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1.
Thromb J ; 21(1): 68, 2023 Jun 22.
Artículo en Inglés | MEDLINE | ID: mdl-37349797

RESUMEN

Right heart thrombus in transit or "free-floating right heart thrombus" is defined as thrombus(i) arising from the deep veins that embolises to the right atrium or right ventricle before reaching the pulmonary vasculature. It is almost always associated with pulmonary thromboembolism and is a medical emergency with reported mortality rates of over 40%. We present two cases of right heart thrombus in transit with pulmonary thromboembolism resulting from venous thrombosis associated with peripherally inserted central catheters that were managed with different approaches. The cases highlight that clinicians should have a low threshold to utilise imaging modalities such as computerised tomography and transthoracic echocardiography when there is an untoward change in physiological parameters among patients with peripherally inserted central catheters, particularly those with risk factors for peripherally inserted central catheter associated venous thrombosis. Furthermore, procedural optimisation surrounding peripherally inserted central catheters, such as insertion technique and choice of lumen size, is underscored.

2.
Postgrad Med J ; 99(1170): 308-312, 2023 May 22.
Artículo en Inglés | MEDLINE | ID: mdl-37227972

RESUMEN

PURPOSE: To evaluate the prevalence and incidence of significant structural heart disease in targeted patients with cardiac symptoms referred by general practitioners (GPs) using open access echocardiography, without prior clinical evaluation by a cardiologist. DESIGN: Data were derived from 488 subjects who underwent transthoracic echocardiography between January and April 2018. Patients were referred directly by GPs in East Berkshire, South England, through an online platform. Echocardiography was performed within 4-6 weeks of referral and all reports were assessed by a consultant cardiologist with expedited follow-up facilitated pro re nata. Results were analysed to determine the frequency of detection of structural abnormalities, particularly of the left ventricle and cardiac valves. RESULTS: Echocardiography was prospectively performed in consecutive subjects (50% male, mean (±SD) age 68.5±22 years; 50% female; mean (±SD) 64.6 (±19.1)). At least one abnormality likely to change management was found in 133 (27.3%) of all open access echocardiograms. Clinical heart failure with left ventricular systolic dysfunction (LVSD) and diastolic dysfunction was confirmed in 46 (9%) and 69 (14%), respectively. Of the 46 patients with LVSD, 33 were new diagnoses. Significant cardiac valve disease was found in 42 (8.6%) patients. 12 of these had known valvular disease or previous valvular surgery, and 30 were new diagnoses. CONCLUSION: Major structural and functional cardiac abnormalities are common in late middle-aged patients who present to GPs with cardiac symptoms and signs. Reported, unrestricted open access echocardiography enables early detection of significant cardiac pathology and timely intervention may improve cardiovascular outcomes.


Asunto(s)
Cardiopatías Congénitas , Insuficiencia Cardíaca , Enfermedades de las Válvulas Cardíacas , Disfunción Ventricular Izquierda , Persona de Mediana Edad , Humanos , Masculino , Femenino , Anciano , Anciano de 80 o más Años , Acceso a la Información , Ecocardiografía/métodos , Insuficiencia Cardíaca/complicaciones , Disfunción Ventricular Izquierda/diagnóstico por imagen , Disfunción Ventricular Izquierda/epidemiología
3.
Postgrad Med J ; 2022 Jan 13.
Artículo en Inglés | MEDLINE | ID: mdl-37076770

RESUMEN

PURPOSE: To evaluate the prevalence and incidence of significant structural heart disease in targeted patients with cardiac symptoms referred by general practitioners (GPs) using open access echocardiography, without prior clinical evaluation by a cardiologist. DESIGN: Data were derived from 488 subjects who underwent transthoracic echocardiography between January and April 2018. Patients were referred directly by GPs in East Berkshire, South England, through an online platform. Echocardiography was performed within 4-6 weeks of referral and all reports were assessed by a consultant cardiologist with expedited follow-up facilitated pro re nata. Results were analysed to determine the frequency of detection of structural abnormalities, particularly of the left ventricle and cardiac valves. RESULTS: Echocardiography was prospectively performed in consecutive subjects (50% male, mean (±SD) age 68.5±22 years; 50% female; mean (±SD) 64.6 (±19.1)). At least one abnormality likely to change management was found in 133 (27.3%) of all open access echocardiograms. Clinical heart failure with left ventricular systolic dysfunction (LVSD) and diastolic dysfunction was confirmed in 46 (9%) and 69 (14%), respectively. Of the 46 patients with LVSD, 33 were new diagnoses. Significant cardiac valve disease was found in 42 (8.6%) patients. 12 of these had known valvular disease or previous valvular surgery, and 30 were new diagnoses. CONCLUSION: Major structural and functional cardiac abnormalities are common in late middle-aged patients who present to GPs with cardiac symptoms and signs. Reported, unrestricted open access echocardiography enables early detection of significant cardiac pathology and timely intervention may improve cardiovascular outcomes.

4.
Nutr Health ; 28(4): 733-739, 2022 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-35360990

RESUMEN

Background: The public are increasingly reliant on the internet and media to access healthcare related information during the Covid-19 pandemic. Vitamin D is essential for musculoskeletal and immune health, with daily supplementation advised by public health bodies. Several studies assessing a possible link between vitamin D and Covid-19 severity have arrived at conflicting results and news articles have been rapidly disseminating such research to the public. There has been little focus on studying the quality of information available. Aim: To identify if online search interest in vitamin D increased with pandemic burden and analyse the accuracy of public health messaging relating to vitamin D in online news articles. Methods: Online search interest data for vitamin D was correlated with pandemic burden, defined as the number of Covid-19 deaths. Online news articles discussing vitamin D and Covid-19 were analysed using qualitative coding. Results: Online search interest for vitamin D increased as pandemic burden increased (p < 0.0001, Spearman's rank). Of the 72 articles identified, most (50%) offered a mixed opinion on the benefit of vitamin D in Covid-19. From articles making a recommendation for vitamin D supplementation, 23% of articles gave mixed messaging or advised against supplementation. 16% of articles recommended a dose which exceeded the safe limit of 4000 IU/day, risking toxicity. Conclusion: A significant number of articles provided mixed messaging or incorrectly advised supratherapeutic doses. This study highlights an opportunity for public health bodies to utilise the increased interest in vitamin D during the pandemic to raise awareness with accurate information.


Asunto(s)
COVID-19 , Humanos , COVID-19/prevención & control , Pandemias/prevención & control , Salud Pública , Vitamina D/uso terapéutico , SARS-CoV-2 , Vitaminas
5.
J Med Virol ; 93(12): 6605-6610, 2021 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-34273116

RESUMEN

AIMS: We have previously demonstrated that vitamin D deficiency might be associated with worse outcomes in hospitalized Covid-19 patients. The aim of our study was to explore this relationship with dexamethasone therapy. METHODS: We prospectively studied two cohorts of hospitalized Covid-19 patients between March and April and between September and December 2020 (n = 192). Patients were tested for serum 25-hydroxyvitamin D (25-OH-D) levels during admission. The first cohort not treated with dexamethasone (n = 107) was divided into vitamin D deficient (25-OH-D ≤ 30 nmol/L) (n = 47) and replete subgroups (25-OH-D > 30 nmol/L) (n = 60). The second cohort treated with dexamethasone (n = 85) was similarly divided into deficient (25-OH-D ≤ 30 nmol/L) (n = 27) and replete subgroups (25-OH-D > 30 nmol/L) (n = 58). Primary outcome was in-hospital mortality and secondary outcomes were elevation in markers of cytokine storm and ventilatory requirement. RESULTS: No mortality difference was identified between cohorts and subgroups. The "no dexamethasone" cohort 25-OH-D deplete subgroup recorded significantly higher peak D-Dimer levels (1874 vs. 1233 µgFEU/L) (p = 0.0309), CRP (177 vs. 107.5) (p = 0.0055), and ventilatory support requirement (25.5% vs. 6.67%) (p = 0.007) compared to the replete subgroup. Among the 25-OH-D deplete subgroup higher peak neutrophil counts, peak CRP, peak LDH, peak ferritin, and lower trough lymphocyte counts were observed, without statistical significance. In the "dexamethasone" cohort, there was no apparent association between 25-OH-D deficiency and markers of cytokine storm or ventilatory requirement. CONCLUSION: Vitamin D deficiency is associated with elevated markers of cytokine storm and higher ventilatory requirements in hospitalized Covid-19 patients. Dexamethasone treatment appears to mitigate adverse effects of vitamin D deficiency.


Asunto(s)
Tratamiento Farmacológico de COVID-19 , Dexametasona/uso terapéutico , Deficiencia de Vitamina D/complicaciones , Anciano , Anciano de 80 o más Años , COVID-19/complicaciones , Síndrome de Liberación de Citoquinas/etiología , Síndrome de Liberación de Citoquinas/prevención & control , Citocinas/sangre , Femenino , Hospitalización , Humanos , Masculino , Estudios Prospectivos , Resultado del Tratamiento , Vitamina D/análogos & derivados , Vitamina D/sangre
6.
Postgrad Med J ; 97(1149): 442-447, 2021 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-32855214

RESUMEN

PURPOSE: Older adults are more likely to be vitamin D deficient. The aim of the study was to determine whether these patients have worse outcomes with COVID-19. METHODS: We conducted a prospective cohort study between 1 March and 30 April 2020 to assess the importance of vitamin D deficiency in older patients with COVID-19. The cohort consisted of patients aged ≥65 years presenting with symptoms consistent with COVID-19 (n=105). All patients were tested for serum 25-hydroxyvitamin D (25(OH)D) levels during acute illness. Diagnosis of COVID-19 was confirmed via viral reverse transcriptase PCR swab or supporting radiological evidence. COVID-19-positive arm (n=70) was sub-divided into vitamin D-deficient (≤30 nmol/L) (n=39) and -replete groups (n=35). Subgroups were assessed for disease severity using biochemical, radiological and clinical markers. Primary outcome was in-hospital mortality. Secondary outcomes were laboratory features of cytokine storm, thoracic imaging changes and requirement of non-invasive ventilation (NIV). RESULTS: COVID-19-positive arm demonstrated lower median serum 25(OH)D level of 27 nmol/L (IQR=20-47 nmol/L) compared with COVID-19-negative arm, with median level of 52 nmol/L (IQR=31.5-71.5 nmol/L) (p value=0.0008). Among patients with vitamin D deficiency, there was higher peak D-dimer level (1914.00 µgFEU/L vs 1268.00 µgFEU/L) (p=0.034) and higher incidence of NIV support and high dependency unit admission (30.77% vs 9.68%) (p=0.042). No increased mortality was observed between groups. CONCLUSION: Older adults with vitamin D deficiency and COVID-19 may demonstrate worse morbidity outcomes. Vitamin D status may be a useful prognosticator.


Asunto(s)
COVID-19 , Neumonía Viral , Deficiencia de Vitamina D , Vitamina D/análogos & derivados , Anciano , Biomarcadores/sangre , COVID-19/sangre , COVID-19/mortalidad , COVID-19/fisiopatología , COVID-19/terapia , Femenino , Productos de Degradación de Fibrina-Fibrinógeno/análisis , Evaluación Geriátrica/métodos , Mortalidad Hospitalaria , Hospitalización/estadística & datos numéricos , Humanos , Masculino , Evaluación de Resultado en la Atención de Salud , Neumonía Viral/diagnóstico por imagen , Neumonía Viral/etiología , Valor Predictivo de las Pruebas , Radiografía Torácica/estadística & datos numéricos , SARS-CoV-2/aislamiento & purificación , Índice de Severidad de la Enfermedad , Reino Unido/epidemiología , Vitamina D/sangre , Deficiencia de Vitamina D/sangre , Deficiencia de Vitamina D/epidemiología , Deficiencia de Vitamina D/terapia
7.
Ann Emerg Med ; 76(2): 191-193, 2020 08.
Artículo en Inglés | MEDLINE | ID: mdl-32241747

RESUMEN

Pseudo-azotemia is the syndrome of hypercreatininemia and hyperkaliemia without a change in glomerular filtration rate or structure of the kidney. A 57-year-old vulnerable woman with learning difficulties experienced an intraperitoneal bladder rupture in the absence of a pelvic fracture after a fall. It is suspected that the blunt force compression of a distended bladder situated above the bony protection of the pelvis resulted in delayed intraperitoneal bladder rupture. Urinary ascites resulted in pseudo-azotemia because of urinary creatinine reabsorption across the peritoneum. This "apparent" renal failure is fully reversible when diagnosis and treatment are prompt, with normalization of abnormal laboratory-investigation results often within 24 hours.


Asunto(s)
Accidentes por Caídas , Lesión Renal Aguda/diagnóstico , Ascitis/diagnóstico , Creatinina/sangre , Diagnóstico Diferencial , Hiperpotasemia/sangre , Absorción Peritoneal , Rotura/diagnóstico , Vejiga Urinaria/lesiones , Traumatismos del Tobillo , Ascitis/etiología , Cistoscopía , Epilepsia , Femenino , Humanos , Hiperpotasemia/etiología , Laparotomía , Discapacidades para el Aprendizaje , Persona de Mediana Edad , Rotura/sangre , Rotura/complicaciones , Rotura/cirugía , Choque/etiología , Traumatismos de los Tejidos Blandos , Tomografía Computarizada por Rayos X , Vejiga Urinaria/cirugía
8.
Cardiovasc Drugs Ther ; 34(6): 755-762, 2020 12.
Artículo en Inglés | MEDLINE | ID: mdl-32648169

RESUMEN

PURPOSE: Sacubitril/valsartan has been demonstrated to improve prognosis and outcomes in heart failure with reduced ejection fraction (HFrEF) patients. We sought to compare the improvement in cardiac function between non-ischaemic and ischaemic cardiomyopathy for patients receiving sacubitril/valsartan. METHODS: We conducted a single centre prospective cohort survey of patients reviewed in the Heart Function Clinic between February 2017 and January 2018. Functional evaluation and measurement of biochemical and echocardiographic parameters occurred before the initiation of sacubitril/valsartan, and after 3 months of treatment. RESULTS: We identified 52 patients (26 non-ischaemic and 26 ischaemic cardiomyopathy) suitable for treatment with sacubitril/valsartan. Treatment was followed by a significant decrease in a New York Heart Association (NYHA) class in both patients with non-ischaemic (2.3 ± 0.6 vs. 1.6 ± 0.7, P < 0.001) and ischaemic cardiomyopathy (2.3 ± 0.5 vs. 1.5 ± 0.6, P < 0.001), along with an increase in ejection fraction in both patients with non-ischaemic (26.2% ± 6.5% vs. 37.2% ± 13.8%, P < 0.001) and ischaemic cardiomyopathy (28.1% ± 5.7% vs. 31.5% ± 8.4%, P = 0.007). The improvement in ejection fraction was significantly greater in the patients with non-ischaemic cardiomyopathy compared to those with ischaemic cardiomyopathy (10.7% ± 13.0% vs. 3.9% ± 6.0%, P = 0.023). CONCLUSION: Our study suggests that treatment with sacubitril/valsartan in patients with non-ischaemic cardiomyopathy is followed by a greater improvement in ejection fraction than in patients with ischaemic cardiomyopathy.


Asunto(s)
Aminobutiratos/uso terapéutico , Bloqueadores del Receptor Tipo 1 de Angiotensina II/uso terapéutico , Compuestos de Bifenilo/uso terapéutico , Cardiomiopatías/tratamiento farmacológico , Insuficiencia Cardíaca/tratamiento farmacológico , Isquemia Miocárdica/complicaciones , Inhibidores de Proteasas/uso terapéutico , Volumen Sistólico/efectos de los fármacos , Valsartán/uso terapéutico , Función Ventricular Izquierda/efectos de los fármacos , Adulto , Anciano , Anciano de 80 o más Años , Cardiomiopatías/diagnóstico , Cardiomiopatías/etiología , Cardiomiopatías/fisiopatología , Combinación de Medicamentos , Femenino , Insuficiencia Cardíaca/diagnóstico , Insuficiencia Cardíaca/etiología , Insuficiencia Cardíaca/fisiopatología , Humanos , Masculino , Persona de Mediana Edad , Neprilisina/antagonistas & inhibidores , Estudios Prospectivos , Recuperación de la Función , Sístole , Factores de Tiempo , Resultado del Tratamiento
9.
Am J Emerg Med ; 38(10): 2142-2146, 2020 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-33046316

RESUMEN

BACKGROUND: The thrombogenic potential of Covid-19 is increasingly recognised. We aim to assess the characteristics of COVID-19 patients diagnosed with pulmonary embolism (PE). METHODS: We conducted a single centre, retrospective observational cohort study of COVID-19 patients admitted between 1st March and 30th April 2020 subsequently diagnosed with PE following computed tomography pulmonary angiogram (CTPA). Patient demographics, comorbidities, presenting complaints and inpatient investigations were recorded. RESULTS: We identified 15 COVID-19 patients diagnosed with PE (median age = 58 years [IQR = 23], 87% male). 2 died (13%), both male patients >70 years. Most common symptoms were dyspnoea (N = 10, 67%) and fever (N = 7, 47%). 12 (80%) reported 7 days or more of non-resolving symptoms prior to admission. 7 (47%) required continuous positive airway pressure (CPAP), 2 (13%) of which were subsequently intubated. All patients had significantly raised D-dimer levels, lactate dehydrogenase (LDH), C-reactive protein (CRP), ferritin and prothrombin times. The distribution of PEs correlated with the pattern of consolidation observed on CTPA in 9 (60%) patients; the majority being peripheral or subsegmental (N = 14, 93%) and only 1 central PE. 10 (67%) had an abnormal resting electrocardiogram (ECG), the commonest finding being sinus tachycardia. 6 (40%) who underwent transthoracic echocardiography (TTE) had structurally and functionally normal right hearts. CONCLUSION: Our study suggests that patients who demonstrate acute deterioration, a protracted course of illness with non-resolving symptoms, worsening dyspnoea, persistent oxygen requirements or significantly raised D-dimer levels should be investigated for PE, particularly in the context of COVID-19 infection. TTE and to a lesser degree the ECG are unreliable predictors of PE within this context.


Asunto(s)
COVID-19/complicaciones , Embolia Pulmonar/etiología , Adulto , Anciano , COVID-19/fisiopatología , Estudios de Cohortes , Angiografía por Tomografía Computarizada , Femenino , Productos de Degradación de Fibrina-Fibrinógeno/metabolismo , Humanos , Masculino , Persona de Mediana Edad , Pandemias , Embolia Pulmonar/diagnóstico por imagen , Estudios Retrospectivos , SARS-CoV-2 , Índice de Severidad de la Enfermedad
10.
Am J Emerg Med ; 38(2): 412.e1-412.e2, 2020 02.
Artículo en Inglés | MEDLINE | ID: mdl-31864870

RESUMEN

Shiitake dermatitis is a rare adverse cutaneous reaction to the ingestion of raw or undercooked shiitake mushrooms (Lentinula edodes). We report the case of a patient who developed a striking linear flagellate dermatitis without urticaria three days after returning from a trip from Tokyo where he had eaten shiitake mushrooms. The rash resolved after two weeks with topical corticosteroids and antihistamines given for symptomatic relief. Shiitake dermatitis is thought to be either a toxic or hypersensitivity reaction to lentinan, a heat-inactivated polysaccharide found in the cell walls of shiitake mushrooms. Although this mushroom is widely consumed in Eastern Asia, with the increasing globalisation of cuisine and travel, cases are likely to become more common in the Western world.


Asunto(s)
Dermatitis/etiología , Hipersensibilidad a los Alimentos/etiología , Lentinano/efectos adversos , Hongos Shiitake/química , Administración Tópica , Corticoesteroides/administración & dosificación , Dermatitis/tratamiento farmacológico , Antagonistas de los Receptores Histamínicos/administración & dosificación , Humanos , Masculino , Persona de Mediana Edad , Piel/patología , Viaje
11.
Postgrad Med J ; 96(1134): 206-211, 2020 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-31732510

RESUMEN

PURPOSE OF THE STUDY: Iron deficiency anaemia (IDA) is associated with increased morbidity and mortality in heart failure patients. The aim of our audit was to evaluate the current practice in diagnosis and assessment of IDA in patients admitted with heart failure. STUDY DESIGN: We conducted a retrospective audit of patients admitted to our hospital between January 2017 and June 2017 with a diagnosis of heart failure, and obtained data regarding each patient's demographics and anaemic status. We also conducted a qualitative survey to assess healthcare professionals' ability to diagnose IDA, and their knowledge of iron replacement in heart failure patients. RESULTS: Our audit identified 218 heart failure patients, nearly two-thirds (n=138, 63.3%) of which were anaemic. Of the 138 anaemic patients, only 40 had a full haematinic screen compared with 98 who had incomplete investigations (29% vs 71%, p=0.007). Iron studies were the most commonly performed haematinic investigation (n=87, 63%), and over half of these patients were iron deficient (n=49, 56.3%). Only 12 (24.5%) iron deficient patients were prescribed oral iron therapy, while 37 (75.5%) were left without iron replacement (X2=12.8, p=0.0003). Our survey demonstrated a lack of awareness among healthcare professionals with only 19.7% of participants being able to correctly define anaemia and 9.1% being aware of guidelines regarding treatment of IDA. CONCLUSION: Many patients admitted to hospital with heart failure also have a concomitant diagnosis of anaemia. The aetiology of the underlying anaemia is often poorly investigated, and where IDA is identified it is poorly treated.


Asunto(s)
Anemia Ferropénica , Insuficiencia Cardíaca , Pruebas Hematológicas , Manejo de Atención al Paciente , Anciano , Anciano de 80 o más Años , Anemia Ferropénica/diagnóstico , Anemia Ferropénica/epidemiología , Anemia Ferropénica/terapia , Auditoría Clínica , Comorbilidad , Femenino , Insuficiencia Cardíaca/sangre , Insuficiencia Cardíaca/epidemiología , Insuficiencia Cardíaca/terapia , Pruebas Hematológicas/métodos , Pruebas Hematológicas/estadística & datos numéricos , Hospitalización/estadística & datos numéricos , Humanos , Masculino , Manejo de Atención al Paciente/métodos , Manejo de Atención al Paciente/estadística & datos numéricos , Prevalencia , Evaluación de Procesos, Atención de Salud , Medición de Riesgo , Reino Unido/epidemiología
13.
Langmuir ; 33(32): 8032-8042, 2017 08 15.
Artículo en Inglés | MEDLINE | ID: mdl-28727441

RESUMEN

In general, proteins in the biological system interact with nanoparticles (NPs) via adsorption on the particle surface. Understanding the adsorption at the molecular level is crucial to explore NP-protein interactions. The increasing concerns about the risk to human health on NP exposure have been explored through the discovery of a handful protein biomarkers and biochemical analysis. However, detailed information on structural perturbation and associated functional changes of proteins on interaction with NPs is limited. Erythrocytes (red blood cells) are devoid of defense mechanism of protecting NP penetration through endocytosis. Therefore, it is important to investigate the interaction of erythrocyte proteins with NPs. Hemoglobin, the most abundant protein of human erythrocyte, is a tetrameric molecule consisting of α- and ß-globin chains in duplicate. In the present study, we have used hemoglobin as a model system to investigate NP-protein interaction with ferric pyrophosphate NPs [NP-Fe4(P2O7)3]. We report the formation of a bioconjugate of hemoglobin upon adsorption to NP-Fe4(P2O7)3 surface. Analysis of the bioconjugate indicated that Fe3+ ion of NP-Fe4(P2O7)3 contributed in the bioconjugate formation. Using hydrogen/deuterium exchange based mass spectrometry, it was observed that the amino termini of α- and ß-globin chains of hemoglobin were involved in the adsorption on NP surface whereas the carboxy termini of both chains became more flexible in its conformation compared to the respective regions of the normal hemoglobin. Circular dichroism spectra of desorbed hemoglobin indicated an adsorption induced localized structural change in the protein molecule. The formation of bioconjugate led to functional alteration of hemoglobin, as probed by oxygen binding assay. Thus, we hypothesize that the large amount of energy released upon adsorption of hemoglobin to NP surface might be the fundamental cause of structural perturbation of human hemoglobin and subsequent formation of the bioconjugate with an altered function.


Asunto(s)
Nanopartículas del Metal , Adsorción , Difosfatos , Hemoglobinas , Humanos , Hierro , Isótopos , Espectrometría de Masas
14.
Hemoglobin ; 41(4-6): 300-305, 2017.
Artículo en Inglés | MEDLINE | ID: mdl-29210301

RESUMEN

In general, the reactivity of cysteine residues of proteins is measured by 5,5'-dithiobis(2-nitrobenzoic acid) (DTNB) kinetics using spectrophotometry. Proteins with several cysteine residues may exhibit varying DTNB kinetics but residue level information can only be obtained with the prior knowledge of their three-dimensional structure. However, this method is limited in its application to the proteins containing chromophores having overlapping absorption profile with 2-nitro-5-thiobenzoic acid, such as hemoglobin (Hb). Additionally, this method is incapable of assigning cysteine reactivity at the residue levels of proteins with unknown crystal structures. However, a mass spectrometry (MS)-based platform might provide a solution to these problems. In the present study, alkylation kinetics of cysteine residues of adult human Hb (Hb A; α2ß2) and sickle cell Hb (Hb S; HBB: c.20A>T) were investigated using matrix-assisted laser desorption/ionization (MALDI) MS. Differential site-specific reactivities of cysteine residues of Hb were investigated using alkylation kinetics with iodoacetamide (IAM). The observed reactivities corroborated well with the differential surface accessibilities of cysteine residues in the crystal structures of human Hb. The proposed method might be used to investigate cysteine reactivities of all the genetic and post-translational variants of Hb discovered to date. In addition, this method can be extended to explore cysteine reactivities of proteins, irrespective of the presence of chromophores and availability of crystal structures.


Asunto(s)
Cisteína/química , Dinitrobencenos/química , Hemoglobinas/química , Espectrometría de Masas/métodos , Humanos
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