Iron acquisition by Mycobacterium tuberculosis: isolation and characterization of a family of iron-binding exochelins.

Mycobacterium tuberculosis, the primary agent of tuberculosis, must acquire iron from the host to cause infection. To do so, it releases high-affinity iron-binding siderophores called exochelins. Exochelins are thought to transfer iron to another type of high-affinity iron-binding molecule in the bacterial cell wall, mycobactins, for subsequent utilization by the bacterium. In this paper, we describe the purification of exochelins of M. tuberculosis and their characterization by mass spectrometry. Exochelins comprise a family of molecules whose most abundant species range in mass from 744 to 800 Da in the neutral Fe(3+)-loaded state. The molecules form two 14-Da-increment series, one saturated and the other unsaturated, with the increments reflecting different numbers of CH2 groups on a side chain. These series further subdivide into serine- or threonine-containing species. The virulent M. tuberculosis Erdman strain and the avirulent M. tuberculosis H37Ra strain produce a similar set of exochelins. Based on a comparison of their tandem mass spectra, exochelins share a common core structure with mycobactins. However, exochelins are smaller than mycobactins due to a shorter alkyl side chain, and the side chain of exochelins terminates in a methyl ester. These differences render exochelins more polar than the lipophilic mycobactins and hence soluble in the aqueous extracellular milieu of the bacterium in which they bind iron in the host.

Plasma steroids and steroid-binding capacity in male semelparous dasyurid marsupials (Phascogale tapoatafa) that survive beyond the breeding season in captivity

The semelparous dasyurids display a unique life history, in that all males die within a few weeks of the completion of the breeding season. Studies of several semelparous species have revealed that the male die-off is stress-related, and accompanied by increased plasma androgen and cortisol levels and decreased corticosteroid binding capacity, resulting in suppression of immune and inflammatory responses. This study examines the endocrine profile of male brush-tailed phascogales (Phascogale tapoatafa) that survive beyond the breeding season in captivity. Plasma cortisol, corticosteroid binding globulin and albumin levels were monitored in both males and females and steroid partitioning calculated. Captive males surviving beyond the breeding season did not show the elevation in plasma cortisol and decrease in corticosteroid binding capacity reported in wild males. Plasma albumin concentrations also remained constant during the sampling period. These data indicate that captive males do not undergo the same stress response described in wild populations. (c) 2006 Elsevier Inc. All rights reserved.

Synthesis and iron binding studies of myo-inositol 1,2,3-trisphosphate and (+/-)-myo-inositol 1,2-bisphosphate, and iron binding studies of all myo-inositol tetrakisphosphates

The first syntheses of the natural products myo-inositol 1,2,3-trisphosphate and (+/-)-myo-inositol 1,2-bisphosphate are described. The protected key intermediates 4,5,6-tri-O-benzoyl-myo-inositol and (+/-)-3,4,5,6-tetra-O-benzyl-myo-inositol were phosphorylated with dibenzyl N,N-di-isopropylphosphoramidite in the presence of 1H-tetrazole and subsequent oxidation of the phosphite. The crystal structures of the synthetic intermediates (+/-)-1-O-(tert-butyldiphenylsilyl)-2,3,O-cyclohexylidene-myo-inos itol and (+/-)-4,5,6-tri-O-benzoyl-1-O-(tert-butyldiphenylsilyl)-2,3-O-cycl ohexylidene- myo-inositol are reported. myo-Inositol 1,2,3-trisphosphate (+/-)-myo-inositol 1,2-bisphosphate, and all isomeric myo-inositol tetrakisphosphates were evaluated for their ability to alter HO. production in the iron-catalysed Haber-Weiss reaction. The results demonstrated that a 1,2,3-grouping of phosphates in myo-inositol was necessary for inhibition also that (+/-)-myo-inositol 1,2-bisphosphate potentiated HO. production. myo-Inositol 1,2,3-trisphosphate resembled myo-inositol hexakisphosphate (phytic acid) in its ability to act as a siderophore by promoting iron-uptake into Pseudomonas aeruginosa.

Iron deficiency anaemia among apparently healthy pre-school children in Lagos, Nigeria.

Background: Iron deficiency, and specifically iron deficiency anaemia, remains one of the most severe and important nutritional deficiencies in the world today. Objective: To estimate the prevalence and associated factors for iron deficiency anaemia among pre-school children in Lagos. Methodology: The study was conducted from December 2009 to February 2010 at the outpatient clinics of Lagos State University Teaching Hospital, Lagos. Serum iron, total iron binding capacity, transferrin saturation and serum ferritin were assayed in subjects. The primary outcome measured was iron deficiency anaemia established based on the following criteria: hemoglobin <11.0 g/dl1 plus 2 or more of the following: MCV <70fl, transferrin saturation <10% or serum ferritin <15ng/ dL. Statistical analysis included Pearson Chi square analysis and logistic regression analysis. Results: A total of 87 apparently healthy subjects were recruited. Only one subject had iron depletion and this child belonged to the ≤ 2 years age category. None of the recruited subjects had iron deficiency without anaemia. Nine of the study subjects (10.11%) had iron deficiency anaemia. The prevalence of iron deficiency anaemia was significantly higher among younger age group than in the older age group (19.1% Vs 2.1%, p = 0.022). The prevalence of iron deficiency anaemia was significantly higher among subjects with weight-for-age, and weight-for-height Z scores below two standard scores (83.3% and 75.0% respectively, p = <0.001 and 0.001 respectively). Conclusion: The overall prevalence of iron deficiency anaemia among study subjects was 10.11%. Iron deficiency anaemia was more common in children aged two years and below. Weight-for-age and weight-for-height Z scores below minus two standard scores were strongly associated with iron deficiency anaemia.

Influence of magnesium on biochemical parameters of iron and oxidative stress in patients with type 2 diabetes

Introduction: Studies have shown that oxidative stress, found in patients with type 2 diabetes, may be due to changes in the metabolism of minerals, such as magnesium and iron. Data related to compartmentalization of these minerals in diabetes are scarce and controversial. Objective: This study assessed the influence of magnesium on biochemical parameters of iron and oxidative stress in patients with type 2 diabetes. Methods: A case-control study in male and female subjects aged 27-59 years, divided into two groups: type 2 diabetes (n=40) and control (n=48). Intake of magnesium and iron was assessed by three-day food record. Plasma, erythrocyte and urinary levels of magnesium, serum iron, ferritin, total iron binding capacity, fasting glucose, glycated hemoglobin, insulin, creatinine clearance and plasma thiobarbituric acid reactive substances (TBARS) were analyzed. Results and Discussion: Magnesium intake and plasma magnesium were lower in diabetic subjects. There was low urinary magnesium excretion, with no difference between groups. Although normal, the diabetic group had lower serum iron and ferritin concentrations compared to control subjects. Plasma TBARS in diabetic patients was higher than control while creatinine clearance was lower. An inverse correlation between erythrocyte magnesium and serum iron and ferritin was observed in the diabetes group. Conclusions: Diabetes induced hypomagnesemia and this, associated with chronic hyperglycemia, may have enhanced oxidative stress. Erythrocyte magnesium may have contributed to prevent iron overload and worsening of oxidative stress and hyperglycemic status.

What's new in hemochromatosis

Hereditary hemochromatosis (HHC) is an inherited disorder of iron metabolism affecting approximately 1 in 200-300 individuals of Northern European descent. Over time, the continued deposition of iron in parenchymal cells of many organs can eventually lead to diabetes mellitus, cardiomyopathy, and hepatic cirrhosis, the last of which is frequently followed by hepatocellular carcinoma. Although the complications of HHC can be devastating, its clinical management is simple and effective if the disease is identified early in its progression. The recent elucidation of the HFE gene has provided insight into the pathogenesis of HHC and provided a means for the early identification of individuals in whom HHC may develop. Two mutations have been implicated in HHC: C282Y and H63D, The former occurs in a homozygous state seen in 75-100% of patients with HHC. The high correlation of HFE to HHC has caused it to be considered as a candidate gene for population-based genetic testing for diagnosis and detection of predisposition to HHC. In addition, mechanisms of iron transport and metabolism are unfolding and are providing clues to the enigma of iron homeostasis and the pathophysiology of iron overload, (C) 2001 Lippincott Williams & Wilkins, Inc.

A population-based study of the biochemical and clinical expression of the H63D hemochromatosis mutation

Background & Aims: Two major mutations are defined within the hemochromatosis gene, HFE. Although the effects of the C282Y mutation have been well characterized, the effects of the H63D mutation remain unclear. We accessed a well-defined population in Busselton, Australia, and determined the frequency of the H63D mutation and its influence on total body iron stores. Methods: Serum transferrin saturation and ferritin levels were correlated with the H63D mutation in 2531 unrelated white subjects who did not possess the C282Y mutation. Results: Sixty-two subjects (2.1%) were homozygous for the H63D mutation, 711 (23.6%) were heterozygous, and 1758 (58.4%) were wild-type for the H63D mutation. Serum transferrin saturation was significantly increased in male and female H63D homozygotes and heterozygotes compared with wild-types. Serum ferritin levels within each gender were not influenced by H63D genotypes. Elevated transferrin saturation greater than or equal to45% was observed in a greater proportion of male H63D carriers than male wild-types. Male H63D homozygotes (9%) and heterozygotes (3%) were more likely to have both elevated transferrin saturation and elevated ferritin greater than or equal to300 ng/mL than male wild-types (0.7%). Homozygosity for H63D was not associated with the development of clinically significant iron overload. Conclusions: Presence of the H63D mutation results in a significant increase in serum transferrin saturation but does hot result in significant iron overload. In the absence of the C282Y mutation, the H63D mutation is not clinically significant.

Increased hepcidin expression in multibacillary leprosy

Iron is essential for all organisms and its availability can control the growth of microorganisms; therefore, we examined the role of iron metabolism in multibacillary (MB) leprosy, focusing on the involvement of hepcidin. Erythrograms, iron metabolism parameters, pro-inflammatory cytokines and urinary hepcidin levels were evaluated in patients with MB and matched control subjects. Hepcidin expression in MB lesions was evaluated by quantitative polymerase chain reaction. The expression of ferroportin and hepcidin was evaluated by immunofluorescence in paucibacillary and MB lesions. Analysis of hepcidin protein levels in urine and of hepcidin mRNA and protein levels in leprosy lesions and skin biopsies from healthy control subjects showed elevated hepcidin levels in MB patients. Decreases in haematologic parameters and total iron binding capacity were observed in patients with MB leprosy. Moreover, interleukin-1 beta, ferritin, soluble transferrin receptor and soluble transferrin receptor/log ferritin index values were increased in leprosy patients. Hepcidin was elevated in lepromatous lesions, whereas ferroportin was more abundant in tuberculoid lesions. In addition, hepcidin and ferroportin were not colocalised in the biopsies from leprosy lesions. Anaemia was not commonly observed in patients with MB; however, the observed changes in haematologic parameters indicating altered iron metabolism appeared to result from a mixture of anaemia of inflammation and iron deficiency. Thus, iron sequestration inside host cells might play a role in leprosy by providing an optimal environment for the bacillus.

Eritrograma, metabolismo do ferro e concentração sérica de eritropoetina em fêmeas caprinas da raça Saanen nos períodos de gestação, parto e pós-parto

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Desempenho e estabilidade de parâmetros bioquímicos em materiais de controle líquidos congelados e sólidos liofilizados

Pós-graduação em Biociências e Biotecnologia Aplicadas à Farmácia - FCFAR

Frequência dos mutantes C282Y e H63D do gene HFE e sua influência no metabolismo do ferro e na expressão da beta talassemia heterozigota

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Biodisponibilidade relativa do ferro de fonte orgânica para leitões desmamados

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Influência dos níveis de ferritina sérica, das mutações no gene da beta globina e dos valores das enzimas de detoxificação Catalase e Glutationa S -Transferase na expressão fenotípica de Beta Talassemia Heterozigota

Pós-graduação em Genética - IBILCE

Increased hepcidin expression in multibacillary leprosy

Iron is essential for all organisms and its availability can control the growth of microorganisms; therefore, we examined the role of iron metabolism in multibacillary (MB) leprosy, focusing on the involvement of hepcidin. Erythrograms, iron metabolism parameters, pro-inflammatory cytokines and urinary hepcidin levels were evaluated in patients with MB and matched control subjects. Hepcidin expression in MB lesions was evaluated by quantitative polymerase chain reaction. The expression of ferroportin and hepcidin was evaluated by immunofluorescence in paucibacillary and MB lesions. Analysis of hepcidin protein levels in urine and of hepcidin mRNA and protein levels in leprosy lesions and skin biopsies from healthy control subjects showed elevated hepcidin levels in MB patients. Decreases in haematologic parameters and total iron binding capacity were observed in patients with MB leprosy. Moreover, interleukin-1 beta, ferritin, soluble transferrin receptor and soluble transferrin receptor/log ferritin index values were increased in leprosy patients. Hepcidin was elevated in lepromatous lesions, whereas ferroportin was more abundant in tuberculoid lesions. In addition, hepcidin and ferroportin were not colocalised in the biopsies from leprosy lesions. Anaemia was not commonly observed in patients with MB; however, the observed changes in haematologic parameters indicating altered iron metabolism appeared to result from a mixture of anaemia of inflammation and iron deficiency. Thus, iron sequestration inside host cells might play a role in leprosy by providing an optimal environment for the bacillus.

Proteinuria e sindrome nefrosica nel cane: studio reptrospettivo di 338 casi

La sindrome nefrosica (SN) è definita come la presenza concomitante di una proteinuria maggiore di 3.5g/24 h, ipoalbuminemia, ipercolesterolemia e presenza di edemi. I pazienti con SN sono più a rischio di quelli che presentano una nefropatia glomerulare non nefrosica (NNGD) per lo sviluppo di ipertensione, ipernatremia, complicazioni tromboemboliche e comparsa di insufficienza renale. In Medicina Veterinaria, la Letteratura riguardante l’argomento è molto limitata e non è ben nota la correlazione tra SN e gravità della proteinuria, ipoalbuminemia e sviluppo di tromboembolismo. L’obiettivo del presente studio retrospettivo è stato quello di descrivere e caratterizzare le alterazioni cliniche e clinicopatologiche che si verificano nei pazienti con rapporto proteine urinarie:creatinina urinaria (UPC) >2 con lo scopo di inquadrare con maggiore precisione lo stato clinico di questi pazienti e individuare le maggiori complicazioni a cui possono andare incontro. In un periodo di nove anni sono stati selezionati 338 cani e suddivisi in base ad un valore cut-off di UPC≥3.5. Valori mediani di creatinina, urea, fosforo, albumina urinaria, proteina C reattiva (CRP) e fibrinogeno sono risultati al di sopra del limite superiore dell’intervallo di riferimento, valori mediani di albumina sierica, ematocrito, antitrombina al disotto del limite inferiore di riferimento. Pazienti con UPC≥3.5 hanno mostrato concentrazioni di albumine, ematocrito, calcio, Total Iron Binding Capacity (TIBC), significativamente minori rispetto a quelli con UPC<3.5, concentrazioni di CRP, di urea e di fosforo significativamente maggiori. Nessuna differenza tra i gruppi nelle concentrazioni di creatinina colesterolo, trigliceridi, sodio, potassio, cloro, ferro totale e pressione sistolica. I pazienti con UPC≥3.5 si trovano verosimilmente in uno “stato infiammatorio” maggiore rispetto a quelli con UPC<3.5, questa ipotesi avvalorata dalle concentrazioni minori di albumina, di transferrina e da una concentrazione di CRP maggiore. I pazienti con UPC≥3.5 non presentano concentrazioni di creatinina più elevate ma sono maggiormente a rischio di anemia.