PubMed Health⌕ Search

Biomedical subjects

S Yonekura

Publications and source records attributed to S Yonekura.

At least 19 recordsLinked to original sources
PubMed2004

Suppressing effects of bisphenol A on the secretory function of ovine anterior pituitary cells.

We investigated the action of bisphenol A (BPA) on cellular GH release and content, cell number, GHmRNA expression, and concentrations of cellular cyclic AMP ([cAMP]c) and calcium ion ([Ca2+]c) in primary cultured ovine anterior pituitary cells. The following results were found: (1) BPA as well as nonylphenol (NP) at 10(-6) to 10(-3) M significantly and concentration-dependently suppressed basal and GHRH-stimulated GH release, and the cellular GH content, (2) BPA suppressed the cell number in a time- and concentration-dependent manner, (3) 10(-4)M BPA suppressed GHmRNA expression to 68% of control (BPA-free), and abolished GHRH (10(-8) M)-induced increases in [cAMP]c and [Ca2+]c. From these findings we conclude that BPA possesses a suppressing action on GH synthesis and release, and this suppressing action is probably related to impairment of cellular signal transduction systems in ovine anterior pituitary cells.

Animals↗
PubMed2004

Effects of long-chain fatty acids on cytosolic triacylglycerol accumulation and lipid droplet formation in primary cultured bovine mammary epithelial cells.

Mammary epithelial cells have recently been shown to express and secrete leptin into milk and to accumulate triacylglycerol (TAG) in cytosol. We examined the effects on the accumulation of cytosolic TAG of free fatty acid addition to the medium bathing bovine mammary epithelial cells (bMEC). Both saturated (palmitic and stearic) and unsaturated (oleic and linoleic) fatty acids stimulated the accumulation of TAG in a concentration-dependent manner from 50 to 400 microM and the expression of mRNA expression for CD36, which is involved in the uptake and secretion of long-chain fatty acids. However, leptin mRNA expression and lipid droplet formation were significantly increased only by the addition of unsaturated, but not saturated, fatty acids. Interestingly, both types of fatty acids stimulated alphas1-casein mRNA expression. These data suggest that the expression of leptin is related to droplet formation, whereas CD36 is related to cytosolic TAG accumulation, and that fatty acids or cytosolic TAG accumulation also have a role to accelerate differentiation of bMEC as shown by casein synthesis.

Animals↗
PubMed2003

Effects of acetate and butyrate on the expression of leptin and short-form leptin receptor in bovine and rat anterior pituitary cells.

The effects of acetate and butyrate on leptin and leptin receptor (OB-R) expression in bovine and rat anterior pituitary were examined. In bovine tissues, leptin gene expression using RT-PCR was observed in fat and anterior pituitary but not in liver. Isolated anterior pituitary cells cultured in Dulbecco's modified Eagle's medium (DMEM) for 3 days were further cultured for 48 h in DMEM containing 10 mM acetate or butyrate or without any fatty acids as control. Western blot analysis revealed that the abundance of leptin protein was greater in the presence of acetate and butyrate than that for the control culture. Leptin abundance was increased in a dose- and time-dependent manner in bovine anterior pituitary cells. However, leptin expression in rat cells, of which the basal level was much greater than that in ovine cells, was significantly decreased by the culture with butyrate. In addition, we studied the effects of both fatty acids on OB-R mRNA expression using semi-quantitative RT-PCR. The results showed that butyrate significantly decreased the expression in both bovine and rat cells. These findings indicate that acetate and butyrate enhance leptin expression in bovine, but not in rat anterior pituitary cells while butyrate suppresses OB-Ra expression in both rat and bovine pituitaries.

Acetates↗
PubMed2002

Effects of nutritional conditions around weaning on carbonic anhydrase activity in the parotid gland and ruminal and abomasal epithelia of Holstein calves.

Thirty-two male Holstein calves were used to investigate the effects of nutritional conditions around weaning and aging on carbonic anhydrase (CA) activity in the parotid gland and epithelium from the rumen and abomasum. We fed calf starter and lucerne hay as well as milk replacer (group N) or fed milk replacer either with (group S) or without (group M) administration of short-chain fatty acids (SCFA) through polypropylene tubing into the forestomach until 13 weeks of age. The diets were fed at 1000 hours and 1600 hours, and SCFA were administrated after milk replacer feeding at 1600 hours. Slaughter and tissue sampling were carried out between 1300 hours and 1430 hours at 1, 3, 7, 13, and 18 weeks of age. Tissue samples from five adult (1.5-2.0 years-old) Holstein steers were obtained from a local abattoir. In group N, CA activity in the parotid gland gradually and significantly increased toward the adult value, whilst in the epithelium from the rumen and abomasum, adult values were reached at 3 and 7 weeks of age, respectively. At 13 weeks, the activity for group N was significantly higher than that for the other two groups in the parotid gland, but there was no significant difference in the epithelium from the rumen and abomasum. The concentration of the carbonic isozyme VI in the parotid gland also changed with age but, in contrast to CA activity, had not reached adult levels by 13 weeks of age. In groups M and S, parotid saliva did not show any change toward an alkaline pH or toward a reciprocal change in the concentrations between Cl(-) and HCO(3)(-), even at 13 weeks of age. From these results we conclude that a concentrate-hay based diet around weaning has a crucial role in CA development in the parotid gland, but not in the epithelium of the rumen and abomasum.

Abomasum↗
PubMed2002

Effects of aging and weaning on mRNA expression of leptin and CCK receptors in the calf rumen and abomasum.

In order to know the effects of weaning and volatile fatty acid feeding on gastric leptin expression, we investigated the expression of leptin and CCK receptor mRNA in the bovine rumen, abomasum and duodenum using RT-PCR in 3-week-old pre-weaning, 13-week-old post-weaning and adult animals. Leptin mRNA was expressed in the rumen and abomasum of 3-week-old pre-weaning animals, but it was abolished in 13-week-old and adult animals. In the duodenum, leptin expression was observed in the 3-, 13-week-old and adult animals. In the rumen, CCK(A) receptor mRNA was expressed in 3-week-old animals, but not in 13-week-old and adult animals. In the abomasum, CCK(B) receptor expression gradually decreased from 3-week-old to adult animals. Expression of CCK(B) receptor and of CCK(A) receptor was slight in the rumen and abomasum, respectively. In the next study, we examined the effect of weaning of 6 weeks or non-weaning (fed on milk replacer alone (milk) or milk replacer with volatile fatty acids (milk+VFA) until 13 weeks old) on leptin mRNA expression in the rumen and abomasum. In 13-week-old calf rumen and abomasum, leptin mRNA expression was detected in non-weaning milk-fed animals at 13 weeks old, although it was not observed in weaning and non-weaned milk+VFA-fed animals. The change in CCK(A) receptor expression in the rumen was similar to those of leptin mRNA expression. CCK(B) receptor transcription in the abomasum of milk-fed animals was higher than that of the weaning and milk+VFA-fed animals. These results indicate that leptin expression is coincident with CCK receptor expression in calf stomachs, and that leptin and CCK receptor mRNA expression are affected by the change in the physiological status brought about by weaning and VFA feeding.

Abomasum↗
PubMed2001

Effects of adenosine 5'-triphosphate and growth hormone on cellular H+ transport and calcium ion concentrations in cloned bovine mammary epithelial cells.

The present experiment was carried out to investigate the effects of exogenous adenosine 5'-triphosphate (ATP) and growth hormone (GH) on cellular H(+) efflux rate (extracellular acidification rate) and Ca(2+) concentration ([Ca(2+)](c)) in cloned bovine mammary epithelial cells (bMEC) raised from the mammary gland of a 26-day-pregnant Holstein heifer. Perifusion of 2-day cultured cells with a medium containing ATP (10, 100 and 1000 micromol/l) for 30 min caused a significant and concentration-dependent increase in the cellular H(+) efflux rate. ATP application (100 micromol/l) caused a transient and large increase in [Ca(2+)](c) in all cells. In contrast, perifusion with a medium containing bovine GH at 10, 50 and 250 ng/ml for 30 min caused a significant decrease in the cellular H(+) efflux rate in a concentration-dependent manner. However, bovine GH application (50 ng/ml) caused a small decrease followed by an increase, in some cases, in [Ca(2+)](c). In bMEC treated with lactogenic hormones (1 microgram/l prolactin, 1 nmol/ml dexamethasone and 5 microgram/ml insulin) for 2 days, the increased H(+) efflux rate induced by ATP was significantly reduced, whereas the negative response induced by GH was inversely and significantly changed to the positive. Treatment of the cells with lactogenic hormones reduced the increase in [Ca(2+)](c) induced by ATP stimulation, while it enhanced the increase in [Ca(2+)](c) induced by GH stimulation. Application of ATP or GH did not cause any significant changes in [pH](c). Treatment with lactogenic hormones enhanced GH receptor (GHR) transcription that was determined by RT-PCR. From these results, we conclude that exogenous application of ATP and GH causes prompt and significant responses in H(+) transport and [Ca(2+)](c) that were significantly changed in the opposite direction by the treatment with lactogenic hormones. The lactogenic hormone treatment also enhanced GHR transcription, which may change post-receptor signal transduction systems for both agents in the bMEC.

Adenosine Triphosphate↗
PubMed2001

[Assessment of hydroxylated metabolites of polychlorinated biphenyls and polychlorinated dibenzofurans as potential estrogens by yeast two-hybrid system].

The estrogenic activities of several hydroxylated metabolites of PCBs and PCDFs were investigated by yeast two-hybrid assay based on the ligand-dependent interaction of estrogen receptor with coactivator. For the hydroxylated PCBs, the order of estrogenic potency was 4-OH-2',4',6'-triCB > 4-OH-4'-monoCB, 4-OH-biphenyl. These compounds were evaluated as 10(3) to 10(4) less potent than 17 beta-estradiol based on the concentrations of test compounds showing 10% activity of 10(-7) M 17 beta-estradiol. 2-OH-3',4,4'-triCB, 4-OH-2',3,4'-triCB and 3-OH-/4-OH-2,2',5,5'-tetraCB, the metabolites of 2,2',5,5'-tetraCB were inactive as estrogens at the highest concentrations used in this study (10(-5) M). Also 4-OH-3,3',4',5-tetraCB, the metabolite of 3,3',4,4'-tetraCB was inactive as estrogen, indicating that this hydroxylated metabolite did not take part in the estrogenic activity of 3,3',4,4'-tetraCB. OH group at 4-position of biphenyl was necessary for the expression of estrogenicity, but one or two chloro-substitution adjacent to OH group inhibited the activity. For the hydroxylated PCDFs, 8-OH-2-monoCDF, 7-OH-3,4-diCDF, 8-OH-3,4-diCDF, 8-OH-3,4,6-triCDF and 3,8-(OH)2-2-monoCDF exhibited estrogenic activity. The estrogenic activity of 3,8-(OH)2-2-monoCDF was comparable to those of 4-OH-2',4',6'-triCB and 4-nonylphenol (mixture of compounds with branched sidechain). The order of activity was 3,8-(OH)2-monoCDF > 8-OH-3,4-diCDF, 7-OH-3,4-diCDF > 8-OH-2-monoCDF, 8-OH-3,4,6-triCDF. These compounds were evaluated as 2.5 x 10(3) to 3 x 10(4) less potent than 17 beta-estradiol. On the other hand, no estrogenic activity was observed for 2-OH-dibenzofuran, 3-OH-2,8-diCDF, 6-OH-3,4-diCDF and 9-OH-3,4-diCDF at concentrations as high as 10(-4) M. Substitution of OH group at 2(8)- or 3(7)-position of dibenzofuran and no chloro-substitution adjacent to OH group was required for the estrogenic activity.

Animals↗
PubMed2001

[Secondary eosinophilia in a patient with hypereosinophilic syndrome after allogeneic bone marrow transplantation from a sibling donor].

A 23-year-old man first visited a local hospital in 1998 because of exertional dyspnea. Peripheral blood examination revealed mild leukocytosis with 82% eosinophils, and he was treated with prednisolone. As the eosinophilia did not improve, he was referred to Tokai University Hospital in March 1999 for further diagnosis and treatment. The patient was diagnosed as having hypereosinophilic syndrome (HES) because of unexplained hypereosinophilia persisting for more than 6 months, resulting in cardiac dysfunction. His disease was progressive in spite of immunosuppressive therapy, interferon-alpha and cytotoxic chemotherapy. Since he had an HLA-identical brother, allogeneic bone marrow transplantation (BMT) was performed in October 1999. After completion of the immunosuppressive therapy on day 79 after BMT, the number of eosinophils gradually increased again. Although we suspected recurrence of the disease, DNA fingerprinting revealed that the peripheral granulocytes were 100% donor type. An increase of interleukin-5 (IL-5) produced by peripheral lymphocytes and a decrease of the Th1/2 ratio suggested that the eosinophilia was related to GVHD. The eosinophilia was eventually controlled by cyclosporin. We conclude that DNA fingerprinting and examination of the IL-5 level and Th1/2 ratio are useful for differentiating between relapse and GVHD in cases of eosinophilia occurring after BMT for HES.

Adult↗
PubMed2000

The Japanese multicenter open randomized trial of ursodeoxycholic acid prophylaxis for hepatic veno-occlusive disease after stem cell transplantation.

Hepatic veno-occlusive disease (VOD) is a common transplant-related complication of stem cell transplantation. There is no safe and proven therapy for established VOD, and attempts have focused on its prevention. Limited studies have suggested that prophylactic use of ursodeoxycholic acid (UDCA) reduced the incidence of VOD. To confirm the preventive effect of UDCA on VOD, we conducted a prospective, unblinded randomized, multicenter study of UDCA involving 132 patients who underwent stem cell transplantation for a variety of disorders. Sixty-seven patients were assigned to the UDCA-treated group, and 65 patients were assigned to the control group. The clinical characteristics of the two groups were similar with respect to primary diagnosis, age, sex, and baseline organ function. The preparative regimen and GVHD prophylaxis did not differ significantly between the two groups. UDCA was highly effective in preventing VOD, which occurred in only 3.0% in the UDCA-treated group, as opposed to 18.5% in the control group (P = 0.0043). There were no adverse effects attributable to UDCA. The initial promising report of a prophylactic effect of UDCA on VOD after stem cell transplantation was confirmed in this prospective study.

Adult↗
PubMed1999

Nurses' perspectives concerning do-not-resuscitate (DNR) orders.

The purpose of this study was to investigate the views of the nursing staff concerning do-not-resuscitate (DNR) orders at the Tokai University Hospital where a controversial incident occurred several years ago. A 'Questionnaire on DNR Orders' was circulated and the anonymous answers were collected two weeks later. The questionnaire was returned by 706 of 780 (90.5%) nurses from every ward/specialty, which revealed that 87% of the nurses felt that DNRs were occasionally necessary, with more than 40% of the nurses answering that they took part in DNR. Further, 36% of the nurses stated that patient consent was indispensable, and 64% thought that the patient's family and physician could decide DNR in the event the patient was physically unable to give consent. Moreover, 66% of the nurses expected the establishment of a DNR order sheet to be formulated as a matter of hospital policy; only 5% of the nurses thought that such an order sheet would not be necessary. Comparing these results with a previous study polling physicians at the Tokai University Hospital, nurses are more likely than physicians to think that patient consent is indispensable, and want the establishment of a standardized DNR order sheet as hospital policy. There is, in fact, a "tacit understanding" between physicians and patients' families in medical practice in Japan. However, DNR is definitely a medical decision. Therefore it should be clearly stated in a standardized format, although such a procedure presently seems unlikely, in view of the Japanese traditional value system.

Adult↗
PubMed1998

Clinical significance of granulocyte colony-stimulating factor (G-CSF) receptor expression in acute myeloid leukemia.

We examined granulocyte colony-stimulating factor (G-CSF) receptor (GR) expression on leukemic cells from 44 adults with newly-diagnosed acute myeloid leukemia (AML). GR expression was higher in female patients. G-CSF was administered to AML patients after initial induction therapy without significant acceleration of leukemia, irrespective of GR expression level. G-CSF administration after initial chemotherapy did not adversely influence clinical outcome of GR-positive patients. However, at first relapse, leukemia regrowth was accelerated in 3 of 15 GR-positive patients who received G-CSF after re-induction. It remains to be determined whether leukemia acceleration due to G-CSF contributes to re-induction failure and if G-CSF therapy is a significant risk in relapsed, GR-positive AML patients.

Acute Disease↗
PubMed1998

A novel variant of B-lymphoid leukemia expressing kappa/lambda light chains.

We studied a patient with an indolent leukemia which behaved similarly to chronic lymphocytic leukemia (CLL). Leukemic cells, however, showed larger cell diameters and lower nuclear/cytoplasmic ratios than typical CLL cells, and contained numerous cytoplasmic vacuoles. The cells also demonstrated some morphologic characteristics of hairy cell leukemia. Furthermore, flow-cytometric analysis demonstrated a distinct population of kappa/lambda double-positive tumor cells, as well as kappa single and lambda single populations. Southern blot analysis confirmed rearranged bands for both light chains with a monoclonal heavy chain rearrangement. Despite a decision not to treat this asymptomatic patient, disease progression was not observed. This case may represent a unique variant of B lymphoid leukemia. Possible mechanisms of abnormal light chain expression are discussed.

Aged↗
PubMed1997

Analysis of intramedullary cell density by MRI using the multiple spin-echo technique.

Analysis of the intramedullary cell distribution by magnetic resonance imaging (MRI) using conventional techniques involves subjectively interpreting images and estimating the cell distribution on the basis of signal intensity characteristics. In recent years, attempts have been made to achieve more precise analysis by new techniques, including chemical shift imaging. The multiple spin-echo (MSE) technique offers some advantages over conventional MRI. Since it allows measurement of the transverse magnetization decay curve at 32 or more points, it is capable of separating several tissue components with different relaxation times. In addition, this technique can be used with MRI instruments having a static magnetic field as low as 1.0 Tesla. In the present study, the intramedullary cell density was assessed by MRI using the MSE technique in 4 patients with aplastic anemia (AA), 4 patients with myelodysplastic syndrome (MDS), and 5 normal subjects. The water component of the marrow (with a short relaxation time) and the fat component (with a long relaxation time) were separated from each other by analyzing MR images obtained using the MSE technique, and the signal intensity ratio of the 2 components was calculated. The ratio was significantly higher in the AA group than in the other groups (AA vs. MDS, P = 0.0209, AA vs. normal controls, P = 0.0143). The present technique appears promising for quantitative assessment of the intramedullary cell density.

Adolescent↗
PubMed1997

Sustained right ventricular dyskinesis complicated by right ventricular infarction.

We encountered a 66-yr-old man with acute left inferior and right ventricular infarction. Tomographic radionuclide ventriculography and Fourier analysis clearly demonstrated reduced wall motion in the inferior walls of both ventricles and markedly delayed phase angles in the inferior right ventricular segment, indicating dyskinesis, which was confirmed by two-dimensional echocardiography and contrast right ventriculography. Four years later, right ventricular dyskinesis was still present and corresponded to a right ventricular perfusion defect on 99mTc-labeled tetrofosmin tomogram. Right ventricular imaging with tomographic radionuclide ventriculography with Fourier analysis and 99mTc-labeled myocardial tomography demonstrates that, even after improved global function and hemodynamics, right ventricular dyskinesis related to right ventricular perfusion defect can be sustained for several years. Thus, these imaging techniques may contribute to diagnosing right ventricular infarction and investigating the pathophysiology.

Aged↗
PubMed1996

Granulocyte colony-stimulating factor production by human bone marrow fibroblasts stimulated with interleukins.

Granulocyte colony-stimulating factor (G-CSF) is a cytokine that mediates the clonal proliferation and differentiation of progenitor cells into mature granulocytes. The kinetics of G-CSF production by human bone marrow fibroblasts (BMF) were investigated by quantitative immunoassays. The spontaneous production of G-CSF by BMF was below the detectable level. Interleukin-1 (IL-1) induced a dose-dependent production of G-CSF, and the production reached a plateau at 50 U/ml of IL-1. G-CSF production by BMF stimulated with IL-1 was cell concentration dependent. Detectable G-CSF was produced by 5 x 10(2) BMF in a 35 x 10-mm plastic dish. The optimal range was 1 x 10(4)-5 x 10(4) BMF. Production of newly synthesized G-CSF was detectable 6 hr after stimulation and continued for approximately 48 hr. A 6-hr pulse exposure to IL-1 was necessary to induce production of G-CSF, and after 48 hr, the adherent BMF could not be restimulated. IL-2, IL-3, IL-4, IL-5, and IL-6 were unable to induce G-CSF production. However, IL-4 promoted G-CSF production after stimulation with IL-1. These results provide useful data with regard to the mechanism of G-CSF production by human BMF.

Adult↗
PubMed1996

Clinical significance of LEA-1 expression in adult acute myeloid leukemia.

In this study, we examined expressions of several adhesion molecules (AdMs), i.e. leukocyte function antigen-1 (LFA-1: CD11a/CD18), Hermes homing receptor (CD44) and intercellular adhesion molecule-1 (ICAM-1: CD54), on leukemia cells from 51 adult patients with newly diagnosed acute myeloid leukemias (AMLs) to elucidate clinical significance of these AdM expressions. Those expressions in lymphoid malignancies have been correlated with tumor evolutions, but CD44 was detected in all the AML cases examined and CD54 expression did not associate with their clinical characteristics or outcomes. However, we found that LFA-1 expressions significantly correlated with splenomegaly, resistance to induction chemotherapies and short survival periods in AML patients.

Acute Disease↗
PubMed1996

Serial changes of left atrial thrombus in mitral stenosis: transesophageal echocardiographic studies in candidates for balloon mitral commissurotomy.

BACKGROUND: Little is known concerning therapeutic modification of left atrial thrombus in mitral stenosis and its formation after successful balloon valvuloplasty (percutaneous transvenous mitral commissurotomy [PTMC]). OBJECTIVE: To test the roles of the clinical use of anticoagulant therapy and PTMC, serial changes in left atrial thrombus were examined by transesophageal echocardiography in 80 patients with mitral stenosis. RESULTS: No difference in embolic history, New York Heart Association functional class, cardiac rhythm, left atrial size or mitral valve area was found between patients with (n=23) and without (n=57) left atrial thrombus. Diuretic use was the prevalent factor for left atrial thrombi, which were dissolved completely in seven (30.4%) and partially in eight (34.7%) of the patients by adequate warfarin. However, after PTMC (n=53), newly formed thrombus was observed in four of 51 (7.8%) patients, which correlated with left atrial size (at least 50mm), atrial fibrillation and poorly controlled warfarin (thrombo test: 63.8 +/- 18.8% versus 35.9 +/- 17.7%, P<0.005). The newly formed thrombi were dissolved within several weeks. CONCLUSION: Left atrial thrombus in symptomatic mitral stenosis exhibits elusive characteristics and should be strictly monitored even after successful PTMC by transesophageal echocardiography in order to achieve adequate anticoagulation.

Atrial Function, Left↗