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Biomedical subjects

M Horimoto

Publications and source records attributed to M Horimoto.

At least 55 records · Page 3Linked to original sources
PubMed1995

Identification of a transforming growth factor beta-1 activator derived from a human gastric cancer cell line.

It has been shown that some types of tumour cells produce activated transforming growth factor beta-1 (TGF-beta 1). However, the mechanism for the activation of TGF-beta 1 derived from tumour cells has not been fully elucidated. The present study was undertaken to characterise an activator of latent TGF-beta 1 secreted from a human gastric cancer cell line, KATO-III. Western blot analyses using antibodies for TGF-beta 1, latency associated peptide (LAP) and latent TGF-beta 1-binding protein (LTBP) revealed that, in the cell lysate of KATO-III, TGF-beta 1 protein was expressed as a small latent complex of TGF-beta 1 and LAP. This was also confirmed by a gel chromatographic analysis of the cell lysate obtained from KATO-III. A 2.5 kb transcript of TGF-beta 1 mRNA was detected in KATO-III cells by Northern blot analysis. A gel chromatographic analysis of the conditioned medium from KATO-III cells revealed, in addition to the active form of TGF-beta 1, a factor which activated latent TGF-beta 1 from NRK-49F cells at fractions near a molecular size of 65,000. This factor was inactivated by heat (100 degrees C), acidification, trypsin and serine protease inhibitors. TGF-beta 1 activity in KATO-III cell lysate was not detected in the untreated state, but potent TGF-beta 1 activity was detected after acid treatment. These results suggest that KATO-III releases not only a latent TGF-beta 1 complex but also a type of serine protease, different from plasmin, plasminogen activator, cathepsin D, endoglycosidase F or sialidase, which activates the latent TGF-beta 1 complex as effectively as acid treatment.

Blotting, Northern↗
PubMed1995

Monoclonal thyroglobulin autoantibodies: variable region analysis and epitope recognition.

A panel of human monoclonal thyroglobulin (Tg) autoantibodies (TgAAb) has been used to analyze autoantigenic determinants on human Tg and to investigate the relationship between variable (V) region gene sequences and epitope specificity. Two monoclonal TgAAb bound to the same (or closely related) epitope on Tg, and these were defined as type I TgAAb. Three other monoclonals bound to a different site and were defined as type II TgAAb. Inhibition studies with mixtures of type I and type II monoclonal TgAAb (Fab)2 preparations indicated that a mixture of the (Fab)2s almost completely inhibited (> 75%) labeled Tg binding to intact TgAAb in the sera of apparently healthy blood donors and patients with autoimmune thyroid disease (AITD). Type I TgAAb predominated in apparently healthy blood donors' sera, whereas type II TgAAb predominated in AITD sera. Analysis of V region gene sequences of the TgAAb indicated that a range of light chain and heavy chain genes from different gene families was used. Furthermore, the same germline genes that are used by TgAAb are also well represented in the genes coding for other self- and nonself-reactive antibodies. No homology in terms of light chain and heavy chain gene families, germline gene usage, or complementarity determining region sequences was observed in TgAAb directed to the same or closely related epitopes. Our studies show that TgAAb are directed to two major conformational epitopes on the Tg molecule and that the proportion of TgAAb directed to these epitopes in apparently healthy blood donors and that in patients with AITD appear to be different. TgAAb derived from different germline genes and with different complementarity determining region sequences can display similar epitope specificity, and this indicates that AAb directed to the same or a closely related epitope show considerable heterogeneity at the molecular level.

Amino Acid Sequence↗
PubMed1995

Bioactivity of thyrotropin (TSH) in patients with central hypothyroidism: comparison between in vivo 3,5,3'-triiodothyronine response to TSH and in vitro bioactivity of TSH.

To investigate the cause(s) of central hypothyroidism with normal or elevated TSH concentrations, we evaluated the bioactivity of serum TSH as well as pituitary and thyroid function. Seven hypothyroid patients had documented deficiencies of anterior pituitary hormones other than TSH. Basal TSH concentrations ranged from 2.2-14.8 microU/mL. Six patients had low T4 and free T4 concentrations; the remaining patient had a low free T4 and a low normal T4 level with an elevated TSH concentration of 14.4 microU/mL. The mean increment in TSH 30, 60, and 90 min after TRH administration (mean delta TSH) in these patients was 13.5 +/- 9.1 microU/mL (mean +/- SD), which was not significantly different from the value in controls (9.2 +/- 3.5 microU/mL). However, the ratio of the T3 increment at 120 min (delta T3) to mean delta TSH (delta T3/mean delta TSH) in patients was 53.9 +/- 29.3 ng/microU, significantly lower than the control value of 239.5 +/- 97.5 ng/microU (P < 0.01), suggesting that the thyroid response to endogenous TSH was blunted. The serum T4 concentration correlated with the mean delta TSH in these patients (r = 0.78; P < 0.05), suggesting that hypothyroidism is dependent on conserved pituitary function. The mean bioactivity to immunoreactivity ratio of basal TSH in patients was 0.97 +/- 0.27 and was not significantly different from the normal value of 1.05 +/- 0.22. One of the two patients with high basal TSH (> 10 microU/mL) had a ratio of 0.59, which is just below the mean +/- SD of normal subjects (0.61), suggesting that most patients had normal TSH bioactivity in vitro. Our findings suggest that in vivo bioactivity of TSH is decreased because of a pituitary disorder, but in vitro bioactivity of TSH is variable in patients with central hypothyroidism.

Adult↗
PubMed1995

Thyroid stimulating antibody in sera of Graves' ophthalmopathy patients as a possible marker for predicting the efficacy of methylprednisolone pulse therapy.

Nine patients with Graves' ophthalmopathy (GO) were treated with intravenous methylprednisolone pulse therapy and followed up by ophthalmological assessment, magnetic resonance imaging, and thyroid-associated autoantibody (thyroid stimulating antibody (TSAb), TSH binding inhibitor immunoglobulins (TBII), and anti-eye muscle antibody (EMAb)). Ophthalmological assessment was performed by the ophthalmopathy index (OI) which was made on the basis of the system recommended by the American Thyroid Association Committee. EMAb was expressed as the ratio of density of the 64 kDa band of eye muscle membrane to that of 92 kDa non-specific band found with all normal sera when assessed by western blotting. Five patients with mild ophthalmopathy (OI < 4) did not show progressive improvement in OI. Three of 4 patients with severe eye disease (OI > 4) showed a progressive and distinct improvement in OI. These 3 patients had high TSAb levels before methylprednisolone pulse therapy. One patient with severe ophthalmopathy did not respond to this pulse therapy; this patient's TSAb was negative. A significant positive correlation was observed between the activity of TSAb before treatment and the improvement in OI (delta OI) (r = 0.86, P < 0.01, n = 9). The relationship between delta OI and EMAb did not reach significance. These results suggest that TSAb in sera of GO patients can be a useful marker for predicting the efficacy of methylprednisolone pulse therapy.

Adolescent↗
PubMed1995

Activation of Na+/H+ exchanger by hepatocyte growth factor in hepatocytes.

The effect of the hepatocyte growth factor (HGF) on the Na+/H+ exchanger was studied using primary cultured hepatocytes. HGF induced intracellular pH (pHi) elevation of 0.10 pH units in hepatocytes cultured for 4 to 7 hours; the response was lower after other culture periods. Even with the same culture period, intercellular heterogeneity was found in the responsiveness to HGF. This heterogeneity may be partially accounted for by the weak but significant correlation observed between the basal pHi level and the degree of pHi elevation caused by HGF in hepatocytes. The pHi elevation caused by HGF was blocked on pretreatment of the hepatocytes with amiloride, suggesting that HGF activates the Na+/H+ exchanger. This hypothesis was confirmed by the fact that HGF increased the initial rapid rate of cell alkalization of acid-loaded hepatocytes. The tyrosine kinase inhibitor, genistein, also blocked the elevation, consistent with the fact that HGF receptor/c-met has a tyrosine kinase domain. To clarify the signal transduction pathway from tyrosine kinase to the Na+/H+ exchanger, we examined the effects of inhibitors of other kinases (H-7, H-8, and W-7) on the HGF-induced pHi elevation and found that only W-7 blocked it. This pHi elevation was also prevented on preincubation of the hepatocytes with thapsigargin, which blocks the calcium response caused by HGF. These results suggest that HGF activates the Na+/H+ exchanger in hepatocytes through a tyrosine kinase-calcium/calmodulin-dependent pathway.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗
PubMed1994

Increased expression of c-met messenger RNA following acute gastric injury in rats.

The aim of the present study was to evaluate messenger RNA expression of c-met, a hepatocyte growth factor receptor gene, after gastric mucosal injury in rats. Male Sprague-Dawley rats were fasted for 24 hours, received 0.6 N hydrochloric acid (HCl), and served for polyadenylated RNA extraction from the oxyntic gastric mucosa. The transcripts of rat c-met gene were analyzed by reverse-transcript polymerase chain reaction and Northern blotting. Although it was detected even before the HCl administration, the c-met expression increased 6, 24 and 48 hours after the HCl administration. Thereafter, gastric mucosal injury diminished and the c-met expression declined. Hepatocyte growth factor reportedly plays an important role in gastric cell proliferation. The increased c-met expression indicates that this gene may participate in the healing process of gastric mucosa after injury.

Amino Acid Sequence↗
PubMed1994

Characterization of signaling pathways to Na+/H+ exchanger activation with epidermal growth factor in hepatocytes.

To investigate the signaling pathways to Na+/H+ exchanger activation with epidermal growth factor in hepatocytes, we measured changes in cytosolic free calcium and intracellular pH levels at the single-cell level using digital imaging fluorescence microscopy of fura-2- or BCECF-loaded hepatocytes in primary culture. Epidermal growth factor induced cytosolic free calcium oscillations consisting of periodic trains of spikes with a latency period of up to several minutes. These calcium responses were inhibited by tyrosine kinase inhibitor genistein (100 mumol/L) and abolished by emptying of intracellular Ca2+ pools with 3 mumol/L thapsigargin, an inhibitor of Ca(2+)-ATPase on the endoplasmic reticulum. Epidermal growth factor (1 nmol/L) induced an intracellular pH increase of 0.12 +/- 0.07 units from the basal level of 7.25 +/- 0.09 units after several minutes of latency. This effect was completely abolished by 1 mmol/L amiloride, an inhibitor of the Na+/H+ exchanger. The epidermal growth factor-induced intracellular pH increase was inhibited by pretreatment of hepatocytes with genistein (100 mumol/L), thapsigargin (3 mumol/L) or calmodulin inhibitor W-7 (25 mumol/L), but not with protein kinase C inhibitor H-7 (50 mumol/L) or with cyclic AMP-dependent kinase inhibitor H-8 (60 mumol/L). Phorbol ester PMA (phorbol 12-myristate 13-acetate), a potent activator of protein kinase C, induced a slight intracellular pH increase significantly smaller than that with epidermal growth factor, whereas this effect was completely blocked by pretreatment with H-7, indicating that PMA-induced intracellular pH increase is mediated by protein kinase C pathways, unlike epidermal growth factor.(ABSTRACT TRUNCATED AT 250 WORDS)

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗
PubMed1994

Transforming growth factor beta 1 secreted from scirrhous gastric cancer cells is associated with excess collagen deposition in the tissue.

To explore the mechanism of increased collagen deposition in scirrhous carcinoma of the stomach, an attempt was made to define the role of transforming growth factor beta 1 (TGF-beta 1), secreted from tumour cells, as a possible humoral factor which functions in a paracrine manner to stimulate the production of collagen in regional fibroblasts. Immunohistochemical staining revealed that tumour cells in scirrhous carcinomas were generally stained more intensively than those in other types of carcinomas. On Northern blot analysis the tumour cells established from scirrhous carcinoma (KATO-III, OCUM-1 and HSC-39) exhibited relatively strong signals compared with those from non-scirrhous carcinoma (MKN-28 and MKN-45). In the culture media of scirrhous carcinoma cells, the active form of TGF-beta 1 was detected, while in those of the non-scirrhous carcinoma cells the latent form was demonstrated by both colony and radioreceptor assays. The culture medium from KATO-III showed strong stimulating activity of collagen synthesis in fibroblasts, and this activity was partially neutralised by an anti-TGF-beta 1 antibody. These results suggest that tumour cells in scirrhous carcinoma produce more active-form TGF-beta 1 than does non-scirrhous carcinoma and thus is partially responsible for the observed enhanced collagen deposition in the region.

Adenocarcinoma, Scirrhous↗
PubMed1994

Close correlation between the dephosphorylation of p53 and growth suppression by transforming growth factor-beta 1 in nasopharyngeal carcinoma cells transduced with adenovirus early region genes.

The mechanism of growth inhibition by transforming growth factor (TGF)-beta 1 was investigated. We examined the growth inhibitory effects of TGF-beta 1 on human nasopharyngeal carcinoma (KB) cells which constitutively expressed p53. TGF-beta 1 suppressed the DNA synthesis of KB cells in a dose-dependent manner. It had minimal effect on adenovirus-2-transduced KB cells expressing either adenovirus early region 1B (E1B) or 1A (E1A) product, which respectively binds to p53 or Rb product and inhibits its function, and no growth inhibition at all was observed with KB cells expressing both E1B and E1A products. Dephosphorylation of the p53 was promoted by TGF-beta 1 stimulation in KB cells, but not in E1B-producing KB cells, which sequestrate the function of p53. The growth inhibition of KB cells by TGF-beta 1 was significantly reduced by treatment with okadaic acid. These results suggest that p53 transduces the antiproliferative signal of TGF-beta 1 possibly through its dephosphorylation.

Adenovirus E1A Proteins↗
PubMed1994

Origin of the right pulmonary artery from the ascending aorta. Longest survivor without receiving surgical repair.

We report a case of origin of the right pulmonary artery from the ascending aorta. Pulmonary arteriography showed an opacification of the enlarged left pulmonary artery without filling of the right pulmonary artery. Pressure study showed that the pulmonary systolic pressure was almost equal to the systemic pressure. The present case is characterized as the longest-term survivor in the literature with aortic origin of right pulmonary artery without receiving surgical repair.

Adult↗
PubMed1993

Expression of the c-met/hepatocyte growth factor receptor gene during rat liver regeneration induced by carbon tetrachloride.

The hepatocyte growth factor is closely related to liver regeneration. And the c-met protooncogene is reported to encode a hepatocyte growth factor receptor. Little is known, however, about how the c-met gene is activated during liver regeneration. In this study, we demonstrated that expression of the c-met gene/hepatocyte growth factor gene was enhanced, with a distinct peak, following carbon tetrachloride administration, i.e., the gene expression was activated at 6 hours after the treatment, then decreased, and again increased. The present study suggested that this gene could be responding to liver regeneration and that the hepatocyte growth factor receptor plays an important role in regulating cell cycle progression prior to elevation of deoxynucleic acid synthesis during liver regeneration.

Animals↗
PubMed1993

Anomalous origin of the left anterior descending coronary artery from the right sinus of Valsalva associated with effort angina pectoris.

A 54-year-old man suffering from effort angina pectoris had an anomalous origin of the left anterior descending coronary artery (LAD) from the right sinus of Valsalva (RSV). The anomalous LAD with a small ostium and without other significant narrowing initially ran into the interventricular septum and subsequently the anterior interventricular groove. Coronary angiography during the anginal attack induced by ergometer exercise testing revealed neither an enhanced narrowing of the LAD ostium, nor myocardial squeezing of the LAD at the interventricular septum level, nor coronary vasospasm. Myocardial ischaemia associated with an anomalous aortic origin of the LAD from the RSV is extremely rare, especially when the vessel runs a septal course. In the present case, the ostial stenosis of the anomalous LAD, probably due to developed atherosclerosis, seemed to be the most likely cause of the exertional angina.

Angina Pectoris↗
PubMed1993

Familial unresponsiveness to thyrotropin by autosomal recessive inheritance.

Unresponsiveness to TSH has been identified and sufficiently studied in only three patients. We report siblings with this defect as the first documentation of familial occurrence. A 26-yr-old woman was diagnosed with congenital hypothyroidism during infancy. The thyroid was atrophic, and thyroid function tests without T4 replacement showed serum free T4 levels below 3 pmol/L, serum TSH of 125 mU/L, and serum thyroglobulin below 5 mg/L. 123I scintigram showed decreased uptake (5% at 24 h), but normal shape at the correct position in the neck. Autoantibodies against thyroglobulin, thyroid peroxidase, and TSH receptor in serum were not detected. The amount of cAMP released into FRTL-5 cell culture in the presence of TSH from the patient was not different from that released by the same amount of TSH from normal subjects, suggesting that TSH bioactivity in our patient was normal. The brother of the patient also had congenital hypothyroidism, and the data on his thyroid function was similar to that for his sister. There was a consanguineous marriage in the parents of the siblings, and the mother of the patients had a normal serum free T4 level, but slightly increased serum TSH and thyroglobulin levels, indicating subclinical hypothyroidism. The possible pathogenesis of TSH unresponsiveness in our patients includes a mutation in the TSH receptor gene, abnormality in transcription-regulating factor, abnormality in GTP-binding protein, and/or inhibition of the action of cAMP. The family history of the patients suggests that the mode of inheritance in TSH unresponsiveness is autosomal recessive.

Adult↗
PubMed1993

Measurement of erythrocyte Na,K-ATPase activity in normal pregnant women.

To investigate the peripheral metabolic status during normal pregnancy, we measured the number of erythrocyte Na,K-ATPase units as well as the cation transport activity of the pump from 32 normal pregnant women and 12 normal controls. The number of pump units determined by maximal ouabain binding to erythrocyte in normal pregnancy was significantly higher than that in normal controls (mean +/- SEM: 0.52 +/- 0.03 vs. 0.39 +/- 0.04 pmol/10(9)RBC, P < 0.05). The total cation transport activity of the pump measured by 86Rb uptake also significantly increased during pregnancy (98.9 +/- 6.4 vs. 73.1 +/- 5.4 nmol/10(9) RBC, P < 0.01). However, the mean cation transport activity per pump unit, which was presumed to be an indicator of the peripheral metabolic status, was unchanged in any of three trimesters when compared with that in normal controls. Serum FT4 levels measured by two different methods were significantly lower in the third trimester than in the first trimester (P < 0.01). In conclusion, erythrocyte Na, K-ATPase activity per pump unit is normal in pregnant women, suggesting that the peripheral metabolic status in pregnancy seems to be normal. Increases in both the number and function of the pump may be influenced by factors other than thyroid function.

Adult↗