Amundsen Sea circulation controls bottom upwelling and Antarctic Pine Island and Thwaites ice shelf melting.

The Pine Island and Thwaites Ice Shelves (PIIS/TIS) in the Amundsen Sea are melting rapidly and impacting global sea levels. The thermocline depth (TD) variability, the interface between cold Winter Water and warm modified Circumpolar Deep Water (mCDW), at the PIIS/TIS front strongly correlates with basal melt rates, but the drivers of its interannual variability remain uncertain. Here, using an ocean model, we propose that the strength of the eastern Amundsen Sea on-shelf circulation primarily controls TD variability and consequent PIIS/TIS melt rates. The TD variability occurs because the on-shelf circulation meanders following the submarine glacial trough, creating vertical velocity through bottom Ekman dynamics. We suggest that a strong or weak ocean circulation, possibly linked to remote winds in the Bellingshausen Sea, generates corresponding changes in bottom Ekman convergence, which modulates mCDW upwelling and TD variability. We show that interannual variability of off-shelf zonal winds has a minor effect on ocean heat intrusion into PIIS/TIS cavities, contrary to the widely accepted concept.

On-shelf circulation of warm water toward the Totten Ice Shelf in East Antarctica.

The Totten Glacier in East Antarctica, with an ice volume equivalent to >3.5 m of global sea-level rise, is grounded below sea level and, therefore, vulnerable to ocean forcing. Here, we use bathymetric and oceanographic observations from previously unsampled parts of the Totten continental shelf to reveal on-shelf warm water pathways defined by deep topographic features. Access of warm water to the Totten Ice Shelf (TIS) cavity is facilitated by a deep shelf break, a broad and deep depression on the shelf, a cyclonic circulation that carries warm water to the inner shelf, and deep troughs that provide direct access to the TIS cavity. The temperature of the warmest water reaching the TIS cavity varies by ~0.8 °C on an interannual timescale. Numerical simulations constrained by the updated bathymetry demonstrate that the deep troughs play a critical role in regulating ocean heat transport to the TIS cavity and the subsequent basal melt of the ice shelf.

Thoracic endovascular aortic repair of an ascending aortic pseudoaneurysm.

A 74-year-old man with a history of two thoracic aortic repairs, including a modified Bentall procedure using a mechanical valve and total arch replacement, was referred to our hospital with the development of hoarseness. Computed tomography revealed an anastomotic pseudoaneurysm between the prosthetic grafts in the ascending aorta. Two aortic cuffs for abdominal aorta were deployed through the left axillary artery using a transcatheter aortic valve replacement guidewire placed at the supra-aortic mechanical valve during ventricular rapid pacing and were successfully covered with an inlet to the pseudoaneurysm on postoperative computed tomography. The postoperative course was favorable.

Ocean variability beneath Thwaites Eastern Ice Shelf driven by the Pine Island Bay Gyre strength.

West Antarctic ice-shelf thinning is primarily caused by ocean-driven basal melting. Here we assess ocean variability below Thwaites Eastern Ice Shelf (TEIS) and reveal the importance of local ocean circulation and sea-ice. Measurements obtained from two sub-ice-shelf moorings, spanning January 2020 to March 2021, show warming of the ice-shelf cavity and an increase in meltwater fraction of the upper sub-ice layer. Combined with ocean modelling results, our observations suggest that meltwater from Pine Island Ice Shelf feeds into the TEIS cavity, adding to horizontal heat transport there. We propose that a weakening of the Pine Island Bay gyre caused by prolonged sea-ice cover from April 2020 to March 2021 allowed meltwater-enriched waters to enter the TEIS cavity, which increased the temperature of the upper layer. Our study highlights the sensitivity of ocean circulation beneath ice shelves to local atmosphere-sea-ice-ocean forcing in neighbouring open oceans.

[Successful Use of Left Ventricular Support Device (Impella 5.0) for Ischemic Heart Disease with Cardiogenic Shock:Report of a Case].

Postoperative hemodynamic support with an Impella 5.0 was effective in an obese man who underwent coronary artery bypass grafting (CABG) for ischemic heart disease and cardiogenic shock. A 43-year-old obese man presented to our hospital complaining severe chest pain. Coronary angiography revealed acute coronary syndrome due to severe triple-vessel disease, and the patient fell into a state of shock, which required veno-arterial extracorporeal membrane oxygenation (VA-ECMO) support. The patient subsequently underwent CABG, but he was unable to be separated from VA-ECMO. Impella 5.0 was introduced through right axillary artery on the next day. VA-ECMO was converted to veno-venous (VV)-ECMO on the 3rd postoperative day to enable respiratory rehabilitation in a sitting posi-tion;his respiratory status gradually improved. VV-ECMO and the Impella 5.0 were discontinued on the 6th and 7th postoperative days, respectively. He was eventually transferred to nearby facility for further rehabilitation three months later. As of two years, his cardiac function has improved and he is doing well at home.

[Isolated Pulmonary Valve Endocarditis Accompanying Multiple Pulmonary Embolisms:Report of a Case].

Isolated pulmonary valve infective endocarditis is rare and accounts for only 1.5% to 2.0% of all cases of infective endocarditis. We present a case of isolated pulmonary valve endocarditis, which was successfully treated by pulmonary valve replacement. A 69-year-old man presented with fever and was diagnosed with active pulmonary valve infective endocarditis. He had no apparent predisposing factors. Blood cultures were positive for Streptococcus viridans, and transesophageal echocardiography showed mobile vegetation. His condition improved transiently with intravenous antibiotic therapy;however, high fever and reduced oxygen saturation recurred. Computed tomography showed multiple infiltrative shadows suggesting septic pulmonary embolisms. Urgent surgery was indicated because antibiotic treatment was ineffective. During the operation, we found that vegetation had destroyed all pulmonary leaflets. We performed pulmonary valve replacement with a stented bioprosthetic valve as well as enlargement of the right ventricular outflow tract with a bovine pericardial patch. The postoperative course was uneventful. Antibiotic therapy was continued for six weeks after surgery. For two years since surgery, the patient has experienced no recurrence of infection.

Multidecadal poleward shift of the southern boundary of the Antarctic Circumpolar Current off East Antarctica.

The southern boundary (SB) of the Antarctic Circumpolar Current, the southernmost extent of the upper overturning circulation, regulates the Antarctic thermal conditions. The SB's behavior remains unconstrained because it does not have a clear surface signature. Revisited hydrographic data from off East Antarctica indicate full-depth warming from 1996 to 2019, concurrent with an extensive poleward shift of the SB subsurface isotherms (>50 km), which is most prominent at 120°E off the Sabrina Coast. The SB shift is attributable to enhanced upper overturning circulation and a depth-independent frontal shift, generally accounting for 30 and 70%, respectively. Thirty years of oceanographic data corroborate the overall and localized poleward shifts that are likely controlled by continental slope topography. Numerical experiments successfully reproduce this locality and demonstrate its sensitivity to mesoscale processes and wind forcing. The poleward SB shift under intensified westerlies potentially induces multidecadal warming of Antarctic shelf water.

Pathways of ocean heat towards Pine Island and Thwaites grounding lines.

In the Amundsen Sea, modified Circumpolar Deep Water (mCDW) intrudes into ice shelf cavities, causing high ice shelf melting near the ice sheet grounding lines, accelerating ice flow, and controlling the pace of future Antarctic contributions to global sea level. The pathways of mCDW towards grounding lines are crucial as they directly control the heat reaching the ice. A realistic representation of mCDW circulation, however, remains challenging due to the sparsity of in-situ observations and the difficulty of ocean models to reproduce the available observations. In this study, we use an unprecedentedly high-resolution (200 m horizontal and 10 m vertical grid spacing) ocean model that resolves shelf-sea and sub-ice-shelf environments in qualitative agreement with existing observations during austral summer conditions. We demonstrate that the waters reaching the Pine Island and Thwaites grounding lines follow specific, topographically-constrained routes, all passing through a relatively small area located around 104°W and 74.3°S. The temporal and spatial variabilities of ice shelf melt rates are dominantly controlled by the sub-ice shelf ocean current. Our findings highlight the importance of accurate and high-resolution ocean bathymetry and subglacial topography for determining mCDW pathways and ice shelf melt rates.

Origin of Circumpolar Deep Water intruding onto the Amundsen and Bellingshausen Sea continental shelves.

Melting of West Antarctic ice shelves is enhanced by Circumpolar Deep Water (CDW) intruding onto the Amundsen and Bellingshausen Seas (ABS) continental shelves. Despite existing studies of cross-shelf and on-shelf CDW transports, CDW pathways onto the ABS originating from further offshore have never been investigated. Here, we investigate CDW pathways onto the ABS using a regional ocean model. Simulated CDW tracers from a zonal section across 67°S (S04P) circulate along the Antarctic Circumpolar Current (ACC) and Ross Gyre (RG) and travel into ABS continental shelf after 3-5 years, but source locations are shifted westward by ~900 km along S04P in 2001-2006 compared to 2009-2014. We find that simulated on- and off-shelf CDW is ~0.1-0.2 °C warmer in the 2009-2014 case than in the 2001-2006 case together with changes in simulated ocean circulation. These differences are primarily caused by lateral, rather than surface, boundary conditions, implying that large-scale atmospheric and ocean circulations are able to control CDW pathways and thus off- and on-shelf CDW properties.

[Surgical Repair of Kommerell's Diverticulum with Right Sided Aortic Arch;Report of a Case].

A 54-year-old woman was referred for assessment of dysphagia and extrinsic compression of the esophagus detected by upper gastrointestinal endoscopy. Computed tomography revealed the rightsided aortic arch with mirror image branching and Kommerell's diverticulum. To relieve the esophageal compression, surgical intervention was indicated. Descending aortic replacement with a Dacron graft was performed through right thoracotomy under partial cardiopulmonary bypass. The patient was discharged without any complication, and her dysphagia disappeared.

Evaluation of a single-dose PIGRET assay for acetaminophen in rats compared with the RBC Pig-a assay.

As a part of a collaborative study of the Pig-a assay by the Mammalian Mutagenicity Study Group of the Japanese Environmental Mutagen Society, a genotoxicity study on acetaminophen (APAP) was performed using the red blood cell (RBC) Pig-a and PIGRET assays. The dose levels were set at 0 (vehicle, 0.5% methylcellulose solution), 500, 1000, and 2000mg/kg, and APAP was administered once by oral gavage to male Sprague Dawley rats. For the positive control group, N-nitroso-N-ethylurea (ENU, 40mg/kg) was administered in the same way. The RBC Pig-a and PIGRET assays were performed using peripheral blood collected at pre-dosing and 1, 2 and 4 weeks after dosing. In both the RBC Pig-a and PIGRET assays, there were no changes in the Pig-a gene mutant frequency (MF) by the APAP treatment at any time point. The Pig-a MFs as measured by the RBC Pig-a assay for the ENU-treated group increased in a time-dependent manner with the maximum value at week 4; however, those using the PIGRET assay reached comparable values at week 1. Based on the above results, APAP was determined to have no mutagenicity under the conditions of this study, and the PIGRET assay could detect mutagenicity of ENU much earlier than the RBC Pig-a assay.

Evaluation of a single-dose PIGRET assay for cisplatin in rats compared with the RBC Pig-a assay.

As a part of a collaborative study of the Pig-a assay by the Mammalian Mutagenicity Study Group of the Japanese Environmental Mutagen Society, a genotoxicity study on cisplatin was performed using red blood cell (RBC) Pig-a and PIGRET assays. The dose levels were set at 0 (vehicle, physiological saline), 0.5, 1, and 2 mg/kg, and cisplatin was administered intravenously once to male F344 rats. The RBC Pig-a and PIGRET assays were performed using peripheral blood collected at pre-dosing and 1, 2 and 4 weeks after dosing. In the RBC Pig-a assay, an increase in the Pig-a mutant frequency (MF) was observed at week 4 in the high dose group. Although a significant increase in the Pig-a MF was also observed at week 2 in all cisplatin-treated groups, it was considered that this change was caused by a low MF in the vehicle control group and not to be biologically relevant. In the PIGRET assay, the Pig-a MF was increased at weeks 1, 2 and 4 in the high dose group. In addition, the means of the vehicle control group's Pig-a MFs in the PIGRET assay were lower than those in the RBC Pig-a assay. Based on the above results, cisplatin was determined to have mutagenicity under the conditions of this study, and it was demonstrated that the PIGRET assay was an appropriate tool to evaluate the in vivo mutagenicity much earlier than the RBC Pig-a assay.

[Ventricular Septal Perforation after Inferior Myocardial Infarction].

We report a rare case of ventricular septal perforation (VSP) after inferior myocardial infarction. Surgical repair of VSP after inferior infarction is technically difficult because of its anatomical location. An 81-year-old female presented with dyspnea on the 8th day after percutaneous coronary intervention for acute inferior myocardial infarction. Echocardiography revealed a ventricular septal perforation. Urgent operation was performed. There was a VSP around the base of the ventricular septum. The myocardial infarction extended to the adjacent muscle of the mitral valve annulus. Two bovine pericardial patches were used in the left ventricular cavity. The patches were sewn on the mitral valve annulus which was the only normal tissue in the region. The 1st patch was used to close the VSP directly, and the 2nd patch was sutured to the normal myocardium to exclude the infracted area. No residual shunt flow was observed. The postoperative course was uneventful.

Three Case Report of Spontaneous Isolated Dissection of the Superior Mesenteric Artery-With an Algorithm Proposed for the Management.

Spontaneous isolated dissection of the superior mesenteric artery (SID-SMA) is a rare condition, and there is still no consensus on optimal management. Here, we present three cases of SID-SMA, that were treated by surgical revascularization with urgent iliomesenteric bypass surgery without intestine resection, endovascular therapy with stent placement, and conservative management. The purpose of this study is to review these three cases and propose an algorithm for optimal management of SID-SMA.

[Bilateral congenital coronary-pulmonary artery fistulas; report of a case].

Bilateral coronary-pulmonary artery fistulas are very rare. We report a case of a 68-year-old woman without any previous medical history, who presented to our hospital after slow onset of chest heaviness on exertion. Coronary computed tomography (CT) and angiography revealed 2 fistulas:one arising from the left anterior descending artery accompanied by an aneurysm and the other from the right coronary artery. We opened the trunk of the pulmonary artery under cardio-pulmonary bypass and cardiac arrest. We recognized the outflow of the shunt just above the right pulmonary cusp, which was closed from the outside. We also closed the aneurysm of the shunt. Neither the fistulas nor the aneurysm was recognized by postoperative CT. The chest symptom disappeared.

[Surgical treatment of coronary sinus orifice atresia; report of a case].

We report a case of a 69-year-old man with coronary sinus orifice atresia incidentally found during mitral and tricuspid valve operation in. Preoperatively, a patent left superior vena cava was noted. An abnormal opening of the coronary sinus was recognized in the inter-atrial septum of the left atrium near the postero-medial commissure of the mitral valve. The coronary sinus was absent in the right atrium. A coronary sinus was created by resecting the inter-atrial septum of the right atrium, and the abnormal opening of the coronary sinus at the left atrium was closed with an autologus pericardial patch. Tricuspid annuloplasty was performed with a 30 mm MC3 ring. Postoperative coronary sinus flow was confirmed normal by enhanced computed tomography (CT). Preoperative recognition of this rare disease is important, especially when the surgical candidate has a patent left superior vena cava.

[Clinical effects of tolvaptan for patients with stage 4-5 chronic kidney disease in cardiac surgery].

We report clinical effects of tolvaptan, a vasopressin V2 receptor antagonist, in cardiac surgery. Tolvaptan was administrated to 5 patients with non-dialysis dependent stage 4-5 chronic kidney disease (CKD) during an early postoperative stage. Tolvaptan increased urine output and improved respiratory function in all patients without causing hemodynamic deterioration. All patients were able to avoid initiating long-term hemodialysis during hospital stay. Tolvaptan was effective and safe after cardiac surgery for patients with severe CKD.

Changes in auditory brainstem response (ABR) in Kanamycin-induced auditory disturbance model rats.

This study was designed to evaluate changes in auditory brainstem response (ABR) in the course of auditory disturbance in rats induced by Kanamycin (KM). KM was administered subcutaneously to 12 CD (SD) male rats aged 6 weeks for 10 days at a dose of 800 mg/kg. Death was observed in one male on day 8 and 2 males on day 10. It was thought that kidney damage was the cause of death from histopathological findings. ABR was recorded before KM treatment and on days 4, 8, 10 and 11 after KM treatment. The ABR changes after KM treatment in rats were as follows. On day 4, 6 rats showed an increase in amplitude of waves I and/or II and on day 8, among those, 4 rats still showed a high amplitude of waves I and/or II. On day 8, 2 rats showed an elevation of ABR threshold (15-40 dB SPL) and a decrease in amplitude of wave I and increase in amplitude of wave II at the same time. On day 11, 7 rats showed a decrease in amplitude of wave I. In addition, ABR threshold shifts (10-70 dB SPL) were observed in those rats. In ABR recording, KM-induced auditory disturbance model rats showed an increase in amplitude of waves I and/or II earlier than an ABR threshold shift. By analyzing temporal alteration of amplitude of the ABR components, we could detect precursory phenomenon of the auditory disturbance at an early phase of treatment. By following the pathway of click-ABR and tone pip-ABR examination, the auditory disturbance of low- frequency to high-frequency range could be analyzed at an early date in detail.

[Mitral valve replacement in a patient with multiple myeloma].

We herein report a case of a 71-year-old male with untreated multiple myeloma (MM) and congestive heart failure due to moderate mitaral regurgitation, who successfully underwent mitral valve replacement and tricuspid annuloplasty. MM has various complications such as bleeding tendency, anemia, renal dysfunction, hyperviscosity syndrome, and susceptibility to bacterial infection. Considering bleeding tendency and post-operative anti-coagulant therapy, a bioprosthesis was chosen in this case. The postoperative course was uneventful. When cardiac surgery is indicated in patients with MM, we must carefully consider and manage the specific perioperative problems and indications for cardiac procedures.

Partial aortic root remodeling with an adventitial inversion technique for an acute type a aortic dissection.

This case report describes a partial aortic root remodeling, which applied a valve-sparing technique, with an adventitial inversion technique for an acute type A aortic dissection with intimal tear extending into the noncoronary sinus of Valsalva. Postoperative computed tomography at six months showed no dissection or pseudoaneurysm in the aortic root.