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We investigated the effects of acute-phase intensive electrical muscle stimulation (EMS) on physical function in COVID-19 patients with respiratory failure requiring invasive mechanical ventilation (IMV) in the intensive care unit (ICU). Consecutive COVID-19 patients requiring IMV admitted to a university hospital ICU between January and April 2022 (EMS therapy group) or between March and September 2021 (age-matched historical control group) were included in this retrospective observational case-control study. EMS was applied to both upper and lower limb muscles for up to 2 weeks in the EMS therapy group. The study population consisted of 16 patients undergoing EMS therapy and 16 age-matched historical controls (median age, 71 years; 81.2% male). The mean period until initiation of EMS therapy after ICU admission was 3.2 ± 1.4 days. The EMS therapy group completed a mean of 6.2 ± 3.7 EMS sessions, and no adverse events occurred. There were no significant differences between the two groups in Medical Research Council sum score (51 vs. 53 points, respectively; P = 0.439) or ICU mobility scale at ICU discharge. Addition of upper and lower limb muscle EMS therapy to an early rehabilitation program did not result in improved physical function at ICU discharge in severe COVID-19 patients.
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COVID-19 , Respiración Artificial , Humanos , Masculino , Anciano , Femenino , Estudios de Casos y Controles , Estudios Retrospectivos , COVID-19/terapia , MúsculosRESUMEN
Background: Coronavirus disease 2019 (COVID-19) features a hypercoagulable state, but therapeutic anticoagulation effectiveness varies with disease severity. We aimed to evaluate the dynamics of the coagulation profile and its association with COVID-19 severity, outcomes, and biomarker trajectories. Methods: This multicenter, prospective, observational study included patients with COVID-19 requiring respiratory support. Rotational thromboelastometry findings were evaluated for coagulation and fibrinolysis status. Hypercoagulable status was defined as supranormal range of maximum clot elasticity in an external pathway. Longitudinal laboratory parameters were collected to characterize the coagulation phenotype. Results: Of 166 patients, 90 (54%) were severely ill at inclusion (invasive mechanical ventilation, 84; extracorporeal membrane oxygenation, 6). Higher maximum elasticity (P=0.02) and lower maximum lysis in the external pathway (P=0.03) were observed in severely ill patients compared with the corresponding values in patients on non-invasive oxygen supplementation. Hypercoagulability components correlated with platelet and fibrinogen levels. Hypercoagulable phenotype was associated with favorable outcomes in severely ill patients, while normocoagulable phenotype was not (median time to recovery, 15 days vs. 27 days, P=0.002), but no significant association was observed in moderately ill patients. In patients with severe COVID-19, lower initial C3, minimum C3, CH50, and greater changes in CH50 were associated with the normocoagulable phenotype. Changes in complement components correlated with dynamics of coagulation markers, hematocrit, and alveolar injury markers. Conclusions: While hypercoagulable states become more evident with increasing severity of respiratory disease in patients with COVID-19, normocoagulable phenotype is associated with triggered by alternative pathway activation and poor outcomes.
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COVID-19 , Trombofilia , Humanos , Estudios Prospectivos , Trombofilia/etiología , Coagulación Sanguínea , FenotipoRESUMEN
This prospective observational cohort study was performed to investigate the physical function and mental health trajectories of novel coronavirus disease 2019 (COVID-19) patients requiring invasive mechanical ventilation (IMV) after discharge from the intensive care unit (ICU). The study population consisted of 64 patients (median age, 60 years; 85.9% male; median IMV duration, 9 days). At ICU discharge, 28.1% of the patients had Medical Research Council (MRC) sum score < 48 points, and prolonged IMV was significantly associated with lower MRC sum score and handgrip strength. Symptoms were similar between groups at ICU discharge, and the symptoms most commonly reported as moderate-to-severe were impaired well-being (52%), anxiety (43%), tiredness (41%), and depression (35%). Although muscle strength and mobility status were significantly improved after ICU discharge, Edmonton Symptom Assessment System score did not improve significantly in the prolonged IMV group. EuroQol five-dimension five-level summary index was significantly lower in the prolonged than short IMV group at 6 months after ICU discharge. We found substantial negative physical function and mental health consequences in the majority of surviving COVID-19 patients requiring IMV, with prolonged period of IMV showing greater negative effects not only immediately but also at 6 months after discharge from the ICU.
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COVID-19 , Fuerza de la Mano , Humanos , Masculino , Persona de Mediana Edad , Femenino , Salud Mental , Estudios Prospectivos , Respiración Artificial , COVID-19/epidemiología , COVID-19/terapiaRESUMEN
We retrospectively analyzed data from the Medical Information Mart for Intensive Care-III critical care database to determine whether visually-assessed right ventricular (RV) dysfunction was associated with clinical outcomes in septic shock patients. Associations between visually-assessed RV dysfunction by echocardiography and in-hospital mortality, lethal arrhythmia, and hemodynamic indicators to determine the prognostic value of RV dysfunction in patients with septic shock were analyzed. Propensity score analysis showed RV dysfunction was associated with increased risk of in-hospital death in patients with septic shock (adjusted odds ratio [OR] 2.15; 95% confidence interval [CI] 1.99-2.32; P < 0.001). In multivariate logistic regression analysis, RV dysfunction was associated with in-hospital death (OR 2.19; 95% CI 1.91-2.53; P < 0.001), lethal arrhythmia (OR 2.19; 95% CI 1.34-3.57; P < 0.001), and tendency for increased blood lactate levels (OR 1.31; 95% CI 1.14-1.50; P < 0.001) independent of left ventricular (LV) dysfunction. RV dysfunction was associated with lower cardiac output, pulmonary artery pressure index, and RV stroke work index. In patients with septic shock, visually-assessed RV dysfunction was associated with in-hospital mortality, lethal arrhythmia, and circulatory insufficiency independent of LV dysfunction. Visual assessment of RV dysfunction using echocardiography might help to identify the short-term prognosis of patients with septic shock by reflecting hemodynamic status.
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Choque Séptico/complicaciones , Disfunción Ventricular Derecha/complicaciones , Anciano , Ecocardiografía , Femenino , Hemodinámica , Mortalidad Hospitalaria , Humanos , Ácido Láctico/sangre , Modelos Logísticos , Masculino , Persona de Mediana Edad , Pronóstico , Puntaje de Propensión , Estudios Retrospectivos , Factores de Riesgo , Choque Séptico/mortalidad , Resultado del Tratamiento , Disfunción Ventricular Derecha/diagnóstico por imagen , Disfunción Ventricular Derecha/mortalidadRESUMEN
Whether a patient with severe coronavirus disease (COVID-19) will be successfully liberated from mechanical ventilation (MV) early is important in the COVID-19 pandemic. This study aimed to characterize the time course of parameters and outcomes of severe COVID-19 in relation to the timing of liberation from MV. This retrospective, single-center, observational study was performed using data from mechanically ventilated COVID-19 patients admitted to the ICU between 1 March 2020 and 15 December 2020. Early liberation from ventilation (EL group) was defined as successful extubation within 10 days of MV. The trends of respiratory mechanics and laboratory data were visualized and compared between the EL and prolonged MV (PMV) groups using smoothing spline and linear mixed effect models. Of 52 admitted patients, 31 mechanically ventilated COVID-19 patients were included (EL group, 20 (69%); PMV group, 11 (31%)). The patients' median age was 71 years. While in-hospital mortality was low (6%), activities of daily living (ADL) at the time of hospital discharge were significantly impaired in the PMV group compared to the EL group (mean Barthel index (range): 30 (7.5-95) versus 2.5 (0-22.5), p = 0.048). The trends in respiratory compliance were different between patients in the EL and PMV groups. An increasing trend in the ventilatory ratio during MV until approximately 2 weeks was observed in both groups. The interaction between daily change and earlier liberation was significant in the trajectory of the thrombin-antithrombin complex, antithrombin 3, fibrinogen, C-reactive protein, lymphocyte, and positive end-expiratory pressure (PEEP) values. The indicator of physiological dead space increases during MV. The trajectory of markers of the hypercoagulation status, inflammation, and PEEP were significantly different depending on the timing of liberation from MV. These findings may provide insight into the pathophysiology of COVID-19 during treatment in the critical care setting.
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BACKGROUND: Airborne personal protective equipment is required for healthcare workers when performing aerosol-generating procedures on patients with infectious diseases. Chest compressions, one of the main components of cardiopulmonary resuscitation, require intense and dynamic movements of the upper body. We aimed to investigate the protective effect of tight-fitting powered air-purifying respirators (PAPRs) during chest compressions. METHODS: This single-center simulation study was performed from February 2021 to March 2021. The simulated workplace protection factor (SWPF) is the concentration ratio of ambient particles and particles inside the PAPR mask; this value indicates the level of protection provided by a respirator when subjected to a simulated work environment. Participants performed continuous chest compressions three times for 2 min each time, with a 4-min break between each session. We measured the SWPF of the tight-fitting PAPR during chest compression in real-time mode. The primary outcome was the ratio of any failure of protection (SWPF <500) during the chest compression sessions. RESULTS: Fifty-four participants completed the simulation. Overall, 78% (n = 42) of the participants failed (the measured SWPF value was less than 500) at least one of the three sessions of chest compressions. The median value and interquartile range of the SWPF was 4304 (685-16,191). There were no reports of slipping down of the respirator or mechanical failure during chest compressions. CONCLUSIONS: Although the median SWPF value was high during chest compressions, the tight-fitting PAPR did not provide adequate protection.
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Reanimación Cardiopulmonar/efectos adversos , Factores Protectores , Dispositivos de Protección Respiratoria/normas , Adulto , Filtros de Aire/normas , Filtros de Aire/estadística & datos numéricos , Reanimación Cardiopulmonar/métodos , Femenino , Humanos , Control de Infecciones/métodos , Control de Infecciones/normas , Control de Infecciones/estadística & datos numéricos , Masculino , Dispositivos de Protección Respiratoria/estadística & datos numéricos , Encuestas y CuestionariosRESUMEN
PURPOSE: Severe hyponatremia, defined as serum sodium concentration ([sNa]) ≤ 120 mEq/L, requires aggressive treatment to prevent potentially fatal cerebral edema, seizures, and other sequelae, but overcorrection can also result in life-threatening cerebral hemorrhage and demyelination. We compared the safety and efficacy of nasal desmopressin to conventional management for the prevention of [sNa] overcorrection. MATERIAL AND METHODS: This retrospective analysis compared 47 patients treated with desmopressin to 17 patients treated conventionally at a university hospital ICU in Japan between 2013 and 2018 using propensity score-based approaches. The primary outcome was safe [sNa] correction, defined as a ≤ 8 mEq/L difference between baseline and follow-up [sNa] at any time within 24h of diagnosis. RESULTS: The 24-h safe correction rate was significantly greater in the desmopressin group than the conventional treatment group (68% [32/47] vs. 41% [7/17], P = 0.039), and dose-response analysis indicated a positive association between cumulative 24-h desmopressin dose and safe correction at 24 h (P = 0.003). Few overcorrections precluded reliable assessment at 48 h. Exacerbation of hyponatremia was comparable in the two treatment groups. CONCLUSIONS: Intranasal desmopressin therapy increased the safe correction of severe hyponatremia. Large prospective trials are warranted to confirm this result.
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Desamino Arginina Vasopresina , Hiponatremia , Estudios de Cohortes , Desamino Arginina Vasopresina/efectos adversos , Humanos , Hiponatremia/inducido químicamente , Hiponatremia/tratamiento farmacológico , Puntaje de Propensión , Estudios Prospectivos , Estudios RetrospectivosRESUMEN
A 37-year-old man diagnosed with diffuse large B-cell lymphoma two weeks previously, visited our emergency department with sudden dyspnea. He had a severe respiratory failure with saturated percutaneous oxygen at 80% (room air). Chest radiography showed a large amount of left pleural effusion. After 1000 mL of the effusion was urgently drained, reexpansion pulmonary edema (RPE) occurred. Despite ventilator management, oxygenation did not improve and venovenous extracorporeal membrane oxygenation (VV-ECMO) was initiated in the intensive care unit. The next day, contrast-enhanced computed tomography showed a massive thrombus in the right pulmonary artery, at this point the presence of pulmonary thromboembolism (PTE) was revealed. Fortunately, the patient's condition gradually improved with anticoagulant therapy and VV-ECMO support. VV-ECMO was successfully discontinued on day 4, and chemotherapy was initiated on day 8. We speculated the following mechanism in this case: blood flow to the right lung significantly reduced due to acute massive PTE, and blood flow to the left lung correspondingly increased, which could have caused RPE in the left lung. Therefore, our observations suggest that drainage of pleural effusion when contralateral blood flow is impaired due to acute PTE may increase the risk of RPE.
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OBJECTIVE: Tracheostomy is an important surgical procedure for coronavirus disease-2019 (COVID-19) patients who underwent prolonged tracheal intubation. Surgical indication of tracheostomy is greatly affected by the general condition of the patient, comorbidity, prognosis, hospital resources, and staff experience. Thus, the optimal timing of tracheostomy remains controversial. METHODS: We reviewed our early experience with COVID-19 patients who underwent tracheostomy at one tertiary hospital in Japan from February to September 2020 and analyzed the timing of tracheostomy, operative results, and occupational infection in healthcare workers (HCWs). RESULTS: Of 16 patients received tracheal intubation with confirmed severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, five patients (31%) received surgical tracheostomy in our hospital. The average consultation time for surgical tracheostomy was 7.4 days (range, 6 - 9 days) from the COVID-19 team to the otolaryngologist. The duration from tracheal intubation to tracheostomy ranged from 14 to 27 days (average, 20 days). The average time of tracheostomy was 27 min (range, 17 - 39 min), and post-wound bleeding occurred in only one patient. No significant differences in hemoglobin (Hb) levels were found between the pre- and postoperative periods (mean: 10.2 vs. 10.2 g/dl, p = 0.93). Similarly, no difference was found in white blood cell (WBC) count (mean: 12,200 vs. 9,900 cells /µl, p = 0.25). After the tracheostomy, there was no occupational infection among the HCWs who assisted the tracheostomy patients during the perioperative period. CONCLUSION: We proposed a modified weaning protocol and surgical indications of tracheostomy for COVID-19 patients and recommend that an optimal timing for tracheostomy in COVID-19 patients of 2 - 3 weeks after tracheal intubation, from our early experiences in Japan. An experienced multi-disciplinary tracheostomy team is essential to perform a safe tracheostomy in patients with COVID-19 and to minimize the risk of occupational infection in HCWs.
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COVID-19/terapia , Respiración Artificial/métodos , Insuficiencia Respiratoria/terapia , Traqueostomía/métodos , Anciano , Femenino , Humanos , Japón , Masculino , Persona de Mediana Edad , Equipo de Protección Personal , Estudios Retrospectivos , SARS-CoV-2 , Factores de Tiempo , Resultado del Tratamiento , Desconexión del VentiladorRESUMEN
BACKGROUND: Novel coronavirus disease 2019 (COVID-19) refers to infection with the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pathogen, and has spread to pandemic levels since its inception in December 2019. While several risk factors for severe presentation have been identified, the clinical course for end-stage renal disease (ESRD) patients on maintenance hemodialysis with COVID-19 has been unclear. Previous studies have revealed that some antiviral agents may be effective against COVID-19 in the general population, but the pharmacokinetics and pharmacodynamics of these agents in ESRD patients remain under investigation. Favipiravir, an antiviral agent developed for treatment of influenza, is one candidate treatment for COVID-19, but suitable dosages for patients with renal insufficiency are unknown. Here we provide a first report on the efficacy of favipiravir in a patient with ESRD undergoing hemodialysis. CASE PRESENTATION: The case involved a 52-year-old woman with COVID-19 who had been undergoing maintenance hemodialysis three times a week for 3 years due to diabetic nephropathy. She had initially been treated with lopinavir/ritonavir and ciclesonide for 5 days, but developed severe pneumonia requiring invasive positive-pressure ventilation. Those antiviral agents were subsequently switched to favipiravir. She recovered gradually, and after 2 weeks was extubated once the viral load of SARS-CoV-2 fell below the limit of detection. Although concentrations of several biliary enzymes were elevated, no major adverse events were observed. CONCLUSION: Favipiravir may be an effective option for the treatment of COVID-19-infected patients with ESRD.
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Amidas/uso terapéutico , Antivirales/uso terapéutico , Tratamiento Farmacológico de COVID-19 , COVID-19/complicaciones , Fallo Renal Crónico/complicaciones , Pirazinas/uso terapéutico , Femenino , Humanos , Fallo Renal Crónico/terapia , Persona de Mediana Edad , Pandemias , Respiración con Presión Positiva , Diálisis Renal , SARS-CoV-2RESUMEN
We treated two patients with COVID-19 pneumonia requiring mechanical ventilation. Case 1 was a 73-year-old Japanese man. Computed tomography (CT) revealed ground-glass opacities in both lungs. He had severe respiratory failure with a partial pressure of oxygen in arterial blood/fraction of inspiratory oxygen ratio (P/F ratio) of 203. Electrocardiogram showed a heart rate (HR) of 56 beats/min, slight ST depression in leads II, III, and aVF, and mild saddle-back type ST elevation in leads V1 and V2. High-sensitivity cardiac troponin T (cTnT) level was slightly elevated. Despite a high fever and hypoxemia, his HR remained within 50-70 beats/min. Case 2 was a 52-year-old Japanese woman. CT revealed ground-glass opacities in the lower left lung. Electrocardiogram showed a HR of only 81 beats/min, despite a body temperature of 39.2 °C, slight ST depression in leads V4, V5, V6, and a prominent U wave in multiple leads. She had an elevated cTnT and a P/F ratio of 165. Despite a high fever and hypoxemia, her HR remained within 50-70 beats/min. Both patients had a poor compensatory increase in their HR, despite their critical status. Relative bradycardia could be a cardiovascular complication and is an important clinical finding in patients with COVID-19.
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RATIONALE: Capillary leak syndrome is a condition that increases systemic capillary permeability and causes characteristic manifestations such as recurrent hypovolemia, systemic edema, and hemoconcentration. Acute limb compartment syndrome is a possible complication of severe capillary leak syndrome. However, timely diagnosis and prompt treatment are challenging because of atypical presentation. PATIENT CONCERNS: An 18-year-old woman with a history of clinical depression was admitted to our intensive care unit (ICU) because of metformin and vildagliptin overdose. She developed marked vasodilatory shock with recurrent severe hypovolemia and disseminated intravascular coagulation. After urgent hemodialysis and plasma exchange, she started to stabilize hemodynamically. However, her limbs became stone-hard with massive edema. Her serum creatinine kinase level increased to an extremely high level. DIAGNOSIS: Extremities were distended, and her skin developed pallor with blistering. Intramuscular pressure in both forearms and lower legs was significantly elevated. INTERVENTIONS: Decompressive fasciotomy was performed. Hemodialysis was continued because of rhabdomyolyses-induced acute kidney injury. OUTCOMES: The patient was finally able to walk by herself at the time of hospital discharge on day 109. LESSONS: The possibility of acute compartment syndrome should be considered in patients with marked capillary leakage, especially after aggressive fluid resuscitation. It is important to be aware of the compartment syndrome in an ICU setting because communication barriers often mask typical symptoms and make diagnosis difficult.
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Síndrome de Fuga Capilar/etiología , Síndromes Compartimentales/etiología , Inhibidores de la Dipeptidil-Peptidasa IV/toxicidad , Metformina/efectos adversos , Adolescente , Síndrome de Fuga Capilar/complicaciones , Síndrome de Fuga Capilar/fisiopatología , Síndromes Compartimentales/fisiopatología , Síndromes Compartimentales/cirugía , Descompresión Quirúrgica/métodos , Inhibidores de la Dipeptidil-Peptidasa IV/efectos adversos , Inhibidores de la Dipeptidil-Peptidasa IV/uso terapéutico , Femenino , Fluidoterapia/efectos adversos , Humanos , Hipoglucemiantes/efectos adversos , Hipoglucemiantes/uso terapéutico , Unidades de Cuidados Intensivos/organización & administración , Metformina/uso terapéutico , Rabdomiólisis/complicaciones , Vildagliptina/efectos adversos , Vildagliptina/uso terapéutico , Vildagliptina/toxicidadRESUMEN
We report weaning from mechanical ventilation with no coughing in a patient with coronavirus disease 2019 (COVID-19). Substituting the endotracheal tube for a supraglottic airway (SGA), which is less stimulating to the trachea, can reduce coughing with weaning from mechanical ventilation and extubation. Personal protective equipment is in short supply worldwide. Reducing spread of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is beneficial in terms of occupational health of health care workers.
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Extubación Traqueal/métodos , Manejo de la Vía Aérea/instrumentación , Infecciones por Coronavirus/terapia , Transmisión de Enfermedad Infecciosa de Paciente a Profesional/prevención & control , Neumonía Viral/terapia , Desconexión del Ventilador/instrumentación , Anciano , Manejo de la Vía Aérea/métodos , Betacoronavirus , COVID-19 , Infecciones por Coronavirus/prevención & control , Infecciones por Coronavirus/transmisión , Tos , Humanos , Intubación Intratraqueal , Masculino , Pandemias/prevención & control , Neumonía Viral/prevención & control , Neumonía Viral/transmisión , Respiración Artificial , SARS-CoV-2 , Desconexión del Ventilador/métodosRESUMEN
Infective endocarditis (IE) is an uncommon clinical problem with diverse, nonspecific presentations. Therefore, information on the clinical features of IE patients presenting to emergency departments (EDs) is scarce. To descriptively analyze the pertinent data, we performed a retrospective chart review. We reviewed 15 consecutive IE patients admitted directly from ED in a university hospital in Japan between 2013 and 2015. We compared their clinical features with those of 14 IE patients admitted during the same period without ED presentations. Patients admitted directly from ED were older than those without ED presentations (median, 78 vs. 52 years; adjusted p = 0.036) and were more likely to have come without referrals (referral rate, 21% vs. 86%; adjusted p = 0.012). These patients were less likely to have been treated with antibiotics before admission (antibiotic-exposure rate, 7% vs. 64%; adjusted p = 0.013) and had earlier blood-culture positivity (median, 2 vs. 5 days; adjusted p = 0.012), resulting in earlier diagnosis (median duration of symptoms before diagnosis, 5 vs. 30 days; adjusted p = 0.012). Other clinical features, including causative pathogens and IE-related comorbidities, were similar between the groups, consistent with previous a nationwide Japanese study. In conclusion, most IE patients admitted to the hospital from ED were elderly, were antibiotic-naïve, and had presented without a referral. Relatively few patients had classical presentations of IE. Given the limited data, more research is needed to confirm that IE patients presenting to EDs constitute a unique group of elderly patients with specific clinical features.
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Endocarditis/diagnóstico , Adulto , Anciano , Anciano de 80 o más Años , Ecocardiografía , Servicio de Urgencia en Hospital/estadística & datos numéricos , Femenino , Humanos , Masculino , Persona de Mediana Edad , Estudios Retrospectivos , Factores de Riesgo , Adulto JovenRESUMEN
Two plasma kallikrein-kinin system inhibitors in the salivary glands of the kissing bug Triatoma infestans, designated triafestin-1 and triafestin-2, have been identified and characterized. Reconstitution experiments showed that triafestin-1 and triafestin-2 inhibit the activation of the kallikrein-kinin system by inhibiting the reciprocal activation of factor XII and prekallikrein, and subsequent release of bradykinin. Binding analyses showed that triafestin-1 and triafestin-2 specifically interact with factor XII and high molecular weight kininogen in a Zn2+-dependent manner, suggesting that they specifically recognize Zn2+-induced conformational changes in factor XII and high molecular weight kininogen. Triafestin-1 and triafestin-2 also inhibit factor XII and high molecular weight kininogen binding to negatively charged surfaces. Furthermore, they interact with both the N-terminus of factor XII and domain D5 of high molecular weight kininogen, which are the binding domains for biological activating surfaces. These results suggest that triafestin-1 and triafestin-2 inhibit activation of the kallikrein-kinin system by interfering with the association of factor XII and high molecular weight kininogen with biological activating surfaces, resulting in the inhibition of bradykinin release in an animal host during insect blood-feeding.
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Proteínas de Insectos/genética , Sistema Calicreína-Quinina/efectos de los fármacos , Glándulas Salivales/metabolismo , Proteínas y Péptidos Salivales/genética , Triatoma/genética , Secuencia de Aminoácidos , Animales , Coagulación Sanguínea/efectos de los fármacos , Clonación Molecular , ADN Complementario/química , ADN Complementario/genética , Relación Dosis-Respuesta a Droga , Electroforesis en Gel de Poliacrilamida , Factor XII/antagonistas & inhibidores , Factor XII/química , Factor XII/metabolismo , Proteínas de Insectos/metabolismo , Proteínas de Insectos/farmacología , Cinética , Cininas/antagonistas & inhibidores , Cininas/sangre , Datos de Secuencia Molecular , Peso Molecular , Filogenia , Calicreína Plasmática/antagonistas & inhibidores , Precalicreína/antagonistas & inhibidores , Precalicreína/química , Precalicreína/metabolismo , Unión Proteica/efectos de los fármacos , Proteínas Recombinantes/química , Proteínas Recombinantes/farmacología , Proteínas y Péptidos Salivales/metabolismo , Proteínas y Péptidos Salivales/farmacología , Análisis de Secuencia de ADN , Homología de Secuencia de Aminoácido , Triatoma/metabolismo , Tiempo de Coagulación de la Sangre Total , Zinc/farmacologíaRESUMEN
A new kallikrein-kinin system inhibitor, designated anophensin, was identified in the salivary glands of the malaria vector mosquito, Anopheles stephensi. In vitro reconstitution experiments showed that anophensin inhibits activation of the kallikrein-kinin system by inhibiting the reciprocal activation of factor XII (FXII) and prekallikrein (PK), and subsequent release of bradykinin. Additionally, anophensin inhibits activation of the kallikrein-kinin system on cultured human umbilical vein endothelial cells (HUVECs). Direct binding assays show that this inhibitory effect is due to Zn(2+)-dependent specific binding of anophensin to both FXII and high molecular weight kininogen (HK). Furthermore, anophensin interacts with both the N-terminus of FXII and domain D5 of HK, which are the binding domains for biological activating surfaces. These results suggest that anophensin inhibits activation of the kallikrein-kinin system by interfering with the association of FXII and HK with biological activating surfaces, resulting in the inhibition of bradykinin release in a host animal during insect blood-feeding.