Search PubMed⌕ Search

Biomedical subjects

M Hirota

Publications and source records attributed to M Hirota.

At least 217 records · Page 12Linked to original sources
PubMed1987

Effect of exercise training on insulin and glucagon release from perfused rat pancreas.

The effect of physical training on insulin and glucagon release in perfused rat pancreas was examined in the spontaneously exercised group running in a wheel cage an average of 1.4 km/day for 3 weeks and in the sedentary control group kept in the cage whose rotatory wheel was fixed on purpose. Pancreatic immunoreactive insulin (IRI) responses to glucose and arginine were reduced by 28% and 47.8% respectively in trained rats compared with untrained rats, while IRI content of the pancreas was similar in these two groups. The demonstrated decrease in insulin secretion of the beta-cell of the trained rats, in response to the glucose and arginine stimulations, may be functional in nature. On the other hand, neither pancreatic glucagon immunoreactivity (GI) response to glucose and arginine nor GI content of the pancreas was modified by exercise training. These results demonstrate that exercise training reduces IRI responses to glucose as well as to arginine stimulations, but does not modify any secretory response of pancreatic GI.

Animals↗
PubMed1987

Identification and localization of glucagon-like peptide-1 and its receptor in rat brain.

The existence and distribution of glucagon-like peptide-1 (GLP-1) and its receptor in rat brain in relation to that of glucagon were examined. The concentration of GLP-1 immunoreactivity (GLP-1-IR), measured by a specific and sensitive RIA established in this study with anti GLP-1 serum (LMT-01), was found to be highest in the thalamus-hypothalamus, followed by the medulla oblongata. The distribution of glucagon-like immunoreactivity was similar to that of GLP-1-IR. However, appreciable glucagon immunoreactivity was detected only in the thalamus-hypothalamus. Gel filtration analysis showed the presence of GLP-1-IR of various molecular weights in the extract of thalamus-hypothalamus including that eluted at the same position as synthetic GLP-1 (1-37); moreover, HPLC analysis also confirmed the presence of GLP-1-IR, eluted at the exact position as synthetic GLP-1 (1-37). The distribution of receptors for GLP-1 corresponded with that of GLP-1-IR in the rat brain, except in the pituitary gland. The distribution of these receptors was also similar to that of glucagon receptors. The thalamus-hypothalamus, pituitary gland, and medulla oblongata were rich in GLP-1 and glucagon-binding sites. The binding affinities of GLP-1 and glucagon were in the nanomolar range [disocciation constant Kd approximately equal to 4 nM]. The presence of specific, high affinity receptors for GLP-1 was confirmed by demonstrating that GLP-1 stimulated cAMP formation in the thalamus-hypothalamus and the pituitary gland. The concentration of GLP-1 required for half-maximal stimulation of cAMP formation in these regions was about 1 nM. These results suggest that GLP-1 may be synthesized in certain parts of the brain and play a role as a neurosignal transmitter.

Animals↗
PubMed1987

Release of glucagon-like peptide 1 immunoreactivity from the perfused rat pancreas.

A reliable radioimmunoassay for glucagon-like peptide 1 (GLP-1) was developed with a detection limit of 12 pmol/l, which enabled us to detect the subtle change in concentrations of this peptide in the perfusate from the perfused rat pancreas. With this RIA, GLP-1 immunoreactivity (GLP-1 IR) was found to be secreted synchronously with glucagon immunoreactivity upon arginine stimulation from the perfused rat pancreas. Gel chromatographic analysis showed the presence of GLP-1 IR in the pancreatic extract which is eluted at the same position as synthetic GLP-1 (1-37). Moreover HPLC analysis confirmed the presence of GLP-1 IR, which eluted at exactly the same position as synthetic GLP-1, in the perfusate from pancreas perfusion upon stimulation of arginine. These results suggest that the pancreas stores and secrets GLP-1 IR concomitantly with glucagon as one of the cleavage products of their common precursor.

Animals↗
PubMed1987

Detection of ganglioside GM2 in sera and tumor tissues of hepatoma patients.

GM2 ganglioside was detected in all five sera of hepatoma patients analyzed by thin-layer chromatography in conjunction with enzyme-immunostaining with rabbit anti-GM2 antibody and horseradish peroxidase-conjugated anti-rabbit IgG, and was quantitated by densitometry. The GM2 contents of these sera were 20 to 100 times higher than those of sera from normal adults. By the method used, an increased GM2 level could be detected with samples of less than 0.1 ml of sera from hepatoma patients. The elevated levels of serum GM2 in hepatoma patients were suggested to be due to elevated GM2 levels in the liver lesions, because the GM2 contents of the liver of five patients with liver cancer, including three with hepatoma, were higher than those of normal liver tissues.

Carcinoma, Hepatocellular↗
PubMed1987

Presence of tumor promoters in the seed oil of Jatropha curcas L. from Thailand.

The seed oil of Jatropha curcas L. was shown to contain skin tumor promoters in a two-stage mouse carcinogenesis experiment. By using the irritant test on mouse ear to monitor activity, the "irritant fraction" was partially purified from the methanol extract of the seed oil by column chromatographies on Florisil and Sephadex LH-20. The irritant fraction obtained induced ornithine decarboxylase in mouse skin and inhibited the specific binding of 3H-12-O-tetradecanoylphorbol-13-acetate to a particulate fraction of mouse skin. After initiation with 7,12-dimethylbenz[a]anthracene (DMBA), this "irritant fraction" induced tumors in the skin of 36% of the mice tested in 30 weeks. Tumor incidences in the groups treated with DMBA alone and "irritant fraction" alone were 7% and 13% in week 30, respectively. Since the skin of Thai people comes into direct contact with this seed oil, an epidemiological study on human skin cancer in Thailand is indicated.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1987

Synthetic analogues (indolactams) of (-)-indolactam-V are new congeners of the teleocidin class of tumor promoters.

(-)-Indolactam-V, which has the partial structure of teleocidins A and B, and has tumor-promoting activity, is a good model for use in studies on the relation between structure and tumor-promoting activity, whereas (+)-indolactam-V has no tumor-promoting activity. In this work, five racemic indolactams differing only in their alkyl group at C-12 of (-)-indolactam-V were synthesized and tested for biological and biochemical activities related to tumor promotion. The activities tested were inductions of ornithine decarboxylase in mouse skin and human promyelocytic leukemia (HL-60) cell adhesion, inhibition of specific [3H]12-O-tetradecanoyl-phorbol-13-acetate binding to a mouse particulate fraction and activation of protein kinase C in vitro. The results showed that (+/-)-indolactam-L and (+/-)-indolactam-F had almost the same activities as (+/-)-indolactam-V, suggesting that (-)-indolactam-L and (-)-indolactam-F are new tumor promoters with as high potency as (-)-indolactam-V. (+/-)-Indolactam-t-L, which has a highly lipophilic group at C-12 of (-)-indolactam-V, showed the highest activities in the above tests. (-)-Indolactam-t-L might have stronger tumor-promoting activity than (-)-indolactam-V. Furthermore, the results with (-)-indolactam-t-L indicated the possibility of designing new tumor promoters with stronger activity than teleocidin.

Animals↗
PubMed1987

[Postoperative changes in serum levels of iron, transferrin and ferritin in surgical patients].

The association of serum levels of iron, transferrin and ferritin with surgical trauma has been analyzed in 21 surgical patients. The apparent decline of serum iron concentration was seen in the early stage of postoperative period, which was significantly manifest among the patients with major surgical process, such as pancreatectomy and hepatectomy etc. And there was no relationship between serum levels of iron and volumes of bleeding during operation and/or volumes of blood transfusion. Similarly, serum transferrin concentration decreased. On the other hand, serum ferritin concentration elevated after operation. These factors gradually returned to the preoperative levels with recovery from surgical injury. The transferrin decline in serum concentration was thought to be due to a change as rapid turnover protein. However, the decline of serum iron concentration and the elevation of serum ferritin concentration might be associated with cellular proliferative activity to repair operative injury. These results suggest that the condition of iron metabolism in management of surgical patients should be important.

Adult↗
PubMed1987

[Immunohistological observation of blood group-related antigens in lung adenocarcinomas using monoclonal antibodies].

The immunohistological distribution of blood group (BG)-related antigens including A, B, H type 2, and sialylated Lex in lung adenocarcinomas was examined using monoclonal antibodies. BG-A, B, and H type 2 compatible with the ABO status in tumor cells were expressed in 60% of the cases. Accumulation of H type 2, associated with loss of BG-A and B, was observed in tumor cells of patients with BG status other than 0. Tumor-associated antigens, Lex and sialylated Lex were detected in 36.0% and 72.0%, respectively. Modification of carbohydrate antigens in cancer may be associated with incomplete synthesis; accumulation of precursor antigen; and activated sialylation.

ABO Blood-Group System↗
PubMed1986

Beta-endorphin in the human gallbladder.

The presence of beta-endorphin-like immunoreactivity (beta-END-LI) in human gallbladder and its release were examined by means of radioimmunochemical measurements and immunohistochemical stainings. beta-END-LI was detected in the gallbladder (27.2 +/- 3.2 ng/g wet weight, mean +/- S.E.). The immunoreactivity in beta-END-LI extracted from the gallbladder was similar to that of synthetic beta-END, judging from the result of its inhibition curve parallel to that of the synthetic substance in the radioimmunoassay (RIA) system. On gel-filtration chromatography of a gallbladder extract, two components of beta-END-LI were found; one eluted on a position of beta-lipotropin (beta-LPH) and another on a position of synthetic beta-END. Specific beta-END-LI positive cells were detectable in metaplastic mucous glands. When human gallbladder mucosa was perfused with a solution of 10(-8) M or 10(-6) M cholecystokinin octapeptide (CCK-8), the release of beta-END-LI from mucosa into the perfusate increased 2-3 fold. These results indicate that beta-END-LI present in human gallbladder is released by the direct action of CCK-8 on the gallbladder mucosa and suggest that it may have a physiological or pathophysiological role.

Chromatography, Gel↗
PubMed1986

Bone lesions and dental caries after gastrectomy--evaluation of milk intolerance and operative procedure.

We investigated the development of bone lesions and dental caries in 350 patients who had undergone gastrectomy during the 11 year period from 1968 to 1978, on the basis of bone mineral content (BMC), decayed missing and filled (DMF) teeth and urinary c-AMP. We found that patients with low BMC and incidence of DMF teeth increased in number during the postoperative years; These abnormalities were, in comparison to the Billroth-I (B-I) and milk intake groups, significant in the Billroth-II (B-II) and non-milk intake groups. Among the gastrectomized patients, those with increased DMF teeth had significantly higher contents of urinary c-AMP. The possibility that secondary hyperparathyroidism resulting from gastrectomy contributes to the development and incidence of dental caries has to be given consideration.

Adolescent↗
PubMed1986

Glucagon-degrading activity in acid-ethanol extract of rat submandibular gland.

To investigate whether immunoreactive glucagon really exists in salivary gland, the integrity of glucagon radioimmunoassay was tested in the acid-ethanol extract of rat submandibular gland. Though immunoreactive glucagon was apparently measured in acid-ethanol extract of rat submandibular gland, the extract contained a significant amount of intact glucagon-degrading activity. The apparent % bound in radioimmunoassay highly correlated with the degradation of [125I] glucagon during incubation. Gel filtration profiles of [125I] glucagon incubated with acid-ethanol extract were the same as those of [125I] glucagon damaged by submandibular acid-saline extract. These data suggest that the immunoreactive glucagon in acid-ethanol extract is, as in the case of acid-saline extract, an artifact due to degradation of [125I] glucagon during radioimmunoassay.

Animals↗