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T Mitsuhashi

Publications and source records attributed to T Mitsuhashi.

At least 91 records · Page 5Linked to original sources
PubMed1994

[Functional domain structure of thyroid hormone receptor and interaction among T3, T3 receptor and T3RE].

Thyroid hormone receptor is a member of the c-erb A nuclear hormone receptor superfamily. As a ligand dependent transcription factor, it has functions such as ligand binding, DNA binding, transactivation and interaction with other factors. While each of these functions is ascribed to a certain region of the receptor molecule called a domain which can function independently of other domains, these domains cooperate with each other to fulfil the integrated receptor function as a signal transduction apparatus. Characteristics of thyroid hormone receptor which are distinct from those of steroid hormone receptors, such as the role of ligand in receptor function, heterogeneity in TREs, heterodimerization with TRAPs and the dominant negative effect, are described in the context of the integrated receptor function.

Base Sequence↗
PubMed1993

[Structure and function of the thyroid hormone receptor].

Cloning of the thyroid hormone receptor and its identification as a cellular counterpart of the viral oncogene v-erbA was a major breakthrough in the study of thyroid hormone action. However, contrary to our initial expectations, many astonishing findings which have accumulated since the receptor cloning, especially the presence of two receptor types, made the elucidation of the thyroid hormone action extremely complicated. In this paper, we mainly did a phylogenic comparison of the amino acid sequence between alpha- and beta-type receptor from Xenopus laevis to humans, hoping to obtain some clue to clarify the functional differences between these receptors. There are several consistent amino acid differences between alpha- and beta-receptor through species in the DNA binding domain, one of which is non-conservative and is located in the portion supposed to be critical to the protein-protein interaction. We believe that clarification of the physiological significance of the presence of two receptor types will facilitate the study of thyroid hormone action.

Amino Acid Sequence↗
PubMed1993

Gas chromatographic determination of trace nitrite after derivatization with ethyl 3-oxobutanoate.

A gas chromatographic method was developed for the determination of nitrite using ethyl 3-oxobutanoate as a derivatization reagent. Nitrite was reacted with ethyl 3-oxobutanoate in the presence of hydrochloric acid to form ethyl 2-hydroxyimino-3-oxobutanoate (EHOB) quantitatively. The resulting EHOB was extracted with ethyl acetate and then determined sensitively by gas chromatography with electron-capture detection. This method has been applied successfully to the determination of nitrite in river water and human saliva, with a detection limit of 2 ng/ml and recoveries of 94-100%.

Acetoacetates↗
PubMed1993

Immunochemical detection of advanced glycation end products in lens crystallins from streptozocin-induced diabetic rat.

To reassess the significance of AGEs in cataract formation in diabetic animals, we measured amounts of AGEs in lens crystallins from STZ-induced diabetic animals with a newly developed ELISA. Lenses were removed at 5 and 20 wk after STZ injection. In 20-wk diabetic rats, all lenses were cataractous but not in control rats. In 20-wk diabetic compared with control rats, significant increases were observed in AGEs (172.3 +/- 18.3 vs. 14.3 +/- 1.7 AU, P < 0.01) and fluorescence (2.04 +/- 0.22 vs. 1.27 +/- 0.10 AU, P < 0.05). The amounts of AGEs in lens crystallins, measured by the ELISA, were > 12-fold higher in diabetic rats. In agreement with earlier studies, we found that fluorescence in lens crystallins increased by 61% in diabetic rats. In 5-wk diabetic rats, all lenses were noncataractous. In 5-wk diabetic compared with control rats, significant increases were observed in AGEs (84.1 +/- 7.7 vs. 9.4 +/- 1.5 AU, P < 0.01) and fluorescence (1.45 +/- 0.06 vs. 1.05 +/- 0.06 AU, P < 0.01). Analysis of the AGE content by ELISA showed that accumulation of AGEs in diabetic lens crystallins does markedly occur with time, and a large amount of AGEs exists in the diabetic (cataractous) lens crystallins. The disproportionate elevation of AGEs, measured by the ELISA, compared with fluorescence suggests that the actual levels of AGEs in cataractous lens crystallins from diabetic animals are higher than previously anticipated, and nonfluorescent AGEs may exist in diabetic lens crystallins.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

Immunochemical detection of advanced glycation end products in renal cortex from STZ-induced diabetic rat.

To reassess the accumulation of advanced glycation end products in diabetic renal cortex, we used a newly developed enzyme-linked immunosorbent assay to measure AGEs in renal cortex from STZ-induced diabetic and age-matched control rats. Kidneys and aortas were obtained from rats after 5 and 20 wk of STZ injection. At 5 wk of diabetes, the mean AGE content in collagenase-digested materials of renal cortex was > 16-fold higher in diabetic animals compared with controls (1044.4 +/- 151.8 vs. 64.3 +/- 5.7 arbitrary units, P < 0.01). At 20 wk of diabetes, it was > 45-fold higher in diabetic compared with control animals (3841.0 +/- 1077.3 vs. 83.8 +/- 12.8 AUs, P < 0.01). These increases were surprisingly large compared with the < 1.5-fold increase in the fluorescence levels both after 5 and 20 wk of diabetes. In control animals, neither the AGE content nor the fluorescence level increased during this period. Moreover, at 20 wk of diabetes, the AGE content was 39-fold higher in renal cortex compared with aorta. This study provided the first immunochemical evidence that collagenase-digested materials of renal cortex, as well as aorta, contained AGE products and that these products were present in much higher levels in diabetic animals than in control animals. With duration of diabetes, the AGE contents increased significantly both in renal cortex and aorta. The excessive accumulation of AGEs was most apparent in the diabetic kidney.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

[Basic and clinical evaluation of EIA (pin immuno assay, PIA) kit for antithyroglobulin antibody (TGAb) and antimicrosomal (antiperoxidase) antibody (TMAb)].

Newly developed enzyme immunoassay kit (Pin Immuno Assay, PIA) for quantitative determination of serum antithyroglobulin antibody (TGAb) and antimicrosomal (-peroxidase) antibody (TMAb) was evaluated. The method utilizes the Sandwich ELISA principle with a unique micropin as solid phase coated with antigen. Reproducibilities assessed by intra- and interassay variation were less than 6.9% (CV) and 7.2% for TGAb or 4.2% and 6.0% for TMAb respectively. Changes in the first or second incubation time did not affect both TGAb and TMAb values. Upper normal limits obtained from 47 healthy subjects were 150 IU/ml for TGAb and 25 IU/ml for TMAb. Positive results in TGAb were obtained 60.0% in patients with Graves' disease and 80.0% in chronic thyroiditis and in TMAb 77.8% in Graves' disease and 66.7% in chronic thyroiditis. Patients with other autoimmune diseases such as SLE, RA were also found high incidence of positive results, 48.3% for TGAb and 65.0% for TMAb respectively. These results indicate that the nonradioisotopic assay technique for thyroid autoantibodies are useful in diagnosis of autoimmune diseases especially thyroid diseases.

Autoantibodies↗
PubMed1992

Developmental expression of mRNAs from a rat C-erbA genomic locus.

The thyroid hormone receptor alpha gene is alternatively spliced to give the alpha receptor and a variant which does not bind thyroid hormones. An additional alpha-like receptor (Rev-erbA alpha) is transcribed on the opposite strand and overlaps the unique variant sequence. The alpha receptor in rat brain reaches peak levels 5-15 days after birth. The variant remains high from 2 days before birth to old age. The Rev-erbA alpha mRNA increases beginning 5 days after birth, maximizing in adulthood. Thyroid hormone decreases and hypothyroidism increases the level of these 3 messages. We conclude that the levels of these messages are similarly controlled by thyroid hormone but have different ontogenetic controls. No functional results can be seen in vivo from potential anti sense pairing of Rev-erbA alpha with the variant.

Aging↗
PubMed1992

[An adult case of anomalous origin of the left coronary artery from the pulmonary artery].

An adult case of anomalous origin of the left coronary artery from the pulmonary artery (ALCAPA) was presented. A 37-year-old male was admitted for ventricular arrhythmia and chest pain. The catheterization, left ventriculography and coronary arteriography revealed ALCAPA with anterolateral ventricular aneurysm and mild mitral regurgitation. An operation using Takeuchi procedure was performed. The postoperative course was uneventful and the results of the catheterization, left ventriculography and coronary arteriography performed immediately and five years after the operation were excellent except mild supravalvular pulmonary stenosis. Six years later, the patient is asymptomatic and well.

Adult↗
PubMed1991

Molecular basis of thyroid hormone regulation of myelin basic protein gene expression in rodent brain.

Regulation of myelin basic protein (MBP) gene expression by thyroid hormone has been investigated in rodent brain. Quantitation of the 4 major alternatively spliced transcripts by RNase protection assay showed that the individual mRNAs, corresponding to MBP isoforms 21.5, 18.5, 17, and 14 kDa, were decreased from 2- to 17-fold at all ages studied (4-60 days) in hypothyroid animals when compared to euthyroid, but the timing of onset of expression was not altered. MBP mRNA was also reduced in young adult rats thyroidectomized at the age of 5-6 weeks and was restored to normal by thyroxine administration. Nuclear run-off assays showed that the rate of MBP gene transcription is dependent on thyroid state. Co-transfection of MBP (-256/+1)-chloramphenicol acetyltransferase chimeric gene with a plasmid expressing thyroid hormone receptor alpha, and in the presence of 3,5,3'-triiodothyronine, into NIH3T3 or NG108-15, increased chloramphenicol acetyltransferase expression 4-fold. Using a footprinting technique and Spodoptera frugiperda 9 (Sf9) nuclear extract infected with baculovirus expressing TR alpha, we have identified a single DNA-binding site (-186/-163) for the receptor. A part of this region contains the AGGACA sequence found in thyroid hormone-responsive elements of other 3,5,3'-triiodothyronine-regulated genes. Our finding of a specific hormone-receptor interaction with the MBP promoter region is the first direct demonstration of a thyroid hormone-responsive element in a brain-specific gene.

Animals↗
PubMed1991

Characterization of antibodies to advanced glycosylation end products on protein.

Antibodies directed against advanced glycosylation end products (AGEs) formed during a Maillard reaction have been generated and characterized. Since protein-bound AGEs recognized by the antibodies were labile to acid hydrolysis, the antibodies were further characterized by using the AGE-alpha-acetyl-L-lysine methyl ester (AGE-ALME) with a brown and fluorescent property as well as the AGE-proteins. The antibodies reacted with fluorescent compounds, rather than brown pigment compounds, in the AGE-ALME. The fluorescent compounds in the AGE-ALME were separated into four fluorescent compounds by reversed-phase thin layer chromatography (TLC). Of the fluorescent compounds tested, compound 3 (Rf = 0.63), as designated on a TLC plate, showed the highest affinity for the antibodies. In addition, the antibody recognition to the cross-linked oligomers with fluorescence in the AGE-protein was investigated by using bovine pancreatic ribonuclease A (RNase), which is known as a model protein for studying AGE-induced cross-linking. Fluorescence in the AGE-RNase existed in both of the oligomers and the monomer. The cross-linked oligomers exhibited higher affinity to the antibodies than did the monomer, which has a similar degree of fluorescent intensity. These results indicate that our antibodies against cross-linked protein-bound AGEs may serve as a useful tool to elucidate pathophysiological roles of advanced Maillard reaction in diabetic complications and aging processes.

Antibodies↗
PubMed1991

Intrasellar cavernous angioma in neurofibromatosis.

A case of neurofibromatosis complicated by a large intrasellar (pituitary) cavernous angioma is reported. Vascular abnormalities, consisting of smooth muscle cell proliferation in the intima of the intermediate and small arteries, were also observed in branches of the renal and pulmonary arteries. An association between neurofibromatosis and intracranial cavernous angioma is discussed.

Autopsy↗
PubMed1991

Malignant T-cell lymphoma of the pancreas.

A case of malignant T-cell lymphoma of the pancreas is presented. Previously reported histological data confirming this disease are reviewed to elucidate features that may suggest this disease and how to differentiate between T- and B-cell lymphoma of the pancreas.

Adult↗
PubMed1991

Isolated central nervous system arteriopathy with multiple aneurysms in an adolescent. A case report.

A 17-year-old male suffered recurrent subarachnoid hemorrhages due to multiple aneurysms in the distal branches of the cerebral arteries. Autopsy revealed arteriopathy as well as the aneurysms. The arteriopathy was widespread, affecting the distal branches of small and medium-sized muscular cerebral arteries, as well as the anterior and posterior spinal arteries, and vasocorona. The arteriopathy was characterized by prominent intimal thickening, discontinuity or absence of the internal elastic lamina, and thinning and/or disappearance of smooth muscle in the tunica media with fibroplasia. Slight intimal thickening was also observed in the arteries of the circle of Willis and its major branches, as well as in the basilar artery. However, the arterioles, venules and veins showed no remarkable features. The arterial lesions were found only in the central nervous system. The multiple aneurysms in the distal branches of the cerebral arteries, which had produced the main symptoms and clinical signs, were due to the arteriopathy.

Adolescent↗
PubMed1991

Reduced calcium sensitivity of dihydropyridine binding to calcium channels in spontaneously hypertensive rats.

To explore the role of calcium channels in hypertension, dihydropyridine ([3H]PN200-110) binding to heart, brain, and skeletal muscle microsomes of 4-, 8- and 15-week-old spontaneously hypertensive rats (SHR) and Wistar-Kyoto (WKY) rats was measured. At a constant Ca2+ ion concentration (pCa 3.0), maximal binding (Bmax) of dihydropyridine binding to heart and brain microsomes was significantly enhanced in 8- and 15-week-old SHR compared with WKY rats (p less than 0.01), whereas this phenomenon was not observed in 4-week-old SHR and WKY rats. Bmax and dissociation constant (Kd) values for skeletal muscle microsomes from SHR showed no difference compared with WKY rats irrespective of age. Dihydropyridine binding to heart microsomes, brain microsomes, and solubilized skeletal muscle microsomes exhibited strong calcium dependence. The Ca2(+)-dependent dihydropyridine binding curves for heart showed a Hill slope, and pK 0.5 values for 15-week-old SHR and WKY rats were 0.70 +/- 0.12 and 4.66 +/- 0.12 versus 0.72 +/- 0.12 and 5.66 +/- 0.08 (n = 4, mean +/- SD), respectively, indicating that 15-week-old SHR require 10-fold higher calcium concentration than WKY rats to promote dihydropyridine binding. The pK 0.5 values of calcium for brain and solubilized skeletal muscle calcium channels in 15-week-old SHR were also significantly lower than in WKY rats. This difference first became apparent in SHR and WKY rats as early as 4 and 8 weeks after birth. These results suggest that enhancement of calcium channel density might occur in the heart and brain of SHR in response to elevated blood pressure and that reduced calcium sensitivity of dihydropyridine binding to calcium channels might be a primary characteristic of this rat strain.

Animals↗
PubMed1991

1,25-dihydroxyvitamin D3 modulates growth of vascular smooth muscle cells.

We examined the effects of 1,25-dihydroxyvitamin D3(1,25-(OH)2D3) on the proliferation of vascular smooth muscle (VSM) cells. Receptors for 1,25-(OH)2D3 were demonstrated in fresh rabbit aortic tissue and in cultured rat VSM using binding of [3H]-1,25-(OH)2D3 in sucrose density gradients of the tissue or cell homogenates. The receptor sedimented at 3.6 S, the sedimentation velocity of 1,25-(OH)2D3 receptors from other sources. 1,25-(OH)2D3 dramatically altered the growth of VSM, but this effect depended importantly on the basal conditions in which the cells were grown. In quiescent VSM deprived of serum for 72 h, 1,25-(OH)2D3 (0.1-10 nM), but not 25-(OH)D3 (up to 100 nM) increased thymidine incorporation up to 12-fold and cell number up to 2.6-fold compared with controls. The maximal effect of 1,25-(OH)2D3 on thymidine incorporation was similar to the maximal effect of the growth factors alpha-thrombin or PDGF. Furthermore, the effects of 1,25-(OH)2D3 and thrombin on thymidine incorporation in quiescent cells were markedly synergistic, yielding a 78-fold increase in thymidine incorporation when both agents were added simultaneously. In "nonquiescent cells" which were exposed to serum-free medium for only 24 h, 1,25-(OH)2D3 (10 nM) also increased DNA synthesis 10-fold compared with controls. However, in striking contrast to what was observed in quiescent cells, 1,25-(OH)2D3 diminished the mitogenic response to thrombin by as much as 50% in nonquiescent cells. 1,25-(OH)2D3 also modulated the transcription of c-myc in response to thrombin. In quiescent cells, transcription was enhanced by 1,25-(OH)2D3, whereas in nonquiescent cells, thrombin-induced c-myc transcription was blunted. Thus, 1,25-(OH)2D3 is a potent modulator of the growth of cultured VSM. The direction of this modulation depends strongly on the conditions under which the cells are cultured.

Animals↗
PubMed1991

Assessment of hypertensive heart by 2-dimensional echocardiography in mass screening.

Two-dimensional echocardiography (2DE) was used in the mass screening of 3,017 participants (1,195 males, 1,822 females, mean age 59) living in 13 areas in Japan. The 2DE findings of left ventricular hypertrophy (LVH) and LV function were compared with the presence and severity of hypertension (Ht). Out of 1,100 patients who had an evident history of Ht above 160/95 mmHg (Ht group), 298 patients (27.4%) were complicated by LVH. In contrast, LVH was also recognized in 60 (11.2%) of 535 borderline Ht cases and in 87 (6.3%) of 1,382 normotension cases. LVH cases in the Ht group were divided into 3 groups: mild (220: 73.8%), moderate (63: 21.2) and severe (15: 5.0). Asymmetric septal hypertrophy (ASH) was recognized in 111 patients (37.2%) of the 298 LVH cases. The prevalence of ASH in these LVH patients was higher according to the severity of the LVH: mild LVH = 31%, moderate LVH = 51% and severe LVH = 67%. The prevalence of LVH was higher in males than in females. This was especially apparent in the moderate to severe LVH groups and also noted to be higher according to the increase of mean blood pressure. The prevalence of mild to moderate LVH was significantly higher in the poorly-controlled group than in the well-controlled group. In contrast, no significant difference in prevalence of severe LVH was noted between the well-controlled and poorly-controlled groups. The prevalence of LV dysfunction was significantly greater in moderate or severe LVH groups than in non or mild LVH groups. It tended to be higher in the poorly-controlled group compared with the well-controlled group. The regression of LVH was frequently detected in the well-controlled group by the follow-up study. We conclude that 2DE observation of LV performance in mass screening will be extremely valuable in the long term follow-up of Ht patients.

Adult↗
PubMed1991

Effect of sodium bicarbonate and deoxycholic acid on the gastric mucosa of the rabbit.

Deoxycholic acid (DC), a secondary bile acid and one of those most toxic to the gastric mucosa, is precipitated and becomes inactive in the acidic lumen of the rabbit stomach. We sought to determine whether or not oral administration of sodium bicarbonate (NaHCO3) and DC injure the rabbit gastric mucosa. Rabbits were divided into six groups. Group 1 was given 10 ml of 10% NaHCO3 followed by 50 ml of 20 mM DC orally every day. These animals had diarrhea and three of five died on the fourth or fifth day. Therefore, the two remaining animals were killed on the fourth day. Animals in group 2 were given 10 ml of water followed by 50 ml of 20 mM DC, those in group 3 were given 10 ml of 10% NaHCO3 followed by 10 mM DC, those in group 4 were given 10 ml of water followed by 50 ml of 10 mM DC, and those in group 5 were given 10 ml of 10% NaHCO3 followed by 50 ml of the DC solution. Group 6 was not treated. Although all animals in the group 2 and one of three in group 3 had diarrhea, they were alive and were killed after eight or nine days. Gross and histological examinations showed that the degrees of gastric mucosal damage in groups 1 and 2 were more severe than in groups 3 and 4. Mucosal damage in group 3 was more severe than in group 4. The gastric mucosa in group 5 was similar to that in untreated animals (group 6). These data suggest that when the gastric lumen is alkalinized by NaHCO3, DC causes more severe damage to the mucosa than it does when the lumen is acidic.

Animals↗