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1.
Cardiovasc Diabetol ; 23(1): 224, 2024 Jun 28.
Artigo em Inglês | MEDLINE | ID: mdl-38943159

RESUMO

BACKGROUND: Sodium-glucose cotransporter 2 (SGLT2) inhibitors reduce the risk of hospitalization for heart failure and cardiovascular death with type 2 diabetes; however, their effect on arrhythmias is unclear. The purpose of this study was to investigate the effects of empagliflozin on ventricular arrhythmias in patients with type 2 diabetes. METHODS: A total of 150 patients with type 2 diabetes who were treated with an implantable cardioverter-defibrillator or cardiac resynchronization therapy defibrillator (ICD/CRT-D) were randomized to once-daily empagliflozin or placebo for 24 weeks. The primary endpoint was the change in the number of ventricular arrhythmias from the 24 weeks before to the 24 weeks during treatment. Secondary endpoints included the change in the number of appropriate device discharges and other values. RESULTS: In the empagliflozin group, the number of ventricular arrhythmias recorded by ICD/CRT-D decreased by 1.69 during treatment compared to before treatment, while in the placebo group, the number increased by 1.79. The coefficient for the between-group difference was - 1.07 (95% confidence interval [CI] - 1.29 to - 0.86; P < 0.001). The change in the number of appropriate device discharges during and before treatment was 0.06 in the empagliflozin group and 0.27 in the placebo group, with no significant difference between the groups (P = 0.204). Empagliflozin was associated with an increase in blood ketones and hematocrit and a decrease in blood brain natriuretic peptide and body weight. CONCLUSIONS: In patients with type 2 diabetes treated with ICD/CRT-D, empagliflozin reduces the number of ventricular arrhythmias compared with placebo. Trial registration jRCTs031180120.


Assuntos
Compostos Benzidrílicos , Desfibriladores Implantáveis , Diabetes Mellitus Tipo 2 , Cardioversão Elétrica , Glucosídeos , Inibidores do Transportador 2 de Sódio-Glicose , Humanos , Diabetes Mellitus Tipo 2/diagnóstico , Diabetes Mellitus Tipo 2/complicações , Diabetes Mellitus Tipo 2/sangue , Diabetes Mellitus Tipo 2/tratamento farmacológico , Glucosídeos/uso terapêutico , Glucosídeos/efeitos adversos , Compostos Benzidrílicos/uso terapêutico , Compostos Benzidrílicos/efeitos adversos , Masculino , Inibidores do Transportador 2 de Sódio-Glicose/uso terapêutico , Inibidores do Transportador 2 de Sódio-Glicose/efeitos adversos , Feminino , Idoso , Pessoa de Meia-Idade , Resultado do Tratamento , Fatores de Tempo , Cardioversão Elétrica/instrumentação , Cardioversão Elétrica/efeitos adversos , Método Duplo-Cego , Japão , Terapia de Ressincronização Cardíaca/efeitos adversos , Glicemia/metabolismo , Glicemia/efeitos dos fármacos
2.
Nat Aging ; 2024 May 30.
Artigo em Inglês | MEDLINE | ID: mdl-38816549

RESUMO

It has been reported that accumulation of senescent cells in various tissues contributes to pathological aging and that elimination of senescent cells (senolysis) improves age-associated pathologies. Here, we demonstrate that inhibition of sodium-glucose co-transporter 2 (SGLT2) enhances clearance of senescent cells, thereby ameliorating age-associated phenotypic changes. In a mouse model of dietary obesity, short-term treatment with the SGLT2 inhibitor canagliflozin reduced the senescence load in visceral adipose tissue and improved adipose tissue inflammation and metabolic dysfunction, but normalization of plasma glucose by insulin treatment had no effect on senescent cells. Canagliflozin extended the lifespan of mice with premature aging even when treatment was started in middle age. Metabolomic analyses revealed that short-term treatment with canagliflozin upregulated 5-aminoimidazole-4-carboxamide-1-ß-D-ribofuranoside, enhancing immune-mediated clearance of senescent cells by downregulating expression of programmed cell death-ligand 1. These findings suggest that inhibition of SGLT2 has an indirect senolytic effect by enhancing endogenous immunosurveillance of senescent cells.

3.
J Cardiol Cases ; 27(6): 258-261, 2023 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-37283907

RESUMO

A 45-year-old woman with no medical history underwent pacemaker implantation for a symptomatic complete atrioventricular block. On day 6, she noticed diplopia and then fever, general malaise, and elevation of serum creatinine kinase (CK). She was transferred to our hospital on day 21. Serum CK was elevated to 4543 IU/L, and echocardiography revealed a left ventricular ejection fraction of 43 %. We diagnosed her with giant cell myocarditis (GCM) via an emergent myocardial biopsy that revealed a proliferation of lymphocytes, eosinophils, and giant cells without granulomas. Initial treatment with high doses of intravenous methylprednisolone and immunoglobulin improved her symptoms in a few days, and prednisolone was given as follow-up treatment. CK was normalized in a week and a thinning of the interventricular septum mimicking cardiac sarcoidosis (CS) occurred. On day 38, we added a calcineurin inhibitor, tacrolimus, and maintained her with a combination of prednisolone and tacrolimus at a target dose of 10-15 ng/mL. Six months after the onset, there were no signs of relapse despite the persistent mild elevation of troponin I levels. We present a case of GCM mimicking CS successfully maintained by a combination of two immunosuppressive agents. Learning objective: Recommended treatment for giant cell myocarditis (GCM), a potentially fatal disease, is a combination of three immunosuppressive agents. However, GCM shares many characteristics with cardiac sarcoidosis (CS), which is treated using prednisolone alone in many cases. Recent studies on GCM and CS suggest they are different spectrums of a common entity. Although they can clinically overlap, they have different progressive speeds and severities. We present a case of GCM mimicking CS successfully treated with a combination of two immunosuppressive agents.

4.
Int Heart J ; 64(2): 196-202, 2023 Mar 31.
Artigo em Inglês | MEDLINE | ID: mdl-36927938

RESUMO

Immunosuppressive therapy with prednisolone (PSL) is the first-line treatment for cardiac sarcoidosis (CS), and 18F-fluoro-2-deoxyglucose positron emission tomography (FDG-PET) is used to evaluate its efficacy to guide treatment. However, the appropriate timing of FDG-PET in CS remains unknown. This single-center, retrospective, observational study included 15 consecutive CS patients who underwent 3 serial FDG-PET scans (at baseline, in the early phase [1-2 months after PSL introduction], and in the late phase [≥ 5 months after PSL introduction with a maintenance dose of PSL]). We adhered to the PSL tapering protocol by the Japanese Circulation Society even when early FDG-PET showed positive results (SUVmax ≥ 4.0). No patient died during the 908 (644-1600) days of observation. Negative results in the late phase were observed in 3 of 6 early-positive patients, and 3 of 9 early-negative patients showed positive results in the late phase. Changes in echocardiographic parameters from baseline to the late phase were significantly better in late-negative patients than in late-positive patients (left ventricular end-diastolic diameter: -0.7 (-9.3-[-0.5]) mm versus +3.5 (0.8-7.5) mm, P = 0.039; left ventricular end-systolic diameter: -4.2 (-6.9-[-0.1]) mm versus +5.1 (0.5-7.0) mm, P = 0.015; left ventricular ejection fraction: +4.7% (-1.0-9.0%) versus -1.5% (-11.3-1.5%), P = 0.045) ), although early FDG-PET did not predict those consequent changes. An interval of ≥ 5 months after introducing the PSL with a maintenance dose of PSL is long enough for FDG-PET to reflect consequent left ventricular functions, while an interval of 1-2 months can be too short.


Assuntos
Cardiomiopatias , Miocardite , Sarcoidose , Humanos , Prednisolona/uso terapêutico , Fluordesoxiglucose F18 , Cardiomiopatias/diagnóstico por imagem , Cardiomiopatias/tratamento farmacológico , Compostos Radiofarmacêuticos , Tomografia por Emissão de Pósitrons/métodos , Sarcoidose/diagnóstico por imagem , Sarcoidose/tratamento farmacológico , Estudos Retrospectivos
5.
Circ J ; 87(8): 1130-1137, 2023 07 25.
Artigo em Inglês | MEDLINE | ID: mdl-36928271

RESUMO

BACKGROUND: Although guideline-directed medical therapy (GDMT), including ß-blockers, angiotensin-converting enzyme inhibitors (ACEi)/angiotensin receptor blockers (ARBs), and mineralocorticoid receptor antagonists (MRAs), improves survival and quality of life, most patients with heart failure with reduced (HFrEF) and mildly reduced (HFmrEF) ejection fraction are treated with inadequate medications. We investigated the prescription patterns of GDMT in elderly patients with HFrEF and HFmrEF and their characteristics, including the certification of long-term care insurance (LTCI), which represents frailty and disability.Methods and Results: This retrospective cross-sectional study analyzed 1,296 elderly patients with symptomatic HFrEF and HFmrEF with diuretic use (median age 78 years; 63.8% male; median left ventricular ejection fraction 40%). Prescription rates of GDMT were inadequate (ACEi, ARBs, ß-blockers, and MRAs: 27.0%, 30.1%, 54.1%, and 41.9%, respectively). LTCI certification was independently associated with reduced prescription of all medications (ACEi/ARB: odds ratio [OR] 0.591, 95% confidence interval [CI] 0.449-0.778, P=0.001; ß-blockers: OR 0.698, 95% CI 0.529-0.920, P<0.001; MRAs: OR 0.743, 95% CI 0.560-0.985, P=0.052). Patients with LTCI certification also had a high prevalence of polypharmacy and prescription of diuretics. CONCLUSIONS: Vulnerable patients with LTCI may be an explanation for the challenges in implementing GDMT, and communicating is required for favorable heart failure care in this population.


Assuntos
Insuficiência Cardíaca , Humanos , Masculino , Idoso , Feminino , Insuficiência Cardíaca/tratamento farmacológico , Insuficiência Cardíaca/epidemiologia , Inibidores da Enzima Conversora de Angiotensina/uso terapêutico , Inibidores da Enzima Conversora de Angiotensina/farmacologia , Antagonistas de Receptores de Angiotensina/uso terapêutico , Volume Sistólico , Estudos Retrospectivos , Qualidade de Vida , Estudos Transversais , Seguro de Assistência de Longo Prazo , Função Ventricular Esquerda , Antagonistas Adrenérgicos beta/uso terapêutico , Antagonistas Adrenérgicos beta/farmacologia , Antagonistas de Receptores de Mineralocorticoides/uso terapêutico , Comorbidade
6.
Clin Res Cardiol ; 112(1): 87-97, 2023 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-35729430

RESUMO

BACKGROUND: In patients with chronic heart failure (CHF) and type 2 diabetes (T2D), sodium-glucose cotransporter-2 (SGLT2) inhibition improves cardiorenal outcomes, but details of the effects on distinct subsets of body fluid volume remain incomplete. METHODS: This was a post hoc analysis of patients with CHF and T2D in the CANDLE trial (UMIN000017669), an investigator-initiated, multi-center, randomized open-label trial that compared the effect of canagliflozin (100 mg, n = 113) with glimepiride (starting dose: 0.5 mg, n = 120) on changes in N-terminal pro-brain natriuretic peptide. The estimated plasma volume (ePV, calculated with the Straus formula) and estimated extracellular volume (eEV, determined by the body surface area) were compared between treatment groups at weeks 4, 12, and 24. RESULTS: Among 233 patients analyzed, 166 (71.2%) had an ejection fraction (EF) > 50%. Reductions in ePV and eEV were observed only in the canagliflozin group until week 12 (change from baseline at week 12, ePV; - 7.63%; 95% confidence interval [CI], - 10.71 to - 4.55%, p < 0.001, eEV; - 123.15 mL; 95% CI, - 190.38 to - 55.92 mL, p < 0.001). While ePV stopped falling after week 12, eEV continued to fall until week 24 ([change from baseline at week 24] - [change from baseline at week 12], ePV; 1.01%; 95%CI, - 2.30-4.32%, p = 0.549, eEV; - 125.15 mL; 95% CI, - 184.35 to - 65.95 mL, p < 0.001). CONCLUSIONS: Maintenance of a modest reduction in ePV and continuous removal of eEV via chronic SGLT2 inhibition suggests that favorable body fluid regulation contributes to the cardiorenal benefits of SGLT2 inhibitors in patients with CHF, irrespective of EF. TRIAL REGISTRATION: UMIN000017669.


Assuntos
Líquidos Corporais , Canagliflozina , Diabetes Mellitus Tipo 2 , Insuficiência Cardíaca , Inibidores do Transportador 2 de Sódio-Glicose , Humanos , Canagliflozina/uso terapêutico , Doença Crônica , Diabetes Mellitus Tipo 2/complicações , Diabetes Mellitus Tipo 2/tratamento farmacológico , Glucosídeos/farmacologia , Insuficiência Cardíaca/tratamento farmacológico , Transportador 2 de Glucose-Sódio , Inibidores do Transportador 2 de Sódio-Glicose/uso terapêutico
7.
Intern Med ; 62(12): 1707-1713, 2023 Jun 15.
Artigo em Inglês | MEDLINE | ID: mdl-36351583

RESUMO

Objective Spontaneous mechanical alternans (MA), or pulsus alternans, has been observed in heart failure patients with hypertension or tachycardia for 150 years and is considered a sign of a poor prognosis. However, in some dilated cardiomyopathy (DCM) patients with MA, optimal medical therapy (OMT) brings left ventricular reverse remodeling (LVRR), a preferable prognostic indicator. This study examined the probability of LVRR in DCM patients with spontaneous MA and whether or not LVRR can be predicted by the baseline blood pressure or heart rate. Methods We conducted a single-center, retrospective observational study of newly diagnosed DCM patients from January 2017 to December 2020. Results Thirty-three newly diagnosed DCM patients were retrospectively examined. Spontaneous MA was observed during diagnostic cardiac catheterization in at least 1 of the pressure waveforms of the aorta, left ventricle, pulmonary artery, or right ventricle in 10 patients (30%) (MA-group). LVRR after OMT was achieved roughly equally in the MA group (6 of 10, 60%) and the non-MA group (12 of 23, 52%). In the MA group, those who achieved LVRR had a significantly higher baseline systolic aortic pressure (more than 120 mmHg in all 6 patients) than those who did not, although the baseline heart rate did not show a significant correlation with LVRR. In contrast, in the non-MA group, LVRR was unrelated to the baseline aortic pressure or heart rate. Conclusion The probability of LVRR in newly-diagnosed DCM patients with spontaneous MA was similar to that in those without spontaneous MA. Spontaneous MA may not necessarily be a sign of a poor prognosis if observed in patients with a preserved blood pressure.


Assuntos
Cardiomiopatia Dilatada , Insuficiência Cardíaca , Humanos , Cardiomiopatia Dilatada/complicações , Função Ventricular Esquerda/fisiologia , Estudos Retrospectivos , Pressão Sanguínea , Prognóstico
8.
Am J Med Genet A ; 191(1): 37-51, 2023 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-36189931

RESUMO

Vascular Ehlers-Danlos syndrome (vEDS) is a hereditary connective tissue disorder (HCTD) characterized by arterial dissection/aneurysm/rupture, sigmoid colon rupture, or uterine rupture. Diagnosis is confirmed by detecting heterozygous variants in COL3A1. This is the largest Asian case series and the first to apply an amplification-based next-generation sequencing through custom panels of causative genes for HCTDs, including a specific method of evaluating copy number variations. Among 429 patients with suspected HCTDs analyzed, 101 were suspected to have vEDS, and 33 of them (32.4%) were found to have COL3A1 variants. Two patients with a clinical diagnosis of Loeys-Dietz syndrome and/or familial thoracic aortic aneurysm and dissection were also found to have COL3A1 variants. Twenty cases (57.1%) had missense variants leading to glycine (Gly) substitutions in the triple helical domain, one (2.9%) had a missense variant leading to non-Gly substitution in this domain, eight (22.9%) had splice site alterations, three (8.6%) had nonsense variants, two (5.7%) had in-frame deletions, and one (2.9%) had a multi-exon deletion, including two deceased patients analyzed with formalin-fixed and paraffin-embedded samples. This is a clinically useful system to detect a wide spectrum of variants from various types of samples.


Assuntos
Síndrome de Ehlers-Danlos Tipo IV , Síndrome de Ehlers-Danlos , Gravidez , Feminino , Humanos , Síndrome de Ehlers-Danlos/diagnóstico , Síndrome de Ehlers-Danlos/genética , Colágeno Tipo III/genética , Variações do Número de Cópias de DNA , Testes Genéticos
9.
iScience ; 25(7): 104547, 2022 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-35754738

RESUMO

Brown adipose tissue (BAT) has a role in maintaining systemic metabolic health in rodents and humans. Here, we show that metabolic stress induces BAT to produce coagulation factors, which then-together with molecules derived from the circulation-promote BAT dysfunction and systemic glucose intolerance. When mice were fed a high-fat diet (HFD), the levels of tissue factor, coagulation Factor VII (FVII), activated coagulation Factor X (FXa), and protease-activated receptor 1 (PAR1) expression increased significantly in BAT. Genetic or pharmacological suppression of coagulation factor-PAR1 signaling in BAT ameliorated its whitening and improved thermogenic response and systemic glucose intolerance in mice with dietary obesity. Conversely, the activation of coagulation factor-PAR1 signaling in BAT caused mitochondrial dysfunction in brown adipocytes and systemic glucose intolerance in mice fed normal chow. These results indicate that BAT produces endogenous coagulation factors that mediate pleiotropic effects via PAR1 signaling under metabolic stress.

10.
Int Heart J ; 63(2): 306-311, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35354751

RESUMO

Since permanent inferior vena cava (IVC) filters increase deep vein thrombosis (DVT), filter retrieval should be performed as possible. Despite the guideline recommendation, IVC filters are not always retrieved in clinical practice. To date, many patients with not-retrieval IVC filters have been prescribed anticoagulant therapy, but the long-term prognosis, including venous thromboembolism (VTE) and bleeding events, remains unknown. In this study, 195 patients who underwent IVC filter implantation between 2006 and 2017 at 3 institutions in Niigata City have been investigated about their deaths, VTE recurrence, and bleeding events. After peaking 2009, the number of IVC filter implantation gradually decreased. During observational period, there were 158 patients with not-retrieval IVC filters (the overall retrieval rate of 19.0%). The not-retrieval group included significantly older and more patients with cancer compared to the retrieval group. Anticoagulation therapy was continued in 88% of the not-retrieval group. During a mean follow-up of 5.0 years, 6 symptomatic DVT events associated with inadequate control of anticoagulation and 13 bleeding events were observed. A total of 52 patients died and only the presence of cancer was prognostic risk factor. Although long-term anticoagulation therapy may be associated with bleeding events, there were few recurrent VTE under optimal anticoagulation. It is anticipated that even if the IVC filter cannot be retrieved, appropriate anticoagulation is useful for prevention of DVT recurrence despite the risk of bleeding.


Assuntos
Filtros de Veia Cava , Tromboembolia Venosa , Anticoagulantes/efeitos adversos , Coagulação Sanguínea , Remoção de Dispositivo/efeitos adversos , Humanos , Filtros de Veia Cava/efeitos adversos , Tromboembolia Venosa/etiologia , Tromboembolia Venosa/prevenção & controle
11.
Circ J ; 86(1): 158-165, 2021 12 24.
Artigo em Inglês | MEDLINE | ID: mdl-34789610

RESUMO

BACKGROUND: Heart failure in elderly people causes physical and cognitive dysfunction and often requires long-term care insurance (LTCI); however, among patients with left ventricular (LV) systolic dysfunction, the incidence and risk factors of future LTCI requirements need to be elucidated.Methods and Results:The study included 1,852 patients aged ≥65 years with an echocardiographic LV ejection fraction (LVEF) ≤50%; we referred to their LTCI data and those of 113,038 community-dwelling elderly people. During a mean 1.7-year period, 332 patients newly required LTCI (incidence 10.7 per 100 person-years); the incidence was significantly higher than that for the community-dwelling people (hazard ratio [HR], 1.47; 95% confidence interval [CI], 1.32-1.64). On multivariate analysis, the risk factors at the time of echocardiography leading to future LTCI requirement were atrial fibrillation (HR, 1.588; 95% CI, 1.279-1.971), history of stroke (HR, 2.02; 95% CI, 1.583-2.576), osteoporosis (HR, 1.738; 95% CI, 1.253-2.41), dementia (HR, 2.804; 95% CI, 2.075-3.789), hypnotics (HR, 1.461; 95% CI, 1.148-1.859), and diuretics (HR, 1.417; 95% CI, 1.132-1.773); however, the LVEF was not a risk factor (HR, 0.997; 95% CI, 0.983-1.011). CONCLUSIONS: In elderly patients with LV systolic dysfunction, the incidence of LTCI requirement was more common than that for community-dwelling people; its risk factors did not include LVEF, but included many other non-cardiac comorbidities and therapies, suggesting the need for interdisciplinary cooperation to prevent disabilities.


Assuntos
Insuficiência Cardíaca , Disfunção Ventricular Esquerda , Idoso , Humanos , Incidência , Seguro de Assistência de Longo Prazo , Japão/epidemiologia , Prognóstico , Fatores de Risco , Volume Sistólico , Disfunção Ventricular Esquerda/diagnóstico por imagem , Disfunção Ventricular Esquerda/epidemiologia , Função Ventricular Esquerda
12.
Acta Biomed ; 92(3): e2021195, 2021 07 01.
Artigo em Inglês | MEDLINE | ID: mdl-34212936

RESUMO

Background Frailty is a multifactorial physiological syndrome most often associated with age but which has received increasing recognition as a component of chronic illnesses such as heart failure. Patients with heart failure are likely to be frail, irrespective of their age. Adipokine dysregulation, which is associated with frailty, occurs in patients with heart failure. In this study, we tested the hypothesis that adipokines are associated with frailty in patients with heart failure. Methods Thirty-five patients with heart failure (age, 67 ± 14 years; 25 males; left ventricular ejection fraction, 45 ± 19%) were included. Serum adipokine levels, physical performance, and body composition were measured. Results Adiponectin and leptin were inversely correlated with grip strength. Adiponectin was inversely correlated with bone mineral density. Leptin was positively correlated with fat mass. Adipokines were not correlated with skeletal muscle mass. Conclusions Adipokines were associated with frailty in patients with heart failure. Adipokine dysregulation may play a role in the development of frailty in heart failure.


Assuntos
Adipocinas , Fragilidade , Insuficiência Cardíaca , Idoso , Idoso de 80 Anos ou mais , Feminino , Fragilidade/complicações , Insuficiência Cardíaca/complicações , Humanos , Leptina , Masculino , Pessoa de Meia-Idade , Volume Sistólico , Função Ventricular Esquerda
13.
Diabetes Ther ; 11(11): 2739-2755, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32968947

RESUMO

INTRODUCTION: Type 2 diabetes (T2DM) is associated with cardiovascular death, including sudden cardiac death due to arrhythmias. Patients with an implantable cardioverter-defibrillator (ICD) are also at high risk of developing a clinically significant ventricular arrhythmia. It has been reported that sodium-glucose cotransporter 2 (SGLT2) inhibitors can reduce cardiovascular deaths; however, the physiological mechanisms of this remain unclear. It is, however, well known that SGLT2 inhibitors increase blood ketone bodies, which have been suggested to have sympatho-suppressive effects. Empagliflozin (EMPA) is an SGLT2 inhibitor. The current clinical trial titled "Placebo-controlled, double-blind study of empagliflozin (EMPA) and implantable cardioverter-defibrillator (EMPA-ICD) in patients with type 2 diabetes (T2DM)" was designed to investigate the antiarrhythmic effects of EMPA. METHODS: The EMPA-ICD study is a prospective, multicenter, placebo-controlled, double-blind, randomized, investigator-initiated clinical trial currently in progress. A total of 210 patients with T2DM (hemoglobin A1c 6.5-10.0%) will be randomized (1:1) to receive once-daily placebo or EMPA, 10 mg, for 24 weeks. The primary endpoint is the number of clinically significant ventricular arrhythmias for 24 weeks before and 24 weeks after study drug administration, as documented by the ICD. The secondary endpoints of the study are the change from baseline concentrations in blood ketone and catecholamine 24 weeks after drug treatment. CONCLUSION: The EMPA-ICD study is the first clinical trial to assess the effect of an SGLT2 inhibitor on clinically significant ventricular arrhythmias in patients with T2DM and an ICD. TRIAL REGISTRATION: Unique trial number, jRCTs031180120 ( https://jrct.niph.go.jp/latest-detail/jRCTs031180120 ).

14.
Int Heart J ; 57(3): 317-22, 2016 May 25.
Artigo em Inglês | MEDLINE | ID: mdl-27181036

RESUMO

The left ventricular contractile force (LV dP/dtmax) of patients with left ventricular systolic dysfunction does not increase effectively with an increase in heart rate. In other words, their force-frequency relationship (FFR) is impaired. However, it is unknown whether a longer coupling interval subsequent to tachycardia causes a stronger contraction (poststimulation potentiation, PSP) in a rate-dependent manner.In 16 patients with idiopathic dilated cardiomyopathy (DCM) (48 ± 2 years old, LVEF 30 ± 10%) and 6 control patients (58 ± 4 years old, LVEF 70 ± 7%), FFR was assessed by right atrial pacing using a micro-manometer-tipped catheter. At each pacing rate, the increase of LV dP/dtmax over basal LV dP/dt (ΔFFR) and the increase of LV dP/dtmax of the first beat after pacing cessation over LV dP/dtmax during pacing (ΔPSP) were evaluated.Patients with DCM had smaller LV dP/dtmax at baseline (872 ± 251 versus 1370 ± 123 mmHg/second, P = 0.0002) and developed smaller ΔFFR (eg, at 120/minute, 77 ± 143 versus 331 ± 131 mmHg/second, P = 0.0011). In contrast, they showed a rate-dependent increase of LV dP/dtmax of PSP and had greater ΔPSP (eg, at 120/minute, 294 ± 173 versus -152 ± 131 mmHg/second, P < 0.0001).Failing left ventricles develop little contractile force during tachycardia despite their rate-dependent enhancement in post-stimulation potentiation, suggesting that refractoriness of contractile force underlies impaired FFR.


Assuntos
Estimulação Cardíaca Artificial , Cardiomiopatia Dilatada/complicações , Insuficiência Cardíaca Sistólica , Frequência Cardíaca , Contração Miocárdica , Disfunção Ventricular Esquerda , Cálcio/metabolismo , Estimulação Cardíaca Artificial/efeitos adversos , Estimulação Cardíaca Artificial/métodos , Cardiomiopatia Dilatada/fisiopatologia , Técnicas Eletrofisiológicas Cardíacas/métodos , Feminino , Insuficiência Cardíaca Sistólica/diagnóstico , Insuficiência Cardíaca Sistólica/etiologia , Insuficiência Cardíaca Sistólica/fisiopatologia , Insuficiência Cardíaca Sistólica/terapia , Humanos , Masculino , Pessoa de Meia-Idade , Período Refratário Eletrofisiológico , Volume Sistólico , Disfunção Ventricular Esquerda/diagnóstico , Disfunção Ventricular Esquerda/metabolismo , Disfunção Ventricular Esquerda/fisiopatologia , Disfunção Ventricular Esquerda/terapia
15.
Protein Sci ; 16(7): 1389-97, 2007 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-17586772

RESUMO

A protein crystal lattice consists of surface contact regions, where the interactions of specific groups play a key role in stabilizing the regular arrangement of the protein molecules. In an attempt to control protein incorporation in a crystal lattice, a leucine zipper-like hydrophobic interface (comprising four leucine residues) was introduced into a helical region (helix 2) of the human pancreatic ribonuclease 1 (RNase 1) that was predicted to form a suitable crystallization interface. Although crystallization of wild-type RNase 1 has not yet been reported, the RNase 1 mutant having four leucines (4L-RNase 1) was successfully crystallized under several different conditions. The crystal structures were subsequently determined by X-ray crystallography by molecular replacement using the structure of bovine RNase A. The overall structure of 4L-RNase 1 is quite similar to that of the bovine RNase A, and the introduced leucine residues formed the designed crystal interface. To characterize the role of the introduced leucine residues in crystallization of RNase 1 further, the number of leucines was reduced to three or two (3L- and 2L-RNase 1, respectively). Both mutants crystallized and a similar hydrophobic interface as in 4L-RNase 1 was observed. A related approach to engineer crystal contacts at helix 3 of RNase 1 (N4L-RNase 1) was also evaluated. N4L-RNase 1 also successfully crystallized and formed the expected hydrophobic packing interface. These results suggest that appropriate introduction of a leucine zipper-like hydrophobic interface can promote intermolecular symmetry for more efficient protein crystallization in crystal lattice engineering efforts.


Assuntos
Cristalografia por Raios X/métodos , Zíper de Leucina , Ribonuclease Pancreático/química , Sequência de Aminoácidos , Humanos , Interações Hidrofóbicas e Hidrofílicas , Modelos Moleculares , Dados de Sequência Molecular , Mutação , Engenharia de Proteínas , Estrutura Secundária de Proteína , Estrutura Terciária de Proteína , Ribonuclease Pancreático/genética , Ribonuclease Pancreático/metabolismo , Homologia de Sequência de Aminoácidos
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