through direct stimulation of osteoblasts by the active vitamin D3, and the increase was not due to deterioration of secondary hyperparathyroidism. The reduction of the increase in the BGP level at the 12th week with insignificant biochemical changes suggest that activation of osteoblasts by vitamin D3 may be transient. In conclusion, intermittent active vitamin D3 increases serum BGP, without deterioration of major biochemical changes even in patients with moderate to severe secondary hyperparathyroidism, although the increase may be transient. These facts suggest that the serum BGP of hemodialysis patients is controlled at least in part by active vitamin D3.(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Oral↗
PubMed1991

Response properties of the periodontal mechanosensitive neurons in the thalamus of the cat: a comparison between the slowly adapting and rapidly adapting neurons.

Slowly adapting (SA) and rapidly adapting (RA) types of the periodontal mechanosensitive units (PM units) were recorded in the thalamus and their response properties were examined in the cat. Both types of the PM units were located in the medial area (PM area) of the nucleus ventralis posteromedialis (VPM) of the thalamus. The SA units were located in a rostro-medial part of the PM area, while the RA units were distributed in the caudo-lateral part. An incidence of the SA and RA units was 45.5 and 54.5%, respectively. The single-tooth units were found in 23.5% of the SA units and in 14.9% of the RA units, and they responded chiefly to mechanical stimulation of the contralateral canine tooth. The multi-tooth units of the SA type had smaller receptive fields than those of the RA type, because the majority of the RA units had their receptive fields at the bilateral and/or bimaxillary area. In total, the units having the contralateral receptive fields were also dominant in both adaptation types. The latency of the neuronal discharges to electrical stimulation of the receptive field was fairly shorter in the SA units than in the RA units. These findings suggest that the SA units of the thalamus receive periodontal inputs directly from the trigeminal nuclear complex (Vcomp) of the brain stem, while the RA units receive them polysynaptically from the Vcomp via other pathways.

Adaptation, Physiological↗
PubMed1991

Response properties of periodontal mechanosensitive neurons in the trigeminal spinal tract nucleus of the cat.

Periodontal mechanosensitive (PM) units were recorded from the trigeminal spinal tract nucleus (Vst) of the cat. The Vst is divided into three subnuclei: oralis (Vo), interpolaris (Vi), and caudalis (Vc). The receptive fields of PM units in Vo and Vi were arranged in a dorsoventral sequence in the mandibular to maxillary divisions, and those in Vc were arranged in a mediolateral sequence. The majority of Vo units were single-tooth ones, whereas more than half the Vi units and all the Vc ones were multitooth units. The PM units in each subnucleus were predominantly responsive to canine tooth stimulation. Most of the PM units in Vo and Vi gave sustained responses to pressure applied to the tooth, were directionally selective, and were most actively excited by canine tooth stimulation in the caudomedial or rostrolateral direction. Vc units, however, were transient. The threshold intensity for firings by canine tooth stimulation was less than 0.05 N. These findings indicate that only the response properties of PM units in the rostral part of Vst resemble those of the trigeminal main sensory nucleus neurons and primary afferent nerves.

Afferent Pathways↗
PubMed1991

Effects of dietary phosphorus restriction on secondary hyperparathyroidism in hemodialysis patients during intermittent oral high-dose 1,25(OH)2D3 treatment.

Phosphorus (P) retention plays an important role in the pathogenesis of secondary hyperparathyroidism (2nd HPT) in chronic renal failure. In recent years, periodic intravenous or intermittent oral administration of high doses of 1,25(OH)2D3 has been reported to improve severe 2nd HPT in hemodialysis patients. The present study was performed to determine the effects of dietary P restriction on 2nd HPT in hemodialysis patients treated with intermittent oral high-dose 1,25(OH)2D3. A high dose of 1,25(OH)2D3 was administered orally twice a week at the end of hemodialysis in 20 hemodialysis patients with 2nd HPT. Dietary P content was estimated from records of the patients' food intake, made twice during the treatment period. Based on this information, dietitians developed appropriate meal plans and instructed the patients. After 8 weeks of the treatment, serum c-parathyroid hormone (c-PTH) and alkaline phosphatase (ALP) levels decreased significantly, from 18.8 +/- 1.9 ng/ml and 347.1 +/- 30.7 U/liter to 9.4 +/- 1.2 ng/ml and 268.3 +/- 19.6 U/liter, respectively. Serum P levels increased gradually during the first 4 weeks of the treatment. Dietary P intake was reduced significantly, from 908 +/- 49 mg/day to 734 +/- 39 mg/day, after the nutritional instructions. As a result of the dietary P restrictions, serum P levels were significantly decreased in the 8th week as compared with those in the 4th week. Serum Ca levels remained unchanged throughout the observation period. There was a significant relationship between the mean values for serum P levels during the study and the percent suppression of serum c-PTH.(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Oral↗