Causa inusual de cianosis en el recién nacido: hemoglobina M / Unusual cause of cyanosis in the newborn: hemoglobin M

Resumen La hemoglobina M es un desorden hereditario infrecuente, causante de metahemoglobinemia y, por ende, cianosis. Las manifestaciones clínicas de esta enfermedad son amplias y variadas, por lo que se debe considerar como diagnóstico diferencial en un recién nacido con cianosis sin otra causa aparente. A continuación, se presenta el caso de un recién nacido de 5 horas de vida con cianosis generalizada desde el nacimiento y con saturaciones de oxígeno de entre 60-70%, en el que se descartaron patologías como hipoxia perinatal, patología pulmonar o cardíaca y sepsis y se documentó un nivel de metahemoglobina elevado, reportado en 21,6%, con lo cual se estableció el diagnóstico de metahemoglobinemia. El tratamiento administrado fueron dos dosis de azul de metileno, pero no hubo respuesta clínica. Por este motivo, se realizó electroforesis de hemoglobina, la cual fue compatible con hemoglobina M (Iwate o Kankakee), lo que se confirma su causa congénita de metahemoglobinemia.

Abstract Hemoglobin M is a rare hereditary disorder that causes ethemoglobinemia and therefore cyanosis. The clinical manifestations of this condition differs considerably, so it should be considered as a differential diagnosis in a newborn with cyanosis, with no other apparent cause. The case of a 5 hours old newborn is presented below, with generalized cyanosis from birth with oxygen saturations between 60-70%, in whom, upon ruling out pathologies such as perinatal hypoxia, pulmonary disease, heart disease and sepsis, a high level of methemoglobin is documented, reported in 21,6%; the diagnosis of methemoglobinemia was established. The treatment administered was two doses of methylene blue with no response. For this reason, hemoglobin electrophoresis was performed, which was compatible with Hemoglobin M (Iwate or Kankakee), confirming its congenital cause.

Acidosis metabólica neonatal por síndrome de enterocolitis inducido por proteína de alimentos: reporte de caso / Neonatal metabolic acidosis caused by food proteininduced enterocolitis syndrome: a case report

El síndrome de enterocolitis inducido por proteínas de los alimentos (FPIES, por su sigla en inglés) es una reacción alérgica no mediada por inmunoglobulina E (IgE) con síntomas gastrointestinales, como vómitos y diarrea. El diagnóstico se basa en criterios clínicos y en una prueba de provocación para confirmarlo. Es una enfermedad desconocida en las unidades neonatales, debido a la inespecificidad de los síntomas en los recién nacidos. La cifra de metahemoglobina elevada es una opción sencilla de aproximación diagnóstica. Se describe el caso clínico de un recién nacido que ingresa al servicio de urgencias por deshidratación, letargia, vómitos, diarrea y acidosis metabólica grave con elevación de metahemoglobina, con mejora clínica y recuperación total tras el inicio del aporte de fórmula elemental. La sospecha diagnóstica se confirmó tras la prueba de provocación positiva.

Food protein-induced enterocolitis syndrome (FPIES) is a non-IgE mediated allergic reaction with gastrointestinal symptoms, such as vomiting and diarrhea. FPIES diagnosis is based on clinical criteria and on a food challenge test. It is an unknown disease in neonatal units due to its nonspecific symptoms in newborn infants. An elevated methemoglobin level is a simple way to approach diagnosis. Here we describe a clinical case of a newborn admitted to the emergency department because of dehydration, lethargy, vomiting, diarrhea, severe metabolic acidosis, and a high methemoglobin level. Clinical improvement and complete recovery was achieved after initiation of elemental formula. The diagnostic suspicion was confirmed after a positive challenge test.

Sulfohemoglobinemia secundaria a zopiclona. Casos clínicos / Sulfhemoglobinemia secondary to the use of zopiclone. Report of two cases

Sulfhemoglobin (SulfHb) is formed by hemoglobin (Hb) oxidation by sulfur compounds. Sulfhemoglobinemia is mainly associated with drugs or intestinal bacterial overgrowth. Patients present with central cyanosis, an abnormal pulse oximetry and normal arterial oxygen partial pressure. These features are shared with methemoglobinemia (MetHb) whose diagnosis requires an arterial co-oximetry. Depending on the device used, SulfHb may produce interference with this technique. We report two females aged 31 and 43 years, consulting at the emergency room with cyanosis. Both had a history of acute and chronic, high dose zopiclone ingestion. Pulse oximetry showed desaturation but with normal arterial oxygen partial pressure. Cardiac and pulmonary diseases were ruled out. Co-oximetry in two different analyzers showed interference or normal MetHb percentages. No other complications ensued, and cyanosis decreased over days. Since MetHb was discarded among other causes of cyanosis in a compatible clinical context, the diagnosis of sulfhemoglobinemia was made. The confirmatory method is not available in Chile. The presence of SulfHb is difficult to diagnose, confirmatory tests are not readily available, and it frequently interferes with arterial co-oximetry. This is attributed to a similar absorbance peak of both pigments in arterial blood. Venous co-oximetry can be useful in this context. SulfHb is a self-limited condition in most cases, however it must be differentiated from methemoglobinemia to avoid inappropriate treatments like methylene blue.

Actividad de enzimas antioxidantes eritrocitarias en una muestra de adultos jóvenes y mayores del Valle Central, Costa Rica / Erythrocyte antioxidant enzymes in Costa Rica

Resumen Introducción El daño oxidativo provocado por los radicales libres de oxígeno, está relacionado con el proceso de envejecimiento, con diversas patologías y con el estilo de vida de las personas pero, en el organismo, existen defensas enzimáticas antioxidantes que confieren una debida protección. Objetivo Determinar la actividad enzimática de la glucosa-6-fosfato deshidrogenasa (G6PD), la catalasa (CAT) y la NADH metahemoglobina reductasa (NADH-MR) en una población costarricense de adultos jóvenes y mayores, para establecer el intervalo de referencia y evaluar el efecto de algunas condiciones donde se presenta daño oxidativo. Materiales y métodos Se determinó la actividad enzimática en una población de 110 individuos de entre 19 y 95 años de edad, utilizando el método propuesto por Ernest Beutler. Se estableció el intervalo de referencia de la población y se evaluó el efecto de la edad, patologías de fondo y el fumado, mediante estadística descriptiva. Resultados Conforme avanza la edad, las enzimas NADH-MR y la CAT disminuyeron su actividad eritrocitaria y la G6PD no presentó cambios significativos. No se encontró evidencia de cambio significativo en la actividad enzimática con respecto al hábito de fumado y las condiciones patológicas estudiadas. Conclusiones Es necesario realizar más investigación en factores ambientales y estilo de vida que influyen en la actividad enzimática antioxidante. El tamaño de las poblaciones, la ausencia de métodos estandarizados y las condiciones del ensayo pueden afectar los resultados y su grado de significancia. Por lo tanto, deben estandarizarse las metodologías, de manera que en futuros proyectos se evalúen los resultados de acuerdo con estas condiciones.

Abstract Introduction The oxidative damage caused by free oxygen radicals is related to the aging process, some pathologies and people's lifestyle. However, in the human body there are antioxidant enzymatic defenses that give us an adequate protection. Objective To determine the enzyme activity of glucose-6-phosphate dehydrogenase (G6PD), catalase (CAT) and NADH methemoglobin reductase (NADH-MR), in a Costa Rican population of younger and older adults, in order to establish the reference range and to evaluate the effect of some conditions where oxidative damage occurs. Materials and methods The enzyme activity in a population of 110 individuals aged 19-95 years old was determined using the method proposed by Ernest Beutler. The population reference range was established and the effect of age, background pathologies and smoking were evaluated, using descriptive statistics. Results As age advances the enzyme NADH-MR and CAT decreased erythrocyte activity and G6PD presented no significant changes. Evidence of a significant change in the enzyme activity, with respect to the smoking habit and the pathological conditions, was not found. Conclusions It is necessary to carry out more research in terms of lifestyle and environmental factors, that influence the antioxidant enzyme activity. The size of populations, the absence of standardized methods and the conditions of the test can affect results and their degree of significance. For which methodologies should be standardized, so that in future projects the results can be evaluated according to these conditions.

Therapeutic effect of ascorbic acid on dapsone-induced methemoglobinemia in rats

OBJECTIVE: Dapsone (diaminodiphenyl sulfone, DDS) is currently used to treat leprosy, malaria, dermatitis herpetiformis, and other diseases. It is also used to treat pneumocystis pneumonia and Toxoplasma gondii infection in HIV-positive patients. The most common adverse effect of DDS is methemoglobinemia from oxidative stress. Ascorbic acid is an antioxidant and reducing agent that scavenges the free radicals produced by oxidative stress. The present study aimed to investigate the effect of ascorbic acid in the treatment of DDS induced methemoglobinemia. METHODS: Male Sprague-Dawley rats were divided into three groups: an ascorbic acid group, a methylene blue (MB) group, and a control group. After DDS (40 mg/kg) treatment via oral gavage, ascorbic acid (15 mg/kg), MB (1 mg/kg), or normal saline were administered via tail vein injection. Depending on the duration of the DDS treatment, blood methemoglobin levels, as well as the nitric oxide levels and catalase activity, were measured at 60, 120, or 180 minutes after DDS administration. RESULTS: Methemoglobin concentrations in the ascorbic acid and MB groups were significantly lower compared to those in the control group across multiple time points. The plasma nitric oxide levels and catalase activity were not different among the groups or time points. CONCLUSION: Intravenous ascorbic acid administration is effective in treating DDS-induced methemoglobinemia in a murine model.

Metahemoglobinemia severa secundaria a sobredosis de dapsona, reporte de caso / Severe metahemoglobinemia associated with dapsone overdosis. Case report / Metemoglobinemia severa secundária à sobredosagem de Dapsona, relato de um caso

Resumen: La metahemoglobinemia es una entidad clínica causada por la oxidación de la hemoglobina (Hb), específicamente del grupo hemo, transforma el hierro de un estado ferroso (Fe2+) a férrico (Fe3+++), dando como resultado la metahemoglobina (MetHb), la cual no es capaz de realizar enlaces con el oxígeno (O2) y por lo tanto no puede trasportarlo, condicionando una disminución en la oxigenación tisular. La Hb puede oxidarse debido a alteraciones genéticas de expresión variable o más frecuentemente por efecto adverso de sustancias exógenas, destacando fármacos como la dapsona. Se describe el cuadro clínico, diagnóstico y tratamiento de una paciente con metahemoglobinemia adquirida por sobredosis de dapsona.

Abstract: Methemoglobinemia is a clinical entity caused by oxidation of hemoglobin (Hb) specifically heme, transforming iron from a ferrous state (Fe2+) to a ferric state (Fe3+++), resulting in methemoglobin (MetHb), which is not capable of bonding with oxygen (O2), and therefore cannot transport it, conditioning tissue irrigation. Hb may oxidize due to variable expression genetic abnormalities expression, or more frequently, as an adverse effect related to exogenous substances, such as dapsone. This work describes the clinical picture, diagnosis and treatment of a patient with metahemoglobinemia-acquired secondary to dapsone overdose.

Resumo: A metemoglobinemia é uma entidade clínica causada pela oxidação da hemoglobina (Hb), especificamente do grupo heme, transformando o ferro de um estado ferroso (Fe2+) para um estado férrico (Fe3+++), dando como resultado a Meta-hemoglobina (MetHb), que não é capaz de fazer ligações com o oxigênio (O2) e, portanto, não pode transportá-lo, condicionando a diminuição na oxigenação tissular. A Hb pode oxidar-se devido a alterações genéticas de expressão variável, ou mais freqüentemente devido ao efeito adverso de substâncias exógenas, destacando drogas como a Dapsona. Descrevemos o quadro clínico, diagnóstico e tratamento de um paciente com metemoglobinemia adquirida por sobredosagem de dapsona.

Rattlesnake Crotalus molossus nigrescens venom induces oxidative stress on human erythrocytes

Abstract Background Globally, snake envenomation is a well-known cause of death and morbidity. In many cases of snakebite, myonecrosis, dermonecrosis, hemorrhage and neurotoxicity are present. Some of these symptoms may be provoked by the envenomation itself, but others are secondary effects of the produced oxidative stress that enhances the damage produced by the venom toxins. The only oxidative stress effect known in blood is the change in oxidation number of Fe (from ferrous to ferric) in hemoglobin, generating methemoglobin but not in other macromolecules. Currently, the effects of the overproduction of methemoglobin derived from snake venom are not extensively recorded. Therefore, the present study aims to describe the oxidative stress induced by Crotalus molossus nigrescens venom using erythrocytes. Methods Human erythrocytes were washed and incubated with different Crotalus molossus nigrescens venom concentrations (0640 g/mL). After 24 h, the hemolytic activity was measured followed by attenuated total reflectance-Fourier transform infrared spectroscopy, non-denaturing PAGE, conjugated diene and thiobarbituric acid reactive substances determination. Results Low concentrations of venom ( 10 g/mL) generates oxyhemoglobin release by hemolysis, whereas higher concentrations produced a hemoglobin shift of valence, producing methemoglobin (>40 g/mL). This substance is not degraded by proteases present in the venom. By infrared spectroscopy, starting in 80 g/mL, we observed changes in bands that are associated with protein damage (1660 and 1540 cm1) and lipid peroxidation (2960, 2920 and 1740 cm1). Lipid peroxidation was confirmed by conjugated diene and thiobarbituric acid reactive substance determination, in which differences were observed between the control and erythrocytes treated with venom. Conclusions Crotalus molossus nigrescens venom provokes hemolysis and oxidative stress, which induces methemoglobin formation, loss of protein structure and lipid peroxidation.

Rattlesnake Crotalus molossus nigrescens venom induces oxidative stress on human erythrocytes

Background Globally, snake envenomation is a well-known cause of death and morbidity. In many cases of snakebite, myonecrosis, dermonecrosis, hemorrhage and neurotoxicity are present. Some of these symptoms may be provoked by the envenomation itself, but others are secondary effects of the produced oxidative stress that enhances the damage produced by the venom toxins. The only oxidative stress effect known in blood is the change in oxidation number of Fe (from ferrous to ferric) in hemoglobin, generating methemoglobin but not in other macromolecules. Currently, the effects of the overproduction of methemoglobin derived from snake venom are not extensively recorded. Therefore, the present study aims to describe the oxidative stress induced by Crotalus molossus nigrescens venom using erythrocytes. Methods Human erythrocytes were washed and incubated with different Crotalus molossus nigrescens venom concentrations (0-640 μg/mL). After 24 h, the hemolytic activity was measured followed by attenuated total reflectance-Fourier transform infrared spectroscopy, non-denaturing PAGE, conjugated diene and thiobarbituric acid reactive substances determination. Results Low concentrations of venom (<10 μg/mL) generates oxyhemoglobin release by hemolysis, whereas higher concentrations produced a hemoglobin shift of valence, producing methemoglobin (>40 μg/mL). This substance is not degraded by proteases present in the venom. By infrared spectroscopy, starting in 80 μg/mL, we observed changes in bands that are associated with protein damage (1660 and 1540 cm−1) and lipid peroxidation (2960, 2920 and 1740 cm−1). Lipid peroxidation was confirmed by conjugated diene and thiobarbituric acid reactive substance determination, in which differences were observed between the control and erythrocytes treated with venom. Conclusions Crotalus molossus nigrescens venom provokes hemolysis and oxidative stress, which induces methemoglobin formation, loss of protein structure and lipid peroxidation.(AU)

A Case of Methemoglobinemia Caused by Primaquine / 대한내과학회지

Primaquine is often administered for the hypnozoite stage of Plasmodium vivax and Plasmodium ovale. Primaquine (with clindamycin) is also an alternative drug for treatment of pneumocystis pneumonia when trimethoprim/sulfamethoxazole cannot be used. Primaquine may cause methemoglobinemia, an altered state of hemoglobin in which the ferrous state of heme is oxidized to the ferric state. We report a case of methemoglobinemia caused by a standard dose of primaquine plus clindamycin in a 27-year-old female recipient of a kidney transplant who was diagnosed with pneumocystis pneumonia.

Determinação da metemoglobina em voluntários fumantes e não fumantes / Determination of methemoglobin in smokers and non smokers volunteers

Objetivo ­ Determinar a concentração de metemoglobina (MetHb) em voluntários fumantes e não fumantes, e comparar com as possíveis alterações bioquímicas. Métodos ­ Os sujeitos do estudo foram voluntários do município de Sorocaba/SP (n=30), sendo metade para o grupo de fumantes (n=15) e outra metade para o grupo de não fumantes (n=15). Foi realizada a extração de saponina utilizando a droga vegetal Quilaia sp., para a realização de hemólise nas amostras de sangue e, então, dosar a metemoglobina dos voluntários. Amostras de sangue foram coletadas diretamente em tubos comerciais à vácuo e a metemoglobina foi determinada através da técnica que dispensa o uso do cianeto, evitando risco tóxico. Resultados ­ Os resultados estão apresentados em Média ± Desvio Padrão da porcentagem de MetHb: Grupo Fumantes foi de 3,4 ± 0,82% e o Grupo Não Fumantes foi de 8,3 ± 4,9% (valor normal: 1,9 a 3,8%), sendo diferentes significativamente. Os valores para a dosagem de glicemia e colesterol total não apresentaram diferença significativa, quando comparado o grupo de Fumantes com o Não Fumantes. Conclusões ­ Conclui-se que os valores de MetHb se apresentaram alterados em indivíduos fumantes, porém serão necessários maiores estudos acerca da comparação da alteração de MetHb com glicemia e/ou colesterol total.

Objective ­ To determine the concentration of methemoglobin (MetHb) in smoker and non-smoker volunteers comparing with possible biochemical alteration. Methods ­ The study were performed with volunteers of city Sorocaba/SP (n=30), separated in two groups: smokers group (n=15) and non-smokers group (n=15). The extraction of saponin was performed using the plant Quilaia sp., for hemolysis in the blood samples and, so, measure mehtemoglobin levels in the volunteers. Blood samples were collected directly in commercial tubes of vacuum and the methemoglobin was determined through of method described that dispenses the use of cyanide, avoiding the toxic risk. Results ­ The results are express in mean ± standard deviation of percentage MetHb: Non-smokers Group 3.4 ± 0.82%; Smokers Group 8.3 ± 4.9% (normal values 1.9%-3.8%), being different significantly. The glycemic and total cholesterol results, do not present significant difference when compared the smokers group with non-smokers group. Conclusions ­ The MetHb results presented are altered in smoker volunteers, however larger studies are needed on the comparison of the change of MetHb with glycaemia and/or total cholesterol.

De novo alpha 2 hemoglobin gene (HBA2) mutation in a child with hemoglobin M Iwate and symptomatic methemoglobinemia since birth

Cyanosis in an apparently healthy newborn baby may be caused by hemoglobin variants associated with the formation of methemoglobin, collectively known as M hemoglobins. They should not be confused with genetic alterations in methemoglobin reductase enzyme systems of red cells since treatment and prognosis are completely different. A newborn male child was noted to be significantly cyanotic at birth and is the basis for this report. Hemoglobin isoelectric focusing, acid and alkaline gel electrophoresis, and HBA/HBB gene sequencing were performed for the child, both parents and a sister. The newborn child was treated with methylene blue in an intensive care unit fearing that he had a defective reductase system and exposure to oxidant drugs or toxins. Newborn hemoglobin screening with high performance liquid chromatography was abnormal on the 10th and 45th days but no conclusive diagnosis was reached. Cyanosis persisted up to four years of age with no other symptoms. Hemoglobin M Iwate [alpha2 87(F8) His>Tyr, HBA2:c.262C>T] was detected. It was not present in the child's presumed mother, father, sister, and brother. The analysis of 15 short tandem repeats in the trio demonstrated a de novo mutation occurrence (p-value < 1 × 10 -8). The family was reassured that no further action was necessary and genetic counseling was provided. Methemoglobins should be considered for differential diagnosis of cyanosis in newborns even if no familial cases are detected. Except for cosmetic consequences, the clinical course of patients with hemoglobin M Iwate is unremarkable.

Dosagem de metemoglobina em pacientes adultos com anemia falciforme: influência do tratamento com hidroxiureia / Methemoglobin measure in adult patients with sickle-cell anemia: influence of hydroxyurea therapy

Introduction: Hemoglobin S (HbS) is unstable hemoglobin that easily oxidizes, causing methemoglobin (MetHb) increased production in patients with sickle-cell anemia (SCA). Objectives: To determine MetHb levels and the influence of hydroxyurea (HU) therapy on this marker in patients with SCA. Materials and methods: Blood samples from 53 patients with SCA at the steady-state, with and without HU therapy, and 30 healthy individuals were collected to evaluate MetHb levels. The MetHb measurement was performed by spectrophotometry. Complete blood count, HU measurements, and fetal hemoglobin (HbF) and HbS concentrations were taken from medical records. Results: MetHb levels were statically higher in patients with SCA when compared to control group (p < 0.001). There was no statistical difference in MetHb level between SCA patients, either using or not HU. We obtained a positive correlation between MetHb measurements and HbS concentration (r = 0.2557; p = 0.0323). Conclusion: HbS presence favored hemoglobin breaking down, and consequently increased MetHb production. Treatment with HU, however, did not influence the levels of this marker...

Introdução: A hemoglobina S (HbS) é uma hemoglobina instável que facilmente se oxida, causando aumento da produção de metemoglobina (MetHb) em pacientes com anemia falciforme (AF). Objetivos: Determinar os níveis de MetHb e verificar a influência do tratamento com a hidroxiureia (HU) sobre as dosagens desse marcador em pacientes com AF. Materiais e métodos: Amostras de sangue de 53 pacientes adultos com AF em estado basal, em uso ou não de HU, e 30 indivíduos saudáveis foram coletadas para avaliar os níveis de MetHb. A dosagem de MetHb foi realizada pelo método espectrofotométrico. Os parâmetros hematológicos, a dosagem de HU e a concentração de hemoglobina F (HbF) e HbS foram retirados dos prontuários médicos. Resultados: Níveis de MetHb apresentaram-se mais elevados estatisticamente em pacientes com AF em relação ao grupo-controle (p < 0,0001). Não foi verificada diferença estatística nos níveis de MetHb entre pacientes em uso ou não de HU. Observou-se correlação positiva entre as dosagens de MetHb e a concentração de HbS (r = 0,2557; p = 0,0323). Conclusão: A presença da HbS favoreceu a degradação da hemoglobina, causando elevação da produção de MetHb. Tratamento com HU, entretanto, não influenciou nos níveis desse marcador...

Histopathological Changes In Kidneys Of Rabbit Exposed To High Nitrate In Drinking Water.

Background: In India, especially in Rajasthan people drink water containing high level of nitrates and concentration up to 500 mg of nitrate ion per liter is not unusual. The ingested nitrate is converted to nitrite in the digestive system and absorb in blood causing methemoglobinemia. The peak of methaemoglobin is observed at 45-95 mg/liter of nitrate concentration in water.. Aims and Objects: To find out the correlation between drinking water nitrate concentration and histopathological changes in kidneys of rabbits of different groups. Materials and Methods: An experimental study was conducted in 10 rabbits between three and half month to four month of age having weight ranging 1.310 kg to 10720 kg. Five groups A, B, C, D and E were formed having two rabbits in each group. The control group A was administered water orally having 06 mg/liter. Group B to E (experimental groups) were administered water orally having concentration of 100mg/liter, 200mg/liter, 400mg/ liter & 500mg/liter of nitrate respectively for 120 days. Then all rabbits were anaesthetized & sacrificed according to guidelines of ICMR and kidneys were removed & processed for paraffin sections. Hemotoxyllin and eosin staining was done for microscopic observations. Results: During experiment, animals were lethargic on 75th day .Intake in quantity of food and water was not altered in the rabbits. Rabbits of all group i.e. A to E showed continuous increase in heart rate (up to 218/ minute in group E) and respiration rate (up to 84/minute in group E) respectively. The microscopic study of kidney showed focal collection of lymphocytes in interstitial tissue, particularly in pericapsular area of kidney which appeared in rabbits of group B. The changes were more pronounced in group C &D in the form of focal collection of plasma cells. The hyaline and cellular casts were observed in proximal & distal tubules which started appearing in animals of group C. The congestion of blood vessels and damaged tubular epithelium were observed in tubules of group E rabbits. Discussion and Conclusion: The Results occurred possibly due to cytochrome b5 reductase activity and its adaptation with increasing water nitrate concentration to compensate methaemoglobinemia.

Exposição ocupacional ao difluobenzuron: avaliação de metemoglobina após a jornada de trabalho dos guardas de endemias atuantes na região do grande Rio de Janeiro / Exposure to difluobenzuron: methemoglobin assessment after work shift of guards endemics operating in the region Rio de Janeiro

Atualmente, a substância utilizada para o combate do vetor da dengue é o diflubenzuron, um larvicida que possui como principal efeito no ser humano a formação demetemoglobina. A determinação do percentual de metemoglobina (MHb) no sangue permite estabelecer a relação com a exposição ao diflubenzuron, sendo utilizada como indicador de efeito. O objetivo do presente trabalho foi avaliar a efetividade do uso da MHb como indicador da exposição ao diflubenzuron por meio da determinação de sua concentração no sangue de guardas de endemias atuantes em dois municípios do Estado do Rio de Janeiro. Para a avaliação da MHb, foi utilizado o método de análise preconizado por Evelyn-Malloy, a espectrofotometria no visível λmáx=630 nm, e as informações complementares foram obtidas por intermédio da aplicação de questionários semiestruturados. Foi observado que a maioria dos trabalhadores não fazia uso de Equipamento de Proteção Individual (EPI) e atuava em condições de trabalho insalubres e sem treinamento adequado. Houve redução de cerca de 0,05% da concentração da MHb após a exposição ao diflubenzuron, com correlação inversa deste indicador de efeito com a variável fumo (R= -0,742; p=0,035). Dado que a MHb pode ser formada após exposição a diversas substâncias químicas e considerando as dificuldades na logística de execução desta análise, estudos sobre novos biomarcadores mais sensíveis e seletivos são necessários.

Currently, the substance used to combat the dengue vector is diflubenzuron, a larvicide which produces methemoglobin (MHb) in humans. During his working process, applicators may be exposed to this substance at different levels, which depend on the care they adopt in handling and application. Knowing the profile of workers is important to characterize the population and assess the risks they face. The determination of the percentage of MHb in the blood allows to establish a relationship with exposure to diflubenzuron, being used as an indicator of effect. The objective of this study was to evaluate the extent to which these factors can affect the exposure of active endemic guards in two municipalities of the State of Rio de Janeiro contributed to a better understanding of the issues arising from this work process. It was observed that most workers did not use Personal Protective Equipment (PPE) and worked in unsafe working conditions and without proper training. Was observed a large difference in knowledge of the risks arising from the work they perform in the two counties, showing weaknesses in the basic training of these professionals. There was a reduction of about 0.05% of the MHb concentration after exposure to diflubenzuron, with an inverse correlation between this indicator variable effect with smoking (R= -0.742; p=0.035). Since MHb can be formed after exposure to various chemicals and considering the logistical difficulties in implementing this analysis, studies on new more sensitive and selective biomarkers are needed. .

Pasteurization affects the physicochemical properties and biological function of hemoglobin? / 中国组织工程研究

BACKGROUND:Pasteurization is a perfect method for albumin virus inactivation, which may not be required for virus inactivation validation. However, there are no systematical reports concerning virus inactivation of hemoglobin blood substitutes. OBJECTIVE:To explore the effects of pasteurization on the physicochemical properties and biological function of hemoglobin blood substitutes. METHODS:Appropriate cord blood samples were taken fol owed by centrifugation, washing blood, rupture of membranes, stabilizer treatment. In the control group, the samples were placed in 55℃water bath, and when the temperature of hemoglobin solution reached (55±1)℃, a heat treatment began and lasted for 2 hours. In the pasteurization group, the samples were placed in 60℃water bath, and when the temperature of hemoglobin solution reached (60±1)℃, a heat treatment began and lasted for 10 hours. The heating process was under continues nitrogen protection. Then, the hemoglobin solution was placed in ice bath and cooled to below 4℃fol owed by low-speed centrifugation and filtration via microporous membrane, purification and viral inactivation thereby to obtain cord blood hemoglobin. RESULTS AND CONCLUSION:The products in the pasteurization group were al red clear liquid. There was no significant difference between the two groups in the yield, methemoglobin concentration, and oxygen-carrying capacity. The purification of the two groups was more than 98%. Two kinds of purification methods had no effects on the oxygen-carrying capacity of hemoglobin. Therefore, pasteurization method can replace thermosensitive purification method of 55℃, 2 hours. The pasteurization method wil not only ensure the physicochemical and biological properties of hemoglobin, but also achieve the purpose of virus inactivation.

Effects of sodium dodecyl sulphate on enhancement of lipoxygenase activity of hemoglobin.

Title: Effects of sodium dodecyl sulphate on enhancement of lipoxygenase activity of hemoglobin Authors: Ezebuo, F C Eze, S O O Chilaka, F C Keywords: Hemoglobin Linoleic acid Lipoxygenase Met-hemoglobin Oxodienes Sodium dodecyl sulphate Issue Date: Dec-2012 Publisher: NISCAIR-CSIR, India Abstract: Lipoxygenases comprise a family of non-heme iron-containing enzymes that catalyze the stereospecific dioxygenation of polyunsaturated fatty acids with 1, 4-cis-cis-pentadiene structure. Hemoglobin, a heme iron-containing protein has been reported to have lipoxygenase activity but the assay conditions that could enhance the activity remain obscure. Therefore, establishment of optimum assay conditions for lipoxygenase activity of hemoglobin could allow modeling of hemoglobin as lipoxygenase. Hemoglobin was extracted from blood of an identified individual of genotype AA. The hemoglobin was dialyzed at 4 oC for 24 h against 50 mM Tris-HCl buffers (pH 8.5 and 7.2) and effects of sodium dodecyl sulphate (SDS) and linoleic studied at pH 5.0 and 7.2 with UV–VIS Titration Spectrophotometry. The results show that 3.3, 8.6 and 88.1% concentrations of met-hemoglobin were found in presence of 0.0 mM SDS at pH 5.0 and 7.2, 1.043 mM SDS at pH 7.2 and 0.404 mM SDS at pH 5.0 respectively. Also, the difference spectra of hemoglobin in presence of linoleic acid showed positive peak at 285 nm which suggest the presence of oxodienes–a reaction product of hydroperoxidase activity of lipoxygenase. Formation of met-hemoglobin/met-myoglobin is highly correlated with lipid oxidation. Since highest concentration of met-hemoglobin (88.1%) was observed in presence of 0.404 mM SDS at pH 5.0, lipoxygenase activity of hemoglobin was enhanced in presence of SDS under these conditions.

Reference values for methemoglobin concentrations in children

OBJECTIVE: The aim of this work was to establish reference values for methemoglobin levels in 6 to 10-year-old children. METHODS: Methemoglobin concentrations were studied in clinically healthy children. The method for methemoglobin measurement used, neither uses highly toxic chemical compounds nor expensive enzymatic methods, thus it is feasible in the laboratory routine. RESULTS: The results showed higher reference values for clinically healthy children (from 3.61 to 6.44 percent) than for adults (from 1.9 to 3.8 percent). CONCLUSIONS: The higher concentrations of methemoglobin in children may be explained by smaller amounts of soluble cofactor cytochrome b5 and reduced activity of the cytochrome b5 reductase enzyme in red blood cells which make children particularly susceptible to the development of methemoglobinemia. Methemoglobin concentrations in children are higher than in normal adult subjects thus, adult reference values cannot be used to interpret infant methemoglobinemia.

Assessment of severity of methaemoglobinemia following fibreoptic bronchoscopy with lidocaine.

Background. Lidocaine is commonly used for topical anaesthesia during fibreoptic bronchoscopy (FOB) and it can cause methaemoglobinemia. The present study was undertaken to evaluate the severity of post-bronchoscopy methaemoglobinemia while using lidocaine as a topical anaesthetic agent. Methods. We prospectively studied consecutive adult patients who underwent diagnostic FOB in our institution. Blood methaemoglobin levels were estimated by co-oximetry before bronchoscopy and one hour after first instillation of lidocaine. Occurrence of symptoms suggestive of mild methaemoglobinemia (i.e., fatigue, palpitation, dizziness, nausea and headache) were recorded in a severity scale before collection of post-bronchoscopy blood samples. Results. A total of 48 adult patients were enrolled in this study. The mean amount of lidocaine used for bronchoscopy during this study was 7.4±1.4mg/kg body weight. The mean pre- and post-bronchoscopy methaemoglobin levels were 0.44mg/mL and 0.80mg/mL, respectively. After bronchoscopy, severe and very severe symptoms were reported by 2.1% to 10.4% patients. However, severities of the symptoms were unrelated to post-bronchoscopy methaemoglobin level or the amount of lidocaine used during the FOB. Conclusions. Blood methaemoglobin levels following FOB remained within the physiological limits when British Thoracic Society recommended dose of lidocaine was used. However, few patients had symptoms similar to mild methaemoglobinemia after FOB.

Cyanosis by methemoglobinemia in tadpoles of Cochranella granulosa (Anura: Centrolenidae)

Tadpoles inhabit generally well oxygenated rivers and streams, nevertheless they were found in areas with limited oxygen availability inside the rivers. To assess this feature, I examined factors that influence centrolenid tadpole behaviour using Cochranella granulosa. The tadpoles were reared in well-oxygenated and hypoxic environments and their development, survivorship and growth were compared. The tadpoles in oxygenated water acquired a pale color, while tadpoles in hypoxic water grew faster and were bright red and more active. In the oxygenated water, the ammonium, which had its origin in the tadpoles’ urine and feces, was oxidized to nitrate. In contrast, in the hypoxic treatment, the nitrogen compounds remained mainly as ammonium. Presumably, the nitrate in oxygenated water was secondarily reduced to nitrite inside the long intestine coils, because all symptoms in the tadpoles point to methemoglobinemia, which can occur when the nitrite passes through the intestine wall into the bloodstream, transforming the hemoglobin into methemoglobin. This could be checked by a blood test where the percentage of methemoglobin was 2.3% in the blood of tadpoles reared in hypoxic condition, while there was a 19.3% level of methemoglobin in the blood of tadpoles reared in oxygenated water. Together with the elevated content of methemoglobin, the growth of the tadpoles was delayed in oxygenated water, which had high nitrate content. The study about quantitative food-uptake showed that the tadpoles benefit more from the food in hypoxic water, although they spent there more energy moving around than the tadpoles living in oxygenated but nitrate-charged water. Rev. Biol. Trop. 58 (4): 1467-1478. Epub 2010 December 01.

Los renacuajos por lo general viven en ríos y arroyos bien oxigenados, sin embargo, como han sido encontrados en áreas con disponibilidad de oxígeno limitada en los ríos, se estudió como influye este factor en su comportamiento. Renacuajos de Cochranella granulosa fueron criados en ambientes bien oxigenados y de hipoxia para comparar su desarrollo, supervivencia y crecimiento. En el agua que no fue cambiada durante al menos un mes, los renacuajos mostraron diferencias en su desarrollo cuando vivían en agua hipóxica u oxigenada. Los renacuajos en el agua aireada tenían un color pálido, mientras que en la hipóxica fueron más activos y de un color rojo brillante. En el agua hipóxica, el nitrógeno que se originó de la orina y las heces de los renacuajos se mantuvo principalmente en forma de amonio; en cambio, el amonio fue oxidado a nitrato en el agua aireada. Presumiblemente, el nitrato en el agua oxigenada se redujo secundariamente a nitrito dentro del intestino, ya que todos los síntomas en los renacuajos que vivían en esta agua apuntaron a una metahemoglobinemia, que se produce cuando el nitrito pasa a través de la pared del intestino a la corriente sanguínea transformando la hemoglobina en metahemoglobina. Esto pudo comprobarse mediante un análisis sanguíneo en donde el porcentaje de metahemoglobina fue del 2.3% en la sangre de los renacuajos criados en condición hipóxica y de un 19.3% de metahemoglobina en aquellos criados en agua aireada. En la misma forma en que la metahemoglobina aumenta en la sangre de los renacuajos que viven en agua oxigenada, su crecimiento disminuye en agua con alto contenido de nitrato. El estudio cuantitativo de la ingestión de nutrientes mostró que el crecimiento de los renacuajos se beneficia más de los alimentos en agua hipóxica, a pesar de que los renacuajos son más activos en sus movimientos que los que viven en agua oxigenada pero cargada de nitratos.

A Patient with Methemoglobinemia after Herbicide Intoxication has Hemolytic Anemia Induced by Methylene Blue

Methylene blue is the first choice for treating methemoglobinemia, any increase in normal methemoglobin levels. Methemoglobin is an abnormal hemoglobin in which the iron has been oxidized to the ferric(+3) state, making it incapable of oxygen transport. Methemoglobinemia most commonly results from exposure to oxidizing chemicals, but may also arise form genetic, dietary, or even idiopathic etiologies. Patients with low methemoglobin levels are asymptomatic, but high methemoglobin levels can lead to headaches or even death. Methylene blue, the first-line treatment for methemoglobinemia, can also produce hemolytic anemia. Jaundice or dark urine during methylene blue treatment may indicate hemolytic anemia. A 47-year-old female patient with a history of depressive mood disorder developed significant methemoglobinemia after ingesting a Propanil overdose. Twenty-two hours after ingestion, methemoglobin levels in the blood were 73.2%. She was treated with intravenous methylene blue in the therapeutic range (1 mg/kg every 4 h for 3days). The 2nd day after methylene blue use, methemoglobin levels in the blood were 33%, and the 5th day decreased to 10% with better general condition. The patient had hyperbilirubinemia after hemolytic anemia, but she recovered completely.