RNF213 Variants, Vasospastic Angina, and Risk of Fatal Myocardial Infarction.

Importance: Vasospastic angina (VSA) is vasospasm of the coronary artery and is particularly prevalent in East Asian populations. However, the specific genetic architecture for VSA at genome-wide levels is not fully understood. Objective: To identify genetic factors associated with VSA. Design, Setting, and Participants: This was a case-control genome-wide association study of VSA. Data from Biobank Japan (BBJ; enrolled patients from 2002-2008 and 2013-2018) were used, and controls without coronary artery disease (CAD) were enrolled. Patients from the BBJ were genotyped using arrays or a set of arrays. Patients recruited between 2002 and 2005 were classified within the first dataset, and those recruited between 2006 and 2008 were classified within the second dataset. To replicate the genome-wide association study in the first and second datasets, VSA cases and control samples from the latest patients in the BBJ recruited between 2013 and 2018 were analyzed in a third dataset. Exposures: Single-nucleotide variants associated with VSA. Main Outcomes and Measures: Cases with VSA and controls without CAD. Results: A total of 5720 cases (mean [SD] age, 67 [10] years; 3672 male [64.2%]) and 153 864 controls (mean [SD] age, 62 [15] years; 77 362 male [50.3%]) in 3 datasets were included in this study. The variants at the RNF213 locus showed the strongest association with VSA across the 3 datasets (odds ratio [OR], 2.34; 95% CI, 1.99-2.74; P = 4.4 × 10-25). Additionally, rs112735431, an Asian-specific rare deleterious variant (p.Arg4810Lys) experimentally shown to be associated with reduced angiogenesis and a well-known causal risk for Moyamoya disease was the most promising candidate for a causal variant explaining the association. The effect size of rs112735431 on VSA was distinct from that of other CADs. Furthermore, homozygous carriers of rs112735431 showed an association with VSA characterized by a large effect estimate (OR, 18.34; 95% CI, 5.15-65.22; P = 7.0 × 10-6), deviating from the additive model (OR, 4.35; 95% CI, 1.18-16.05; P = .03). Stratified analyses revealed that rs112735431 exhibited a stronger association in males (χ21 = 7.24; P = .007) and a younger age group (OR, 3.06; 95% CI, 2.24-4.19), corresponding to the epidemiologic features of VSA. In the registry, carriers without CAD of the risk allele rs112735431 had a strikingly high mortality rate due to acute myocardial infarction during the follow-up period (hazard ratio, 2.71; 95% CI, 1.57-4.65; P = 3.3 × 10-4). As previously reported, a possible overlap between VSA and Moyamoya disease was not found. Conclusions and Relevance: Results of this study suggest that vascular cell dysfunction mediated by variants in the RNF213 locus may promote coronary vasospasm, and the presence of the risk allele could serve as a predictive factor for the prognosis.

AMPD2 plays important roles in regulating hepatic glucose and lipid metabolism.

Dysregulation of hepatic glucose and lipid metabolism can instigate the onset of various metabolic disorders including obesity, dyslipidemia, insulin resistance, type 2 diabetes, and fatty liver disease. Adenosine monophosphate (AMP) deaminase (AMPD), which converts AMP to inosine monophosphate, plays a key role in maintaining adenylate energy charge. AMPD2 is the major isoform present in the liver. However, the mechanistic link between AMPD2 and hepatic glucose and lipid metabolism remains elusive. In this study, we probed into the hepatic glucose and lipid metabolism in AMPD2-deficient (A2-/-) mice. These mice exhibited reduced body weight, fat accumulation, and blood glucose levels, coupled with enhanced insulin sensitivity while maintaining consistent calorie intake and spontaneous motor activity compared with wild type mice. Furthermore, A2-/- mice showed mitigated obesity and hyper-insulinemia induced by high-fat diet (HFD) but elevated levels of the serum triglyceride and cholesterol. The hepatic mRNA levels of several fatty acid and cholesterol metabolism-related genes were altered in A2-/- mice. RNA sequencing unveiled multiple alterations in lipid metabolic pathways due to AMPD2 deficiency. These mice were also more susceptible to fasting or HFD-induced hepatic lipid accumulation. The liver exhibited elevated AMP levels but unaltered AMP/ATP ratio. In addition, AMPD2 deficiency is not associated with the adenosine production. In summary, this study established a link between purine metabolism and hepatic glucose and lipid metabolism via AMPD2, providing novel insights into these metabolic pathways.

Genome-wide association study identifies risk loci within the major histocompatibility complex region for Hunner-type interstitial cystitis.

Hunner-type interstitial cystitis (HIC) is a rare, chronic inflammatory disease of the urinary bladder with unknown etiology and genetic background. Here, we conduct a genome-wide association study of 144 patients with HIC and 41,516 controls of Japanese ancestry. The genetic variant, rs1794275, in the major histocompatibility complex (MHC) region (chromosome 6p21.3) is associated with HIC risk (odds ratio [OR] = 2.32; p = 3.4 × 10-9). The association is confirmed in a replication set of 26 cases and 1,026 controls (p = 0.014). Fine mapping demonstrates the contribution to the disease risk of a completely linked haplotype of three human leukocyte antigen HLA-DQß1 amino acid positions, 71, 74, and 75 (OR = 1.94; p = 5 × 10-8) and of HLA-DPß1 amino acid position 178, which tags HLA-DPB1∗04:02 (OR = 2.35; p = 7.5 × 10-8). The three HLA-DQß1 amino acid positions are located together at the peptide binding groove, suggesting their functional importance in antigen presentation. Our study reveals genetic contributions to HIC risk that may be associated with class II MHC molecule antigen presentation.

Long-term durability of a reimplantation valve-sparing aortic root replacement can be expected in both Marfan syndrome and Loeys-Dietz syndrome.

OBJECTIVES: The goal of this study was to evaluate the surgical outcomes of a valve-sparing root replacement using the reimplantation technique for annuloaortic ectasia in patients with Marfan syndrome (MFS) and in those with Loeys-Dietz syndrome (LDS). METHODS: We reviewed 103 patients with MSF with mutations in the fibrillin-1 gene and 28 patients with LDS with mutations in the transforming growth factor-beta receptor and 2, SMAD3 and transforming growth factor beta-2 from 1988 to 2020. RESULTS: Forty-four (42.7%) patients with MFS [26 men, 31 (7.6) years] and 10 (35.7%) patients with Loeys-Dietz syndrome (LDS) [7 men, 22 (standard deviation: 8.6) years] who had no aortic dissection and underwent valve-sparing root replacement were included. The preoperative sinus diameter [46 (45-50.5) mm in those with MFS vs 48 (47-50) mm in those with LDS, p = 0.420] and the percentage of aortic insufficiency > grade 2+ [31.8% (10/44) in patients with MFS vs 10.0% (1/10) in those with LDS, p = 0.667] revealed no significant differences between the 2 groups. The cumulative incidences of aortic insufficiency greater than grade 1 (p = 0.588) and aortic valve reoperation (p = 0.310) were comparable between the 2 groups. Patients with LDS had a higher tendency towards aortic dissection after the initial operation (p = 0.061) and a significantly higher cumulative incidence of aortic reoperation (p = 0.003) versus those with MFS. CONCLUSIONS: Patients with MFS and those with LDS showed similar cumulative incidences of recurrent aortic valve insufficiency and aortic valve reoperation. Those with LDS revealed a higher cumulative incidence of aortic reoperation and a greater tendency towards aortic dissection after the initial operation compared with those with MFS.

The differences in surgical long-term outcomes between Marfan syndrome and Loeys-Dietz syndrome.

OBJECTIVE: The aim of this study was to disclose the differences of surgical outcomes between Marfan syndrome with mutations in fibrillin-1 gene and Loeys-Dietz syndrome with mutations in transforming growth factor-beta receptor 1 and 2. METHODS: We reviewed 368 patients aged less than 50 years who underwent surgery for thoracic aortic diseases between 1988 and 2019, and enrolled 99 patients with Marfan syndrome (26.9%; 57 men, 33 ± 7.5 years) and 24 patients with Loeys-Dietz syndrome (6.5%; 13 men, 28 ± 11 years). RESULTS: Freedom from all causes of mortality was similar between the 2 groups (P = .40, log-rank). The cumulative incidence of reintervention was significantly lower in the Marfan syndrome group than in the Loeys-Dietz syndrome group (P = .016, Gray). The cumulative incidence of first aortic arch reoperation for aortic arch aneurysm was significantly lower in the Marfan syndrome group than in the Loeys-Dietz syndrome group (P < .001, Gray). The cumulative incidence of first aortic root reoperation for aortic root aneurysm (P = .57, Gray) and first descending aorta reoperation for descending aortic aneurysm (P = .76, Gray) was similar between the 2 groups. The cumulative incidence of aortic dissection after initial surgery was significantly lower in Marfan syndrome than in Loeys-Dietz syndrome (P = .0059, Gray). CONCLUSIONS: Loeys-Dietz syndrome with mutations in transforming growth factor-beta receptor 1 and 2 revealed higher rates of reoperation, and more specifically the arch reoperation was higher in those with Loeys-Dietz syndrome than those with Marfan syndrome. Aggressive arch surgery in the initial operation on the proximal aorta is recommendable in Loeys-Dietz syndrome to avoid additional aortic events. In Marfan syndrome, this is controversial in patients without dissection because of a low possibility to expand.

Combined landscape of single-nucleotide variants and copy number alterations in clonal hematopoiesis.

Clonal hematopoiesis (CH) in apparently healthy individuals is implicated in the development of hematological malignancies (HM) and cardiovascular diseases. Previous studies of CH analyzed either single-nucleotide variants and indels (SNVs/indels) or copy number alterations (CNAs), but not both. Here, using a combination of targeted sequencing of 23 CH-related genes and array-based CNA detection of blood-derived DNA, we have delineated the landscape of CH-related SNVs/indels and CNAs in 11,234 individuals without HM from the BioBank Japan cohort, including 672 individuals with subsequent HM development, and studied the effects of these somatic alterations on mortality from HM and cardiovascular disease, as well as on hematological and cardiovascular phenotypes. The total number of both types of CH-related lesions and their clone size positively correlated with blood count abnormalities and mortality from HM. CH-related SNVs/indels and CNAs exhibited statistically significant co-occurrence in the same individuals. In particular, co-occurrence of SNVs/indels and CNAs affecting DNMT3A, TET2, JAK2 and TP53 resulted in biallelic alterations of these genes and was associated with higher HM mortality. Co-occurrence of SNVs/indels and CNAs also modulated risks for cardiovascular mortality. These findings highlight the importance of detecting both SNVs/indels and CNAs in the evaluation of CH.

Esm1 and Stc1 as Angiogenic Factors Responsible for Protective Actions of Adipose-Derived Stem Cell Sheets on Chronic Heart Failure After Rat Myocardial Infarction.

BACKGROUND: Although adipose-derived stem cell (ADSC) sheets improve the cardiac function after myocardial infarction (MI), underlying mechanisms remain to be elucidated. The aim of this study was to determine the fate of transplanted ADSC sheets and candidate angiogenic factors released from ADSCs for their cardiac protective actions.Methods and Results:MI was induced by ligation of the left anterior descending coronary artery. Sheets of transgenic (Tg)-ADSCs expressing green fluorescence protein (GFP) and luciferase or wild-type (WT)-ADSCs were transplanted 1 week after MI. Both WT- and Tg-ADSC sheets improved cardiac functions evaluated by echocardiography at 3 and 5 weeks after MI. Histological examination at 5 weeks after MI demonstrated that either sheet suppressed fibrosis and increased vasculogenesis. Luciferase signals from Tg-ADSC sheets were detected at 1 and 2 weeks, but not at 4 weeks, after transplantation. RNA sequencing of PKH (yellow-orange fluorescent dye with long aliphatic tails)-labeled Tg-ADSCs identified mRNAs of 4 molecules related to angiogenesis, including those of Esm1 and Stc1 that increased under hypoxia. Administration of Esm1 or Stc1 promoted tube formation by human umbilical vein endothelial cells. CONCLUSIONS: ADSC sheets improved cardiac contractile functions after MI by suppressing cardiac fibrosis and enhancing neovascularization. Transplanted ADSCs existed for >2 weeks on MI hearts and produced the angiogenic factors Esm1 and Stc1, which may improve cardiac functions after MI.

Surgical Outcome and Histological Differences between Individuals with TGFBR1 and TGFBR2 Mutations in Loeys-Dietz Syndrome.

PURPOSE: To identify differences in surgical outcomes between patients with transforming growth factor-beta receptor (TGFBR) 1 and TGFBR2 mutations in Loeys-Dietz syndrome (LDS). METHODS: In all, 22 LDS patients between 1998 and 2015 were divided into the two groups: TGFBR1 (n = 11) and TGFBR2 mutation (n = 11). RESULTS: The freedom from aortic reoperation was similar between the two groups (p = 0.19, log-rank). In the subanalysis, the freedom from aortic reoperation was lower in female patients with TGFBR2 mutations (n = 6) than in other patients (p = 0.08). The freedom from aortic dissection (AD) after the initial surgery was also lower in female patients with TGFBR2 mutation than in other patients (p = 0.025). All patients with TGFBR2 mutations revealed grade III cystic medial necrosis (CMN), whereas 67% of patients with TGFBR1 mutations showed CMN (p = 0.033) and only one patient had grade III (p <0.001). CONCLUSION: LDS patients with TGFBR2 mutations had higher grade of CMN than those of TGFBR1 mutations. In particular, in female patients with TGFBR2 mutations, AD after the initial surgery and reoperation were more frequent than those of other LDS patients.

High Prevalence of Left Ventricular Non-Compaction and Its Effect on Chemotherapy-Related Cardiac Dysfunction in Patients With Hematological Diseases.

BACKGROUND: Recent progress in chemotherapy has prolonged the survival of patients with hematological diseases, but has also increased the number of patients with chemotherapy-related cardiac dysfunction (CTRCD). However, the causes of individual variations and risk factors for CTRCD have yet to be fully elucidated.Methods and Results:Consecutive echocardiograms of 371 patients were retrospectively evaluated for the presence of left ventricular (LV) non-compaction (LVNC). Individual LV ejection fraction (LVEF) outcome estimates were made using bivariate linear regression with log-transformed duration Akaike information criterion (AIC) model fitting. The prevalence of LVNC was 6-fold higher in patients with hematological diseases than in those with non-hematological diseases (12% vs. 2%; risk ratio 6.1; 95% confidence interval [CI] 2.0, 18.2). Among patients with hematological diseases, the ratio of myeloid diseases was significantly higher in the group with LVNC (P=0.031). Deterioration of LVEF was more severe in patients with than without LVNC (-14.4 percentage points/year [95% CI -21.0, -7.9] vs. -4.6 percentage points/year [95% CI -6.8, -2.4], respectively), even after multivariate adjustment for baseline LVEF, background disease distributions, cumulative anthracycline dose, and other baseline factors. CONCLUSIONS: LVNC is relatively prevalent in patients with hematological diseases (particularly myeloid diseases) and can be one of the major risk factors for CTRCD. Detailed cardiac evaluations including LVNC are recommended for patients undergoing chemotherapy.

Histologic differences between the ascending and descending aortas in young adults with fibrillin-1 mutations.

OBJECTIVES: This study aimed to review the clinical results of young adult patients with aortic disease associated with mutations in the fibrillin-1 gene (FBN1) and disclose the histologic differences between the ascending and descending aortas. METHODS: Between 2012 and 2015, 94 patients aged less than 50 years underwent surgery for thoracic aortic diseases. Forty-two patients (44.7%) had FBN-1 mutations. Of these, 40 patients (42.5%) with surgical specimens for histologic evaluation were included in the study. With the histologic results including the specimen sampled at their previous operations, cystic medial necrosis was classified into 3 grades according to the degree of the cystic area. RESULTS: Thirty-nine patients (97.5%) had aortic root dilatation (Z ≥2), and 13 patients (32.5%) had ectopia lentis. Thirty-nine patients (97.5%) fulfilled the diagnostic criteria for Marfan syndrome. There were no in-hospital deaths. The majority (27/29: 93.1%) of the specimens of the ascending aorta revealed cystic medial necrosis pattern. With grade III being the most severe condition, these cases were classified into grade I (n = 2), grade II (n = 5), and grade III (n = 20). In contrast, only 6 specimens (6/17: 35.3%) of the descending aorta showed a cystic medial necrosis pattern that was classified into grade I (n = 2) and grade III (n = 4), (P < .00001). CONCLUSIONS: Fewer specimens of the descending aorta revealed cystic medial necrosis compared with those of the ascending aorta. This difference might influence the characteristic aortic disease in Marfan syndrome associated with FBN-1 mutations.

A mutation update on the LDS-associated genes TGFB2/3 and SMAD2/3.

The Loeys-Dietz syndrome (LDS) is a connective tissue disorder affecting the cardiovascular, skeletal, and ocular system. Most typically, LDS patients present with aortic aneurysms and arterial tortuosity, hypertelorism, and bifid/broad uvula or cleft palate. Initially, mutations in transforming growth factor-ß (TGF-ß) receptors (TGFBR1 and TGFBR2) were described to cause LDS, hereby leading to impaired TGF-ß signaling. More recently, TGF-ß ligands, TGFB2 and TGFB3, as well as intracellular downstream effectors of the TGF-ß pathway, SMAD2 and SMAD3, were shown to be involved in LDS. This emphasizes the role of disturbed TGF-ß signaling in LDS pathogenesis. Since most literature so far has focused on TGFBR1/2, we provide a comprehensive review on the known and some novel TGFB2/3 and SMAD2/3 mutations. For TGFB2 and SMAD3, the clinical manifestations, both of the patients previously described in the literature and our newly reported patients, are summarized in detail. This clearly indicates that LDS concerns a disorder with a broad phenotypical spectrum that is still emerging as more patients will be identified. All mutations described here are present in the corresponding Leiden Open Variant Database.

Impact of connective tissue disease on the surgical outcomes of aortic dissection in patients with cystic medial necrosis.

BACKGROUND: A retrospective analysis was performed to determine the impact of genetically diagnosed connective tissue disease (CTD) on the early and late outcomes of surgical treatment for aortic dissection in patients having aortic pathology associated with cystic medial necrosis (CMN). METHODS: Between 2003 and 2013, a total of 43 patients (37 ± 12.8 years old, 23 men, 20 women) who had undergone surgery for aortic dissection associated with CMN in the aortic wall underwent genetic examinations. Subsequently, there were 30 patients with CTD (CTD group) and 13 without CTD (non-CTD group). RESULTS: There were no early or late deaths (the follow-up rate was 100% for 57.1 ± 43.0 months). The median age was significantly lower in the CTD group (p = 0.030). The rate of elastic fiber loss was significantly higher in the CTD group (p = 0.014). In the long-term follow-up, there were no significant differences in the incidences of re-dissection (p = 0.332). However, re-operations were required more frequently in the CTD group (p = 0.037). CONCLUSIONS: In patients with CTD as well as CMN, the onset of aortic dissection tends to be earlier, which would result in higher rates of re-operation, compared with the non-CTD group. Closer and stricter follow-up with medication and adequate surgical treatments with appropriate timing are mandatory for such high-risk patients.

Clinical outcomes of aortic repair in young adult patients with ACTA2 mutations.

OBJECTIVES: Actin, alpha-2, smooth muscle, aorta (ACTA2) mutations are one of the major causes of familial thoracic aortic aneurysms and dissections. The aim of this study was to review our clinical results of young adult patients with aortic disease caused by ACTA2 mutations. METHODS: We reviewed the medical records of 251 patients (<50 years old) who underwent surgery for thoracic aortic diseases between 2004 and 2014. Among them, nine patients (3.5%) had ACTA2 mutations. Their average age was 35 years (range 22-47) and two patients (22.2%) were males. No patients fulfilled the diagnostic criteria for Marfan syndrome. Preoperative diagnoses included annulo-aortic ectasia (n = 2), localized dissection of the sinus of Valsalva (n = 2), acute type B aortic dissection (n = 1), and chronic type B (n = 4). Eight patients (88.9%) had hypertension. RESULTS: A thoracoabdominal aortic replacement was required in three patients who had descending replacement for residual chronic type B aortic dissection. A patient who had thoracic endovascular aortic repair for complicated acute type B aortic dissection showed no aortic dilatation for 7 years after TEVAR. Histological results revealed cystic medial necrosis (CMN) in most cases (7/8; 87.5%). CONCLUSION: Surgical outcomes for patients with ACTA2 mutations were satisfactory. CMN was a major histological finding and family history of aortic event was detected in only half of the patients with ACTA2 mutations. Despite no characteristic physical findings besides hypertension, connective tissue disease including ACTA2 mutations should be considered for aortic dissection in young adult patients.

Urat1-Uox double knockout mice are experimental animal models of renal hypouricemia and exercise-induced acute kidney injury.

Renal hypouricemia (RHUC) is a hereditary disease characterized by a low level of plasma urate but with normal urinary urate excretion. RHUC type 1 is caused by mutations of the urate transporter URAT1 gene (SLC22A12). However, the plasma urate levels of URAT1 knockout mice are no different from those of wild-type mice. In the present study, a double knockout mouse, in which the URAT1 and uricase (Uox) genes were deleted (Urat1-Uox-DKO), were used as an experimental animal model of RHUC type 1 to investigate RHUC and excise-induced acute kidney injury (EIAKI). Mice were given a variable content of allopurinol for one week followed by HPLC measurement of urate and creatinine concentrations in spot urine and blood from the tail. The urinary excretion of urate in Urat1-Uox-DKO mice was approximately 25 times higher than those of humans. With allopurinol, the plasma urate levels of Urat1-Uox-DKO mice were lower than those of Uox-KO mice. There were no differences in the urinary urate excretions between Urat1-Uox-DKO and Uox-KO mice administered with 9 mg allopurinol /100 g feed. In the absence of allopurinol, plasma creatinine levels of some Urat1-Uox-DKO mice were higher than those of Uox-KO mice. Consequently, hypouricemia and normouricosuria may indicate that the Urat1-Uox-DKO mouse administered with allopurinol may represent a suitable animal model of RHUC type 1. Urat1-Uox-DKO mice without allopurinol exhibited acute kidney injury, thus providing additional benefit as a potential animal model for EIAKI. Finally, our data indicate that allopurinol appears to provide prophylactic effects for EIAKI.

International Registry of Patients Carrying TGFBR1 or TGFBR2 Mutations: Results of the MAC (Montalcino Aortic Consortium).

BACKGROUND: The natural history of aortic diseases in patients with TGFBR1 or TGFBR2 mutations reported by different investigators has varied greatly. In particular, the current recommendations for the timing of surgical repair of the aortic root aneurysms may be overly aggressive. METHODS AND RESULTS: The Montalcino Aortic Consortium, which includes 15 centers worldwide that specialize in heritable thoracic aortic diseases, was used to gather data on 441 patients from 228 families, with 176 cases harboring a mutation in TGBR1 and 265 in TGFBR2. Patients harboring a TGFBR1 mutation have similar survival rates (80% survival at 60 years), aortic risk (23% aortic dissection and 18% preventive aortic surgery), and prevalence of extra-aortic features (29% hypertelorism, 53% cervical arterial tortuosity, and 27% wide scars) when compared with patients harboring a TGFBR2 mutation. However, TGFBR1 males had a greater aortic risk than females, whereas TGFBR2 males and females had a similar aortic risk. Additionally, aortic root diameter prior to or at the time of type A aortic dissection tended to be smaller in patients carrying a TGFBR2 mutation and was ≤45 mm in 6 women with TGFBR2 mutations, presenting with marked systemic features and low body surface area. Aortic dissection was observed in 1.6% of pregnancies. CONCLUSIONS: Patients with TGFBR1 or TGFBR2 mutations show the same prevalence of systemic features and the same global survival. Preventive aortic surgery at a diameter of 45 mm, lowered toward 40 in females with low body surface area, TGFBR2 mutation, and severe extra-aortic features may be considered.

AMPD1 regulates mTORC1-p70 S6 kinase axis in the control of insulin sensitivity in skeletal muscle.

BACKGROUND: Insulin resistance triggered by excess fat is a key pathogenic factor that promotes type 2 diabetes. Understanding molecular mechanisms of insulin resistance may lead to the identification of a novel therapeutic target for type 2 diabetes. AMPD1, an isoform of AMP deaminase (AMPD), is suggested to play roles in the regulation of glucose metabolism through controlling AMP-activated protein kinase (AMPK) activation. We reported that the diet-induced insulin resistance was improved in AMPD1-deficient mice compared to wild type mice. To further delineate this observation, we studied changes of insulin signaling in skeletal muscle of wild type (WT) and AMPD1-deficient mice. METHODS: Phosphorylation levels of kinases and expression levels of mTOR components were quantified by immunoblotting using protein extracts from tissues. The interaction between mTOR and Raptor was determined by immunoblotting of mTOR immunoprecipitates with anti-Raptor antibody. Gene expression was studied by quantitative PCR using RNA extracted from tissues. RESULTS: Phosphorylation levels of AMPK, Akt and p70 S6 kinase in skeletal muscle were higher in AMPD1-deficient mice compared to WT mice after high fat diet challenge, while they did not show such difference in normal chow diet. Also, no significant changes in phosphorylation levels of AMPK, Akt or p70 S6 kinase were observed in liver and white adipose tissue between WT and AMPD1-deficient mice. The expression levels of mTOR, Raptor and Rictor tended to be increased by AMPD1 deficiency compared to WT after high fat diet challenge. AMPD1 deficiency increased Raptor-bound mTOR in skeletal muscle compared to WT after high fat diet challenge. Gene expression of peroxisome proliferator-activated receptor-γ coactivator 1α and ß, downstream targets of p70 S6 kinase, in skeletal muscles was not changed significantly by AMPD1 deficiency compared to the wild type after high fat diet challenge. CONCLUSION: These data suggest that AMPD1 deficiency activates AMPK/Akt/mTORC1/p70 S6 kinase axis in skeletal muscle after high fat diet challenge, but not in normal chow diet. These changes may contribute to improve insulin resistance.

Acute rupture of chordae tendineae of the mitral valve in infants: a nationwide survey in Japan exploring a new syndrome.

BACKGROUND: Recently, infant cases of acute heart failure attributable to rupture of the mitral chordae tendineae have been reported. However, little is known about the pathogenesis and clinical course of this condition. METHODS AND RESULTS: Ninety-five children with rupture of mitral chordae tendineae were identified in nationwide surveys of Japan diagnosed from 1995 to 2013. The clinical manifestations, management strategies, and prognosis were investigated. Eighty-one (85%) patients were between 4 and 6 months (median, 5 months) of age. In 63 (66%) patients, rupture occurred during the spring or summer. The underlying conditions before rupture included Kawasaki disease (10 cases), maternally derived anti-SSA antibodies (2 cases), and infective endocarditis (1 case). Surgery was performed in 80 patients (94 operations), and the final operations included plasty of mitral chordae in 52 cases and mechanical valve replacement in 26 cases. The histopathologic examinations of the mitral valves and chordae (n=28) revealed inflammatory reactions with predominant mononuclear cell infiltration in 18 cases (64%) and increased fibrous and myxoid tissue in 11 cases (39%), suggesting that nonbacterial infectious or autoimmune endocarditis and myxoid changes are involved in the pathogenesis. Eight patients (8.4%) died before (n=6) and shortly after (n=2) the operation, and significant neurological complications persisted in 10 cases (11%). CONCLUSIONS: Acute heart failure attributable to rupture of the mitral chordae tendineae in infants is a unique disease resulting from diverse causes. This condition should be recognized as a significant cardiovascular disorder that may cause sudden onset of cardiogenic shock and death in infants.

Acute dilatation of the ascending aorta and aortic valve regurgitation in Loeys-Dietz syndrome.

Loeys-Dietz syndrome (LDS) is a recently recognized connective tissue disorder caused by mutations of the transforming growth factor (TGF)-ß receptors. It is an autosomal dominant syndrome characterized by the triad of arterial tortuosity and aneurysms, hypertelorism, and bifid uvula or cleft palate. We treated an 18-year-old woman with a 100-mm-diameter aortic root aneurysm and severe aortic valve regurgitation. She underwent urgent aortic root replacement and bioprosthetic valve implantation. LDS was diagnosed by postoperative genetic screening results. Histopathologic examination of the aortic wall showed diffuse degeneration and elastin fragmentation in the media.

AMPD2 regulates GTP synthesis and is mutated in a potentially treatable neurodegenerative brainstem disorder.

Purine biosynthesis and metabolism, conserved in all living organisms, is essential for cellular energy homeostasis and nucleic acid synthesis. The de novo synthesis of purine precursors is under tight negative feedback regulation mediated by adenosine and guanine nucleotides. We describe a distinct early-onset neurodegenerative condition resulting from mutations in the adenosine monophosphate deaminase 2 gene (AMPD2). Patients have characteristic brain imaging features of pontocerebellar hypoplasia (PCH) due to loss of brainstem and cerebellar parenchyma. We found that AMPD2 plays an evolutionary conserved role in the maintenance of cellular guanine nucleotide pools by regulating the feedback inhibition of adenosine derivatives on de novo purine synthesis. AMPD2 deficiency results in defective GTP-dependent initiation of protein translation, which can be rescued by administration of purine precursors. These data suggest AMPD2-related PCH as a potentially treatable early-onset neurodegenerative disease.

AMP deaminase 3 plays a critical role in remote reperfusion lung injury.

Remote reperfusion lung injury following skeletal muscle ischemia and reperfusion accounts for high morbidity and mortality. AMP deaminase (AMPD), a key enzyme for nucleotide cycle, has been implicated in the regulation of this phenomenon. However, the function of Ampd2 and Ampd3 subtype has not been elucidated in remote reperfusion rodent lung injury. We utilized AMPD3 and AMPD2-deficient mice. The two types of AMPD-deficient mice and wild-type (WT) littermates were subjected to ischemia-reperfusion injury. After 3h bilateral hind-limb ischemia and reperfusion, AMPD3 mRNA, AMPD activity and inosine monophosphate (IMP) increased significantly in WT and AMPD2-deficient mice lungs, while they did not show significant alterations in AMPD3-deficient mice lungs. Genetic inactivation of Ampd3 resulted in markedly accelerated myeloperoxidase (MPO) activity along with exaggerated neutrophils infiltration and hemorrhage in the lungs compared to WT and AMPD2-deficient mice, furthermore, IMP treatment significantly attenuated MPO activity and neutrophils infiltration in WT and the two types of AMPD-deficient mice lungs after 3h reperfusion. These findings demonstrate for the first time in AMP-deficient mice models that AMPD3 plays a critical role in remote reperfusion lung injury via generation of IMP and validate the potential to use IMP into the clinical arena to attenuate remote ischemia-reperfusion lung injury.