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Biomedical subjects

T Sakurada

Publications and source records attributed to T Sakurada.

At least 253 records · Page 14Linked to original sources
PubMed1984

[The parathyroid function in patients with hyperthyroidism].

The parameters of calcium metabolism were determined in 22 patients with untreated hyperthyroidism (5 males and 17 females) and 5 control subjects. Hypercalcemia was found in the patients with hyperthyroidism in comparison with the control subjects (serum Ca: 10.0 +/- 0.56 vs. 9.0 +/- 0.18, p less than 0.001 and Ca++: 5.1 +/- 0.28 vs. 4.6 +/- 0.15 mg/dl, p less than 0.001, mean +/- SD). Although the urinary excretion of calcium was decreased in many patients, abnormalities of phosphate metabolism were not found in this study. The parameters of bone resorption, urinary hydroxyproline, serum alkaline phosphatase and acid phosphatase, were increased in all patients with hyperthyroidism. Serum immunoreactive PTH was decreased (0.23 +/- 0.05 vs. 0.29 +/- 0.05 ngEq/ml, p less than 0.05). In vitamin D metabolites, 25-OH-D did not differ from the control (16.9 +/- 7.76 vs. 17.9 +/- 5.52 ng/ml), 1,25-(OH)2D showed a tendency to decrease (32.6 +/- 19.53 vs. 37.2 +/- 13.75 pg/ml) and 24,25-(OH)2D was obviously increased (5.57 +/- 3.582 vs. 1.73 +/- 0.619 ng/ml, p less than 0.001) in the hyperthyroid patients. Thus, the parathyroid function was suppressed in the patients with hyperthyroidism, and hypercalcemia in hyperthyroidism was suggested to be due to the direct action of thyroid hormone upon the bone.

Adult↗
PubMed1984

[Peripheral K lymphocytes in patients with subacute thyroiditis].

In a previous study, we showed that immunosuppressive acidic protein (IAP) was markedly increased in the acute phase in patients with subacute thyroiditis (SAT). In order to investigate the immunological abnormalities in SAT, peripheral K lymphocytes in SAT and hyperthyroidism were measured by the plaque-forming technique using sheep-red-blood cells as a target. The effect of the patients' serum on K-cells in normal lymphocytes was also investigated. The percentages of K-cells in 5 patients with SAT in the acute and recovery phases were 2.3 +/- 1.9 (mean +/- S.D.) and 5.3 +/- 2.2%, respectively. The former was significantly lower than the latter (p less than 0.05). Furthermore, the value in the acute phase showed a significant decrease against that of the normal controls (7.3 +/- 3.4, n = 14, p less than 0.01). The percentage of K-cells in 16 patients with hyperthyroidism was 2.8 +/- 2.2%, which was also significantly lower than that of the normal controls (p less than 0.05). The degree of inhibition of K-cells in normal lymphocytes by sera from 12 SAT in the acute and recovery phases was 69 +/- 21% and 35 +/- 22%, respectively, which was significantly higher (p less than 0.01 and p less than 0.05, respectively) than that in 12 normal sera (15 +/- 20%). Furthermore, the inhibition was markedly higher in the acute phase than in the recovery (p less than 0.01). The sera from 10 patients with hyperthyroidism also inhibited K-cells of normal lymphocytes (p less than 0.01). It was suggested that in the sera of SAT and hyperthyroidism there is some factor which inhibits K-cells.

Adolescent↗
PubMed1984

D-Arg2-dermorphin tetrapeptide analogs: a potent and long-lasting analgesic activity after subcutaneous administration.

To examine pharmacological properties of D-Arg2-dermorphin tetrapeptides, six tetrapeptide analogs based on the following formulas, H-Tyr-D-Arg-Phe-Gly-OX (X = H, ethyl, n-propyl), H-Tyr-D-Arg-Phe-Sar-OX (Sar = sarcosine; X = H, methyl, ethyl), were prepared. All these analogs exhibited highly potent and long-lasting analgesia as compared with that of morphine after subcutaneous administration in mice. Among analogs tested, H-Tyr-D-Arg-Phe-Sar-OH showed the highest activities, which were 21, 30 and 58 times more active than morphine in the tail pressure, tail flick and phenylbenzoquinone writhing tests, respectively, on a molar basis.

Analgesics↗
PubMed1984

[Free thyroxine estimation for screening of hyper- and hypothyroidism in an adult population].

Serum free thyroxine (FT4) was determined in 1,114 adults (male 239, female 875) in a periodic health evaluation in 1980 to detect unsuspected thyroid dysfunction, especially hyper- and hypothyroidism. The participants were dwelling in two towns of Miyagi prefecture. Beside FT4, serum T4 and T3 were also determined by radioimmunoassay. If thyroid dysfunction was suspected, further detailed examinations such as TRH-test (500 micrograms i.v.), radioimmunologic determinations of serum TSH and TBG, resin-sponge T3-uptake, 24-hr thyroid radioiodine 131I-uptake, radioiodine thyroid scan and anti-thyroid antibodies were performed. There were 3 patients with hyperthyroidism (0.27%), 4 with hypothyroidism (0.36%), 3 taking thyroid medication (2; Hashimoto's disease, 1; goiter), 3 on estrogen administration, 4 with Hashimoto's disease and 1 with goiter. Excluding these 18 patients, FT4, T4 and T3 values in 1,096 euthyroid subjects, 236 males and 860 females, were 1.1 +/- 0.3 (mean +/- S.D.), 1.1 +/- 0.3 and 1.0 +/- 0.3 ng/100 ml, 8.9 +/- 1.5, 8.8 +/- 1.6 and 9.0 +/- 1.5 micrograms/100 ml, and 122 +/- 33, 125 +/- 26 and 122 +/- 35 ng/100 ml, respectively. Serum FT4, T4 and T3 showed the distribution of logarithmic normal probability. The 95% normal range for free T4 was 0.60 to 1.80 ng/100 ml, total T4 6.0 to 11.8 micrograms/100 ml, and T3 84 to 176 ng/100 ml, respectively. Out of 1,114 subjects examined, the cases to be reexamined for the higher serum concentration than normal were 26 in FT4, 35 in T4 and 27 in T3, respectively. And the cases for lower values were 28 in FT4, 31 in T4 and 24 in T3, respectively. Serum FT4 values in the subjects during the administration of estrogens were within the normal range. FT4 and T4 were low in four patients with hypothyroidism, but two of them showed normal T3 values. Determinations of serum FT4, total T4 and total T3 were all useful for the screening of hyperthyroidism. But serum FT4 was the most reliable of the three. Determination of either serum FT4 or total T4 was suitable for the screening of hypothyroidism, but serum total T3 measurement did not cover all patients with hypothyroidism.

Adult↗
PubMed1984

Antinociceptive effects of neonatal capsaicin in rats with adjuvant arthritis.

Rats were treated with capsaicin (50 mg/kg, SC) either on the second day or on the second and third days of life. A significant attenuation of the responses to noxious stimuli was obtained in the capsaicin treated animals as measured by the hot-plate or paw pressure tests but not by the tail-flick test. Furthermore, neonatal capsaicin produced a significant reduction of response in the formalin test. Capsaicin reduced the reaction latency in rats with adjuvant arthritis as measured by the hot-plate and paw pressure tests, though capsaicin did not alter the overall time course of the response to Freund's adjuvant. Capsaicin also attenuated the weight loss or the decreased ambulatory and rearing behaviours which occurred in the control animals with adjuvant arthritis. It is suggested that neonatal treatment with capsaicin may relieve the responsiveness to long-lasting nociceptive stimuli by adjuvant in rats.

Analgesics↗
PubMed1984

Comparison of the antinociceptive effects of intracerebroventricular injection of kyotorphin, cyclo (N-methyl-Tyr-Arg) and Met-enkephalin in mice.

Intracerebroventricular (i.c.v.) administration of kyotorphin (L-Tyrosine-L-Arginine) or Metenkephalin (Met-ENK) to conscious mice resulted in a dose-dependent antinociceptive effect as measured by three pain tests. Cyclo(N-methyl-L-Tyrosine-L-Arginine) (cyclo NMTA), an analogue of kyotorphin, increased the reaction time in the tail-pressure and tail-flick tests. Both dipeptides also decreased writhing induced by acetic acid. However, the antinociceptive activity of cyclo NMTA was substantially greater than that of kyotorphin or Met-enkephalin. At the maximum effective dose of 62.7 nmol/mouse, this cyclic dipeptide produced a more long-lasting antinociceptive effect than did kyotorphin or Met-enkephalin. Antinociception induced by cyclo NMTA or kyotorphin was significantly reversed by pretreatment with naloxone (2 or 8 mg/kg, i.p.), though naloxone was not as effective an antagonist of the antinociceptive action of these peptides as it was against Met-enkephalin. The results indicate that the antinociceptive effect induced by cyclo NMTA may in part involve the endogenous opioid system in mice.

Analgesia↗
PubMed1984

Comparison of the antinociceptive effect between D-Arg containing dipeptides and tetrapeptides in mice.

D-Arg containing dipeptides, H-Tyr-D-Arg-OMe and H-Tyr (Et)-D-Arg-OMe, and D-Arg2 substituted N-terminal tetrapeptides of dermorphin, H-Tyr-D-Arg-Phe-Gly-OEt and H-Tyr (Et)-D-Arg-Phe-Gly-OEt administered intracerebroventricularly exhibited dose-dependent antinociceptive activities in mice as measured by the tail pressure and phenylbenzoquinone writhing tests. The effects of these peptides used were significantly antagonized by the pretreatment with naloxone, indicating that these effects must be produced through opioid receptors. Furthermore, it is of conspicuous interest that the effects of tetrapeptides revealed in infinitestimal order (ED50 = 12.5 and 355.0 pmole in the tail pressure test and 3.1 and 53.0 pmole in the phenylbenzoquinone writhing test, respectively) and was much more potent and prolonged than those of morphine, not to mention dipeptides used. However, judging from the difference of peak times and the degree of the antagonism by naloxone, it was suggested that dipeptides and tetrapeptides used might act on different sites of action in the central nervous system.

Analgesia↗
PubMed1984

Structure-antinociceptive activity studies with neurotensin.

The antinociceptive effects of synthetic neurotensin (NT), its fragments and analogues administered into the lateral cerebroventricle have been compared in the conscious mouse. Intracerebroventricular (i.c.v.) administration of NT produced a dose-dependent antinociceptive effect in the tail pressure test. The NT fragments and analogues, NT(8-13), NT(8-10), NT(9-13), NT(9-11), NT(8-11) NHEt and NT(9-11) NHEt were also effective antinociceptive peptides. The potency of NT(8-13) and the duration of its effects were found to be approximately equal to those of NT. The antinociceptive effects produced by NT, NT(8-13) and NT(9-13) were significantly reversed by the opioid antagonist naloxone but not by thyrotropin releasing hormone. It is concluded that NT(8-13) is required for the full expression of the antinociceptive effects of NT which may be mediated in part through the brain opioid system.

Analgesics↗
PubMed1984

Potentiation of cyclo (N-methyl-Tyr-Arg)-induced antinociceptive activity by thyrotropin-releasing hormone in mice.

The effect of thyrotropin-releasing hormone (TRH) and its metabolite, cyclo(His-Pro) (C.HP), on cyclo(N-methyl-Tyr-Arg) (C.NMTA)-induced antinociception as measured by the tail-pressure test in mice has been examined. C.NMTA-induced antinociception was significantly potentiated by simultaneously intracerebroventricular or intraperitoneal injection of TRH (approximately 20-50%) in a dose-dependent manner, whereas the effect of morphine was not influenced significantly by TRH. C.HP had no significant effect on the antinociceptive response induced by C.NMTA or morphine. It is concluded that the mechanism of C.NMTA-induced antinociception may be involved in TRH neuronal system in the brain.

Analgesics↗
PubMed1984

Comparison of the antinociceptive effect between the cyclic dipeptide cyclo[Tyr(Et)-homoarginine] and the linear dipeptide Boc-Tyr(Et)-homoarginine-OMe in rats.

The antinociceptive effect of the cyclic dipeptide cyclo[Tyr(Et)- homoarginine] (C.TEHA) was examined utilizing the tail flick test and the digitus pinching test in rats in comparison with the linear dipeptide Boc-Tyr(Et)-homoarginine-OMe (B.TEHM). Though both dipeptides administered into the lateral, 3rd and 4th cerebroventricles produced antinociceptive effects equipotent to morphine, except for the 4th cerebroventricular administration of B.TEHM, the administration into the spinal subarachnoid space was without effect. The effect of B.TEHM was completely antagonized by the pretreatment of naloxone (i.p.) when administered into the 3rd cerebroventricle where its effect was demonstrated to be the most potent. However, naloxone had no significant effect on C.TEHA administered into the 3rd cerebroventricle in both tests. It was concluded that both dipeptides act on the upper brain stem, especially around the 3rd cerebroventricle. Moreover, it was also thought that the effect of B.TEHM may be involved in the brain opioid system, and that of C.TEHA can be produced via a naloxone-resistant opioid system or a non-opioid system.

Analgesics↗
PubMed1984

Changes in thyroxine monodeiodination in rat liver, kidney and placenta during pregnancy.

Monodeiodination of thyroxine (T4) was studied in the liver, kidney and placenta of pregnant rats. Age matched female non-pregnant and pregnant Sprague-Dawley rats on the 7th, 14th, 17th and 21st days of gestation were used. The 800 X g supernatants of tissue homogenates (protein 1 mg/tube) were incubated with 1 microgram of stable T4 in the presence of 5 mM dithiothreitol (DTT) at 37 degrees C for 60 min at pH 7.5. Net triiodothyronine (T3) generation from T4 in rat liver homogenates on the 7th day of gestation was significantly lower than that in the non-pregnant rat. Thereafter it increased, but values on the 14th, 17th and 21st days of gestation were not significantly different from those obtained in the non-pregnant rat. Net renal T3 generation from T4 on the 14th day was significantly lower than that in the non-pregnant rat. It was increased thereafter and the values at the 17th and 21st days of gestation were not significantly different from those in the non-pregnant rat. Net reverse T3 (rT3) generation from T4 in the placenta rose from the 14th to the 17th day and then dropped by the 21st day and the value at the 17th day was significantly higher than those at the 14th and 21st days of gestation. These results indicate that 1) both T4 outer-ring monodeiodination in the pregnant rat liver and kidney, and T4 inner-ring monodeiodination in the placenta show significant variation with the progress of gestation; 2) the time course of the T4 outer-ring monodeiodination in pregnant rat liver and kidney is completely different from T4 inner-ring monodeiodination in the placenta.

Animals↗
PubMed1984

Monodeiodination of thyroxine in the maternal and fetal dog kidneys and placenta.

We studied the monodeiodinating activities of the dog placenta and the pregnant dog kidney and compared them with those of the non-pregnant dog kidney and fetal kidney. Each tissue was homogenized in 50 mM Tris/HC1 buffer, pH 7.5. The homogenate (1 mg protein) was incubated with 1 microgram of T4 at 37 degrees C in the air for 15 min or 60 min in the presence of 5 mM DTT. The T3 and reverse T3 generated in the reaction mixture were extracted into cold ethanol and then measured by RIA. Sulfhydryl group content in each tissue was determined. The characteristics of monodeiodinating activity of the dog placenta were in good concordance with those of the rat and human placentas. Net reverse T3 production in the dog placenta was 1.4-13.2 (6.1 +/- 5.3, mean +/- S.D.) ng/mg protein/micrograms T4/60 min but net T3 production was negligible. Although it seemed that the T3 production/reverse T3 production ratio in the pregnant dog kidney was lower than that in the non-pregnant dog kidney, there was no statistical significance. It is conceivable that the characteristics of deiodination in the placenta are tissue specific, independent of the changes in internal conditions induced by pregnancy. In the fetal dog kidney homogenate, T3 and reverse T3 were metabolized only minimally and productions of T3 and reverse T3 were also very low. An increase in DTT concentration up to 100 mM had no effect on the production rates of these triiodothyronines . Total and non-protein SH group contents in the fetal dog kidney homogenate were about the half of those in the maternal tissue.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1984

Enhanced prolactin secretion in patients with primary hypothyroidism during thyroid replacement.

Thyroid hormones are known to exert some influence on prolactin (PRL) secretion indirectly via the hypothalamic dopaminergic system and directly at the level of pituitary gland. In order to study the effect of thyroid hormones on the activity of hypothalamic dopamine neurons, lactotrophs and thyrotrophs, we administered increasing doses of thyroid hormones to patients with primary hypothyroidism, and examined the changes of basal PRL, TSH and PRL responses to a dopamine receptor blocker (sulpiride). Among 24 patients with primary hypothyroidism, hyperprolactinemia was observed in 10 cases (18.0-236 ng/ml, mean +/- S.E. 58.6 +/- 20.0 ng/ml), while elevated TSH levels were observed in all of them (6.6-972 microU/ml, mean +/- S.E. 231.4 +/- 53.9 microU/ml). There was a significant negative relationship between plasma T3 or T4 levels and basal plasma TSH levels (p less than 0.05), whereas a poor correlation was observed between the thyroid hormones and basal plasma PRL levels (r = -0.25, p greater than 0.05). Following the administration of gradually increasing doses of thyroid hormones, plasma PRL showed paradoxical and transient increases, while plasma TSH decreased steadily. Plasma PRL response to sulpiride also became exaggerated during the treatment. The elevated basal PRL level and the enhanced response to sulpiride turned to be within the normal range when the patients became euthyroid by treatment. These results may indicate that thyroid hormones stimulate not only hypothalamic dopaminergic activity, but also the lactotroph activity in a long term hypothyroid state. Regarding the paradoxical elevation of basal PRL, one can postulate that the activation of lactotroph by a small dose of thyroid hormone may be able to overcome the hypothalamic dopaminergic inhibition.

Adult↗
PubMed1984

[Effect of elcatonin on experimental osteoporosis induced by ovariectomy and low calcium diet in beagles].

Effect of elcatonin, a synthesized analogue of eel calcitonin, on experimental osteoporosis in beagles induced by ovariectomy and a low calcium diet was studied. Twelve female beagles, 15-18 months old, were divided equally into 3 groups. The first group of beagles were ovariectomized and then fed a low calcium diet, Ca: 0.08%, (ovariectomy plus low Ca diet group); the second group was subjected to the same procedure and diet plus daily injection of elcatonin, 1.0 u/kg, i.m., (elcatonin group); and the third group was fed a standard diet, Ca: 1.36%, (control group) for 6 months. The undecalcified bone sections from the iliac crest were analyzed using histomorphometric methods following in vivo double labeling with Calcein. In the ovariectomy plus low Ca diet group, there were a decrease in trabecular bone volume and an increase in both resorption and formation surface of the trabeculae compared with the control group. These changes of trabecular bone volume and resorption surface were significantly prevented by daily injection of elcatonin. The increase of formation surface of trabeculae and mineral appositional rate was noted in the elcatonin group in comparison with the ovariectomy plus low Ca diet group. These results suggested that elcatonin could prevent bone loss caused by deficiency of sex hormone and dietary calcium.

Alkaline Phosphatase↗