A Novel Peptide Reagent for Investigating Disulfide-Coupled Folding Intermediates of Mid-Size Proteins.

Investigations of protein folding have largely involved the use of disulfide-containing proteins, since the disulfide-coupled folding of proteins allows folding intermediates to be trapped and their conformations determined. However, studies of the folding mechanisms of mid-size proteins face several problems, one of which is that detecting folding intermediates is difficult. Therefore, to solve this issue, a novel peptide reagent, maleimidohexanoyl-Arg5-Tyr-NH2, was designed and applied to the detection of folding intermediates of model proteins. BPTI was chosen as a model small protein to estimate the ability of the novel reagent to detect folding intermediates. In addition, a precursor protein (prococoonase) of Bombyx mori cocoonase was used as a model mid-size protein. Cocoonase is classified as a serine protease and has a high homology with trypsin. We recently found that the propeptide sequence of prococoonase (proCCN) is important for the folding of cocoonase. However, it was difficult to study the folding pathway of proCCN since the folding intermediates could not be separated on a reversed-phase HPLC (RP-HPLC). Therefore, to separate the folding intermediates by RP-HPLC, the novel labeling reagent was used to accomplish this for proCCN. The results indicated that the peptide reagent allowed the intermediates to be captured, separated on SDS-PAGE, and analyzed by RP-HPLC without the occurrence of undesirable disulfide-exchange reactions during the labeling reactions. The peptide reagent reported herein is a practical tool for investigating the mechanisms of disulfide-coupled folding of mid-size proteins.

Degradation-Suppressed Cocoonase for Investigating the Propeptide-Mediated Activation Mechanism.

Cocoonase is folded in the form of a zymogen precursor protein (prococoonase) with the assistance of the propeptide region. To investigate the role of the propeptide sequence on the disulfide-coupled folding of cocoonase and prococoonase, the amino acid residues at the degradation sites during the refolding and auto-processing reactions were determined by mass spectrometric analyses and were mutated to suppress the numerous degradation reactions that occur during the reactions. In addition, the Lys8 residue at the propeptide region was also mutated to estimate whether the entire sequence is absolutely required for the activation of cocoonase. Finally, a degradation-suppressed [K8D,K63G,K131G,K133A]-proCCN protein was prepared and was found to refold readily without significant degradation. The results of an enzyme assay using casein or Bz-Arg-OEt suggested that the mutations had no significant effect on either the enzyme activity or the protein conformation. Thus, we, herein, provide the non-degradative cocoonase protein to investigate the propeptide-mediated protein folding of the molecule. We also examined the catalytic residues using the degradation-suppressed cocoonase. The point mutations at the putative catalytic residues in cocoonase resulted in the loss of catalytic activity without any secondary structural changes, indicating that the mutated residues play a role in the catalytic activity of this enzyme.

False lumen thrombus following aortic dissection diagnosed as the source of repeat lower extremity emboli with angioscopy: a case report.

BACKGROUND: Acute arterial embolization caused by a free-floating thrombus of the false lumen after surgery for acute aortic dissection is a rare complication; hence, determining its cause may be difficult. We report a case in which angioscopy was valuable in diagnosing and treating the unstable thrombus within the false lumen. CASE PRESENTATION: The patient was a 71-year-old woman who underwent hemiarch replacement for Stanford type A acute aortic dissection. Two months after the operation, left renal infarction occurred. Eighteen months after the operation, the patient visited the hospital for treatment of intermittent claudication of her left leg. Computed tomography (CT) showed occlusion below the left common femoral artery. Surgical thrombectomy was performed for acute lower extremity arterial occlusion. One month later, thrombectomy was performed again for the same phenomenon and again after 2 months. She had no history of cardiac arrhythmia. No obvious source for the repeat embolization could be found on echocardiography or enhanced CT. Angiography was performed to further identify the cause, revealing a new entry site at the distal anastomosis, which exhibited antegrade flow into the false lumen. Furthermore, selective false lumen angiography via the re-entry revealed a thrombus in the false lumen corresponding to the descending aorta. A non-obstructive angioscopy system in the false lumen revealed a free-floating thrombus. As the patient had undergone multiple surgeries over a short period and desired minimally invasive treatment, coil embolization of the new entry site as well as false lumen was performed. As a result, blood flow from the true to the false lumen resolved. More than 1 year has passed following coil embolization with no signs of embolism. CONCLUSIONS: We experienced a case of repeat embolism caused by unstable thrombus formation in the false lumen resulting from antegrade blood flow in the false lumen secondary to development of a new entry site. Angioscopy revealed that this antegrade flow caused formation of an unstable thrombus which caused recurrent acute lower extremity arterial occlusion. Therefore, angioscopy may be a useful option for the diagnosis of false lumen thrombosis.

DNMT1 regulates the timing of DNA methylation by DNMT3 in an enzymatic activity-dependent manner in mouse embryonic stem cells.

DNA methylation (DNAme; 5-methylcytosine, 5mC) plays an essential role in mammalian development, and the 5mC profile is regulated by a balance of opposing enzymatic activities: DNA methyltransferases (DNMTs) and Ten-eleven translocation dioxygenases (TETs). In mouse embryonic stem cells (ESCs), de novo DNAme by DNMT3 family enzymes, demethylation by the TET-mediated conversion of 5mC to 5-hydroxymethylation (5hmC), and maintenance of the remaining DNAme by DNMT1 are actively repeated throughout cell cycles, dynamically forming a constant 5mC profile. Nevertheless, the detailed mechanism and physiological significance of this active cyclic DNA modification in mouse ESCs remain unclear. Here by visualizing the localization of DNA modifications on metaphase chromosomes and comparing whole-genome methylation profiles before and after the mid-S phase in ESCs lacking Dnmt1 (1KO ESCs), we demonstrated that in 1KO ESCs, DNMT3-mediated remethylation was interrupted during and after DNA replication. This results in a marked asymmetry in the distribution of 5hmC between sister chromatids at mitosis, with one chromatid being almost no 5hmC. When introduced in 1KO ESCs, the catalytically inactive form of DNMT1 (DNMT1CI) induced an increase in DNAme in pericentric heterochromatin and the DNAme-independent repression of IAPEz, a retrotransposon family, in 1KO ESCs. However, DNMT1CI could not restore the ability of DNMT3 to methylate unmodified dsDNA de novo in S phase in 1KO ESCs. Furthermore, during in vitro differentiation into epiblasts, 1KO ESCs expressing DNMT1CI showed an even stronger tendency to differentiate into the primitive endoderm than 1KO ESCs and were readily reprogrammed into the primitive streak via an epiblast-like cell state, reconfirming the importance of DNMT1 enzymatic activity at the onset of epiblast differentiation. These results indicate a novel function of DNMT1, in which DNMT1 actively regulates the timing and genomic targets of de novo methylation by DNMT3 in an enzymatic activity-dependent and independent manner, respectively.

Sarcopenia Aneurysm Scoring System Predicts Early and Midterm Mortality After Endovascular Repair for Abdominal Aortic Aneurysm.

OBJECTIVE: The objective of the study was to develop a better model of prediction after EVAR using the psoas muscle index (PMI). SUMMARY BACKGROUND DATA: The Glasgow Aneurysm Score (GAS), the modified Leiden Score (mLS), the Comorbidity Severity Score (CSS), and the Euro Score (ES) are known prognostic scoring after EVAR. Similarly, sarcopenia measured by PMI has been reported to be an important predictor. This study investigated a new scoring system using PMI predicting short and midterm overall mortality after EVAR. METHODS: Three hundred ten patients were retrospectively evaluated. The primary endpoint was all-cause death. One hundred three patients were assigned to the derivation cohort and 207 patients to the validation cohort. RESULTS: The all-cause mortality rates were 8.8% at 1 year, 23.5% at 3 years, and 32.8% at 5 years. In a multivariate analysis, age, aneurysm diameter, eGFR, and PMI were associated with all-cause mortality in the derivation cohort. The SAS system was defined as the sum of the following factors: elderly (75 years), large aneurysm (65 mm), low eGFR (30 mL/min/1.73m 2 ), and low PMI (males: 48.2 cm 2 /m 2 , females: 36.8 cm 2 /m 2 ). We compared the SAS with the other prognostic scoring for 5-year mortality evaluating the area under the receiver operating characteristic curves in the validation cohort (GAS: 0.731, mLS: 0. 718, CSS: 0. 646, ES: 0.661, and SAS: 0.785, P = 0.013). CONCLUSION: We developed the SAS to predict all-cause mortality after elective EVAR and this scoring showed excellent predictive performance.

Aortic Wall Enhancement Detected by Contrast Computed Tomography Scan Predicts Aortic Remodeling after Conservative Therapy for Acute Uncomplicated Type B Dissection.

BACKGROUND: The Investigation of Stent Grafts in Aortic Dissection with extended length of follow-up trial showed that pre-emptive thoracic endovascular aneurysm repair (TEVAR) for the uncomplicated type B dissection (TBAD) in the subacute phase promotes aortic remodeling and avoids aortic-related death 5 years after onset. However, there are some patients with complete aortic remodeling (CAR) with optimal medical treatment (OMT) and severe complications after TEVAR such as retrograde type A dissection. Therefore, which patients should undergo pre-emptive TEVAR and optimal surgical timing are still under debate. We reported that aortic wall enhancement (AWE) after endovascular aneurysm repair for abdominal aortic aneurysm was associated with sac shrinkage. However, there is no report about the relationship between AWE and aortic dissection. Herein, we evaluated the relationship between AWE and acute TBAD. METHODS: From March 2012 to May 2018, consecutive patients with acute TBAD were retrospectively collected. We retrospectively analyzed 35 patients with acute TBAD who were treated with OMT and without pre-emptive TEVAR in the subacute phase. AWE was defined as an increase of more than 20 Hounsfield units in mean computed tomography (CT) values, comparing images in delayed contrast-enhanced scans with those in plain scans evaluated within 3 months from onset. The measurement points were all slices including the wall of the false lumen. The patients with traumatic dissection, type A dissection, acute complicated type B dissection, chronic (>12 weeks) dissection, and those lost to follow-up within 3 months from onset were excluded. The primary end point was spontaneous CAR under OMT, as determined by the latest contrast-enhanced CT scan. RESULTS: The median follow-up period from onset was 86 weeks and there were 25 cases (71.4%) with AWE. Under OMT, CAR was observed in 20 patients (57.1%); this was significantly associated with abdominal branch dissection (6/15 [40%] vs. 2/20 [10%], P = 0.050), number of tears more than 2 at onset (11/15 [73%] vs. 4/20 [20%], P = 0.003), multiple tears at 1 month after onset (9/15 [60%] vs. 4/20 [20%], P = 0.020), maximal false lumen diameter at 1 month after onset (14 vs. 8 mm, P = 0.025), and AWE within 3 months of onset (7/15 [47%] vs. 18/20 [90%], P = 0.010). Multivariate analysis demonstrated a significant difference with multiple tears at onset (P = 0.014) and AWE within 3 months of onset (P = 0.047). CONCLUSIONS: AWE was associated with CAR under OMT for acute TBAD which is out of indication of pre-emptive TEVAR. Presence of AWE may be useful in predicting prognosis of TBAD.

Two cases of asymptomatic axillary artery occlusion difficult to diagnose preoperatively: pitfalls and its solution in endovascular therapy when approaching from the upper extremity.

BACKGROUND: Approaching from the left brachial artery is an important access route in endovascular therapy for complicated aortic and peripheral artery cases. Here, we report two cases of a poor access route from the left brachial artery because of asymptomatic axillary artery occlusion (AAO), despite no preoperative upper arm blood pressure laterality, a normal ankle brachial pressure index, and absence of occlusion of the subclavian artery on CT scan. CASE 1: Seventy-six-year-old female. We planned endovascular aneurysm repair (EVAR) for para-renal abdominal aortic aneurysm using the snorkel technique in the renal artery, but we failed to pass through the left subclavian artery when approaching from the left brachial artery because of AAO. CASE 2: Seventy-three-year-old female. We planned zone 2 thoracic endovascular aneurysm repair (TEVAR) for thoracic aortic aneurysm and embolization of the left subclavian artery via the left brachial artery, but we failed to pass through the left subclavian artery because of AAO, and therefore, we simply covered the orifice of the left subclavian artery using a stent graft without embolization. CONCLUSIONS: The presence of an asymptomatic AAO may alter the treatment plan but may be difficult to diagnose preoperatively. In those cases in which a brachial or radial artery access is planned, contrast medium should be injected from the contralateral upper extremity during preoperative enhanced CT since the absence of halation of the ipsilateral subclavian/axillary vein provides improved visualization of the AAO which may lead to a better preoperative strategy including the choice of the side of upper extremity access.

Initial results of thoracic endovascular repair for uncomplicated type B aortic dissection involving the arch vessels using a semicustom-made thoracic fenestrated stent graft.

OBJECTIVE: Thoracic endovascular aortic repair (TEVAR) for selected type B aortic dissection (TBAD) is a standard treatment; however, TBAD involving the aortic arch is difficult to treat because of the need for arch vessel reconstruction. We report our initial results of TEVAR for uncomplicated TBAD involving the arch vessels using a semicustom-made fenestrated stent graft. METHODS: This is a retrospective study of 24 patients treated by fenestrated (F group) or debranching (D group) TEVAR from August 2011 to July 2017. The patients in the F group received the Najuta semicustom-made fenestrated stent graft (Kawasumi Laboratories, Tokyo, Japan). The fenestrated graft ensures sufficient sealing at the proximal healthy aorta without the need for arch vessel reconstruction. The primary end point was aorta-related mortality; the secondary end points were technical success and major adverse events (stroke, type IA endoleak, retrograde type A aortic dissection, and secondary intervention). RESULTS: During the study period, we treated 65 TBAD cases by TEVAR, including 17 complicated cases. Of the 48 uncomplicated cases, 24 underwent TEVAR with arch vessel involvement (13 in the F group and 11 in the D group). The technical success rates in the F and D groups were 92.3% and 100.0%, respectively (P > .99, NS). The mean operation time was significantly shorter in the F group (158 minutes) than in the D group (202 minutes; P = .0426), and the mean postoperative hospital stay was also significantly shorter in the F group (7 days) than in the D group (22 days; P = .0168). The primary patency rate of the reconstructed branch vessel was 100%, and there were no aorta-related deaths or retrograde type A aortic dissection in either group. One patient had a type IA endoleak in the F group. In the D group, one patient had a postoperative stroke and two patients required secondary interventions for stent graft-induced new entry at the descending aorta. The median follow-up period was 14.1 months (range, 1-37 months). The rate of freedom from aorta-related death was 100% in both groups (P > .99, NS); the rate of freedom from major adverse events at 24 months was 92.3% in the F group and 72.7% in the D group (P = .749, NS). CONCLUSIONS: The initial results of TEVAR with aortic arch vessel reconstruction for uncomplicated TBAD were acceptable. The fenestrated graft may be a less invasive option for the treatment of TBAD involving the aortic arch.

Case Series of Aortic Arch Aneurysm in Patients with Bovine Arch Treated with Proximal Scalloped and Fenestrated Stent Graft.

PURPOSE: The bovine arch is the most common variant of the aortic arch and occurs when the innominate artery shares a common origin with the left common carotid artery. We report an endovascular repair of aortic arch aneurysm in patients with a bovine arch using the Najuta proximal scalloped and fenestrated stent graft. MATERIALS AND METHODS: Thoracic endovascular aneurysm repairs using the Najuta stent graft were performed at our facility. It was inserted and deployed at a zone 0 with precise positional adjustment of the scallop of the stent graft to the brachiocephalic trunk. RESULTS: Overall, eight patients with bovine aortic arch were treated with fenestrated endovascular aneurysm repair. Technical success was 100% with no 30-day death. The follow-up period ranged from 7 to 29 (median 12) months. None of the patients had a stroke or paraplegia, and no endoleak was observed. All brachiocephalic trunks scalloped, and the left subclavian artery fenestrated vessels remained patent during the follow-up period. CONCLUSION: The Najuta stent graft repair of aortic arch aneurysms in patients with a bovine arch is a safe and effective treatment option, with good immediate and short-term results.

Muscarinic suppression of ATP-sensitive K+ channels mediated by the M3/Gq/11/phospholipase C pathway contributes to mouse ileal smooth muscle contractions.

ATP-sensitive K+ (KATP) channels are expressed in gastrointestinal smooth muscles, and their activity is regulated by muscarinic receptor stimulation. However, the physiological significance and mechanisms of muscarinic regulation of KATP channels are not fully understood. We examined the effects of the KATP channel opener cromakalim and the KATP channel blocker glibenclamide on electrical activity of single mouse ileal myocytes and on mechanical activity in ileal segment preparations. To explore muscarinic regulation of KATP channel activity and its underlying mechanisms, the effect of carbachol (CCh) on cromakalim-induced KATP channel currents ( IKATP) was studied in myocytes of M2 or M3 muscarinic receptor-knockout (KO) and wild-type (WT) mice. Cromakalim (10 µM) induced membrane hyperpolarization in single myocytes and relaxation in segment preparations from WT mice, whereas glibenclamide (10 µM) caused membrane depolarization and contraction. CCh (100 µM) induced sustained suppression of IKATP in cells from both WT and M2KO mice. However, CCh had a minimal effect on IKATP in M3KO and M2/M3 double-KO cells. The Gq/11 inhibitor YM-254890 (10 µM) and PLC inhibitor U73122 (1 µM), but not the PKC inhibitor calphostin C (1 µM), markedly decreased CCh-induced suppression of IKATP in WT cells. These results indicated that KATP channels are constitutively active and contribute to the setting of resting membrane potential in mouse ileal smooth muscles. M3 receptors inhibit the activity of these channels via a Gq/11/PLC-dependent but PKC-independent pathways, thereby contributing to membrane depolarization and contraction of smooth muscles. NEW & NOTEWORTHY We systematically investigated the regulation of ATP-sensitive K+ channels by muscarinic receptors expressed on mouse ileal smooth muscles. We found that M3 receptors inhibit the activity of ATP-sensitive K+ channels via a Gq/11/PLC-dependent, but PKC-independent, pathway. This muscarinic suppression of ATP-sensitive K+ channels contributes to membrane depolarization and contraction of smooth muscles.