The Experts below are selected from a list of 3939 Experts worldwide ranked by ideXlab platform
Eric B Carstens - One of the best experts on this subject based on the ideXlab platform.
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nucleotide sequence of a gene essential for viral dna replication in the baculovirus autographa californica nuclear polyhedrosis virus
Virology, 1991Co-Authors: Eric B CarstensAbstract:Abstract The nucleotide sequence of the 60.1- to 65.5-m.u. region of Autographa californica nuclear polyhedrosis virus (AcMNPV) was determined. Seven large open reading frames were identified. Two open reading frames potentially encoding gene products of 143 and 38 kDa were found in the Counterclockwise Direction upstream of the p6.9 gene. Four additional open reading frames were found in the opposite Direction. Analysis of the predicted amino acid sequence of the 143-kDa gene revealed a potential leucine zipper motif, a putative nuclear localization signal, and seven amino acid motifs previously identified in a number of proteins involved in NTP binding and DNA/RNA unwinding. The mutation in a DNA replication defective temperature-sensitive mutant was fine mapped to the carboxy terminus of the ORF1(pt 43) gene. Sequence analysis of the mutation site identified a single base change of a guanine to an adenine, resulting in the substitution of a methionine for valine. This mutation resides seven amino acids downstream of the putative NTP-binding motif of the ORF1(p143) gene product and results in a DNA negative mutant. Together these data strongly suggest that the ORF1(p143) gene product is a baculovirus helicase.
Mario D Gonzalez - One of the best experts on this subject based on the ideXlab platform.
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role of the tricuspid annulus and the eustachian valve ridge on atrial flutter relevance to catheter ablation of the septal isthmus and a new technique for rapid identification of ablation success
Circulation, 1996Co-Authors: Hiroshi Nakagawa, Ralph Lazzara, Terrance Khastgir, Karen J Beckman, J H Mcclelland, Shinobu Imai, Jan Pitha, Anton E Becker, Mauricio Arruda, Mario D GonzalezAbstract:Background Typical atrial flutter (AFL) results from right atrial reentry by propagation through an isthmus between the inferior vena cava (IVC) and tricuspid annulus (TA). We postulated that the eustachian valve and ridge (EVR) forms a line of conduction block between the IVC and coronary sinus (CS) ostium and forms a second isthmus (septal isthmus) between the TA and CS ostium. Methods and Results Endocardial mapping in 30 patients with AFL demonstrated atrial activation around the TA in the Counterclockwise Direction (left anterior oblique projection). Double atrial potentials were recorded along the EVR in all patients during AFL. Pacing either side of the EVR during sinus rhythm also produced double potentials, which indicated fixed anatomic block across EVR. Entrainment pacing at the septal isthmus and multiple sites around the TA produced a Δ return interval ≤8 ms in 14 of 15 patients tested. Catheter ablation eliminated AFL in all patients by ablation of the septal isthmus in 26 patients and the p...
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role of the tricuspid annulus and the eustachian valve ridge on atrial flutter relevance to catheter ablation of the septal isthmus and a new technique for rapid identification of ablation success
Circulation, 1996Co-Authors: Hiroshi Nakagawa, Ralph Lazzara, Terrance Khastgir, Karen J Beckman, J H Mcclelland, Shinobu Imai, Jan Pitha, Anton E Becker, Mauricio Arruda, Mario D GonzalezAbstract:Background Typical atrial flutter (AFL) results from right atrial reentry by propagation through an isthmus between the inferior vena cava (IVC) and tricuspid annulus (TA). We postulated that the eustachian valve and ridge (EVR) forms a line of conduction block between the IVC and coronary sinus (CS) ostium and forms a second isthmus (septal isthmus) between the TA and CS ostium. Methods and Results Endocardial mapping in 30 patients with AFL demonstrated atrial activation around the TA in the Counterclockwise Direction (left anterior oblique projection). Double atrial potentials were recorded along the EVR in all patients during AFL. Pacing either side of the EVR during sinus rhythm also produced double potentials, which indicated fixed anatomic block across EVR. Entrainment pacing at the septal isthmus and multiple sites around the TA produced a Δ return interval ≤8 ms in 14 of 15 patients tested. Catheter ablation eliminated AFL in all patients by ablation of the septal isthmus in 26 patients and the p...
Hiroki Nishida - One of the best experts on this subject based on the ideXlab platform.
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a chordate species lacking nodal utilizes calcium oscillation and bmp for left right patterning
Proceedings of the National Academy of Sciences of the United States of America, 2020Co-Authors: Takeshi A Onuma, Momoko Hayashi, Fuki Gyoja, Kanae Kishi, Kai Wang, Hiroki NishidaAbstract:Larvaceans are chordates with a tadpole-like morphology. In contrast to most chordates of which early embryonic morphology is bilaterally symmetric and the left-right (L-R) axis is specified by the Nodal pathway later on, invariant L-R asymmetry emerges in four-cell embryos of larvaceans. The asymmetric cell arrangements exist through development of the tailbud. The tail thus twists 90° in a Counterclockwise Direction relative to the trunk, and the tail nerve cord localizes on the left side. Here, we demonstrate that larvacean embryos have nonconventional L-R asymmetries: 1) L- and R-cells of the two-cell embryo had remarkably asymmetric cell fates; 2) Ca2+ oscillation occurred through embryogenesis; 3) Nodal, an evolutionarily conserved left-determining gene, was absent in the genome; and 4) bone morphogenetic protein gene (Bmp) homolog Bmp.a showed right-sided expression in the tailbud and larvae. We also showed that Ca2+ oscillation is required for Bmp.a expression, and that BMP signaling suppresses ectopic expression of neural genes. These results indicate that there is a chordate species lacking Nodal that utilizes Ca2+ oscillation and Bmp.a for embryonic L-R patterning. The right-side Bmp.a expression may have arisen via cooption of conventional BMP signaling in order to restrict neural gene expression on the left side.
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vitelline membrane proteins promote left sided nodal expression after neurula rotation in the ascidian halocynthia roretzi
Developmental Biology, 2019Co-Authors: Yuka Tanaka, Shiori Yamada, Samantha L Connop, Noritaka Hashii, Hitoshi Sawada, Yu Shih, Hiroki NishidaAbstract:Abstract Stereotyped left–right asymmetry both in external and internal organization is found in various animals. Left-right symmetry is broken by the neurula rotation in the ascidian, Halocynthia roretzi. Neurula embryos rotate along the anterior–posterior axis in a Counterclockwise Direction, and the rotation stops when the left side of the embryo is oriented downwards, resulting in contact of the left-side epidermis with the vitelline membrane at the bottom of perivitelline space. Then, such contact induces the expression of nodal and its downstream Pitx2 gene in the left-side epidermis. Vitelline membrane is required for the promotion of nodal expression. Here, we showed that a chemical signal from the vitelline membrane promotes nodal gene expression, but mechanical stimulus at the point of contact is unnecessary since the treatment of devitellinated neurulae with an extract of the vitelline membrane promoted nodal expression on both sides. The signal molecules are already present in the vitelline membranes of unfertilized eggs. These signal molecules are proteins but not sugars. Specific fractions in gel filtration chromatography had the nodal promoting activity. By mass spectrometry, we selected 48 candidate proteins. Proteins that contain both a zona pellucida (ZP) domain and epidermal growth factor (EGF) repeats were enriched in the candidates of the nodal inducing molecules. Six of the ZP proteins had multiple EGF repeats that are only found in ascidian ZP proteins. These were considered to be the most viable candidates of the nodal-inducing molecules. Signal molecules are anchored to the entire vitelline membrane, and contact sites of signal-receiving cells are spatially and mechanically controlled by the neurula rotation. In this context, ascidians are unusual with respect to mechanisms for specification of the left-right axis. By suppressing formation of epidermis monocilia, we also showed that epidermal cilia drive the neurula rotation but are dispensable for sensing the signal from the vitelline membrane.
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wavy movements of epidermis monocilia drive the neurula rotation that determines left right asymmetry in ascidian embryos
Developmental Biology, 2019Co-Authors: Shiori Yamada, Yuka Tanaka, Motohiko Saigou, Kaoru S Imai, Takeshi A Onuma, Hiroki NishidaAbstract:Abstract Tadpole larvae of the ascidian, Halocynthia roretzi, show morphological left–right asymmetry in the brain structures and the orientation of tail bending within the vitelline membrane. Neurula embryos rotate along the anterior–posterior axis in a Counterclockwise Direction, and then this rotation stops when the left side of the embryo is oriented downwards. Contact of the left-side epidermis with the vitelline membrane promotes nodal gene expression in the left-side epidermis. This is a novel mechanism in which rotation of whole embryos provides the initial cue for breaking left–right symmetry. Here we show that epidermal monocilia, which appear at the neurula rotation stage, generate the driving force for rotation. A ciliary protein, Arl13b, fused with Venus YFP was used for live imaging of ciliary movements. Although overexpression of wild-type Arl13b fusion protein resulted in aberrant movements of the cilia and abrogation of neurula rotation, mutant Arl13b fusion protein, in which the GTPase and coiled-coil domains were removed, did not affect the normal ciliary movements and neurula rotation. Epidermis cilia moved in a wavy and serpentine way like sperm flagella but not in a rotational way or beating way with effective stroke and recovery stroke. They moved very slowly, at 1/7 Hz, consistent with the low angular velocity of neurula rotation (ca. 43°/min). The tips of most cilia pointed in the opposite Direction of embryonic rotation. Similar motility was also observed in Ciona robusta embryos. When embryos were treated with a dynein inhibitor, Ciliobrevin D, both ciliary movements and neurula rotation were abrogated, showing that ciliary movements drive neurula rotation in Halocynthia. The drug also inhibited Ciona neurula rotation. Our observations suggest that the driving force of rotation is generated using the vitelline membrane as a substrate but not by making a water current around the embryo. It is of evolutionary interest that ascidians use ciliary movements to break embryonic left–right symmetry, like in many vertebrates. Meanwhile, ascidian embryos rotate as a whole, similar to embryos of non-vertebrate deuterostomes, such as echinoderm, hemichordate, and amphioxus, while swimming.
Hiroshi Nakagawa - One of the best experts on this subject based on the ideXlab platform.
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role of the tricuspid annulus and the eustachian valve ridge on atrial flutter relevance to catheter ablation of the septal isthmus and a new technique for rapid identification of ablation success
Circulation, 1996Co-Authors: Hiroshi Nakagawa, Ralph Lazzara, Terrance Khastgir, Karen J Beckman, J H Mcclelland, Shinobu Imai, Jan Pitha, Anton E Becker, Mauricio Arruda, Mario D GonzalezAbstract:Background Typical atrial flutter (AFL) results from right atrial reentry by propagation through an isthmus between the inferior vena cava (IVC) and tricuspid annulus (TA). We postulated that the eustachian valve and ridge (EVR) forms a line of conduction block between the IVC and coronary sinus (CS) ostium and forms a second isthmus (septal isthmus) between the TA and CS ostium. Methods and Results Endocardial mapping in 30 patients with AFL demonstrated atrial activation around the TA in the Counterclockwise Direction (left anterior oblique projection). Double atrial potentials were recorded along the EVR in all patients during AFL. Pacing either side of the EVR during sinus rhythm also produced double potentials, which indicated fixed anatomic block across EVR. Entrainment pacing at the septal isthmus and multiple sites around the TA produced a Δ return interval ≤8 ms in 14 of 15 patients tested. Catheter ablation eliminated AFL in all patients by ablation of the septal isthmus in 26 patients and the p...
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role of the tricuspid annulus and the eustachian valve ridge on atrial flutter relevance to catheter ablation of the septal isthmus and a new technique for rapid identification of ablation success
Circulation, 1996Co-Authors: Hiroshi Nakagawa, Ralph Lazzara, Terrance Khastgir, Karen J Beckman, J H Mcclelland, Shinobu Imai, Jan Pitha, Anton E Becker, Mauricio Arruda, Mario D GonzalezAbstract:Background Typical atrial flutter (AFL) results from right atrial reentry by propagation through an isthmus between the inferior vena cava (IVC) and tricuspid annulus (TA). We postulated that the eustachian valve and ridge (EVR) forms a line of conduction block between the IVC and coronary sinus (CS) ostium and forms a second isthmus (septal isthmus) between the TA and CS ostium. Methods and Results Endocardial mapping in 30 patients with AFL demonstrated atrial activation around the TA in the Counterclockwise Direction (left anterior oblique projection). Double atrial potentials were recorded along the EVR in all patients during AFL. Pacing either side of the EVR during sinus rhythm also produced double potentials, which indicated fixed anatomic block across EVR. Entrainment pacing at the septal isthmus and multiple sites around the TA produced a Δ return interval ≤8 ms in 14 of 15 patients tested. Catheter ablation eliminated AFL in all patients by ablation of the septal isthmus in 26 patients and the p...
Kazuaki Negishi - One of the best experts on this subject based on the ideXlab platform.
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pericardiectomy is associated with improvement in longitudinal displacement of left ventricular free wall due to increased Counterclockwise septal to lateral rotational displacement
Journal of The American Society of Echocardiography, 2015Co-Authors: Arun Dahiya, Zoran B Popovic, Hirohiko Motoki, Chadi M Alraies, Kazuaki Negishi, Tomoko Negishi, Srisakul Chirakarnjanakorn, Allan L KleinAbstract:Background Pericardiectomy is an effective intervention for constrictive pericarditis. Speckle-tracking echocardiography can provide quantitative information not only about longitudinal strain (LS) but about longitudinal displacement (LD) and septal-to-lateral rotational displacement (SLRD). The aim of this study was to investigate whether pericardiectomy improves myocardial mechanics using speckle-tracking analysis. Methods Eighty-three patients with constrictive pericarditis who underwent echocardiography were retrospectively assessed (mean age, 58 ± 12 years; 72 men; 50 idiopathic, 20 postoperative, four viral, three radiation, and six others) and compared with 20 healthy volunteers. LD and SLRD were measured from the apical four-chamber view and global LS from three apical views. Results LD was less in the constrictive pericarditis group compared with control subjects ( P P P = .48). In pre- and post–pericardial surgery comparisons ( n = 27), values of septal and lateral LD were almost identical (mean, 13.6 ± 4.7 vs 13.3 ± 5.4 mm; P = .70) before pericardiectomy, but septal LD decreased (mean, 9.3 ± 3.5 mm; P P = .0106) after the surgery, even though the difference in LS between the septal and lateral walls decreased (from 5.6 ± 5.3% to 2.5 ± 4.2%, P = .008). Systolic whole-heart swinging motion significantly increased to a Counterclockwise Direction after surgery (mean SLRD, −0.8 ± 3.3° vs 2.1 ± 3.0°; P = .001). Although the change in SLRD after pericardiectomy was not different between patients with decreases and increases in New York Heart Association class, SLRD change was significantly greater in patients who received fewer diuretics after surgery (mean, 4.00 ± 0.91 vs 0.27 ± 1.47; P = .027). Conclusions After surgical removal of the pericardium, LD of the septal and lateral walls became significantly different, and Counterclockwise SLRD increased, reflecting loss of pericardial support.
