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Biomedical subjects

T Ohyama

Publications and source records attributed to T Ohyama.

At least 289 records · Page 16Linked to original sources
PubMed1985

Body surface distributions of ST segment changes after exercise in effort angina pectoris without myocardial infarction.

To investigate the sites of exercise-induced ST segment changes on the body surface in effort angina pectoris without myocardial infarction, we performed 87-lead ECG mapping in 61 patients before and 1.5 and 5 minutes after treadmill exercise. ST segment depression most often occurred in the left anterior chest leads and ST segment elevation developed mainly in the right upper chest leads. There was a good correlation between the number of lead points that showed ST segment depression (nSTd) and the number of those that showed ST segment elevation (nSTe) 1.5 minutes after exercise (r = 0.92). From 1.5 to 5 minutes after exercise, changes in nSTd for individual patients correlated well with changes in nSTe (r = 0.89). It was suggested that the ST segment elevation observed in this study directly reflected the subendocardial ischemia of the left ventricle. In patients with one-vessel disease (n = 32), there was wide overlap in the sites of ST segment changes among patients with left anterior descending artery disease (n = 19), those with left circumflex artery disease (n = 6), and those with right coronary artery disease (n = 7). These findings should lead to a better understanding of exercise-induced ST segment changes for the diagnosis of coronary artery disease.

Adult↗
PubMed1985

Gigantism associated with McCune-Albright's syndrome.

The case of a 16 year-old boy with McCune-Albright's syndrome which is rarely accompanied by gigantism was studied endocrinologically. The stimulation of growth hormone (GH) release by hypoglycemia, the decline of elevated GH by hyperglycemia and a little lower somatostatin like immunoreactivity (SLI) may support abnormalities of hypothalamic function, but the existence of pituitary microadenoma cannot be ruled out because of the paradoxical suppression of GH release by oral administration of bromocriptine (CB-154) and L-DOPA and the stimulation of GH release by intravenous administration of TRH.

Adolescent↗
PubMed1985

Studies on T. utilis tRNATyr variants with enzymatically altered D-loop sequences. I. Deletion of the conserved sequence Gm-G and its effects on aminoacylation and conformation.

Variants of T. utilis tRNATyr containing deletions or substitutions of nucleotides in the D-loop region have been prepared by several enzymatic reaction steps in vitro. Although these variants lack the "conserved" nucleotides Gm18-G19 in their D-loop, their tyrosine-accepting capacities are indistinguishable from that of the native tRNATyr. Thermal denaturation studies with tRNATyr variants lacking the Gm18-G19 sequence have revealed a biphasic nature of the melting profile, suggesting the loss of tertiary interactions between Gm18-G19 and somewhere in the molecule (probably in the T psi C-loop region). These results indicate that nucleotide sequences around Gm18-G19 (i.e. D16-D-Gm-G19 or Gm18-G-D-D21) themselves are not essential sites for the recognition of tRNATyr by T. utilis tyrosyl-tRNA synthetase and that tRNATyr variants with an apparently "relaxed" conformation still have full aminoacylation capacities at around 30 degrees C.

Acylation↗
PubMed1985

Serum cyclic 3',5'-nucleotide phosphodiesterase in patients with various thyroid disorders.

Previous observations that cyclic 3',5'-nucleotide phosphodiesterase activity exists in mammalian sera including human serum prompted us to investigate the phosphodiesterase levels in sera of patients with various thyroid disorders. Both serum cyclic AMP phosphodiesterase (cAMP-PDE) and cyclic GMP phosphodiesterase (cGMP-PDE) activities measured in a low substrate concentration were elevated 3-fold in subacute thyroiditis and slightly in hyperthyroidism, compared to the normal. Slight decreases of these enzyme activities were observed in primary hypothyroidism. PDE activities were positively correlated with the value of T3-RSU and serum thyroid hormone levels in hyper- and hypothyroidism. Altered enzyme activities returned to normal during the course of recovery. Identical results were obtained when plasma was tested. These results suggest that serum PDE activities may be partly related to the thyroid function.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed1985

Diagnosis of coronary artery disease by body surface mapping--body surface distribution of exercise-induced ST changes in patients without myocardial infarction.

In 36 patients with effort angina pectoris without myocardial infarction, the sites of exercise-induced ST changes (depression and elevation) on the body surface were investigated. Exercise-induced ST depression was most often seen in left anterior chest leads. The body surface distribution of ST depression failed to identify the obstructed coronary artery. Exercise-induced myocardial ischemia was thought to extend to the greater part of the subendocardial region of the left ventricle. Exercise-induced ST elevation was mainly found on the upper right anterior chest. It has been suggested that these leads face the interior of the left ventricle and the observed ST elevation directly reflects subendocardial ischemia of the left ventricle. This data is important for evaluating ST changes in exercise electrocardiography.

Coronary Disease↗
PubMed1985

Effect of hypophysectomy on cyclic 3',5'-nucleotidemetabolizing enzymes in the rat thyroid gland.

Adenylate cyclase and cyclic AMP phosphodiesterase activities in the thyroid gland were significantly reduced after hypophysectomy, followed by a gradual restoration of the enzyme activities to the levels seen in sham-operated rats whereas a slight and persistent reduction was evident in guanylate cyclase and cyclic GMP phosphodiesterase activities in the same tissue. These changes in enzyme activities were restored by TSH administration but not by ACTH. The recovery of activity produced by TSH administration was inhibited by cycloheximide. Hypophysectomy, or TSH and cycloheximide administration, did not produce any significant changes in the concentrations of calmodulin, suggesting that the alteration of these enzyme activities is not induced by a decrease in the concentration of calmodulin. Since forskolin activation of adenylate cyclase did not restore the reduced activity in the hypophysectomized rat thyroid to the level found in the sham-operated control rat thyroid, we conclude that there is a reduction of the amount of enzyme after hypophysectomy rather than a change of the active site on adenylate cyclase. The spontaneous restoration of adenylate cyclase and cyclic AMP phosphodiesterase activities after hypophysectomy implies that cyclic AMP-metabolizing enzymes are responsive to an autoregulatory mechanism in thyroid follicular cells.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed1985

Serum cyclic 3',5'-nucleotide phosphodiesterase activity in myocardial infarction.

The activities of cyclic 3',5'-nucleotide phosphodiesterases which hydrolyze cyclic 3',5'-nucleotides were measured in sera from patients with an acute myocardial infarction, angina pectoris and other heart diseases. Cyclic AMP and cyclic GMP phosphodiesterase activities were significantly elevated in acute myocardial infarction, but not in angina pectoris and other cardiovascular diseases. The peak activity appeared approximately within 24 hours following the acute attack of chest pain, and then gradually decreased as the patient recovered. The observed changes of cyclic 3',5'-nucleotide phosphodiesterase activity were similar to that of the other enzyme activities such as GOT, CPK and LDH in sera of acute myocardial infarction. These data reflect damage of myocardial cells during myocardial infarction.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed1985

Effects of a conformational change in tRNA on its aminoacylation capacity: a study using enzymatically reconstructed variants of T. utilis tRNATyr.

Variants of T. utilis tRNATyr containing deletion or substitution of the "conserved" sequence Gm18-G19 in the D-loop have been enzymatically reconstructed in vitro. Conformational analyses of these variants by measuring melting profiles, electrophoretic mobility in "native" polyacrylamide gels, and by the analysis of RNase T1 digestion patterns on sequencing gels laid a stress on the significance of the Gm18-G19 sequence for the maintenance of L-shaped tertiary structure of tRNATyr. Aminoacylation assays with the variant tRNAs at various temperatures revealed that the highly ordered tertiary structure is needed for full aminoacylation capacity.

Candida↗
PubMed1984

[Circulating free T3 in pregnancy, liver diseases, diabetes mellitus and thyroid diseases].

Measurement of serum concentrations of free triiodothyronine (FT3) is considered to be an accurate index of thyroid function in the patient. In this study, we measured serum concentrations of FT3, free thyroxine (FT4) and reverse triiodothyronine (rT3) by radioimmunoassay in blood samples taken from the navel cord of 20 newborns as well as 20 nonpregnant women, 20 pregnant women, 10 patients with liver diseases, 25 patients with diabetes mellitus, 65 patients with hyperthyroidism, 30 patients with primary hypothyroidism and 29 normal subjects. In pregnant women, serum FT3 and FT4 levels gradually decreased as the pregnancy progressed. In cord blood, FT3 levels were less than a quarter of the values found during the first trimester of pregnancy or that of non-pregnant women, whereas serum rT3 levels were drastically increased. In chronic hepatitis, liver cirrhosis and diabetes mellitus, serum FT3 and FT4 levels were significantly lower than that in the controls. In thyroid diseases, serum FT3 levels varied parallel to other thyroid hormone levels. In primary hypothyroidism, however, serum FT3 levels were still lower than these in the controls after treatment with 1-thyroxine, whereas other thyroid hormone levels and TSH levels returned to control levels.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1984

Isosafrole-induced cytochrome P2-450 in DBA/2N mouse liver. Characterization and genetic control of induction.

Mouse "cytochrome P2-450" is defined as that form of isosafrole-induced P-450 in DBA/2N liver most specifically correlated with isosafrole metabolism. Isosafrole pretreatment does not induce aryl hydrocarbon hydroxylase activity ("cytochrome P1-450") in C57BL/6N or DBA/2N mice, induces acetanilide 4-hydroxylase activity ("cytochrome P3-450") more than 3-fold in C57BL/6N but not in DBA/2N mice, and induces isosafrole metabolite formation more than 3-fold in both C57BL/6N and DBA/2N mice. P2-450 was, therefore, purified from isosafrole-treated DBA/2N liver microsomes having negligible amounts of contaminating P1-450 and P3-450. The apparent molecular weight of P2-450 is 55,000, and the protein appears homogeneous on sodium dodecyl sulfate-polyacrylamide gels. The Soret peak of the reduced purified cytochrome X CO complex is 448 nm. Purified P2-450, reconstituted in vitro, metabolizes acetanilide poorly and benzo[a]pyrene hardly at all. Anti-(P2-450) inhibits (90 to 100%) liver microsomal isosafrole metabolite formation, yet has no effect on aryl hydrocarbon hydroxylase, acetanilide 4-hydroxylase, biphenyl 2- or 4-hydroxylase, or 7-ethoxycoumarin O-de-ethylase activities. 3-Methylcholanthrene induces anti-(P2-450)-precipitable protein about 12-fold in C57BL/6N and 2-fold in DBA/2N liver; 2,3,7,8-tetrachlorodibenzo-p-dioxin (10 micrograms/kg), about 12-fold in both C57BL/6N and DBA/2N liver; isosafrole, more than 3-fold in both C57BL/6N and DBA/2N. Benzo[a]anthracene at maximal doses induces anti-(P2-450)-precipitable protein in C57BL/6N liver no more than 2-fold, yet is known to be a highly potent inducer of P1-450 mRNA in C57BL/6N liver. The sensitivity of the P2-450 induction process to isosafrole is inherited as an autosomal additive trait; studies of offspring from the C57BL/6N(DBA/N)F1 X DBA/2N backcross confirm involvement of the Ah locus or s closely segregating gene. In contrast, among crosses between C57BL/6N and DBA/2N, sensitivity of the P1-450 and P3-450 induction process to 3-methylcholanthrene or 2,3,7,8-tetrachlorodibenzo-p-dioxin is inherited as an autosomal dominant trait. These data suggest that, although P1-450, P2-450, and P3-450 proteins are controlled by the Ah locus, either a P-450 protein polymorphism exists between C57BL/6N and DBA/2N mice or subtle differences may exist in the interaction of various inducers with Ah receptor.

Animals↗
PubMed1984

Inhibitory effect of thyroid hormones on pituitary cyclic amp phosphodiesterase activity in vitro.

Thyroid hormones effectively inhibited partially purified cyclic AMP phosphodiesterase from the anterior and posterior lobes of bovine pituitary gland competitively with the substrate, but thyronine, diiodotyrosine, monoiodotyrosine, thyrotropin, thyrotropin releasing hormone, dexamethasone, and luteinizing hormone releasing hormone did not inhibit this enzyme activity. Ki values were found to be 1.0 and 2.5 microM for thyroxine, and 8.0 and 13.5 microM for triiodothyronine in the anterior and posterior lobes, respectively.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed1984

[A clinicopathological study on hematogenous recurrence of colo-rectal cancer--with special reference to prediction and prevention of the recurrence].

Hematogenous recurrence was investigated in 325 cases of colo-rectal cancer. Hematogenous recurrence was confirmed in 34 cases including 25 liver, 5 lung, 2 bone, one brain and one skin recurrence. Most of the cases (28 cases, 82.4%) revealed a single or multiple hematogenous recurrences without showing additional other types of recurrence. Histological examination of cancer lesions indicated that patients with the findings consisting of moderate and/or high grade of vein invasion (v2-3), subserosal and extramural vein invasion with node metastasis showed high recurrent rate. One and two year survival rate of the patients treated with MF-MF' adjuvant chemotherapy was greater those the patients with F-F' chemotherapy or those without chemotherapy. However, 3-, 4- and 5- year survival rate did not show significant difference among 3 therapeutic groups. The analysis of survival curves also indicated no significant difference among 3 therapeutic groups. These results may suggest that hematogenous recurrence is derived from pre- and/or intra-operative micrometastasis or transplantation of cancer cells, that patients with the above mentioned histological evidence must be clinically treated as a high risk group for recurrence and that MF-MF' adjuvant chemotherapy can be effective in lowering the recurrence rate during the first one or two years after operation.

Antineoplastic Agents↗
PubMed1984

[A clinicopathological study on carcinoma of the gastric stump, with special reference to mucosal change].

Ten carcinomas of the gastric stump reconstructed by Billroth I (one case) and Billroth II (9 cases) methods were treated an average of 20 (range: 7-46) years after partial gastrectomy. Because of highly advanced carcinoma, total gastrectomy with resection of invaded organs was performed. The 5-year survival rate was 33%, and was not different from that in patients with carcinoma of the cardia. Thus, the prognosis of gastric stump carcinoma was not poor if extended radical operation was carried out. The mucosa showed severe atrophic gastritis with intestinal metaplasia or atrophic and hypertrophic gastritis in patients with carcinoma. However, the mucosa was hyperplasia of the glands in almost all patients with stomal ulcer. Thus, our findings suggest that atrophic change with intestinalization plays a role in gastric carcinogenesis.

Adenocarcinoma↗