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Biomedical subjects

H Yamada

Publications and source records attributed to H Yamada.

At least 217 records · Page 12Linked to original sources

Insulin response patterns contribute to different perinatal risks in gestational diabetes.

The aim of this study was to evaluate the insulin dynamics of patients with gestational diabetes mellitus (GDM) and to compare perinatal outcomes according to the insulin response patterns. Twenty-two out of 925 consecutive women examined were diagnosed as having GDM. One hundred and ten women who experienced a normal pregnancy were used as controls. Plasma glucose levels and insulin responses were evaluated by a 2-hour 75-gram oral glucose tolerance test (OGTT). Immunoreactive insulin (IRI), the area under the curve (AUC) of glucose (AUCg) and insulin (AUCi), and the insulinogenic index (II = DeltaIRI 30 min/DeltaBS 30 min) were measured. The GDM patients were divided into three subgroups, consisting of hyper-, normo- and hypoinsulinemic groups, according to the mean +/- 2 SD of the AUCi obtained from the controls. Clinical and laboratory findings were compared among the GDM subgroups and controls. The GDM patients showed impaired insulin secretion to glucose stimuli, with low plasma insulin levels (at 30 min) and reduced insulin/glucose ratios (at 30 and 60 min) early in the 75-gram OGTT. The II and AUCi/AUCg values of GDM patients were reduced as compared with those of controls. These reduced insulin responses were remarkable in hypo- and normoinsulinemic GDM patients, but were not detected in hyperinsulinemic GDM patients. The number of babies large for their gestational age in normo- and hypoinsulinemic GDM patients was significantly higher than that in hyperinsulinemic GDM patients or controls. Hyperinsulinemic GDM patients had a high frequency of pregnancy-induced hypertension (40%). The body mass index prior to pregnancy of hyperinsulinemic GDM patients was significantly higher than that of normoinsulinemic GDM patients or controls. It was demonstrated that not only insulin secretion, but also perinatal clinical characteristics, differed among the GDM subgroups. The heterogeneity of the disease was thus confirmed.

Adult↗

NK cell activity and subsets in women with a history of spontaneous abortion. Cause, number of abortions, and subsequent pregnancy outcome.

OBJECTIVE: The aim of this study was to assess the role of NK cells in nonpregnant women with a history of spontaneous abortion. STUDY DESIGN: 113 nonpregnant women with a history of spontaneous abortion were assessed for peripheral NK cell activity and percentage of NK cell subsets, in relation to the cause of abortions, the number of spontaneous abortions, and subsequent pregnancy outcome (n = 56). RESULTS: Neither NK cell activity nor subsets showed a significant difference in relation to the cause or number of spontaneous abortions. NK cell activity in nonpregnant women who later experienced subsequent abortion with normal chromosomes (n = 10) (mean +/- SD: 42.8 +/- 15.8%) was relatively higher than that in women with subsequent live birth (control, n = 39) (32.1 +/- 13.7%) (p = 0.099). NK cell activity in women who later experienced subsequent abortion with abnormal chromosomes (n = 7) (28.7 +/- 21.4%) was the same as the level in the control. CONCLUSION: Peripheral NK cell activity or subsets during nonpregnant status were not related to the cause or number of previous spontaneous abortions. A relation between preconceptional NK cell activity and later experiencing abortion with normal chromosomes should be further studied.

Abortion, Habitual↗

Regulation of surface FcepsilonRI expression on human eosinophils by IL-4 and IgE.

BACKGROUND: Recent studies have demonstrated that eosinophils from allergic patients express low levels of FcepsilonRI on their surface, but the regulatory mechanisms of eosinophil surface FcepsilonRI expression are not fully understood. We investigated whether IL-4 and IgE, which are reported to regulate surface FcepsilonRI expression on human mast cells, are able to affect surface FcepsilonRI expression in normal human eosinophils. METHODS: Eosinophils purified from peripheral blood were cultured with IL-5 and with or without IL-4 and/or IgE, and surface FcepsilonRI expression was analyzed by flow cytometry using an anti-FcepsilonRI mAb, CRA-1. RESULTS: Apparent FcepsilonRI expression (approximately 1% of mast cell FcepsilonRI levels) was observed in eosinophils cultured with both IL-4 and IgE. A combination of IL-4 (>or=1 ng/ml) and IgE (>or= 0.5 microg/ml) was necessary for the maximal induction of surface FcepsilonRI expression. In the presence of IL-4 and IgE, eosinophils cultured for 2 days demonstrated low but statistically significant levels of surface FcepsilonRI, which reached a plateau after 7 days of culture. However, cross-linkage of surface FcepsilonRI molecules by CRA-1 or anti-IgE did not induce any eosinophil activation. CONCLUSIONS: IL-4 and IgE can affect the levels of surface FcepsilonRI on normal human eosinophils. FcepsilonRI expression on eosinophils may be regulated by a mechanism similar to that in mast cells.

Cells, Cultured↗

Macrophage- and neutrophil-dominant arthritis in human IL-1 alpha transgenic mice.

To study the effects of IL-1 alpha in arthritis, we generated human IL-1 alpha (hIL-1 alpha). Transgenic mice expressed hIL-1 alpha mRNA in various organs, had high serum levels of hIL-1 alpha, and developed a severe polyarthritic phenotype at 4 weeks of age. Not only bone marrow cells but also synoviocytes from knee joints produced biologically active hIL-1 alpha. Synovitis started 2 weeks after birth, and 8-week-old mice showed hyperplasia of the synovial lining layer, the formation of hyperplastic synovium (pannus) and, ultimately, destruction of cartilage. Hyperplasia of the synovial lining was due to the accumulation of macrophage-like cells expressing F4/80 molecules. hIL-1 alpha was widely distributed in macrophage- and fibroblast-like cells of the synovial lining cells, as well as synovial fluid monocytes. T and B cells were rare in the synovial fluid, and analysis of marker expression suggests that synoviocytes were directly histolytic and did not act as antigen-presenting cells. In the joints of these mice, we found elevated levels of cells of the monocyte/macrophage and granulocyte lineages and of polymorphonuclear neutrophils (PMNs), most of which expressed Gr-1, indicating that they were mature, tissue-degrading PMNS: Cultured synoviocytes and PMNs from these animals overexpress GM-CSF, suggesting that the hematopoietic changes induced by IL-1 and the consequent PMN activation and joint destruction are mediated by this cytokine.

Animals↗

Impairment of gingival fibroblast adherence by IL-6/sIL-6R.

Interleukin-6 (IL-6) binds to human gingival fibroblasts (HGF) in the presence of a soluble form of IL-6 receptor (sIL-6R). We investigated the effects of IL-6 on the functions of HGF in the presence of sIL-6R. HGF changed their morphology from spindle-shaped to round, and detached from the culture dish by stimulation with IL-6/sIL-6R. In this condition, a signal transducer gp130 and a transcription factor Stat3 were phosphorylated, resulting in activation of transcription factors Stat3 and C/EBPbeta. Cytoskeletal beta-actin and adhesion molecule integrin-alpha5, a subunit of alpha5beta1 integrin (VLA-5), were found to possess potential binding domains for these transcription factors in their promoters. Accumulation of beta-actin and integrin-alpha5 mRNA decreased, contrary to the expectation of the induction of gene transcription. Furthermore, the decrease in their mRNAs was associated with reduced expression of both actin and VLA-5 proteins. These results suggest that the expression of VLA-5 and actin was down-regulated in HGF through an IL-6 signaling pathway, resulting in impairment of HGF adherence.

Actins↗

Promotion of beta-cell regeneration by betacellulin in ninety percent-pancreatectomized rats.

Betacellulin is thought to promote growth and differentiation of pancreatic beta-cells. We investigated the effect of betacellulin on regeneration of pancreatic beta-cells in 90%-pancreatectomized rats. Ninety percent pancreatectomy was performed in male Wistar rats and betacellulin (0.5 microg/g body weight) or saline was administered daily for 10 d starting immediately after pancreatectomy. In pancreatectomized rats, the morning-fed plasma glucose was significantly lower and the plasma insulin concentration was significantly higher in betacellulin-treated rats than those in control rats for up to 4 wk. Thirty days after pancreatectomy, a glucose tolerance test was performed. Betacellulin reduced the plasma glucose response to ip glucose loading. In control rats, the plasma insulin concentration was significantly lower and did not respond to glucose. In contrast, the plasma insulin concentration increased slightly but significantly in betacellulin-treated rats. Thirty days after pancreatectomy, the beta-cell mass was greater and the insulin content was significantly higher in betacellulin-treated rats than those in control rats. The numbers of islet cell-like cluster and bromodeoxy uridine/insulin double- positive cells in both islet cell-like cluster and islets were significantly higher in betacellulin-treated rats. These results indicate that administration of betacellulin improves glucose metabolism by promoting beta-cell regeneration in 90%-pancreatectomized rats.

Animals↗

Medication management skill and regimen compliance are deteriorated in the elderly even without obvious dementia.

We investigated whether regimen comprehension deteriorated in the elderly patients who did not suffer from obvious dementia. Eligible patients were ambulatory elderly patients who did not show any signs of dementia and could visit our outpatient clinic by themselves. 138 patients (age: 43-89, 75 males and 63 females, underlying diseases: hypertension, hyperlipidemia, arrhythmia etc.) were tested with a regimen comprehension scale (RCS: Jpn J Geriat 1997; 34: 209-214). The differences in scores among individuals increased with age. Scores of 5 or less in the RCS were recorded in 10 out of 69 patients aged 65 or more, but no such scores were recorded in younger patients (p < 0.01). The 60 patients who scored less than full marks were classified into two groups, the T-group (tutored by pharmacists), and a Non Tutored group. RCS was tested again in both groups. Only in the T-group (n = 28), did the second scores increase significantly (from 7.2 +/- 0.9 to 8.6 +/- 2.0 (m +/- SD); p < 0.01) after tutorial by pharmacists. Comparing the 7 patients who obtained an RCS score of 5 or less and age- and gender-matched controls who got full marks, there was no difference in the HDS-R test. These results suggest that even in elderly patients who did not show any signs of dementia, the regimen comprehension deteriorated with age, and tutorials in medication protocols were considered to be effective.

Adult↗

Effect of cilnidipine on left ventricular diastolic function in hypertensive patients as assessed by pulsed Doppler echocardiography and pulsed tissue Doppler imaging.

The purpose of the present study was to examine the mechanisms of improvement in left ventricular (LV) diastolic function in hypertensive patients treated with cilnidipine, a new and unique calcium antagonist that has both L-type and N-type voltage-dependent calcium channel blocking actions, using pulsed Doppler echocardiography and pulsed tissue Doppler imaging. The study comprised 35 untreated patients with essential hypertension (19 men and 16 women; mean age 65+/-10 years). The peak early diastolic and atrial systolic transmitral flow velocities (E and A, respectively) and their ratio (E/A), and the peak early diastolic and atrial systolic motion velocities (Ew and Aw, respectively) of the LV posterior wall and their ratio (Ew/Aw) were determined in all patients before and after 1, 3 and 6 months on cilnidipine (10 mg/day). One month: Systolic and diastolic blood pressures were significantly decreased. E and E/A were significantly increased, whereas there were no significant changes in Ew and Ew/Aw. Three months: Ew and Ew/Aw were significantly increased compared to those before and 1 month after cilnidipine. Six months: E and E/A were significantly increased compared with before and 3 months after cilnidipine, and Ew and Ew/Aw were significantly increased compared with before cilnidipine. Moreover, the LV mass index was significantly decreased compared to that before cilnidipine. In summary, changes in LV diastolic performance in patients with essential hypertension following cilnidipine treatment were biphasic with an initial increase in early diastolic transmitral flow velocity and a later increase in early diastolic LV wall motion velocity. The initial and later changes can be related to an acute change in afterload and a later improvement in LV relaxation.

Aged↗

Possible involvement of calcium-calmodulin pathways in the positive chronotropic response to angiotensin II on the canine cardiac sympathetic ganglia.

We investigated the ganglionic effects of angiotensin II (Ang II) and the signal transduction involved in the cardiac sympathetic ganglia by the direct administration of agents to the ganglia through the right subclavian artery and monitoring the heart rate as an indicator of the ganglionic function in pithed dogs. Ang II given i.a. caused increases in the heart rate, which was inhibited by the treatment with the AT1-receptor antagonist forasartan, but not by the AT2-receptor antagonist PD-123319. The stimulation by Ang II, but not by acetylcholine, was inhibited after treatment with an inhibitor of phospholipase C, U-73122; a cell-permeant modulator of the Ins(1,4,5)P3 receptors, 2-aminoethoxydiphenyl borate; an intracellular calcium and calcium-associated protein kinase inhibitor, HA-1077; calmodulin (CaM) inhibitor, W-7; Ca2+/CaM-dependent protein kinase II inhibitor, KN-93; a selective protein kinase C inhibitor, calphostin C; and Na+H+ exchange inhibitor, dimethylamiloride. These results suggest that Ang II stimulates the ganglionic transmission at postsynaptic sites via the activation of AT1 receptor coupled to either activation of phospholipase C, phosphoinositide hydrolysis and subsequent increase in intracellular Ca2+ and activation of protein kinase C and Ca2+/CaM kinase II, although this ganglionic stimulation seems to involve, at least in part, the protein kinases-dependent increase of amiloride-sensitive Na+ inflow.

Amiloride↗

Acid phosphatase/phosphotransferases from enteric bacteria.

We have investigated the enzymatic phosphorylation of nucleosides and found that Morganella morganii phoC acid phosphatase exhibits regioselective pyrophosphate (PP(i))-nucleoside phosphotransferase activity. In this study, we isolated genes encoding an acid phosphatase with regioselective phosphotransferase activity (AP/PTase) from Providencia stuartii, Enterobacter aerogenes, Escherichia blattae and Klebsiella planticola, and compared the primary structures and enzymatic characteristics of these enzymes with those of AP/PTase (PhoC acid phosphatase) from M. morganii. The enzymes were highly homologous in primary structure with M. morganii AP/PTase, and are classified as class A1 acid phosphatases. The synthesis of inosine-5'-monophosphate (5'-IMP) by E. coli overproducing each acid phosphatase was investigated. The P. stuartii enzyme, which is most closely related to the M. morganii enzyme, exhibited high 5'-IMP productivity, similar to the M. morganii enzyme. The 5'-IMP productivities of the E. aerogenes, E. blattae and K. planticola enzymes were inferior to those of the former two enzymes. This result underlines the importance of lower K(m) values for efficient nucleotide production. As these enzymes exhibited a very high degree of homology at the amino acid sequence level, it is likely that local sequence differences in the binding pocket are responsible for the differences in the nucleoside-PP(i) phosphotransferase reaction.

Journal Article↗

Purification and molecular characterization of a quinoprotein alcohol dehydrogenase from Pseudogluconobacter saccharoketogenes IFO 14464.

We have cloned and verified a gene for a novel quinoprotein alcohol dehydrogenase (ADH) from Pseudogluconobacter saccharoketogenes IFO 14464 that has the ability to oxidize L-sorbose to 2-keto-L-gulonic acid (2-KLGA). The enzyme was purified from the soluble fraction of the bacterium and was estimated to be a monomeric protein with a molecular weight of 65 kDa from the analyses of SDS-PAGE and gel-filtration chromatography. An open reading frame of 1824 bp for 608 amino acid residues was estimated as the gene for ADH because of the consistency of the calculated molecular mass and the elucidated partial amino acid sequences of the native enzyme. Homology search revealed that the enzyme showed close similarity to quinoprotein alcohol dehydrogenases isolated from Methylobacterium extorquens and Acetobacter aceti, particularly in the tryptophan docking motifs in the alpha-subunits of those dehydrogenases. The ability to convert L-sorbose to 2-KLGA was found when the lysate of recombinant Escherichia coli DH10B transformed with the gene for ADH was mixed with CaCl2and pyrroloquinoline quinone (PQQ). These data indicate that the cloned DNA is the desired gene for the ADH in which CaCl2 and PQQ are essential for enzymatic activity.

Journal Article↗

Characterization of the RcsC-->YojN-->RcsB phosphorelay signaling pathway involved in capsular synthesis in Escherichia coli.

Escherichia coli and other enteric microorganisms produce an extracellular polysaccharide capsule, called colanic acid, under certain environmental conditions. This capsular synthesis is regulated by the RcsC (sensor kinase)-->YojN (phosphotransfer intermediate)-->RcsB (response regulator) phosphorelay signal transduction under certain growth conditions. Nonetheless, little is known about signals that exaggerate the Rcs-system. To gain insight into signals that activate the Rcs-system, here we searched for genes that activate the Rcs-system, provided that those on a multicopy plasmid were introduced into E. coli. We identified several such genes, namely, rcsB, rcsA, djlA, lolA, and ompG. The DjlA, LolA, and OmpG proteins are particularly interesting in that they are all located on the cell surface, where the primary sensor RcsC histidine-kinase is localized. Implications of these findings are discussed with special reference to the mechanism by which RcsC perceives external signals.

Bacterial Proteins↗

The effects of vagotomy on the abomasum in calves: radiography and protein gene product 9.5 immunohistochemistry.

Abomasal disorders of calves with total vagotomy, operated on at 1 week old, were investigated with radiography and protein gene product (PGP) 9.5 immunohistochemistry. Radiographic findings indicated abomasal atony with dilatation in all calves 2 weeks after vagotomy, while 4 weeks after vagotomy abomasal dilatation was detected in 2 calves and another 2 calves showed dilatation and impaction. The densities of PGP 9.5-immunoreactive nerves in the tunica muscularis decreased significantly in the corpus region of the greater curvature 2 weeks after vagotomy and in the pyloric region of the lesser curvature 4 weeks after vagotomy, and it was at its lowest 4 weeks after vagotomy in all regions examined. In conclusion, abomasal dilatation and/or impaction in vagotomized calves confirmed by radiography were related with a decreased frequency of nerves in the tunica muscularis of the abomasum.

Abomasum↗

TIMP-1 promotes VEGF-induced neovascularization in the retina.

Proteolysis of vascular basement membranes and surrounding extracellular matrix is a critical early step in neovascularization. It requires alteration of the balance between matrix metalloproteinases (MMPs) and proteins that bind to and inactivate MMPs, tissue inhibitors of metalloproteinases (TIMPs). TIMP-1 has been demonstrated to inhibit neovascularization in chick chorioallantoic membranes. However, TIMP-1 has also been shown to either promote or inhibit cell proliferation and migration in different settings. To determine whether genetic alteration of the MMP/TIMP-1 ratio would alter retinal neovascularization, we crossed mice that express vascular endothelial growth factor (VEGF) in photoreceptors with TIMP-1-deficient mice or mice that overexpress TIMP-1. Compared to VEGF transgene-positive/TIMP-1-sufficient mice, VEGF transgene-positive/TIMP-1-deficient mice showed smaller neovascular lesions. There was also no difference between the two groups of mice in the appearance of the neovascularization by light or electron microscopy. Compound VEGF/TIMP-1 transgenic mice had increased expression of both VEGF and TIMP-1 in the retina, and had more neovascularization than mice that had increased expression of VEGF alone. These gain- and loss-of-function data suggest that alteration of the TIMP-1/MMP ratio modulates retinal neovascularization in a complex manner and not simply by altering the proteolytic activity and thereby invasiveness of endothelial cells.

Actins↗

Loss of nuclear localization of the S100C protein in immortalized human fibroblasts.

It is well known that cancer develops through a multistep process. In vitro transformation studies of normal human cells have shown that the immortalization step is critical for neoplastic transformation of cells. Furthermore, studies of cell fusion between normal and immortalized cells have indicated that the normal phenotype is dominant and the immortal phenotype is recessive. Thus we looked for cellular proteins that were down-regulated in immortalized human cells by two-dimensional gel electrophoresis to elucidate the mechanisms of immortalization of human cells. We found that the S100C protein was down-regulated in immortalized cells. This protein was localized in the cytoplasm of cells at the semiconfluent stage, while at the confluent stage it moved into the nuclei of normal cells but not into those of immortalized cells. Microinjection of an S100C antibody into normal confluent cells diminished the level of nuclear S100C protein, resulting in DNA synthesis. Taken together, loss of nuclear localization of the S100C protein, which may be related to DNA synthesis, is thought to be one of the mechanisms of immortalization.

Amino Acid Sequence↗