Oxidative stress enhances the expression of sulfur assimilation genes: preliminary insights on the Enterococcus faecalis iron-sulfur cluster machinery regulation

The Firmicutes bacteria participate extensively in virulence and pathological processes. Enterococcus faecalis is a commensal microorganism; however, it is also a pathogenic bacterium mainly associated with nosocomial infections in immunocompromised patients. Iron-sulfur [Fe-S] clusters are inorganic prosthetic groups involved in diverse biological processes, whose in vivo formation requires several specific protein machineries. Escherichia coli is one of the most frequently studied microorganisms regarding [Fe-S] cluster biogenesis and encodes the iron-sulfur cluster and sulfur assimilation systems. In Firmicutes species, a unique operon composed of the sufCDSUB genes is responsible for [Fe-S] cluster biogenesis. The aim of this study was to investigate the potential of the E. faecalis sufCDSUB system in the [Fe-S] cluster assembly using oxidative stress and iron depletion as adverse growth conditions. Quantitative real-time polymerase chain reaction demonstrated, for the first time, that Gram-positive bacteria possess an OxyR component responsive to oxidative stress conditions, as fully described for E. coli models. Likewise, strong expression of the sufCDSUB genes was observed in low concentrations of hydrogen peroxide, indicating that the lowest concentration of oxygen free radicals inside cells, known to be highly damaging to [Fe-S] clusters, is sufficient to trigger the transcriptional machinery for prompt replacement of [Fe-S] clusters.

Repeat Blood Donors and Iron Deficiency Anemia / 대한수혈학회지

Recently, there is a growing concern for loss of iron among repeat blood donors. We evaluated the effects of blood donation to iron deficiency in several studies and propose following measures to prevent iron depletion among repeat blood donors. We reviewed and analyzed comprehensively results of several domestic and foreign studies and cited Korean blood donor's statistics data. There is a high prevalence of iron depletion in repeat blood donors. Predictors of iron depletion (serum ferritin <12~15 ng/mL) included a high frequency of blood donation, short donation interval, and female gender regardless of blood donation type. Taking iron supplements reduced the risk of iron depletion for repeat blood donors. We would like to propose the following preventive measures for repeat blood donors. 1) Test for serum ferritin for repeat donors who donate at least three times per year. If the donors show low serum ferritin level which is below 15 ng/mL, 2) Increase the donation interval or limit of blood donation frequency and 3) Recommend iron supplement for a certain period.

Establishment of Reference Range of Serum Ferritin by Turbidimetric Immunoassay in Korean First Time Blood Donors / 대한수혈학회지

BACKGROUND: Regular blood donation can lead to iron deficiency. Serum ferritin is sensitive indicator of body iron depletion. The aim of this study is to evaluate serum ferritin reagents using the turbidimetric immunoassay (TIA) and to establish a reference range in first time blood donors in Korea. METHODS: The study was prospectively conducted, between Feb. 2011 and Apr. 2011, on 120 male and 120 female blood donors at five blood centers. Serum ferritin was determined by TIA using two brands of reagents (Beckman Coulter Inc., USA; HBi, South Korea) and two automated chemistry analyzers (AU640, Beckman Coulter Inc.; Hitachi7180, Hitachi High-Technologies Corp., Japan). Precision, linearity, limit of detection, analytical measurement range and correlation with chemiluminescent immunoassay (CLIA) were evaluated. A reference range for serum ferritin in first time donors was established. RESULTS: The coefficients of variation of precision were less than 4%. Linearity was observed up to 312.7~450 microg/L depending on which reagent used. Both reagents had good correlation with CLIA results. Serum ferritin levels for first time donors showed left skewed distribution. The reference ranges for males and females were 34.1~385.9 microg/L and 6.8~121 microg/L using Beckman Coulter (AU) reagent, and 18.7~271.3 microg/L and 4~83.7 microg/L using HBi (AU) reagent, and 15.2~274.7 microg/L and 6~84 microg/L using HBi (Hitachi) reagent. CONCLUSION: A reference range for serum ferritin in first time donors in Korea was established using automated chemistry analyzers with inexpensive TIA reagents.

The prevalence of anemia and iron depletion in the population aged 10 years or older

BACKGROUND: Anemia and iron depletion continue to be common disorders in the world. This study was aimed at assessing the prevalence of anemia and iron depletion in apparently healthy Koreans aged 10 years or more. METHODS: We used the data of the 4th Korean National Health & Nutrition Examination Survey (KNHANES), which assessed 7,607 individuals (3,337 males and 4,270 females). Iron depletion was defined as serum ferritin less than 15 ng/mL. RESULTS: In males, mean hemoglobin (Hb) concentration decreased after the age of 50. The prevalence of anemia was 7.1% in 60 to 69 year olds and 12.3% in men aged 70 or older. As for females, the prevalence of anemia was 8.8% in 15 to 17 year olds, 16.7% in 18 to 49 year olds, 10.9% in 60 to 69 year olds, and 18.2% women aged 70 or older. In males, the prevalence of iron depletion was 8.6% at ages 10 to 14 years, 3.9% at 15 to 17, and 2.6% at 70 years or older. In females, the prevalence of iron depletion was 17.2% at ages 10 to 14 years, 24.1% at 15 to 17, 33.0% at 18 to 49, and 5.7% at 70 years or older. Although normocytic anemia was most common in both males and females, the proportion of microcytosis and macrocytosis increased at age 70 or older. CONCLUSION: The prevalence of anemia and iron depletion was high in women of reproductive age and in the elderly. Considering the rapid increase in the older population, an intervention to prevent anemia and iron depletion is imperative.

Variation in the molecular weight of Photobacterium damselae subsp. piscicida antigens when cultured under different conditions in vitro

The antigenicity of Photobacterium damselae (Ph. d.)subsp. piscicida, cultured in four different growth media[tryptone soya broth (TSB), glucose-rich medium (GRM),iron-depleted TSB (TSB+IR-), and iron-depleted GRM(GRM+IR-)] was compared by enzyme-linked immuno-sorbent assay (ELISA) and Western blot analysis usingsera obtained from sea bass (Dicentrarchus labrax) raisedagainst live or heat-killed Ph. d. subsp. piscicida. Theantigenic expression of Ph. d. subsp. piscicida was found todiffer depending on the culture medium used. A significantlyhigher antibody response was obtained with iron-depletedbacteria by ELISA compared with non-iron depletedbacteria obtained from the sera of sea bass raised againstlive Ph. d. subsp. piscicida. The sera from sea bass raisedagainst live bacteria showed a band at 22kDa in bacteriacultured in TSB+IR- or GRM+IR- when bacteria thathad been freshly isolated from fish were used for thescreening, while bands at 24 and 47kDa were observedwith bacteria cultured in TSB or GRM. When bacteriawere passaged several times on tryptic soya agar prior toculturing in the four different media, only bands at 24 and47kDa were recognized, regardless of the medium used toculture the bacteria. It would appear that the molecularweight of Ph. d. subsp. piscicida antigens change in thepresence of iron restriction, and sera from sea bassinfected with live bacteria are able to detect epitopes onthe antigens after this shift in molecular weight.

A study of iron depletion prophylaxis by the use of iron-containing formulas

This is a preliminary report actually based on observations of 48 infants in the present stage of the study. The results suggest strongly that milk with iron preparations given to infants from birth might play an important role in iron depletion prophylaxis. (Conclusion)