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Biomedical subjects

M Itoh

Publications and source records attributed to M Itoh.

At least 1,099 records · Page 61Linked to original sources
PubMed1982

Dopaminergic suppression of pancreatic somatostatin secretion.

To characterize dopaminergic influences on pancreatic islet D cell function and its potential interaction with islet A and B cell function, the effect of dopamine (0.5-100 micro M) on immunoreactive somatostatin (IRS), insulin (IRI), and glucagon (IRG) release from rat islets incubated in vitro was studied. Dopamine significantly suppressed the release of IRS (P less than 0.001) and IRI (P less than 0.001) and augmented IRG release (P less than 0.001). Maximum suppression of IRS and IRI release was evident at 20 micro M dopamine with half-maximal suppression occurring at 0.5-1 micro M. Maximal stimulation of IRG release was observed at 100 micro M dopamine with a half-maximal response occurring at 5-10 micro M. Suppression of IRS secretion by dopamine (20 micro M) was completely reversed by the dopaminergic antagonists haloperidol (5 micro M) and pimozide (5 micro M) but was only partially reversed by the alpha adrenergic antagonist phentolamine (2 micro M), and was further suppressed by the beta adrenergic antagonist phentolamine (2 micro M). Suppression of IRI release by dopamine was completely reversed by propranolol, but was unaffected by haloperidol, pimozide, and phentolamine. There results indicate that dopamine directly affects pancreatic islet D cell function, and that islet B and D cells appear to be more sensitive to dopamine than are A cells. Dopamine suppresses IRS secretion predominantly through activation of dopaminergic receptors, whereas it suppresses IRI release through an alpha adrenergic mechanism and stimulates IRG release through a beta adrenergic mechanism.

Adrenergic alpha-Antagonists↗
PubMed1982

[Studies on acid glycosaminoglycans in rabbit uterine cervix and body (author's transl)].

We aimed to identified cervical ripening at term pregnancy by measuring acid glycosaminoglycans (aGAG) in nonpregnant and immediately postpartum rabbits cervix and body. aGAG was extracted from the uterine tissues by the modified method of K. Anno (1964) and determined by the carbazole method (Bitter, 1962). Components of aGAG were separated by two dimensional electrophoresis (0.1M pyridine-0.47M formic acid in the first and 0.1M calcium acetate buffer in the second) using acetate cellulose strips. aGAG were separated five spots that were identified hyaluronic acid, heparan sulfate, chondroitin sulfate A, dermatan sulfate and chondroitin sulfate C. These results were confirmed by method of hyaluronidase, chondroitinase AC and ABC digestion test.

Animals↗
PubMed1981

Nucleotide sequences of mouse genomic loci including a gene or pseudogene for U6 (4.8S) nuclear RNA.

We have isolated four clones which hybridize with U6 (4.8S) nuclear RNA, a mammalian small nuclear RNA(nRNA), from DNA of BALB/C mouse liver. Their restriction maps are totally different from each other, indicating that they derived from different loci in the mouse genome. The nucleotide sequences around the hybridizing region in the three clones have been determined. One clone gives a gene that is co-linear with the U6 RNA. There is a sequence TATAAAT beginning 31 nucleotides upstream of the gene, which may suggest that the U6 RNA is transcribed by RNA polymerase II. The other two clones contain a pseudogene for the U6 RNA which has 7 or 9 nucleotide changes from the RNA. The pseudogenes are surrounded by radically different sequences from those surrounding the gene, and they are closely linked to a pseudogene for another snRNA, 4.5S-I RNA, or a part of highly repetitive an interspersed sequence B1.

Animals↗
PubMed1981

Predominant T3 synthesis in the metastatic thyroid carcinoma in a patient with T3-toxicosis.

A metastatic mixed papillary and follicular thyroid carcinoma synthesizing predominantly triiodothyronine (T3) producing thyrotoxicosis is described. There was a concentration of 131I in numerous masses on the lung as well as a mass in the neck. BMR was +38%. Serum T4, T3-RU and T3 were 6.6 microgram/100 ml, 35.1% and 9.0 ng/ml, respectively. Serum TSH was not detectable and was not increased by the injection of 500 microgram of synthetic TRH. Decompressive surgery, performed while the patient was receiving no thyroid medication, yielded tumor tissue for chemical analysis. The mass measured 4.5 cm X 4.0 cm X 3.0 cm. The normal thyroid tissue was found to be atrophic. Sedimentation pattern of the soluble protein revealed a small peak at 18 S without a 27 S peak, suggesting an accelerated hydrolysis of thyroglobulin (Tg). Both the Tg content of the tumor and the degree of iodination of the Tg were low, 0.53% (based on wet weight of tissue) and 0.07%, respectively. DIT-I, MIT-I, T4-I, and T3-I in hydrolysate of the tumor tissue were 17.8%, 29.1%, 7.1%, and 41.7%, respectively. Therefore, the high T3 in the serum in this case seems to arise mainly from the cancer tissue. Possible mechanisms for this predominant T3 production are discussed.

Adenocarcinoma↗
PubMed1981

Novel models for RNA splicing that involve a small nuclear RNA.

Nucleotide sequences of mammalian small nuclear RNAs (snRNAs) have been analyzed with a computer program for complementarity with sequences around a splice junction of various eukaryotic mRNA precursors (pre-mRNAs). A region in U2 RNA or some other snRNAs can form base pairs with both exons surrounding an intron of certain pre-mRNAs and, thereby, can align the two junctions leading to correct splicing of the pre-mRNA. These findings suggest that a snRNA such as U2 can be involved in splicing certain pre-mRNAs by pairing with exons, which we we call an "exon model" for splicing, as compared with the model involving U1 RNA presented by Lerner et al. [Lerner, M. R., Boyle, J. A., Mount, S. M., Wolin, S. L. & Steitz, J. A. (1980) Nature (London) 283, 220-224]. We constructed a secondary structure model of U1 RNA and studied the capacity of base pairing with pre-mRNAs on the basis of both primary and secondary structures of U1 RNA. We present an alternative model for splicing that involves U1 RNA, which assumes base pairing of noncontiguous regions of U1 RNA with an intron of a pre-mRNA. Pairing of an snRNA with exons could explain correct matching of the two junctions that bound one and the same intron, which is not explained by pairing with consensus sequences at the ends of an intron as proposed by Lerner et al. Pairing of an intron with U1 RNA and pairing of the surrounding exons with another snRNA such as U2 RNA could take place at the same time to insure specificity of splicing.

Animals↗
PubMed1981

Metabolic detoxication of bis-(2-hydroxy-3, 5-dichlorophenyl)-sulfoxide in man.

The metabolic detoxication of bis(2-hydroxy-3, 5-dichlorophenyl)sulfoxide (BTS) in man was investigated. Bis(2-hydroxy-3, 5-dichlorophenyl)sulfide (BT) was identified in beta-glucuronidase treated urine following the administration of BTS by thin-layer chromatography, gas chromatography, ultraviolet spectrum and quantitative analysis. No other metabolites were detectable. BT-glucuronide was also identified in urine. It was assumed that BTS was reduced to BT and successively conjugated with glucuronide in man, and excreted as BT-glucuronide in the urine.

Antiplatyhelmintic Agents↗