Influence of iron deprivation on virulence traits of mycobacteria

ABSTRACT Novel strategies to combat the ever increasing burden of drug resistance in Mycobacterium tuberculosis (MTB) causing tuberculosis (TB) remains a global concern. The ability of MTB to sense and adapt to restricted iron conditions in the hostile environment is essential for their survival and confers the basis of their success as dreadful pathogen. The striking and clinically relevant virulence trait of MTB is its ability to form biofilms and adhere to the host cells. The present study elucidated the effect of iron deprivation on biofilm formation and cell adherence of Mycobacterium smegmatis, a non-pathogenic surrogate of MTB. Firstly, we showed that iron deprivation leads to enhanced cell sedimentation rate and altered colony morphology depicting alterations in cell surface envelope properties. We explored that biofilm formation and cell adherence to polystyrene surface as well as human oral epithelial cells were considerably reduced under iron deprivation both in presence of 2,2 BP (iron chelator) and siderophore mutant Δ011-14 strain. We further investigated that the potency of three first line anti-TB drugs (Isoniazid, Ethambutol, Rifampicin) to inhibit both biofilm formation and cell adhesion were enhanced under iron deprivation in contrast to the drugs when tested alone. Taken together, by virtue of the indispensability of iron for functional virulence traits in mycobacteria, iron deprivation strategies could be further exploited against this notorious human pathogen to explore novel drug targets.

Influence of 120 kDa Pyruvate:Ferredoxin Oxidoreductase on Pathogenicity of Trichomonas vaginalis

Trichomonas vaginalis is a flagellate protozoan parasite and commonly infected the lower genital tract in women and men. Iron is a known nutrient for growth of various pathogens, and also reported to be involved in establishment of trichomoniasis. However, the exact mechanism was not clarified. In this study, the author investigated whether the 120 kDa protein of T. vaginalis may be involved in pathogenicity of trichomonads. Antibodies against 120 kDa protein of T. vaginalis, which was identified as pyruvate:ferredoxin oxidoreductase (PFOR) by peptide analysis of MALDI-TOF-MS, were prepared in rabbits. Pretreatment of T. vaginalis with anti-120 kDa Ab decreased the proliferation and adherence to vaginal epithelial cells (MS74) of T. vaginalis. Subcutaneous tissue abscess in anti-120 kDa Ab-treated T. vaginalis-injected mice was smaller in size than that of untreated T. vaginalis-infected mice. Collectively, the 120 kDa protein expressed by iron may be involved in proliferation, adhesion to host cells, and abscess formation, thereby may influence on the pathogenicity of T. vaginalis.

Análise proteômica em cérebro de ratos submetidos a tratamento subcrônico com chumbo: influência da suplementação com ferro / Proteomic analysis of brain in rats submitted to subchronic treatment with lead: influence of iron supplementation

O chumbo (Pb) é um metal pesado que pode ocasionar alterações em todos os sistemas. Porém os maiores danos à saúde ocorrem quando este acomete o sistema nervoso central (SNC). Muitos estudos demonstram as alterações clinicas/comportamentais causadas pela ação do Pb no SNC. Entretanto, ainda são necessários estudos que demonstrem as alterações bioquímicas causadas pelo Pb neste sistema. Por outro lado, tem sido relatado que o ferro (Fe) parece ter um efeito protetor na toxicidade cerebral causada pelo Pb. Assim, o objetivo deste estudo foi analisar a concentração de Pb no tecido cerebral, bem como realizar análise proteômica em cérebro de ratos intoxicados por Pb, submetidos à suplementação com Fe ou não. O experimento foi realizado com 30 ratos recém-desmamados (Rattus norvegicus, variedade Wistar) divididos em 6 grupos (n=5/grupo), de acordo com o tratamento recebido por 6 semanas, a saber: Controle (não exposto ao Pb ou Fe), Controle Fe (exposto à administração de 20 mg/Kg p.c. de FeSO4 a cada 2 dias, por gavagem gástrica), Pb 100 (exposto à água contendo 100 mg/L de Pb), Pb 400 (exposto à água contendo 400 mg/L de Pb) Pb100 + Fe (exposto à água contendo 100 mg/L de Pb e à gavagem com FeSO4) e Pb400 + Fe (exposto à água contendo 400 mg/L de Pb e à gavagem com FeSO4). Decorrido o período experimental, os animais foram eutanasiados e o cérebro dos animais foi removido, sendo descartados o cerebelo e o tronco encefálico. O restante foi submetido à concentração de Pb e à análise proteômica. Foi observada uma dose-resposta em relação à concentração de Pb no cérebro. A administração de FeSO4 reduziu os níveis de Pb no cérebro, embora sem significância estatística. A análise dos géis com os spots proteicos demonstrou uma redução na quantidade destes de acordo com o tratamento recebido pelos grupos. O grupo controle mostrou a maior quantidade de spots, ao passo que os grupos que receberam a maior concentração de Pb (400 mg/L) apresentaram as menores quantidade de...

Lead (Pb) is a heavy metal that may yield changes in all body systems, yet the greatest health damages occur when it affects the central nervous system (CNS). Many studies demonstrate the clinical/behavioral changes caused by the action of Pb on the CNS. However, studies are necessary to demonstrate the biochemical changes caused by Pb in this system. Conversely, it has been reported that iron (Fe) seems to play a protective role on the brain toxicity caused by Pb. Therefore, this study analyzed the concentration of Pb in the brain tissue, and conducted proteomic analysis in the brain of rats intoxicated by Pb, submitted or not to Fe supplementation. The study was conducted on 30 weaning rats (Rattus norvegicus, Wistar type) divided in 6 groups (n=5/group), according to the treatment established for 6 weeks, as follows: Control (not exposed to Pb or Fe), Control Fe (exposed to administration of 20 mg/Kg p.c. of FeSO4 at every 2 days, by gastric gavage), Pb 100 exposed to water containing 100 mg/L of Pb), Pb 400 (exposed to water containing 400 mg/L of Pb) Pb100 + Fe (exposed to water containing 100 mg/L of Pb and gavage with FeSO4) and Pb400 + Fe (exposed to water containing 400 mg/L of Pb and gavage with FeSO4). After the experimental period, the animals were killed and the brains of animals were removed, discarding the cerebellum and brainstem. The remaining structure was submitted to analysis of Pb concentration and proteomic analysis. A dose-response relationship was observed in Pb concentration in the brain. The administration of FeSO4 reduced the levels of Pb in the brain, though without statistical significance. The analysis of gels with proteic spots demonstrated reduction in their quantity according to the treatment performed in the groups. The control group exhibited greater concentration of spots, while groups receiving higher Pb concentration (400 mg/L) presented the lowest quantity of spots...

Análise proteômica em cérebro de ratos submetidos a tratamento subcrônico com chumbo: influência da suplementação com ferro / Proteomic analysis of brain in rats submitted to subchronic treatment with lead: influence of iron supplementation

O chumbo (Pb) é um metal pesado que pode ocasionar alterações em todos os sistemas. Porém os maiores danos à saúde ocorrem quando este acomete o sistema nervoso central (SNC). Muitos estudos demonstram as alterações clinicas/comportamentais causadas pela ação do Pb no SNC. Entretanto, ainda são necessários estudos que demonstrem as alterações bioquímicas causadas pelo Pb neste sistema. Por outro lado, tem sido relatado que o ferro (Fe) parece ter um efeito protetor na toxicidade cerebral causada pelo Pb. Assim, o objetivo deste estudo foi analisar a concentração de Pb no tecido cerebral, bem como realizar análise proteômica em cérebro de ratos intoxicados por Pb, submetidos à suplementação com Fe ou não. O experimento foi realizado com 30 ratos recém-desmamados (Rattus norvegicus, variedade Wistar) divididos em 6 grupos (n=5/grupo), de acordo com o tratamento recebido por 6 semanas, a saber: Controle (não exposto ao Pb ou Fe), Controle Fe (exposto à administração de 20 mg/Kg p.c. de FeSO4 a cada 2 dias, por gavagem gástrica), Pb 100 (exposto à água contendo 100 mg/L de Pb), Pb 400 (exposto à água contendo 400 mg/L de Pb) Pb100 + Fe (exposto à água contendo 100 mg/L de Pb e à gavagem com FeSO4) e Pb400 + Fe (exposto à água contendo 400 mg/L de Pb e à gavagem com FeSO4). Decorrido o período experimental, os animais foram eutanasiados e o cérebro dos animais foi removido, sendo descartados o cerebelo e o tronco encefálico. O restante foi submetido à concentração de Pb e à análise proteômica. Foi observada uma dose-resposta em relação à concentração de Pb no cérebro. A administração de FeSO4 reduziu os níveis de Pb no cérebro, embora sem significância estatística. A análise dos géis com os spots proteicos demonstrou uma redução na quantidade destes de acordo com o tratamento recebido pelos grupos. O grupo controle mostrou a maior quantidade de spots, ao passo que os grupos que receberam a maior concentração de Pb (400 mg/L) apresentaram as menores quantidade de...

Lead (Pb) is a heavy metal that may yield changes in all body systems, yet the greatest health damages occur when it affects the central nervous system (CNS). Many studies demonstrate the clinical/behavioral changes caused by the action of Pb on the CNS. However, studies are necessary to demonstrate the biochemical changes caused by Pb in this system. Conversely, it has been reported that iron (Fe) seems to play a protective role on the brain toxicity caused by Pb. Therefore, this study analyzed the concentration of Pb in the brain tissue, and conducted proteomic analysis in the brain of rats intoxicated by Pb, submitted or not to Fe supplementation. The study was conducted on 30 weaning rats (Rattus norvegicus, Wistar type) divided in 6 groups (n=5/group), according to the treatment established for 6 weeks, as follows: Control (not exposed to Pb or Fe), Control Fe (exposed to administration of 20 mg/Kg p.c. of FeSO4 at every 2 days, by gastric gavage), Pb 100 exposed to water containing 100 mg/L of Pb), Pb 400 (exposed to water containing 400 mg/L of Pb) Pb100 + Fe (exposed to water containing 100 mg/L of Pb and gavage with FeSO4) and Pb400 + Fe (exposed to water containing 400 mg/L of Pb and gavage with FeSO4). After the experimental period, the animals were killed and the brains of animals were removed, discarding the cerebellum and brainstem. The remaining structure was submitted to analysis of Pb concentration and proteomic analysis. A dose-response relationship was observed in Pb concentration in the brain. The administration of FeSO4 reduced the levels of Pb in the brain, though without statistical significance. The analysis of gels with proteic spots demonstrated reduction in their quantity according to the treatment performed in the groups. The control group exhibited greater concentration of spots, while groups receiving higher Pb concentration (400 mg/L) presented the lowest quantity of spots...

The effect of iron on Streptococcus mutans biofilm and on enamel demineralization

Iron (Fe) may have an anticaries effect by specific inhibition of glycosyltransferase (GTF) enzymes of Streptococcus mutans, but this hypothesis has not yet been clarified. In this study, S. mutans biofilms were formed on blocks of bovine dental enamel of a predetermined surface hardness (SH). These biofilms were exposed eight times/day to 10% sucrose, and two times/day they were subjected to one of the following treatments: G1, 0.9% NaCl as a negative control; G2, 0.12% chlorhexidine digluconate (CHX) as a positive antibacterial control; G3, 0.05% NaF (225 ppm F) as a positive anticaries control; G4, G5, and G6, ferrous sulfate (Fe2+) at concentrations of 1.0, 10.0, and 100.0 µg Fe/mL, respectively. The experiment was performed in triplicate and was repeated three times (n = 9). The pH of the culture medium was determined every 24 h as an indicator of the biofilm's acidogenicity. The biofilm formed on each block was collected for determination of the viable bacteria and concentration of extracellular polysaccharides (EPS). Enamel SH was again determined and the percentage of SH loss (%SHL) was calculated as an indicator of demineralization. Iron treatment reduced the number of viable bacteria formed in the S. mutans biofilm (p = 0.04), in a dose-dependent manner, and also reduced the enamel's %SHL (p = 0.005). At 100 µg/mL, Fe reduced enamel demineralization as effectively as CHX and NaF (p < 0.05), but it did not inhibit EPS production. In conclusion, the data suggest that the anticaries mechanism of action of Fe may not involve the oxidative inhibition of GTFs.

Zinc y desnutrición / Zinc and undernutrition

Son cuatro los nutrientes en que su deficiencia es importante en niños: hierro, yodo, vitamina A y zinc. Más o menos se calcula que hay 2 billones de personas en el mundo con algún grado de déficit de zinc. Los pacientes que están en riesgo de presentar deficiencias de zinc son los recién nacidos con bajo peso al nacimiento, bien sea prematuros, desnutridos in útero o hijos de madres desnutridas, en los cuales sus depósitos están reducidos. A diferencia de otros oligoelementos o micronutrientes, determinar el estado de déficit no es fácil. Los niveles séricos de zinc, están influenciados por factores no dietarios como infección, estrés o actividad física extenuante; al igual que por el ciclo circadiano.

Four nutrient deficiency that is important in children, iron, iodine, vitamin A and zinc. More or less it is estimated that 2 billion people in the world with some degree of zinc deficiency. Patients who are at risk for zinc deficiency are infants with low birth weight, either premature or malnourished in utero, undernourished mothers, in which their deposits are reduced. Unlike other trace elements or micronutrients, determine the deficit is not easy. Serum levels of zinc are not influenced by dietary factors such as infection, stress or strenuous physical activity, as well as by the circadian cycle.

Consideraciones para la transformación del sistema de salud del Ecuador desde una perspectiva de equidad / Equity-based considerations for transforming the Ecuadorian health system

Objectivo El propósito del presente estudio es analizar las inequidades socioeconómicas en la utilización de servicios de salud en el Ecuador, las inequidades en la distribución geográfica de recursos humanos en salud, y reflexionar sobre los retos de equidad que el sistema de salud ecuatoriano enfrenta en la actualidad. Métodos Se utilizó la Encuesta Demográfica y de Salud Materno-Infantil (ENDEMAIN 2004) como la principal fuente de datos, cuya muestra es representativa de la población ecuatoriana. Para estimar los efectos en utilización de servicios de salud utilizamos análisis multivariado multinivel (usando el paquete estadístico MLWiN 2.02) y análisis espacial de recursos en salud (usando GeoDa 1.0.1 ). Resultados Nuestro análisis encontró que inequidades sociales, económicas y geográficas limitan el acceso a servicios de salud en el Ecuador. Hogares de bajos recursos, indígenas y aquellos que viven enáreas rurales (muchos con las tres características a la vez) tienen menos posibilidades de utilizar servicios de salud. A pesar de la marcada concentración de proveedores de salud en zonas urbanas, encontramos que la presencia de personal de salud (excluyendo a médicos) en entidades públicas rurales incrementa la posibilidad de utilización de servicios preventivos y curativos. Conclusiones Los esfuerzos para transformar el sistema de salud deben reducir barreras sociales, culturales, financieras; y las desigualdades en la distribución de recursos humanos en salud, particularmente en elárea rural. Consideramos que la orientación comunitaria y familiar de los servicios, y el incremento de espacios de participación ciudadana son necesarios para reducir dichas inequidades.

Objective The present study was aimed at analysing socioeconomic inequity regarding the use of health services in Ecuador, inequity regarding the geographic distribution of healthcare-related human resources and reflecting on the challenges concerning equity which the Ecuadorian health system is currently facing. Methods The Ecuadorian Demographic, Maternal and Infant Health Survey (2004) was used as the main data source, as its sample was representative of the Ecuadorian population. Multilevel multivariate analysis (MLWiN 2.02 statistical software) and spatial data analysis regarding health resources (GeoDa 1.0.1) were used for estimating the effects of using health services. Results It was found that social, economic and geographic inequity limited access to health services in Ecuador. People living in low economic resource households or indigenous housing and people living in rural areas (many of them having all three characteristics at the same time) had less possibility of using health services. In spite of a marked concentration of health-service providers in urban areas, it was found that the presence of healthcare personnel (excluding doctors) in rural public entities increased the possibility of using preventative and curative services. Conclusions Efforts at transforming the Ecuadorian health system must be aimed at reducing social, cultural and financial barriers and inequality regarding the distribution de healthcare-related human resources, particularly in rural areas. Community and family orientation of the services and increasing spaces for citizen participation are necessary for reducing such inequity.

Effect of Iron on Adherence and Cytotoxicity of Entamoeba histolytica to CHO Cell Monolayers

Iron is an essential element for almost all living organisms. The possible role of iron for growth, adherence and cytotoxicity of Entamoeba histolytica was evaluated in this study. The absence of iron from TYI-S-33 medium stopped amebic growth in vitro. However, iron concentrations in the culture media of 21.4-285.6 microM did not affect the growth of the amebae. Although growth was not retarded at these concentrations, the adhesive abilities of E. histolytica and their cytotoxicities to CHO cell monolayer were correlated with iron concentration. Amebic adhesion to CHO cell monolayers was significantly reduced by low-iron (24.6 +/- 2.1%) compared with 62.7 +/- 2.8 and 63.1 +/- 1.4% of amebae grown in a normal-iron and high-iron media, respectively. E. histolytica cultured in the normal- and high-iron media destroyed 69.1 +/- 4.3% and 72.6 +/- 5.7% of cultured CHO cell monolayers, but amebae grown in the low-iron medium showed a significantly reduced level of cytotoxicity to CHO cells (2.8 +/- 0.2%). Addition of divalent cations other than iron to amebic trophozoites grown in the low-iron medium failed to restore levels of the cytotoxicity. However, when E. histolytica grown in low-iron medium were transferred to normal-iron medium, the amebae showed completely restored cytotoxicity within 7 days. The result suggests that iron is an important factor in the adherence and cytotoxicity of E. histolytica to CHO cell monolayer.

Effect of Iron on Adherence and Cytotoxicity of Entamoeba histolytica to CHO Cell Monolayers

Iron is an essential element for almost all living organisms. The possible role of iron for growth, adherence and cytotoxicity of Entamoeba histolytica was evaluated in this study. The absence of iron from TYI-S-33 medium stopped amebic growth in vitro. However, iron concentrations in the culture media of 21.4-285.6 microM did not affect the growth of the amebae. Although growth was not retarded at these concentrations, the adhesive abilities of E. histolytica and their cytotoxicities to CHO cell monolayer were correlated with iron concentration. Amebic adhesion to CHO cell monolayers was significantly reduced by low-iron (24.6 +/- 2.1%) compared with 62.7 +/- 2.8 and 63.1 +/- 1.4% of amebae grown in a normal-iron and high-iron media, respectively. E. histolytica cultured in the normal- and high-iron media destroyed 69.1 +/- 4.3% and 72.6 +/- 5.7% of cultured CHO cell monolayers, but amebae grown in the low-iron medium showed a significantly reduced level of cytotoxicity to CHO cells (2.8 +/- 0.2%). Addition of divalent cations other than iron to amebic trophozoites grown in the low-iron medium failed to restore levels of the cytotoxicity. However, when E. histolytica grown in low-iron medium were transferred to normal-iron medium, the amebae showed completely restored cytotoxicity within 7 days. The result suggests that iron is an important factor in the adherence and cytotoxicity of E. histolytica to CHO cell monolayer.

Iron mediated regulation of growth and siderophore production in a diazotrophic cyanobacterium Anabaena cylindrica.

Iron mediated regulation of growth and siderophore production has been studied in a diazotrophic cyanobacterium Anabaena cylindrica. Iron-starved cells of A. cylindrica exhibited reduced growth (30%) when the cells were growing under N2-fixing conditions. In contrast, N03-, NO2-, NH4' and urea grown cells exhibited almost 50% reduction in their growth in the absence of iron as compared to their respective counterparts cultured in the presence of iron. However, at 60 microM of iron, A. cylindrica cells exhibited almost equal growth regardless of the nitrogen source available. Siderophore production in A. cylindrica was started after day 2nd of the cell growth and attained its optimal level on day 5th when the cells were at their mid-log phase. No siderophore production was, however, recorded on day 2nd at all the concentrations of iron tested. The production of siderophore in A. cylindrica further increased with increase in iron concentration and attained its optimum level on day 5th at 60 microM iron. A. cylindrica cells took at least 3 days for initiation of siderophore production and produced about 60% siderophore on day 5th even under iron-starved condition. A. cylindrica produced dihydroxamate type of siderophore.

Impacto obtenido sobre la morbilidad infantil suplementando vitamina A, hierro y cinc a niños <5 años de edad residentes en una zona de alta pobreza: caso: Relleno Sanitario Sector Walter Marquez / The impact obtained about infantile morbidity supplement with vitamin A, iron and zinc to children <5 years old that live in poverty places

La ciencia y la tecnología nunca resolverán todos los problemas suscitados por la insuficiencia de alimentos y la falta de servicios de salud y saneamiento, propiciantes de la desnutrición infantil. Pero los éxitos de los adelantos científicos y los conocimientos obtenidos, han dado pie a nuevas esperanzas de lograr vidas más saludables y productivas, tanto para los niños como para los adultos. Parte de estos conocimientos, como el fortalecimiento del sistema de inmunidad gracias a los efectos de la vitamina A, están bien establecidos. Con el objetivo de demostrar que la suplementación de micro nutrientes a niños en situaciones de pobreza puede propiciar una reducción en la aparición de enfermedades infecciosas más frecuentes, se diseñó un estudio experimental de campo, descriptivo y longitudinal, sobre una población integrada por niños de educación inicial ubicados en el Barrio “Hugo Rafael Chávez” del Sector Walter Márquez de San Josecito, Municipio Torbes. Luego de visitas de inducción, capacitación y censo de morbilidad, se procedió a desparasitar con albendazol y a suministrar dosis pediátricas de vitamina A en capsulas blandas 3 días, sulfato de cinc en tabletas 15 días y sulfato ferroso en jarabe 3 meses, para cumplir un plan de seguimiento mensual durante tres meses. Se incorporan 25 niños y niñas, de los cuales el 50 por ciento de los menores de 2 años de edad tenían algún grado de desnutrición aguda. Mientras que el 36 por ciento de los mayores de dos años tenían desnutrición crónica. De las enfermedades conseguidas, las del aparato respiratorio fueron las más frecuentes, seguidas por las intestinales. Dentro de las respiratorias, las gripes, rinitis y catarro fueron el 81,3 por ciento. Las diarreas fueron el 57,8 por ciento de las digestivas. Las piodermitis fueron el 50 por ciento de las infecciones de piel. Finalmente, la caries dental como enfermedad infecciosa bucal, fue el 55,8 por ciento de otras enfermedades.

Role of iron in the nitric oxide-mediated fungicidal mechanism of IFN-gamma-activated murine macrophages against Paracoccidioides brasiliensis conidia

Iron is an essential growth element of virtually all microorganisms and its restriction is one of the mechanisms used by macrophages to control microbial multiplication. Paracoccidioides brasiliensis, the agent of paracoccidioidomycosis, an important systemic mycosis in Latin America, is inhibited in its conidia-to-yeast conversion in the absence of iron. We studied the participation of iron in the nitric oxide (NO)-mediated fungicidal mechanism against conidia. Peritoneal murine macrophages activated with 50U/mL of IFN-gamma or treated with 35 æM Deferoxamine (DEX) and infected with P. brasiliensis conidia, were co-cultured and incubated for 96 h in the presence of different concentrations of holotransferrin (HOLO) and FeS0(4). The supernatants were withdrawn in order to assess NO2 production by the Griess method. The monolayers were fixed, stained and observed microscopically. The percentage of the conidia-to-yeast transition was estimated by counting 200 intracellular propagules. IFN-gamma-activated or DEX-treated Mthetas presented marked inhibition of the conidia-to-yeast conversion (19 and 56 percent, respectively) in comparison with non-activated or untreated Mthetas (80 percent). IFN-gamma-activated macrophages produced high NO levels in comparison with the controls. Additionally, when the activated or treated-macrophages were supplemented with iron donors (HOLO or FeSO4), the inhibitory action was reversed, although NO production remained intact. These results suggest that the NO-mediated fungicidal mechanism exerted by IFN-gamma-activated macrophages against P. brasiliensis conidia, is dependent of an iron interaction.

O ferro é elemento essencial para o crescimento de microrganismos e sua limitação é um dos mecanismos usados por macrófagos para controlar a multiplicação microbiana. Paracoccidioides brasiliensis, o agente da paracoccidioidomicose, uma das micoses sistêmicas mais importantes na América Latina, é inibido em sua conversão de conídia-à-levedura na ausência do ferro. Estudamos a participação do ferro no mecanismo fungicida mediado pelo óxido nítrico (NO) na sua interação com as conídias do fungo. Macrófagos peritoneais murinos ativados com 50U/mL de IFN-gama ou tratados com 35 æM Deferoxamina (DEX) e infectados com conídias do P. brasiliensis foram co-cultivados e incubados por 96 h na presença de concentrações diferentes de holotransferrina (HOLO) e FeS0(4). Os sobrenadantes foram retirados a fim de avaliar a produção de NO2 pelo método de Griess. Os macrófagos eram fixados, corados e observados ao microscópio. A porcentagem da transição de conídia-à-levedura foi estimada contando 200 propágulos intracelulares. Os macrófagos ativados com citocina ou tratados com DEX apresentaram inibição marcada da conversão de conídia-à-levedura (19 e 56 por cento, respectivamente) em comparação com macrófagos controle (80 por cento). Os macrófagos ativados com IFN-gama produziram elevação nos níveis de NO em comparação com macrófagos não-tratados ou não-activados. Adicionalmente, quando as monocapas ativadas ou tratadas foram suplementadas com doadores do ferro (HOLO ou FeSO4), a ação inibitória foi revertida embora a produção de NO permanecesse intacto. Estes resultados sugerem que o mecanismo fungicida mediado pelo NO exercido por macrófagos ativados com IFN-gama contra conídias do P. brasiliensis é dependente de uma interação do ferro.

Iron induced metabolic changes in the diazotrophic cyanobacterium Anabaena PCC 7120.

Iron induced changes in growth, N2-fixation, CO2 fixation and photosynthetic activity were studied in a diazotrophic cyanobacterium Anabaena PCC 7120. Iron at 50 microM concentration supported the maximum growth, heterocyst frequency, CO2 fixation, photosystem I (PS I), photosystem II (PS II) and nitrogenase activities in the organism. Higher concentration of iron inhibited these processes. Chl a and PS II activities were more sensitive to iron than the protein and PS I activity.

Modulatory effect of dietary factors on iron-induced in vivo lipid peroxidation in liver and serum of albino rats.

Effect of a computed diet based on cereals and spices incorporated with either crude palm oil (CPO)/soybean oil (SBO)/cod liver oil (CLO) at 10% level in the diet in modulating iron-induced in vivo lipid peroxidation was carried out during a 12 week study in albino rats. Three groups of rats, each divided into three sets were fed diets based on casein/ragi/jowar incorporated with CPO or SBO or CLO. The casein group of rats did not receive any spice mixture, while the ragi and jowar groups received spice mixture at 2.5% level. Serum lipid analysis showed significant increase in cholesterol, LDL-c + VLDL-c and decrease in HDL-c levels in all the iron treated group of animals. In liver, non-significant increase in total cholesterol triglyceride and decrease in phospholipid levels were noted. Fatty acid profile of liver tissue exhibited low 18:2 levels in various experimental groups due to peroxidation of membrane lipids. Histopathological examination of liver tissue in particular showed mild cytoplasmic vacuolation in control group of rats fed ragi/jowar and moderate vacuolation in all the iron-treated groups. The results demonstrate that different dietary components can beneficially modulate free radical mediated oxidative stress induced by lipid peroxidation.

Antioxidant responses of cortex neurons to iron loading

Brain cells have a highly active oxidative metabolism, yet they contain only low to moderate superoxide dismutase and catalase activities. Thus, their antioxidant defenses rely mainly on cellular reduced glutathione levels. In this work, in cortical neurons we characterized viability and changes in reduced and oxidized glutathione levels in response to a protocol of iron accumulation. We found that massive death occurred after 2 days in culture with 10 mM Fe. Surviving cells developed an adaptative response that included increased synthesis of GSH and the maintenance of a glutathione-based reduction potential. These results highlight the fundamental role of glutathione homeostasis in the antioxidant response and provide novel insights into the adaptative mechanisms of neurons subjected to progressive iron loads.

Effect of iron on the activation of the MAPK/ERK pathway in PC12 neuroblastoma cells

Recent evidence suggests that reactive oxygen species function as second messenger molecules in normal physiological processes. For example, activation of N-Methyl-D-Aspartate receptor results in the production of ROS, which appears to be critical for synaptic plasticity, one of the cellular mechanisms that underlie learning and memory. In this work, we studied the effect of iron in the activation of MAPK/ERK pathway and on Ca2+ signaling in neuronal PC12 cells. We found that iron-dependent generation of hydroxyl radicals is likely to modulate Ca2+ signaling through RyR calcium channel activation, which, in turn, activates the MAPK/ERK pathway. These findings underline the relevance of iron in normal neuronal function.

Spectrophotometric method for quantitative determination of iron III from iron polymaltose complex in pharmaceutical formulations

A visible spectrophotometric method has been developed for the quantification of iron [III] from iron polymaltose complex in pure and in pharmaceutical preparations. The method is based on hydrolysis of iron polymaltose complex under acidic conditions and the formation of red colored chromogen with ammonium thiocyanate, which showed absorption peak at 471 nm. This absorption wavelength can be used for the determination of iron [III] from iron polymaltose complex. The limit of detection of iron polymaltose complex at 476 nm was 6.207 ng mL-1. The calibration was linear in the range of 19.8'22.2 micro g mL-1. Analytical parameters such as stability, selectivity, accuracy and precision have been established for the method in HAEMOTYL [R] syrup and evaluated statistically to assess the application of the method. The method was validated under the ICH and USP guidelines and found to comprise the advantages for simplicity, stability, sensitivity, reproducibility and accuracy for using as a method for the routine analysis of the drug in pharmaceutical formulations and in pharmaceutical investigations involving iron polymaltose complex

Iron Supplementation in Experimental Hyperthyroidism: Effects on Oxidative Stress in Skeletal Muscle Tissue

This study was designed to investigate the effects of iron supplementation on the parameters of oxidative stress in the skeletal muscle tissue of hyperthyroidism induced rats. Hyperthyroidism was found to cause an increase in thiobarbituric acid-reactive substances (TBARS) and copper zinc superoxide dismutase (Cu, Zn SOD) activity, but decreases in the glutathione-peroxidase (GSH Px) activity and glutathione (GSH). Iron supplementation caused an increase in TBARS and a decrease in GSH. Iron supplementation in hyperthyroid rats attenuated the hyperthyroid state, but lowered the plasma ferritin level, which is considered an indicator of thyroid hormone action. Iron supplementation caused no additional increase in the TBARS in hyperthyroid rats, ameliorated the decrease in GSH content and abolished the induction of Cu, Zn SOD. Our findings suggested no increase, but a decrease, in the risk of oxidative stress in iron supplemented hyperthyroid rats. Whether supplementation of iron would have similar effects in humans should be further investigated in clinical studies.

Effect of iron on growth in iron deficient anemic school going children.

Iron deficiency anemia (IDA) in children has been associated with retardation in growth and the cognitive development. In the ongoing study on the effects of IDA in school going children, the effects on anthropometric parameters such as height (Ht), Weight (Wt), head circumference (HC), body mass index (BMI) and the mid arm circumference (MAC) were studied along with the hematological parameters such as hemoglobin (Hb), hematocrit (Hct), MCV, MCH, serum iron (SI), total iron binding capacity (TIBC) and % saturation. The pre-supplementation values of all these parameters were taken in anemic and control groups of girls and boys. After deworming all the children with albendazole (400 mg), the anemic group was put on iron supplementation (Ferrous iron 3-4 mg/kg body weight/day) along with vitamin C (100 mg OD) and the control children were given vitamin C (100 mg OD), for 90 days. Pre-supplementation values of IDA children were significantly lower for MAC and HC in girls and for Ht and MAC in boys, when compared to the control group. After the therapy both the groups of girls showed improvement in the hematological parameters though it was greater in the anemic girls. Ht and Wt of both groups also improved significantly but the anemic girls showed increase in BMI also. Both the control and anemic boys showed gain in weight. Post therapy, improvement in hematological parameters for both the anemic girls and boys were greater than their respective control groups. The MAC value for anemic girls were in the control range but those of anemic boys remained lesser than the control boys. So, it can be concluded from the present study that the IDA children lagged behind the control children in terms of anthropometric parameters and they benefited relatively more in terms of anthropometric improvement and hematological improvement after iron supplementation.

Physiological and biochemical alterations in Anabaena 7120 under iron stress.

Various physiological and biochemical process like growth, NO3- -uptake, nitrate reductase, glutamine synthetase and ATPases (Mg2+ and Ca2+ dependent) in the cyanobacterium Anabaena 7120 were observed under iron stress. Growth was found to be maximum in 50 microM Fe3+ added cells however, 20 microM Fe3+ (the Fe3+ concentration generally used for routine culturing of cyanobacterial cell in Chu 10 medium) incubation resulted in lower growth. Fe3+ starvation on the other hand showed very poor growth up to 4th day but once the growth started it reached at significant level on 7th day. Higher Fe3+ concentration reflected reduced growth with lethality at 500 microM Fe3+. Chlorophyll a fluorescence under Fe3+ stress reflected almost the similar results as in case of growth. However, the pigment was found to be more sensitive as compared to protein under Fe3+ stress. Similar results have been observed in case of NO3-uptake with only 80% reduction in nutrient uptake in 500 microM Fe3+ incubated cells. Nitrate reductase activity was lower in Fe3+ starved cells as compared to significant enzyme activity in 20 and 50 microM Fe3+ incubated cells. Similar to nitrate reductase, glutamine synthetase also showed maximum level in 50 microM Fe3+ added cells, however, higher Fe3+ concentration (300-500 microM ) resulted in reduced enzymatic activity. Glutamine synthetase activity was less sensitivity as compared to nitrate reductase activity under Fe3+ stress. ATPase (Mg2+ and Ca2+ dependent) always showed higher level with increasing Fe3+ concentration.