Biomedical subjects

T Emoto

Publications and source records attributed to T Emoto.

At least 19 recordsLinked to original sources

PubMed1997

Simultaneous observation of endocrine and exocrine functions of the pancreas responding to somatostatin in man.

Six patients who underwent segmental autotransplantation of the caudal pancreas (SAT) following total pancreatectomy for pancreatic cancer were investigated. The graft was transplanted to the left groin, and pancreatic juice was diverted outside through a polyethylene tube indwelled into the main pancreatic duct. In these SAT patients, the responses of insulin (IRIS) in terms of plasma levels and pancreatic secretion to subcutaneous injections of somatostatin octreotide (Sandostatin: SMS201-995) were simultaneously observed. Four doses (0.039, 0.156, 0.625 and 2.5 micrograms/kg) of SMS201-995 were given on separate days. As a control, saline was injected subcutaneously. Standard liquid test meal was given 1 h after the subcutaneous injection. The basal plasma IRI were significantly decreased with doses greater than 0.156 microgram/kg. The postprandial responses of IRI was also significantly suppressed with the same doses. On the other hand, the basal pancreatic exocrine secretion was significantly suppressed with doses greater than 0.625 microgram/kg. The postprandial pancreatic exocrine secretion was also significantly suppressed with doses greater than 0.625 microgram/kg. Those suppressions were dose-dependent. The postprandial CCK secretion was also significantly suppressed in dose-dependent manner with SMS201-995. The CCK suppression was significantly correlated with the suppression of pancreatic exocrine secretion. This clinical study under the setting of SAT demonstrated not only the direct inhibitory effect of somatostatin on both the islet and acinar cells but also, probably, the indirect inhibitory effect on the acinal cells via suppression of CCK release in humans.

Aged↗

PubMed1997

Effects of amino acid replacements on cadmium binding of metallothionein alpha-fragment.

To evaluate whether only 20 cysteine residues at invariant positions are needed to bind and coordinate the metals in metallothioneins (MTs), and whether changing the positions of cysteine residues in the sequence affects the metal-binding capacity and the coordination of MTs, we examined the cadmium-binding affinities of seven mutant MT alpha s using an Escherichia coli expression system. Five mutant MT alpha s in which the constitutive amino acid residues other than cysteines of the alpha-fragment were replaced with glycine residues, and the remaining two mutant MT alpha s in which the invariant positions of the cysteine residues of the alpha-fragment were shifted, were analysed for their ability to be expressed as cadmium-binding forms and for their biochemical properties. The results showed that extreme alteration of the constitutive amino acid residues other than cysteines in the MT alpha-fragment leads to disruption of their cadmium-binding abilities and of their structure. However, mutant MT alpha s containing changes of the invariant positions of the cysteine residues were expressed in a cadmium-binding form in Escherichia coli, although the invariant positions of 20 cysteine residues in the MTs are thought to be important for their metal-binding abilities. These results suggest that the position of cysteine residues and the chemical nature of the other amino acids in the amino acid sequence of MTs are less critical than expected.

Amino Acid Sequence↗

PubMed1997

Restriction of cadmium transfer to eggs from laying hens exposed to cadmium.

The transfer of Cd to eggs of white Leghorn laying hens has been shown to be restricted. After Cd was injected ip into laying hens, the Cd concentrations in the blood, livers, ovaries, and eggs were measured. Although the Cd concentrations in the maternal blood and livers increased remarkably at certain levels of administrations, the Cd concentration in the yolks of eggs was not significantly increased, and was less than 0.04 microgram/g wet weight. After egg production stopped in the highest injected group (7.5 mg Cd/kg), Cd in the yolks of eggs had an accumulated range of 0.02-0.03 microgram/g wet weight. This was despite the high Cd accumulation in the liver. Furthermore, the Cd concentration in the follicle walls of the ovary increased and was 13- to 52-fold higher than in the follicle yolks. An additional experiment was conducted in order to estimate whether hatching success is affected by the Cd in the laid eggs of Cd-injected laying hens. The ratio of hatching success in the 0.3 or 1.2 micrograms Cd/egg-injected groups was similar to that in the saline-injected group, indicating that a small amount of Cd in the eggs might exert no marked influence on the hatching success. In conclusion, Cd transfer from laying hen to eggs was restricted after the maternal bird was exposed to Cd. Furthermore, Cd accumulates in the follicle walls of ovary. These results suggest that the follicle walls might play a role in protecting the follicle yolks against Cd toxicity.

Animals↗

PubMed1996

Roles of the conserved serines of metallothionein in cadmium binding.

The sequence of six amino acid residues -Ser-Cys-Cys-Ser-Cys-Cys- is present in all mammalian metallothionein sequences and has been highly conserved during evolution, although the metallothioneins have divergent primary sequences. To determine whether two serines in the sequence play a crucial role in metal-binding of metallothioneins, a mutant metallothionein with these two serines replaced by leucines was obtained using an Escherichia coli expression system. The expressed protein was analyzed for its chemical and spectroscopic properties. It was confirmed that the mutant metallothionein (MT) bound cadmium through a metal-thiolate complex and that there was no strong difference between the mutant and the wild-type MTs in retaining the metal-binding cluster. However, the metal-binding cluster of the mutant metallothionein was more unstable than that of the wild-type metallothionein. The two conservative serines could play a role in the stability of metal-binding ligands.

Amino Acid Sequence↗

PubMed1996

Independent self-assembly of cadmium-binding alpha-fragment of metallothionein in Escherichia coli without participation of beta-fragment.

We examined the independent self-assembly of the alpha- and beta-fragments of human metallothionein (MT) into cadmium-binding conformation in an Escherichia coli expression system, in addition to wild-type MT expression. The expressed alpha-fragment formed independently the structure of a metal-binding cluster without the aid of the beta-fragment. The alpha-fragment and wild-type MT expressed in E.coli were purified and analyzed for their biochemical and spectroscopic properties. The apparent cadmium binding of the alpha-fragment was approximately 12-fold greater than that for the wild-type MT, whereas in other respects the studied biochemical properties were similar. In contrast, we were unable to obtain any independently expressed beta-fragment as the cadmium-binding form in this study. Possible explanations for this phenomenon are discussed.

Amino Acid Sequence↗

PubMed1995

An effect of somatostatin on neurotensin secretion.

A somatostatin analog (SMS201-995) was administered subcutaneously to six totally pancreatectomized (TP) patients at five dose levels from 0 microgram/kg (control) to 2.5 micrograms/kg before ingestion of a liquid test meal, and plasma levels of neurotensin (NT) were measured. There were no significant differences in basal levels of NT between the doses of somatostatin. The NT levels were significantly elevated after ingestion of the test meal in the normal controls (n = 14). In the TP patients postprandial hypersecretion of NT was observed. The hypersecretion of NT in the patients was suppressed by SMS201-995 dose-dependently.

Adult↗

PubMed1995

Expression of human metallothionein-2 in Escherichia coli: cadmium tolerance of transformed cells.

A genetic approach was undertaken to investigate the physiological roles of human metallothionein-2. A constructed expression plasmid, pEXPMTII, in which human metallothionein-IIA cDNA was inserted downstream of a tryptophan-lactose promoter, was used to transform Escherichia coli JM105 strain. Cadmium-binding metallothionein was successfully expressed in E. coli in the medium containing cadmium, while copper and zinc-metallothioneins were scarcely observed in copper- or zinc-containing medium. The amino acid composition and sequence of the biosynthesized cadmium-metallothionein were analyzed. The selectivity of metals bound to metallothionein and the stability of metal-binding forms of metallothionein in E. coli were discussed. In addition, cadmium, zinc, or copper resistance of the cells expressing metallothionein was examined. Cells transformed with the plasmid pEXPMTII and cultured in a medium containing cadmium exhibited tolerance only to cadmium. It was demonstrated that human metallothionein-2 functioned for cadmium detoxification in E. coli.

Base Sequence↗

PubMed1992

[Identification of a 3' splice site mutation in the thyroglobulin gene in a case of congenital familial goiter].

A case of congenital familial goiter with impaired thyroglobulin (Tg) synthesis has been reported. The patient is the fifth in a family of six children, three of whom have a goiter. The parents are cousins. The patient's thyroid function tests showed low T4 (1.0 microgram g/dl) and free T4 (0.2 ng/dl), normal or slightly increased T3 (1.8 ng/ml) and free T3 (7.4 pg/ml), and high TSH (57 micrograms U/ml). Serum Tg was 5.1 ng/ml (normal less than 30). The thyroidal 123I-uptake was 59.8% before and 54.5% after perchlorate test. Gel filtration with Bio-Gel A 5m demonstrated the presence of albumin-like protein probably iodinated as a major protein in the thyroid and very low content of Tg which was smaller than the normal 19S Tg. Histologically microfollicular adenoma and negative Tg immunostaining were the dominant findings. Segregation of Tg alleles in the family was studied by Southern blotting with a probe revealing a diallelic RFLP. The results demonstrated that the affected siblings had received the same alleles from both parents and were homozygous for the RFLP. Northern blotting analysis of the goiter RNA with a Tg probe revealed that, whereas the amount of Tg mRNA was normal, its size seemed slightly reduced. PCR amplification of Tg mRNA as six overlapping cDNA fragments demonstrated that a 200bp fragment was missing from the 5' region of the goiter mRNA. Subcloning and sequencing of the cDNA fragments, and of the patient's genomic DNA amplified from this region, revealed that this aberrant splicing is due to a cytosine to guanine transversion at position minus 3 in the acceptor splice site of intron 3. The presence in exon 4 of a putative donor tyrosine residue (tyr 130) involved in thyroid hormone formation provides a coherent explanation of the hypothyroid status of the patient. To our knowledge, this is the first identified mutation responsible for congenital familial goiter in humans.

Adult↗

PubMed1992

Effects of inorganic iodide, epidermal growth factor and phorbol ester on hormone synthesis by porcine thyroid follicles cultured in suspension.

Porcine thyroid follicles cultured in suspension for 96 h synthesized and secreted thyroid hormones in the presence of thyrotropin (TSH). The secretion of newly synthesized hormones was assessed by determining the contents of thyroxine (T4) and triiodothyronine (T3) in the media and by paperchromatographic analysis of 125I-labelled hormones in the media where the follicles were cultured in the presence and absence of inhibitors of hormone synthesis. The hormone synthesis and secretion was modified by exogenously added NaI (0.1-100 microM). The maximal response was obtained at 1 microM. Thyroid peroxidase (TPO) activity in the cultured follicles with TSH for 96 h was dose-dependently inhibited by NaI. One hundred microM of NaI completely inhibited TSH-induced TPO activity. Moreover, both epidermal growth factor (EGF: 10(-9) and 10(-8) M) and phorbol 12-myristate 13-acetate (PMA: 10(-8) and 10(-7) M) inhibited de novo hormone synthesis. An induction of TPO activity by TSH was also inhibited by either agent. These data provide direct evidences that thyroid hormone synthesis is regulated by NaI as well as TSH at least in part via regulation of TPO activity and also that both EGF and PMA are inhibitory on thyroid hormone formation.

Animals↗

PubMed1992

Effects of epidermal growth factor, phorbol ester, and retinoic acid on hormone synthesis and morphology in porcine thyroid follicles cultured in collagen gel.

Epidermal growth factor (EGF), phorbol esters (PEs), and retinoic acid (RA) inhibit differentiated functions of thyrocytes. In the present study the inhibitory effects of these growth-promoting factors on hormone synthesis were studied in thyroid follicles cultured in type-I collagen gel, and morphologic alteration by these factors was examined by light and electron microscopy (EM). Porcine open thyroid follicles obtained by treatment with 0.1% collagenase were embedded in collagen gel and cultured in Ham's F12 medium supplemented with 6H (insulin, hydrocortisone, somatostatin, transferrin, glycyl-his-lys, and thyrotropin) + 0.5% fetal bovine serum (FBS). After 1 week these open follicles developed to closed follicles, and the medium was changed to one containing 6H + 0.5% FBS + 0.1 microM sodium iodide (NaI). Some media were supplemented with either EGF, phorbol 12-myristate 13-acetate (PMA), or all-trans RA. The closed follicles retained ability for hormone synthesis for 2 weeks after the medium change in the presence of 6H + FBS + NaI. The amounts of T4 and T3 secreted into the culture medium from day 9 to day 12 after the medium change were 60% and 45% of those from day 0 to day 4, respectively. EGF reduced production of T4 and T3 by 61% and 69%, respectively; PMA, by 87% and 99%; and RA, by 55% and 44%. In the medium supplemented with 6H + 0.5% FBS, the follicles exhibited intact polarity. Apical surfaces with microvilli were oriented to the follicular lumen and tight junctions were on the apical side of cell-to-cell contacts. Desmosomes were found on both the apical and basal halves of the cell contacts.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1991

Elevation of plasma endothelin concentrations during endotoxin shock in dogs.

The effect of endotoxin on the release of endothelin, a novel potent vasoconstrictor peptide, was examined in anesthetized dogs and in cultured endothelial cells. Administration of 2.63 mg lipopolysaccharide, E. coli 0111:B4/kg body weight caused shock in the animals and produced a long-lasting increase in the plasma immunoreactive endothelin-1 level that remained higher than the basal level (1.83 pg/ml as mean level) from 30 to 120 min after the injection, with a peak at 90 min (8.15 pg/ml as mean level). In vitro immunoreactive endothelin-1 in a culture medium, in which calf pulmonary artery endothelial cells were incubated in the presence of 10% fetal bovine serum, increased dose dependently with the concentration of added lipopolysaccharide between 0.01 and 10 micrograms/ml. These data indicate that plasma endothelin increases during endotoxin shock and that stimulation by endotoxin, per se, in the presence of serum participates at least partially in the mechanism for its release.

Adrenocorticotropic Hormone↗

PubMed1991

Effect of glucose and insulin on immunoreactive endothelin-1 release from cultured porcine aortic endothelial cells.

We measured the release of immunoreactive endothelin-1 (IR-ET-1) by cultured porcine aortic endothelial cells under normoglycemic (5.5 mmol/L) and hyperglycemic (27.5 and 55 mmol/L) conditions. Compared with cells incubated in the presence of a normal glucose concentration, cells incubated in 27.5 mmol/L glucose medium released 52% less IR-ET-1, and those incubated in 55 mmol/L glucose medium released 54% less IR-ET-1. The observed effects of elevated glucose on IR-ET-1 release were both sugar-specific and not due to increased osmolarity. Fetal calf serum (FCS)-stimulated IR-ET-1 release in the presence of elevated glucose was also less than that in the presence of a normal glucose concentration. In addition, the effects of two hormones, insulin and insulin-like growth factor 1 (IGF-1), on IR-ET-1 release were examined. Both insulin and IGF-1 dose-dependently stimulated IR-ET-1 release. Twenty micrograms/mL insulin and 10(-8) mol/L IGF-1 increased IR-ET-1 release by 38% and by 44%, respectively. These results indicate that hyperglycemic condition results in reduction of IR-ET-1 release from cultured porcine aortic endothelial cells and that insulin and IGF-1 stimulate its release. The possible relevance of these observations to physiological regulation of ET-1 release in vivo and pathological processes in diabetes remains to be established.

Animals↗

PubMed1991

Abnormal copper accumulation in non-cancerous and cancerous liver tissues of LEC rats developing hereditary hepatitis and spontaneous hepatoma.

We studied the copper concentrations in the non-cancerous and cancerous liver tissues of LEC rats with hereditary hepatitis and spontaneous hepatoma by atomic absorption spectrophotometry. Copper concentration in the non-cancerous livers of 29-month-old male LEC rats was comparable to that in the livers of LEC rats aged 2, 3 and 8 months whose hepatic copper concentrations were more than 40 times those of normal LEA rats. Copper concentration in spontaneously developed hepatocellular carcinomas of the 29-month-old male LEC rats was lower than that in the surrounding non-cancerous liver tissues, but was still more than 39 times that of 8-month-old male LEA rats. These findings suggest that in LEC rats an abnormal copper metabolism may be maintained during the process of hepatic carcinogenesis.

Age Factors↗

PubMed1991

Spontaneous hepatic copper accumulation in Long-Evans Cinnamon rats with hereditary hepatitis. A model of Wilson's disease.

Long-Evans Cinnamon (LEC) rats, an inbred strain of a mutant rat isolated from Long-Evans rats, develop hereditary hepatitis. To elucidate the role of copper metabolism in the development of the hepatitis in LEC rats, we examined the copper concentration in the tissues and serum levels of copper and ceruloplasmin. Copper concentration in the liver of LEC rats was over 40 times that of normal Long-Evans Agouti (LEA) rats, while the serum ceruloplasmin and copper concentrations in LEC rats decreased significantly. The hepatocytes of LEC rats show steatosis in cytoplasm and pleomorphism of mitochondria, resembling the histologic features of the liver in Wilson's disease. These findings suggest that the hereditary hepatitis in LEC rats is closely associated with copper toxicity, and may be dealing with a rat form of Wilson's disease. Thus the LEC rats will provide a unique and useful animal model for clarifying the mechanism and for developing treatment strategies for Wilson's disease and other abnormal copper metabolism in humans.

Animals↗

PubMed1990

Immunoreactive endothelin concentrations in maternal and fetal blood.

Immunoreactive-endothelin (ir-ET) concentrations were determined in peripheral maternal blood and in umbilical cord blood just after delivery. The concentrations in both the umbilical artery (2.83 +/- 1.36 pmol/l plasma, Mean +/- SD) and vein (3.37 +/- 1.53 pmol/l) were significantly higher than those found in maternal venous blood (1.43 +/- 1.02 pmol/l). On the other hand, ir-ET levels in maternal blood were not significantly different when compared with those found in non-pregnant women (1.50 +/- 0.83 pmol/l). No significant difference of ir-ET levels between the umbilical artery and vein was observed. A highly significant correlation (r = 0.60, p less than 0.01) of ir-ET levels between the umbilical artery and vein was observed. Also, a significant correlation (r = 0.48, p less than 0.01) between umbilical vein and maternal vein ir-ET levels with a weaker correlation (r = 0.36, p less than 0.05) between umbilical artery and maternal vein ir-ET levels was demonstrated. The present study indicates that ir-ET may be actively secreted in fetal circulation and the plasma levels in maternal and fetal circulation may have a possible relation.

Adult↗

PubMed1990

Inhibition by protein kinase-C inhibitor and cycloheximide of phorbol ester- and epidermal growth factor-induced arachidonic acid metabolism in cultured porcine thyroid cells.

In an attempt to elucidate possible mechanism(s) for stimulated arachidonic acid metabolism by phorbol 12-myristate 13-acetate (PMA) and epidermal growth factor (EGF) in porcine thyroid cells, we examined the effects of protein kinase inhibitors, isoquinolinesulfonamide derivatives (H-7 and HA-1004), and cycloheximide. The production of PGE2 stimulated by either PMA or EGF was strongly inhibited by H-7, with an ID50 value of approximately 20 to 25 mumol/L in each case, as well as by cycloheximide, with an ID50 value of less than 0.5 micrograms/mL in each case. In contrast, 100 mumol/L of HA-1004 showed less inhibition of PGE2 production provocated by either PMA or EGF. On the other hand, PGE2 production in basal or stimulated condition by exogenously added arachidonic acid, was inhibited to an even lesser extent by both H-7 and cycloheximide. The EGF- and PMA-stimulated release of 3H-arachidonic acid from the cells was also strongly inhibited by H-7 and cycloheximide. These results suggest an induction of synthesis of some proteins responsible for the release of arachidonic acid, which might be attributed to protein kinase-C activation in arachidonic acid metabolism stimulated by PMA or EGF. Moreover, PGE2 production was potently induced by PMA and slightly by EGF in the cyclooxygenase-inactivated cells by acetyl salicylate pretreatment, which also suggests that both agents might induce the synthesis of cyclooxygenase in cultured porcine thyroid cells, although we did not measure its activity.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗

PubMed1990

Presence of high affinity receptor for interleukin-1 (IL-1) on cultured porcine thyroid cells.

Using 125I-interleukin-1 beta (125I-IL-1 beta) as a ligand, a specific receptor of high affinity dissociation constant (1.1 +/- 0.2 x 10(-10) M) with binding sites (350 +/- 40/cell) for interleukin-1 beta (IL-1 beta) has been demonstrated on cultured porcine thyroid cells. IL-1 alpha almost equally cross-reacted with the receptor (Kd = 1.2 +/- 0.3 x 10(-10) M and 350 +/- 50 binding sites/cell). TSH, IL-2 and other peptide hormones did not inhibit the binding of 125I-IL-1 beta to thyroid cells. Crosslinking study revealed a major band (approximately 95 kD) with a corrected molecular mass of approximately 78 kD. Moreover, both IL-1 beta and IL-1 alpha stimulated prostaglandin E2 production of cultured porcine thyroid cells, although the potency of IL-1 alpha was slightly greater than that of IL-1 beta. These results suggest that IL-1 may be involved in the regulation of thyroid cell function.

Animals↗

PubMed1990

[Hepatocellular carcinoma with extrahepatic malignancies].

A clinical investigation of 16 hepatocellular carcinoma (HCC) patients with extrahepatic malignancies (13 male, 3 female) has been conducted. The age of these patients ranged from 55 to 76 years. Three of these double cancer cases were hemocronous, and 13 were heterochronous. The duration between the occurrence of the cancers ranged from 2 years and 4 months to 22 years. As for the site of the other cancer, the stomach was the most common organ (12 cases). In nine cases out of 16, the HCC was resected, whereas the other cases were treated with a TAE and hepatic artery ligation because the cancer were far advanced stages. Early detection of an HCC by AFP or an ultrasonographic examination, and a subsequent surgical resection in cases of a postoperative cancer patient with a liver dysfunction may lead to a more favorable prognosis.

Aged↗