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T Tabei

Publications and source records attributed to T Tabei.

At least 55 records · Page 3Linked to original sources
PubMed1977

Scintigraphic evaluation of cold thyroid nodules.

Scintagraphic patterns of cold thyroid nodules taken by the scintillation camera with radioactive iodine-131 were reported. Previous reports published by others on this subject were based on the scintillation scanner which gave us less sharp resolution than the scintillation camera. Our data indicate that the defect pattern is largely dependent upon the existence of the capsule as well as the size of the nodule. In general, a benign nodule shows defect having a rather smooth margin with somewhat distended normal thyroid tissue, whereas malignant one, if it has no capsule, shows an irregular or straight margin. However, the defect pattern of malignant nodule covered with a capsule is similar to that of benign nodule. A defect of the entire unilateral lobe and highly irregular-shaped defect spread over bilateral lobes are suggestive of malignancy. These findings seem to be generally similar to those reported by others. However, pull-up phenomenon of lower pole coexisting with the defect in the upper half is highly suggestive of malignancy, especially of papillary type. As long as defect (negative) pattern is investigated, the diagnosis of cold nodule inevitably meets certain limitations. To avoid this problem, the radiopharmaceutical which exclusively concnetrates in malignant nodule should be searched. Then, the scintigraphic diagnosis of thyroid nodule will become more reliable.

Adenoma↗
PubMed1976

Diagnosis of placental sulfatase deficiency..

Placental sulfatase deficiency has been found in four pregnancies (cases 1 to 4) with inappropriately low levels of urinary estriol excretion (less than 1.3 mg. per day near term gestation) associated with healthy neonates. The basis of the diagnosis in these cases was the greatly limited capacities for hydrolysis of 14C-dehydroepiandrosterone sulfate (DHA-S) and 3H-estrone sulfate (0.2 mugCi each) to the free steroids during incubation of placental homogenates. Placental aromatase activities in vitro for free DHA and the concentrations of appropriate estrogen precursors in cord blood were normal or elevated. The defect was diagnosed prenatally in two of these cases on the basis of failure to increase the maternal excretion of urinary estriol (0.6 to 0.7 and 1.3 to 1.3 mg. per day, respectively) following acute instillation of DHA-S (250 mg.) into the amniotic fluid and on normal levels of estrogen precursors in cord blood. In comparison, a twofold increase in maternal estriol excretion was observed after infusing DHA-S into the amniotic cavity of a "high-risk" pregnancy having normal sulfatase and aromatase activities in vitro (case 5). These enzyme activities were also found to be similarly normal in another placenta from an undergrown fetus (case 6) and in six normal placentas. The clinical features of these pregnancies, the first ones described from the western hemisphere, are similar to reported cases: the newborn progeny are healthy males who appear to be developing normally. The prenatal diagnosis of the sex-specific placental enzyme defect has been made possible by the use of an intra-amniotic DHA-S loading test.

Amniotic Fluid↗
PubMed1976

Bone scanning with 99m-Tc-phosphates: a comparison and problems in the detection of tumor metastasis.

A comparative study on 99m-Tc-phosphate compounds (TcPP) in detecting tumor metastasis to bone and problems accompanying it are reported. TcPP revealed metastatic foci which are unrecognized by conventional bone survey. To recognize these foci, exclusion of following problems is necessary: Accumulation at front of neck, asymmetrical image of joint, increased bone density of the aged, Tc-photon absorption and radiotherapy effect. The mechanism of TcPP accumulation is discussed.

Absorption↗
PubMed1976

Neonatal effect of clomiphene and o,p'-DDT on hepatic oxidative metabolism of male rats.

The hepatic oxidative metabolism of dehydroepiandrosterone (DHA) and aminopyrine has been investigated in adult rats of both sexes treated neonatally with either clomiphene citrate (100 mug on day 3) or o,p'-DDT (1 mg daily on days 2-3). The rates of 16 alpha-, 7 alpha- and 7 beta-hydroxylase activities of DHA and the N-demethylase activities of aminopyrine in hepatic microsomes of normal males were significantly (p less than 0.05) higher than those of females. Treatment with clomiphene citrate reduced significantly (p less than 0.05) the 16 alpha-hydroxylase activities of males and appeared to suppress the 7 alpha-hydroxylase and N-demethylase activities to a lesser extent. Neonatal o,p'-DDT also reduced these hepatic oxidative activities. Neither treatment affected the 7 beta-hydroxylase activities. On the other hand, no significant differences in these activities were observed between the control and the treated females, all of which had persistent vaginal estrus. Therefore, it appears that treatment of male neonates with these weak estrogenic compounds antagonizes the androgen-mediated expression of the DHA-16alpha-hydroxylase activity in liver.

Animals↗
PubMed1975

Enzymatic oxidation and reduction of C19-delta5-3beta-hydroxysteroids by hepatic microsomes. IV. Induction of DHA hydroxylases and aminopyrine N-demethylase in immature male rats by androgens.

The capacities of various C19 steroids for prematurely inducing the normal metabolic patterns of rat liver in adulthood (70 days old) have been studied with hepatic microsomes of 42-day-old males castrated on day 24, 30, 32, or 34 of life. Dehydroepiandrosterone 16alpha-hydroxylase activity was significantly reduced (P less than 0.05) by castration during this 10-day interval but the 7alpha- and 7beta-hydroxylases, the N-demethylation of aminopyrine, and cytochrome P-450 concentration were unaffected. Daily administration of testosterone stimulated the DHA 16-alpha- and 17beta-hydroxylases, aminopyrine N-demethylation, and increased the P-450 content, but suppressed the 7alpha-hydroxylase. These effects only appeared with more than 1 week of the continuous treatment. Testosterone was the most active of the androgens studied; dihydrotestosterone (DHT) increased the DHA 16alpha-hydroxylase to a lesser extent, but this steroid and etiocholanolone stimulated DHA 7alpha-hydroxylation; androsterone was totally ineffective. These data suggest that testosterone rather than DHT from pubertal testes plays a significant role in control of hepatic oxidative enzyme activities during puberty.

Age Factors↗
PubMed1975

Enzymatic oxidation and reduction of C19-delta5-3beta-hydroxysteroids by hepatic microsomes. V. Testosterone as a neonatal determinant in rats of the 7- and 16alpha-hydroxylation and reduction of 3beta-hydroxyandrost-5-en-17-one (DHA).

The oxido-reductive metabolism of [14C]dehydroepiandrosterone (DHA) by hepatic microsomes from 40- or 70-day-old rats of either sex castrated neonatally has been compared after several treatment regimens with testosterone propionate (TP). The low transformation rate of DHA to 16-oxygenated metabolites produced by neonatal orchiectomy (0.09 +/- 0.04 nmoles min-1 mg-1), was not restored in 70-day-old males by either neonatal or pubertal treatment with TP. The rates were only partially restored (0.74 +/- 0.44) toward nromal adult levels (1.30 +/- 0.16) by the combination of neontal and pubertal treatments, in increments that maintained normal body weight but produced no visible growth of the male accessory glands. The combination of neonatal and pubertal treatments with larger doses of TP enough to produce normal accessory gland growth, stimulated the enzymatic rates of 16alpha-7alpha-, or 7beta-hydroxylases to levels that exceeded those of intact adult males. In 40-day-old males, the 16-oxygenation rate was restored by the latter regimen, but only to the levels characteristic of yound males (0.56 +/- 0.24), and young females responded more (1.03 +/- 0.33) than the males. The 7-oxygenation rate of DHA responded in both age groups to smaller doses of TP than did that of the 16-oxygenation. None of these manipulations altered the reduction of DHA to androst-5-ene-3bets-17beta-diol. We conclude that testosterone activates hepatic DHA hydroxylases in pubertal male rats only if neonatal imprinting by testosterone preceeds the subsequent stimulus. In addition, the DHA 16alpha-hydroxylase of young males is less sensitive than that of young females, but this pattern is reversed by 70 days of age. The hepatic males are both sensitive to testosterone, but the response of the glands is diminished by age.

Aging↗
PubMed1975

Formation of 6-hydroxylated progesterone in the human placenta and response to hCG.

The in vitro metabolism of 7alpha-3-H-pregnenolone by five term human placentas obtained from repeat cesarean section was studied. Incubations were carried out either with minced tissue for 1 h or by organ culture for 6 h and 24 h. Twenty-one experiments were performed to determine the effect of human chorionic gonadotropin (hCG), human placental lactogen (hPL), and heat-inactivated hCG on the metabolism of pregnenolone. The major radioactive product was progesterone (40-60%); unchanged pregnenolone accounted for only 5-15% of the radioactivity. 3-H-6beta-OH-progesterone was found and rigorously identified. In control experiments 6beta-OH-progesterone was 2-4% of the radioactivity. In the presence of hCG there was a significant (P smaller than 0.005) 2-3-fold increase of 3-H-6beta-OH-progesterone in the 1-h mince incubations and the 24-h organ cultures. There was no increase of 3-H-6beta-OH-progesterone over control values with hCG after 6-h organ cultures; with heat-inactivated hCG; or with hPL. These findings provide additional data that hCG affects steroid metabolism in the human placenta. In addition, 3-H-6alpha-OH-progesterone was found and rigorously identified in yields of approximately 0.5-1%. The effect of hCG on 6alpha-hydroxylation was not determined. This appears to be the first demonstration of 6alpha-hydroxylation of C21 steroids by human tissue.

Chorionic Gonadotropin↗