Search PubMed⌕ Search

Biomedical subjects

T Yoshimasa

Publications and source records attributed to T Yoshimasa.

84 records · Page 5Linked to original sources
PubMed1983

Occurrence of methionine-enkephalin-Arg6-Gly7-Leu8 with methionine-enkephalin, leucine-enkephalin and methionine-enkephalin-Arg6-Phe7 in human gastric antrum.

Recent studies on the nucleotide sequence of cloned DNA complementary to mRNA for preproenkephalin from bovine adrenal medulla and human pheochromocytoma have revealed that this precursor molecule contains four copies of methionine-enkephalin (Met-Enk) and one copy each of leucine-enkephalin (Leu-Enk), methionine-enkephalin-Arg6-Gly7-Leu8 (Met-Enk-Arg6-Gly7-Leu8) and methionine-enkephalin-Arg6-Phe7 (Met-Enk-Arg6-Phe7). We have demonstrated the existence of Met-Enk-Arg6-Gly7-Leu8 together with Met-Enk, Leu-Enk and Met-Enk-Arg6-Phe7 in human gastric antrum, using high performance liquid chromatography (HPLC) coupled with radioimmunoassays for these opioid peptides. The ratio of molar concentrations of these peptides in human gastric antrum is similar to the ratio of these peptides contained in preproenkephalin. Furthermore, gel filtration studies on Sephadex G-50 showed that most of immunoreactivities of these peptides were eluted at the elution position of each synthetic peptide without any detectable immunoreactivities at high molecular weight positions. These results indicate the presence of Met-Enk-Arg6-Gly7-Leu8 together with Met-Enk, Leu-Enk and Met-Enk-Arg6-Phe7 in human gastric antrum and further suggest that these opioid peptides are derived from the same preproenkephalin as that in the adrenal medulla and that the processing of preproenkephalin is almost complete in the gut.

Adult↗
PubMed1983

gamma 1-Melanotropin-like immunoreactivity in bovine and human adrenocorticotropin-producing tissues.

gamma 1 MSH-like immunoreactivity in bovine pituitary glands, hypothalami, human pituitary glands, ectopic ACTH-producing tumors, and human gastric antral mucosa was investigated using a newly developed RIA for gamma 1 MSH. The minimum detectable quantity of gamma 1 MSH was 3 pg/tube, and the antibody did not cross-react with gamma 2 MSH, gamma 3 MSH, alpha MSH, beta MSH, ACTH, beta-lipotropin, or beta-endorphin. Bovine anterior pituitary, intermediate-posterior pituitary, and hypothalamus contained more than two molecular weight forms of gamma 1 MSH-like immunoreactivities. On the other hand, gamma 1 MSH-like immunoreactivity was not detected in human pituitary glands or human gastric antral mucosa, but was detected in one of seven ectopic ACTH-producing tumors. These results suggest a limited processing of the ACTH-beta-lipotropin precursor to gamma 1 MSH in human tissues, although a rapid degradation of gamma 1 MSH could not be ruled out completely.

Adrenocorticotropic Hormone↗
PubMed1983

Plasma methionine-enkephalin and leucine-enkephalin in normal subjects and patients with pheochromocytoma.

Plasma methionine-enkephalin-like and leucine-enkephalin-like immunoreactivity (met-enkephalin-LI and leu-enkephalin-LI, respectively) in six normal subjects and six patients with pheochromocytoma were determined. The contents of met-enkephalin-LI and leu-enkephalin-LI in two of six pheochromocytomas were 40- to 50-fold higher and those in the other four pheochromocytomas were less than those in normal human adrenal medulla. The former two patients showed high plasma met-enkephalin-LI and leu-enkephalin-LI levels. As plasma catecholamines levels returned to the normal range after extirpation of tumors, met-enkephalin-LI and leu-enkephalin-LI in plasma became undetectable in these patients. In contrast, neither met-enkephalin-LI nor leu-enkephalin-LI was detected in plasma from the latter four patients. Met-enkephalin-LI and leu-enkephalin-LI concentrations were higher in the adrenal vein than in the peripheral vein in three patients. Plasma met-enkephalin-LI and leu-enkephalin-LI increased concomitantly with catecholamines after glucagon stimulation and during a spontaneous attack in a patient with pheochromocytoma. Plasma met-enkephalin-LI changed in parallel with leu-enkephalin-LI in all cases. High performance liquid chromatography coupled with RIAs has shown that met-enkephalin and leu-enkephalin circulate in plasma from a patient with pheochromocytoma as intact pentapeptides. None of normal subjects showed detectable concentrations of met-enkephalin-LI and leu-enkephalin-LI in plasma (more than 5 pg/ml and 3 pg/ml, respectively). It is concluded that met-enkephalin and leu-enkephalin are released concomitantly with catecholamines from pheochromocytomas.

Adrenal Gland Neoplasms↗
PubMed1983

Immunocytochemical demonstration of the co-storage of noradrenaline with Met-enkephalin-Arg6-Phe7 and Met-enkephalin-Arg6-Gly7-Leu8 in the carotid body chief cells of the dog.

Cellular and ultrastructural localization of catecholamines in the dog carotid body was investigated by peroxidase-antiperoxidase method for light microscopy and by protein A-colloidal gold technique for electron microscopy, and compared with that of preproenkephalin A-related opioid peptides, i.e., Met-enkephalin-Arg6-Phe7 (Met-Enk-Arg-Phe) and Met-enkephalin-Arg6-Gly7-Leu8 (Met-Enk-Arg-Gly-Leu). Immunocytochemistry at the light microscopic level using consecutive semi-thin sections of Araldite-embedded tissue showed that some 30% of the chief cells contained immunoreactive noradrenaline together with Met-Enk-Arg-Phe and Met-Enk-Arg-Gly-Leu. A considerable number of chief cells exhibited immunoreactivities representing one or two of these three kinds of substances. A few chief cells showed none of the specific immunoreactivities. Immunoreactive adrenaline was not demonstrated in any cells of the dog carotid body. At the electron microscopic level, co-existence of noradrenaline with Met-Enk-Arg-Phe or Met-Enk-Arg-Gly-Leu in the same secretory granules was shown using the double labeling protein A-colloidal gold technique. Possible interactions of catecholamines and opioid peptides deserve consideration for the understanding of the chief cell's role in the carotid body chemoreceptor.

Adrenal Medulla↗
PubMed1982

Methionine-enkephalin and leucine-enkephalin in human sympathoadrenal system and pheochromocytoma.

To elucidate the physiological and pathophysiological significance of methionine- and leucine-enkephalin (Met-and Leu-enkephalin, respectively) in human sympathoadrenal system, the contents of these peptides in normal human sympathetic nervous system, adrenal medulla, and pheochromocytomas were determined by specific radioimmunoassays combined with reverse-phase high-performance liquid chromatography. Met-enkephalin-LI and Leu-enkephalin-LI, respectively) were detected by radioimmunoassay in adrenal glands, adrenal medulla, stellate ganglia, sympathetic trunks, and celiac ganglia, and their contents in adrenal medulla were highest. Existence of authentic Met- and Leu-enkephalin was confirmed by reverse-phase high-performance liquid chromatography. Met-enkephalin was approximately 74% of Met-enkephalin-LI, whereas Leu-enkephalin was approximately 30% of Leu-enkephalin-LI in human adrenal medulla. The ratio of Met- to Leu-enkephalin was 2.6 in human adrenal medulla, whereas it was higher in sympathetic ganglia or trunks. In four cases of pheochromocytoma marked difference in Met- and Leu-enkephalin contents was found between medullary and extramedullary tumors. The contents were about three orders higher and the Met- to Leu-enkephalin ratio was lower in medullary than in extramedullary pheochromocytomas, reflecting the tissues where the tumors arose. These results suggest the physiological roles of Met- and Leu-enkephalin in sympathetic nervous system and adrenal glands and their pathophysiological significances in pheochromocytomas.

Adrenal Gland Neoplasms↗
PubMed1981

Presence of dynorphin-like immunoreactivity in rat pituitary gland and hypothalamus.

Using a highly specific and sensitive radioimmunoassay for dynorphin(1-13), dynorphin-like immunoreactivity (dynorphin-LI) was detected in rat pituitary and hypothalamus. Gel chromatographic studies on Sephadex G-50 revealed three components of dynorphin-LI with molecular weights of approximately 7500-9500 (big dynorphin), 3500-5500 (intermediate dynorphin) and 1600-1900 (small dynorphin), the latter of which eluted at the same position as authentic dynorphin contamination in porcine ACTH extracts (Sigma). Dynorphin-LI in rat anterior pituitary existed mainly as big dynorphin, whereas dynorphin-LI in rat intermediate-posterior pituitary and hypothalamus eluted mainly at the position of authentic small dynorphin.

Animals↗
PubMed1981

Presence of dynorphin-like immunoreactivity in pheochromocytomas.

Using a highly specific and sensitive radioimmunoassay for dynorphin(1-13), dynorphin-like immunoreactivity (dynorphin-LI) was detected in two extramedullary pheochromocytomas and a medullary pheochromocytoma. The contents of dynorphin-LI of two extramedullary and a medullary tumors were 9.2, 2.2, and 34.0 pmole/g, respectively. Gel chromatographic studies of tumor extracts on Sephadex G-50 revealed a peak of dynorphin-LI eluting at the same position as dynorphin-LI contaminated in porcine ACTH extract (Sigma) and another portion of dynorphin-LI eluting in a range of molecular weights larger than that of dynorphin-LI in porcine ACTH extract. These results indicate the presence of dynorphin and possibly its precursor peptide(s) in pheochromocytoma.

Adrenal Gland Neoplasms↗
PubMedDate not supplied

Big form of gamma-melanotropin-like immunoreactivity in normal human plasma.

Using a radioimmunoassay for gamma 3-melanotropin (gamma 3-MSH), gamma-melanotropin-like immunoreactivity (gamma-MSH-LI) was detected in plasma extracts of normal subjects before and after metyrapone administration. Plasma gamma-MSH-LI from four normal men rose significantly after a single oral administration of metyrapone (30 mg/kg of body weight). Gel chromatographic study of plasma extract after metyrapone administration showed a single peak of gamma-MSH-LI near the elution position of mouse 16K fragment, however smaller forms of gamma-MSH-LI were not detected.

Adrenocorticotropic Hormone↗
PubMedDate not supplied

Immunohistochemical localization of Met-enkephalin, Met-enkephalin-Arg6-Gly7-Leu8, Met-enkephalin-Arg6-Phe7 and Leu-enkephalin in human adrenal medulla and pheochromocytomas.

Immunohistochemical localization of Met-enkephalin, Met-enkephalin-Arg6-Gly7-Leu8, Met-enkephalin-Arg6-Phe7 and Leu-enkephalin was studied in human adrenal medulla and pheochromocytomas at the light and electron microscopic levels. Both adrenal medulla and pheochromocytomas (4 adrenal, 1 extra-adrenal) showed scattered or clustered cells which contained all of the above peptides and suggested the production of proenkephalin A. The presence of these peptides predominantly in the secretory granules suggested that proenkephalin A is processed to final products mainly in the secretory granules. The localization of Met-enkephalin-Arg6-Gly7-Leu8 and Met-enkephalin-Arg6-Phe7 in cisternae of rough endoplasmic reticula indicated their actual production in pheochromocytomas.

Adrenal Gland Neoplasms↗
PubMedDate not supplied

Cross-talk between cellular signalling pathways suggested by phorbol-ester-induced adenylate cyclase phosphorylation.

Receptor-mediated activation of both adenylate cyclase and phosphatidylinositide hydrolysis systems occurs through guanine nucleotide regulatory proteins and ultimately leads to specific activation of either cyclic AMP-dependent protein kinase A or Ca2+/phospholipid-dependent protein kinase C. Given the remarkable diversity of agents that influence cellular metabolism through these pathways and the similarities of their components, interactions between the two signalling systems could occur. In fact, stimulation of cells with 12-O-tetradecanoyl phorbol-13-acetate (TPA), a phorbol ester that activates protein kinase C, influences hormone-sensitive adenylate cyclase. In some cells TPA induces desensitization of receptor-mediated stimulation of adenylate cyclase, whereas in others, such as frog erythrocytes, phorbol ester treatment results in increased agonist-stimulated as well as basal, guanine nucleotide- and fluoride ion-stimulated adenylate cyclase activities. We show here that TPA produces phosphorylation of the catalytic unit of adenylate cyclase in frog erythrocytes. Moreover, purified protein kinase C can directly phosphorylate in vitro the catalytic unit of adenylate cyclase purified from bovine brain. These results suggest that phosphorylation of the catalytic unit of adenylate cyclase by protein kinase C may be involved in the phorbol ester-induced enhancement of adenylate cyclase activity. In addition to providing the first direct demonstration of a covalent modification of the catalytic unit of adenylate cyclase, these results provide a potential biochemical mechanism for a regulatory link between the two major transmembrane signalling systems.

Adenylyl Cyclases↗