PubMed Health⌕ Search

Biomedical subjects

Michiko Watanabe

Publications and source records attributed to Michiko Watanabe.

At least 19 recordsLinked to original sources
PubMed2004

Hypoxia-responsive signaling regulates the apoptosis-dependent remodeling of the embryonic avian cardiac outflow tract.

We proposed a model in which myocardial hypoxia triggers the apoptosis-dependent remodeling of the avian outflow tract (OFT) in the transition of the embryo to a dual circulation. In this study, we examined hypoxia-dependent signaling in cardiomyocyte apoptosis and outflow tract remodeling. The hypoxia-inducible transcription factor HIF-1alpha was specifically present in the nuclei of OFT cardiomyocytes from stages 25-32, the period of hypoxia-dependent OFT remodeling. HIF-1alpha expression was sensitive to changes in ambient oxygen concentrations, while its dimerization partner HIF-1beta was constitutively expressed. There was not a simple relationship between HIF-1alpha expression and apoptosis. Apoptotic cardiomyocytes were detected in HIF-1alpha-positive and -negative regions, and a hypoxic stimulus sufficient to induce nuclear accumulation of HIF-1alpha did not induce cardiomyocyte apoptosis. The hypoxia-dependent expression of the vascular endothelial growth factor receptor (VEGFR2) in the distal OFT myocardium may be protective as cardiomyocyte apoptosis in the early stages (25-30) of OFT remodeling was absent from this region. Furthermore, recombinant adenoviral-mediated expression of dominant negative Akt, an inhibitor of tyrosine kinase receptor signaling, augmented cardiomyocyte apoptosis in the OFT and constitutively active Akt suppressed it. Adenovirus-mediated forced expression of VEGF165 induced conotruncal malformation such as double outlet right ventricle (DORV) and ventricular septal defect (VSD), similar to defects observed when apoptosis-dependent remodeling of the OFT was specifically targeted. We conclude that normal developmental remodeling of the embryonic avian cardiac OFT involves hypoxia/HIF-1-dependent signaling and cardiomyocyte apoptosis. Autocrine signaling through VEGF/VEGFR2 and Akt provides survival signals for the hypoxic OFT cardiomyocytes, and regulated VEGF signaling is required for the normal development of the OFT.

Animals↗
PubMed2004

Role of myocardial hypoxia in the remodeling of the embryonic avian cardiac outflow tract.

The embryonic cardiac outflow myocardium originates from a secondary heart-forming field to connect the developing ventricles with the aortic sac. The outflow tract (OFT) subsequently undergoes complex remodeling in the transition of the embryo to a dual circulation. In avians, elimination of OFT cardiomyocytes by apoptosis (stages 25-32) precedes coronary vasculogenesis and is necessary for the shortening of the OFT and the posterior rotation of the aorta. We hypothesized that regional myocardial hypoxia triggers OFT remodeling. We used immunohistochemical detection of the nitroimidazole EF5, administered by intravascular infusion in ovo, as an indicator of relative tissue oxygen concentrations. EF5 binding was increased in the OFT myocardium relative to other myocardium during these stages (25-32) of OFT remodeling. The intensity of EF5 binding paralleled the prevalence of apoptosis in the OFT myocardium, which are first detected at stage 25, maximal at stage 30, and diminished by stage 32. Evidence of coincident hypoxia-dependent responses included the expression of the vascular endothelial growth factor (VEGF) receptor 2 by the OFT myocardium, the predominant expression of VEGF122 (diffusible) isoform in the OFT, and the recruitment of QH1-positive pro-endothelial cells to the OFT and vasculogenesis. Exposure of embryos to hyperoxia (95% O(2)/5% CO(2)) during this developmental window reduced the prevalence of cardiomyocyte apoptosis and attenuated the shortening and rotation of the OFT, resulting in double-outlet right ventricle morphology, similar to that observed when apoptosis is directly inhibited. These results suggest that regional myocardial hypoxia triggers cardiomyocyte apoptosis and remodeling of the OFT in the transition to a dual circulation, and that VEGF autocrine/paracrine signaling may regulate these processes.

Animals↗
PubMed2004

Fas ligand gene transfer to the embryonic heart induces programmed cell death and outflow tract defects.

The remodeling of the embryonic avian cardiac outflow tract (OFT) involves the removal of cardiomyocytes by programmed cell death (PCD). In contrast, the prevalence of PCD is low in the atrial or ventricular myocytes during this period of development. To determine if this selective PCD is due to the unique ability of the OFT cardiomyocytes to execute PCD, we transduced the embryonic chicken heart in ovo with recombinant adenovirus expressing a death (FasL) ligand. This resulted in programmed cell death in atrial, ventricular, and OFT cardiomyocytes as evidenced by chromosomal fragmentation, accumulation of lysosomes, and Caspase enzymatic activity. Consistent with the widespread induction of PCD, transcripts for the Fas receptor were detected in all chambers of the heart throughout development. The precocious and widespread activation of PCD in the OFT myocardium resulted in a marked dimunition of the subpulmonic myocardial infundibulum, and transposition of the aorta side-by-side with the pulmonary artery and connecting to the right ventricle. Defects in other cardiac structures are also described. We conclude that the regulated removal of OFT cardiomyocytes by PCD is required for the great vessels to make their proper connections with the ventricles in the transition to a dual circulation. The malalignment of the great vessels described in this animal model are similar to those described in congenital human conotruncal heart defects, suggesting that PCD-dependent remodeling of the OFT myocardium could be a target of genetic mutations or teratogens that cause human conotruncal heart defects.

Animals↗
PubMed2004

Functional imaging of the embryonic pacemaking and cardiac conduction system over the past 150 years: technologies to overcome the challenges.

Early analyses of cardiac pacemaking and conduction system (CPCS) development relied on classic histology and visual inspection of the beating heart. Current techniques that facilitate delineation of the CPCS include the use of specific antibody markers and transgenic mouse lines specifically expressing reporter genes. Assaying the function of tiny embryonic hearts required an increase in the level of spatial and temporal resolution. Current methods for such analyses include the use of intracellular and extracellular microelectrodes, echocardiography, rapid optical imaging using fluorescent dyes, and most recently optical coherence tomography. This review will focus on methods developed to investigate the functional emergence of the embryonic cardiac conduction system. Where appropriate, the methods used to delineate the anatomic pathways will also be discussed. The combination of techniques to capture both morphological and functional data from the CPCS will further improve with continued interdisciplinary collaboration. The Supplementary Material referred to in this article can be found at the Anatomical Record website (http://www.interscience.wiley.com/jpages/0003-276X/suppmat).

Action Potentials↗
PubMed2004

Dynamic patterns of apoptosis in the developing chicken heart.

The outflow tract (OFT) is abnormal in many congenital heart defects. One critical mechanism for morphogenesis of this complex structure is apoptosis. Chicken embryos (stages 19-38; ED4-10) stained with a fluorescent supravital lysosomal dye (LysoTracker Red; LTR) revealed the three-dimensional relationship between structural changes and apoptosis. The LTR staining peaked in the OFT myocardium at stages 27-32, consistent with our previous analyses using other apoptosis assays. While LTR stained under both the pulmonary artery and the aorta, it was most prevalent in the subaortic myocardium before its elimination. Furthermore, LTR staining was most abundant in the myocardium under intensely cytokeratin-positive, thick epicardium. These data support the hypothesis that temporally and spatially restricted apoptosis in the OFT myocardium allows the aorta and pulmonary artery to dock at the appropriate angle and level with the proper ventricle. These data also support a relationship between the differentiating epicardium and cardiomyocyte apoptosis.

Animals↗
PubMed2004

The development of the embryonic outflow tract provides novel insights into cardiac differentiation and remodeling.

The embryonic cardiac outflow tract (OFT) connects the developing ventricles with the aortic sac. In birds and mammals, OFT cardiomyocytes are generated from a "secondary (anterior)," heart-forming field well after the formation of the primitive heart tube. The OFT cardiomyocytes have unique properties and developmental fates as compared with the myocytes of the atrial and ventricular chambers. Many of the OFT cardiomyocytes of the avian embryo are eliminated by programmed cell death (PCD) during OFT remodeling in the transition from a single- to a dual-series circulation. Targeted PCD gain and loss-of-function studies indicate that PCD drives the shortening and rotation of the OFT required for the aorta and pulmonary artery to connect with the left and right ventricles, respectively. Defects in this process model aspects of the relatively common and often life-threatening congenital human conotruncal heart defects. Using indicators of tissue hypoxia, we suggest that OFT myocardial hypoxia may be the trigger for the PCD-dependent remodeling of the OFT. This review discusses these aspects of the formation and remodeling of the embryonic OFT in the context of the broader questions of cardiac muscle biology.

Animals↗
PubMed2004

[Long-term prognosis of hepatocellular carcinoma patients treated with adoptive immunotherapy].

Adoptive immunotherapy was performed for patients with multiple hepatocellular carcinoma (HCC) using LAK cells via the hepatic arterial catheter. One case study: A 45-year-old male patient was performed an absolute-non-cure operation. The operation was a success. However, some residual tumors remained in the liver. After the operation, adoptive immunotherapy was performed for 7 times in 5 weeks. The total inoculated LAK cells were 6.9x10(9). After the adoptive immunotherapy, no residual tumors were detected in the liver. He survived for 7 years in remission. Our results show that adoptive immunotherapy with LAK cells is useful and effective for patients with multiple HCC.

Aged↗
PubMed2003

Sculpting the cardiac outflow tract.

The cardiac outflow tract is the site of anomalies that affect a substantial proportion of individuals with congenital heart defects. The morphogenesis of this site is complex, and requires coordinated development of many cell types and tissues. It is therefore not surprising that developmental mistakes arise here, and that the steps and mechanisms of morphogenesis are still controversial and poorly understood, despite advances in molecular techniques. Recent findings have provided new insight into mechanisms of outflow tract morphogenesis, including clarification of its origins and the fate of cardiomyocytes, as well as invading cell populations. Application of new and old techniques and a wide range of approaches to tackle the unanswered questions about the outflow tract calls for collaboration among investigators from different disciplines including anatomists, physiologists, and molecular biologists.

Animals↗
PubMed2003

Possible role of nicaraven in neuroprotective effect on hippocampal slice culture.

Nicaraven is an agent that is especially beneficial in vasospasm or brain damage caused by subarachnoid hemorrhage. It ameliorates neurological deficits of patients and protects the central nervous system from ischemia. We investigated the neuroprotective effect of nicaraven against oxygen-glucose deprivation (OGD) induced or N-methyl-D-aspartic acid (NMDA) induced hippocampal neuronal cell death in organotypic brain slice cultures. The effect of nicaraven on hippocampal neuronal injury was evaluated by inhibition of uptake of propidium iodide (PI) into dead cells. The results demonstrated that nicaraven protected neuronal cells from both OGD- and NMDA-induced cell death. While nicaraven has a strong hydroxyl radical scavenging effect, another radical scavenger, N-acetyl-L-cysteine (NAC), inhibited cell death only caused by OGD. In contrast, the poly(ADP-ribose) synthetase (PARS) inhibitors 3-aminobenzamide (3-AB) and theophylline protected cells from both OGD- and NMDA-induced cell death. Since nicaraven has an inhibitory effect in PARS, as well as a radical scavenging effect, these results suggest that inhibition of hippocampal cell death caused by NMDA may be attributable to PARS inhibition by nicaraven.

Animals↗
PubMed2003

A culture device demonstrates that hydrostatic pressure increases mRNA of RGS5 in neuroblastoma and CHC1-L in lymphocytic cells.

Previous studies demonstrated that mechanical forces affect a wide range of cellular behaviors. These forces regulate important cellular responses in the human body and consist of gravity, hydrostatic pressure, stretch, and shear stress, which is exerted on the vascular system by the passage of blood flow. We reasoned that these forces might be significant and dynamic regulators of cellular functions within the human body. While cellular effects of stretch and shear stress have been studied particularly with endothelial cells, little is known about the effects of gravity and hydrostatic pressure to cells. To examine the direct effect of hydrostatic pressure, we developed a culture device to confer hydrostatic pressures to cells ranging from 0 to 1,000 psi. We subjected human neuroblastoma cells and rIL-2-activated lymphocytes to a constant pressure of 20 or 100 psi for 48 h and attempted to identify genes regulated by hydrostatic pressure. Genes of regulator of G-protein signaling 5 in neuroblastoma cells and CHC1-L in lymphocytes increased after exposure to hydrostatic pressure. The results demonstrated that hydrostatic pressure directly regulates the expression of specific genes in mammalian cells. Moreover, there may be some underlying mechanisms that have common effects in altered physical environments. Our in vitro culture system may provide some insight into the mechanisms through the intracellular processes affected by mechanical forces.

Cell Culture Techniques↗
PubMed2003

Polyphenols from some foodstuffs as inhibitors of ovalbumin permeation through caco-2 cell monolayers.

Some spices showed high inhibitory activity against ovalbumin permeation through Caco-2 cell monolayers. Pimentol from allspice, rosmarinic acid and luteolin-7-O-beta-glucuronide from thyme, quercetin-3-O-beta-glucuronide from coriander and rutin from tarragon were identified as the active principles. A structure-activity relationship study among the active isolates and their related compounds indicated that the presence of a catechol structure played an important role in the inhibitory activity of each compound.

Anti-Allergic Agents↗
PubMed2003

Developmental transitions in cardiac conduction.

The proper sequence of electrical activation of the mature four-chambered heart requires specialized conduction pathways including the His-Purkinje system and a nearly complete separation of the atrial and ventricular myocardium. We tracked the emergence of the structure of the mature His-Purkinje system in the developing chicken embryo with anti-polysialylated neural cell adhesion molecule (PSA-NCAM) and the HNK1 antibody against a sulfated carbohydrate epitope. The function of the His-Purkinje system was assayed using extracellular electrodes and high-resolution voltage-sensitive two-dimensional optical mapping. The appearance of the mature form of the His-Purkinje system delineated by the markers coincided with the onset of the mature electrophysiological pattern of ventricular activation. These data suggest that, at the completion of ventricular septation, the His-Purkinje system undergoes critical structural and functional transitions that impact on the global pattern of conduction and contraction of the developing four-chambered heart.

Action Potentials↗
PubMed2002

The essential role of Cited2, a negative regulator for HIF-1alpha, in heart development and neurulation.

Cited2 is a cAMP-responsive element-binding protein (CBP)/p300 interacting transcriptional modulator and a proposed negative regulator for hypoxia-inducible factor (HIF)-1alpha through its competitive binding with HIF-1alpha to CBP/p300. Disruption of the gene encoding Cited2 is embryonic lethal because of defects in the development of heart and neural tube. Morphological and Doppler echocardiographic analyses of Cited2(-/-) embryos reveal severe cardiovascular abnormalities, including pulmonic arterial stenosis and ventricular septal defects accompanied by high peak outflow velocities, features of the human congenital cardiac defect termed tetralogy of Fallot. The mRNA levels of several HIF-1alpha-responsive genes, such as vascular endothelial growth factor (VEGF), Glut1, and phosphoglycerate kinase 1, increased in the Cited2(-/-) hearts. The increase of VEGF levels is significant, because defects in the Cited2(-/-) embryos closely resemble the major defects observed in the VEGF transgenic embryos. Finally, compared with wild-type, cultured fibroblasts from Cited2(-/-) embryos demonstrate an enhanced expression of HIF-1alpha-responsive genes under hypoxic conditions. These observations suggest that functional loss of Cited2 is responsible for defects in heart and neural tube development, in part because of the modulation of HIF-1 transcriptional activities in the absence of Cited2. These findings demonstrate that Cited2 is an indispensable regulatory gene during prenatal development.

Animals↗
PubMed2002

Initiation of apoptosis in the developing avian outflow tract myocardium.

Apoptosis occurs within the cardiac outflow tract (OFT) myocardium during normal development of chick hearts. This peak of apoptosis occurs at stage 30-31 and coincides with dramatic remodeling of the OFT, suggesting that apoptosis occurs to allow proper alignment of the great vessels over their respective ventricles. The signals that initiate apoptosis in this setting are unknown. The aim of this study was to characterize the cells undergoing apoptosis in the cardiac OFT myocardium and the cells that may influence this process. Two cell populations that may initiate apoptosis of the cardiomyocytes are the cardiac neural crest (CNC) cells and epicardial cells. We examined stage 30-31 chick embryos that had undergone removal of the CNC cells or had delayed epicardial growth for alterations of apoptosis. Removal of the CNC cells did not reduce the levels or pattern of apoptosis in the OFT myocardium. In contrast, impeding the growth of the epicardium over the OFT resulted in a 57% reduction in apoptotic cells in the OFT myocardium. Analysis of the apoptotic cells within the OFT myocardium showed that as many as 92% of them expressed cardiomyocyte markers. In the quail, the endothelial marker QH1 identified a component from the epicardium, endothelial cells, in regions where apoptosis is elevated in the OFT myocardium. These results suggest that a component from the epicardium, possibly endothelial cells, is required for the initiation of apoptosis in OFT cardiomyocytes.

Animals↗
PubMed2002

The pros and cons of apoptosis assays for use in the study of cells, tissues, and organs.

Programmed cell death or apoptosis occurs in many tissues during normal development and in the normal homeostasis of adult tissues. Apoptosis also plays a significant role in abnormal development and disease. Increased interest in apoptosis and cell death in general has resulted in the development of new techniques and the revival of old ones. Each assay has its advantages and disadvantages that can render it appropriate and useful for one application, but inappropriate or difficult to use in another. Understanding the strengths and limitations of the assays would allow investigators to select the best methods for their needs.

Animals↗
PubMed2002

An active compound against allergen absorption in hypoallergenic wheat flour produced by enzymatic modification.

Hypoallergenic wheat flour produced by modification with cellulase and actinase showed inhibitory activity against ovalbumin permeation in an in vitro model by using the Caco-2 cell monolayer. The activity was found in the cellulase preparation used for producing the flour. An active compound was isolated by HPLC and identified as Trp-Ser-Asn-Ser-Gly-Asn-Phe-Val-Gly-Gly-Lys by 1H-NMR data and Edman degradation. The undecapeptide, some oligopeptides with the N-terminal sequences and Trp ethyl ester showed activity at 10(-7) M, acetyl Trp being active at 10(-2) M. These data suggest that the Trp residue without a free carboxyl group would be required for the inhibitory activity of ovalbumin absorption through the intestinal tract.

Absorption↗
PubMed2002

[Direct assay for urine cortisol with cortisol kit [TFB]].

We examined Cortisol Kit [TFB] for direct assay of urine cortisol. And the multiplication by dilution factor of urine cortisol values in this kit was examined. The coefficient of correlation of cortisol levels (46 urine samples) between Cortisol Kit [TFB] and Chemilumi ACS-Cortisol II, which is another kit for direct assay of urine cortisol, was r = 0.858, y = 1.86x + 38.2 (p < 0.001). There were differences between the both cortisol levels of each urine sample in spite of the good coefficient of correlation. The urine cortisol values obtained from the standard curve in addition of 50 microliters of zero standard were 50-80% of the values obtained from the standard curve in the package insert. These results suggest that the specificity of the antibodies of both direct assay kits for urine cortisol may be different each other, and the multiplication by 1.09, the dilution factor due to the addition of zero standard to only urine sample, is unnecessary although it is indispensable for urine samples to add zero standard. Cortisol Kit [TFB] was very convenient for its easy assay procedure and short incubation.

Evaluation Studies as Topic↗