The metalloprotein YhcH is an anomerase providing N-acetylneuraminate aldolase with the open form of its substrate.

N-acetylneuraminate (Neu5Ac), an abundant sugar present in glycans in vertebrates and some bacteria, can be used as an energy source by several prokaryotes, including Escherichia coli. In solution, more than 99% of Neu5Ac is in cyclic form (≈92% beta-anomer and ≈7% alpha-anomer), whereas <0.5% is in the open form. The aldolase that initiates Neu5Ac metabolism in E. coli, NanA, has been reported to act on the alpha-anomer. Surprisingly, when we performed this reaction at pH 6 to minimize spontaneous anomerization, we found NanA and its human homolog NPL preferentially metabolize the open form of this substrate. We tested whether the E. coli Neu5Ac anomerase NanM could promote turnover, finding it stimulated the utilization of both beta and alpha-anomers by NanA in vitro. However, NanM is localized in the periplasmic space and cannot facilitate Neu5Ac metabolism by NanA in the cytoplasm in vivo. We discovered that YhcH, a cytoplasmic protein encoded by many Neu5Ac catabolic operons and belonging to a protein family of unknown function (DUF386), also facilitated Neu5Ac utilization by NanA and NPL and displayed Neu5Ac anomerase activity in vitro. YhcH contains Zn, and its accelerating effect on the aldolase reaction was inhibited by metal chelators. Remarkably, several transition metals accelerated Neu5Ac anomerization in the absence of enzyme. Experiments with E. coli mutants indicated that YhcH expression provides a selective advantage for growth on Neu5Ac. In conclusion, YhcH plays the unprecedented role of providing an aldolase with the preferred unstable open form of its substrate.

Systemic effects and impact on the gut microbiota upon subacute oral exposure to silver acetate in rats.

CONTEXT: The addition of silver (Ag) to food items, and its migration from food packaging and appliances results in a dietary exposure in humans, estimated to 70-90 µg Ag/day. In view of the well-known bactericidal activity of Ag ions, concerns arise about a possible impact of dietary Ag on the gut microbiota (GM), which is a master determinant of human health and diseases. Repeated oral administration of Ag acetate (AgAc) can also cause systemic toxicity in rats with reported NOAELs of 4 mg AgAc/b.w./d for impaired fertility and 0.4 mg AgAc/b.w./d for developmental toxicity. OBJECTIVE: The objective of this study was to investigate whether oral exposure to AgAc can induce GM alterations at doses causing reproductive toxicity in rats. METHODS: Male and female Wistar rats were exposed during 10 weeks to AgAc incorporated into food (0, 0.4, 4 or 40 mg/kg b.w./d), and we analyzed the composition of the GM (α- and ß-diversity). We documented bacterial function by measuring short-chain fatty acid (SCFA) production in cecal content. Ferroxidase activity, a biomarker of systemic Ag toxicity, was measured in serum. RESULTS AND CONCLUSIONS: From 4 mg/kg b.w./d onwards, we recorded systemic toxicity, as indicated by the reduction of serum ferroxidase activity, as well as serum Cu and Se concentrations. This systemic toxic response to AgAc might contribute to explain reprotoxic manifestations. We observed a dose-dependent modification of the GM composition in male rats exposed to AgAc. No impact of AgAc exposure on the production of bacterial SCFA was recorded. The limited GM changes recorded in this study do not appear related to a reprotoxicity outcome.

Reference values of trace elements in blood and/or plasma in adults living in Belgium.

OBJECTIVES: Trace elements (TEs) from natural and anthropogenic sources are ubiquitous. Essential or not, their relevance for human health and disease is constantly expanding. Biological monitoring is a widely integrated tool in risk assessment both in occupational and environmental settings. However, the determination of appropriate and accurate reference values in the (specific) population is a prerequisite for a correct interpretation of biomonitoring data. This study aimed at determining the reference distribution for TEs (Al, As, Sb, Be, Bi, Cd, Co, Cu, Mn, Hg, Mo, Ni, Pb, Se, Tl, Sn, V, Zn) in the blood and/or plasma of the adult population in Belgium. METHODS: Blood and plasma samples were analyzed for 178 males and 202 females, recruited according to an a priori selection procedure, by inductively coupled plasma mass spectrometry (ICP-MS). RESULTS: Reference values were established with high confidence for AsT, Cd, Cu, HgT, Mn, Mo, Pb, Sn, Se, Tl and Zn. Compared to previously published data in the Belgian population, a decreasing time trend is observed for Zn, Cd and Pb. Globally, the results also indicate that the current exposure levels to TEs in the Belgian population are similar to those from other recent national surveys. CONCLUSIONS: These reference values and limits obtained through validated analytical and statistical methods will be useful for future occupational and/or environmental surveys. They will contribute to decision-making concerning both public health policies but also exposure assessments on an individual scale.

Contribution of macrophages in the contrast loss in iron oxide-based MRI cancer cell tracking studies.

Magnetic resonance imaging (MRI) cell tracking of cancer cells labeled with superparamagnetic iron oxides (SPIO) allows visualizing metastatic cells in preclinical models. However, previous works showed that the signal void induced by SPIO on T2(*)-weighted images decreased over time. Here, we aim at characterizing the fate of iron oxide nanoparticles used in cell tracking studies and the role of macrophages in SPIO metabolism.In vivo MRI cell tracking of SPIO positive 4T1 breast cancer cells revealed a quick loss of T2* contrast after injection. We next took advantage of electron paramagnetic resonance (EPR) spectroscopy and inductively coupled plasma mass spectroscopy (ICP-MS) for characterizing the evolution of superparamagnetic and non-superparamagnetic iron pools in 4T1 breast cancer cells and J774 macrophages after SPIO labeling. These in vitro experiments and histology studies performed on 4T1 tumors highlighted the quick degradation of iron oxides by macrophages in SPIO-based cell tracking experiments.In conclusion, the release of SPIO by dying cancer cells and the subsequent uptake of iron oxides by tumor macrophages are limiting factors in MRI cell tracking experiments that plead for the use of (MR) reporter-gene based imaging methods for the long-term tracking of metastatic cells.

Urinary trace element concentrations in environmental settings: is there a value for systematic creatinine adjustment or do we introduce a bias?

Systematic creatinine adjustment of urinary concentrations of biomarkers has been a challenge over the past years because the assumption of a constant creatinine excretion rate appears erroneous and the issue of overadjustment has recently emerged. This study aimed at determining whether systematic creatinine adjustment is to be recommended for urinary concentrations of trace elements (TEs) in environmental settings. Paired 24-h collection and random spot urine samples (spotU) were obtained from 39 volunteers not occupationally exposed to TEs. Four models to express TEs concentration in spotU were tested to predict the 24-h excretion rate of these TEs (TEµg/24h) considered as the gold standard reference: absolute concentration (TEµg/l); ratio to creatinine (TEµg/gcr); TEµg/gcr adjusted to creatinine (TEµg/gcr-adj); and concentration adjusted to specific gravity (TEµg/l-SG). As, Ba, Cd, Co, Cr, Cu, Hg, Li, Mo, Ni, Pb, Sn, Sb, Se, Te, V and Zn were analyzed by inductively coupled argon plasma mass spectrometry. There was no single pattern of relationship between urinary TEs concentrations in spotU and TEµg/24h. TEµg/l predicted TEµg/24h with an explained variance ranging from 0 to 60%. Creatinine adjustment improved the explained variance by an additional 5 to ~60% for many TEs, but with a risk of overadjustment for the most of them. This issue could be addressed by adjusting TE concentrations on the basis of the regression coefficient of the relationship between TEµg/gcr and creatinine concentration. SG adjustment was as suitable as creatinine adjustment to predict TEµg/24h with no SG-overadjustment (except V). Regarding Cd, Cr, Cu, Ni and Te, none of the models were found to reflect TEµg/24h. In the context of environmental exposure, systematic creatinine adjustment is not recommended for urinary concentrations of TEs. SG adjustment appears to be a more reliable alternative. For some TEs, however, neither methods appear suitable.

(89)Zr-labeled anti-endoglin antibody-targeted gold nanoparticles for imaging cancer: implications for future cancer therapy.

AIMS: Antibody-labeled gold nanoparticles represent an attractive tool for cancer imaging and therapy. In this study, the anti-CD105 antibody was conjugated with gold nanoparticles (AuNPs) for the first time. The antibody biodistribution in mice before and after conjugation to AuNPs was studied, with a focus on tumor targeting. MATERIALS & METHODS: Antibodies were radiolabeled with 89Zr before conjugation to AuNPs (5 nm). Immunonanoconjugates were characterized in vitro in terms of size, stability in plasma and binding to the target. Quantitative PET imaging and ICP-MS analysis assessed in vivo distribution and specific tumor targeting of tracers. RESULTS: The tumor uptake of immunoconjugates was preserved up to 24 h after injection, with high tumor contrast and selective tumor targeting. No major tracer accumulation was observed over time in nonspecific organs. ICP-MS analysis confirmed the antibody specificity after nanoparticle conjugation. CONCLUSION: The anti-CD105 antibody conjugation to AuNPs did not greatly affect CD105-dependent tumor uptake and the efficacy of tumor targeting for cancer detection.

Associations of urinary cadmium with age and urinary proteins: further evidence of physiological variations unrelated to metal accumulation and toxicity.

BACKGROUND: The current risk assessment for environmental cadmium (Cd) largely relies on the assumption that urinary Cd (U-Cd) is a reliable biomarker of the Cd body burden. Recent studies have questioned the validity of this assumption. OBJECTIVES: We studied the lifetime trend of U-Cd as a function of diuresis, gender, smoking status, and protein tubular reabsorption. We also analyzed the associations between U-Cd and urinary proteins. METHODS: Cd, retinol-binding protein, and albumin were measured in the urine of six cohorts of the general population of Belgium, with a mean age ranging from 5.7 to 88.1 years (n = 1,567). Variations of U-Cd with age were modeled using natural cubic splines. RESULTS: In both genders, U-Cd decreased to a minimum (~ 0.20 µg/L) at the end of adolescence, then increased until 60-70 years of age (~ 0.60 µg/L in never-smokers) before leveling off or decreasing. When U-Cd was expressed in micrograms per gram of creatinine, these variations were amplified (minimum, 0.15 µg/g creatinine; maximum, 0.70 µg/g creatinine) and much higher U-Cd values were observed in women. We observed no difference in U-Cd levels between never-smokers and former smokers, and the difference with current smokers did not increase over time. Lifetime curves of U-Cd were higher with increasing urinary retinol-binding protein or albumin, a consequence of the coexcretion of Cd with proteins. CONCLUSIONS: At low Cd exposure levels, U-Cd and age are associated through nonlinear and nonmonotonic relationships that appear to be driven mainly by recent Cd intake and physiological variations in the excretion of creatinine and proteins.

Reference values and upper reference limits for 26 trace elements in the urine of adults living in Belgium.

BACKGROUND: Trace elements (TEs) are ubiquitous and their potential interest for human health has been constantly expanding. Biological monitoring is generally considered to be a useful tool to assess human exposure to chemical agents in risk assessment both at occupational and environmental levels. However, the knowledge of accurate reference values, which may vary across countries or regions, is a prerequisite for correct interpretation of biomonitoring data. This study aimed at determining the reference distribution and the upper reference limit for 26 TEs (Al, As, Sb, Ba, Be, Bi, Cd, Cr, Co, Cu, In, Li, Mn, Hg, Mo, Ni, Pd, Pt, Pb, Se, Te, Tl, Sn, U, V, Zn) in the urine of the general adult population residing in Belgium. METHODS: In total, 1022 adults not occupationally or extra-occupationally (mainly via hobbies, drugs) exposed to these TEs were recruited by occupational physicians and toxicologists according to an a priori selection procedure. Non-fasting spot urine samples were analyzed for 460 males and 541 females by inductively coupled plasma mass spectrometry (ICP-MS). Careful control was applied during collection, handling and analyses of the samples to avoid any contamination. RESULTS: Globally, the results indicate that the exposure levels of the Belgian population to these TEs are low and grossly similar to those recently published by other national surveys. CONCLUSIONS: These new reference values and upper reference limits will be useful for future occupational and/or environmental surveys.

Thicker is better? Synthesis and evaluation of well-defined polymer brushes with controllable catalytic loadings.

Polymer brushes (PBs) have been used as supports for the immobilization of palladium complexes on silicon surfaces. The polymers were grown by surface-initiated atom-transfer radical polymerization (SI-ATRP) and postdecorated with dipyridylamine (dpa) ligands. The pendant dpa units were in turn complexed with [Pd(OAc)(2)] to afford hybrid catalytic surfaces. A series of catalytic samples of various thicknesses (ca. 20-160 nm) and associated palladium loadings (ca. 10-45 nmol cm(-2)) were obtained by adjusting the SI-ATRP reaction time and characterized by ellipsometry, X-ray reflectivity, X-ray photoelectron spectroscopy, and inductively coupled plasma mass spectrometry (ICP-MS). ICP-MS revealed a near-linear relationship between thickness of the polymer brush and palladium content, which confirmed the robustness of the preparation and postmodification sequence presented herein, rendering possible the creation of functional architectures with predefined catalytic potential. The activities of the catalytic PBs were determined by systematically exploring a full range of substrate-to-catalyst ratios in a model palladium(0)-catalyzed reaction. Quantitative transformations were observed for loadings down to 0.03 mol % and a maximum turnover number (TON) of around 3500 was established for the system. Comparison of the catalytic performances evidenced a singular influence of the thickness on conversions and TONs. The limited recyclability of the hairy catalysts has been attributed to palladium leaching.

Grafting control of mainstay terpyridine self-assembled monolayers for the preparation of planar silicon surfaces with variable catalytic loadings.

Monolayers of terpyridine-derivatized silanes were self-assembled, with accurately controlled grafting densities, on single-crystal silicon surfaces. Complexation of the resulting terpyridine monolayers with Pd(OAc)(2) afforded a series of catalytic surfaces covering a full range of Pd loadings (0.14-0.85 nmol.cm(-2)) in the aim to explore their impact on catalysis methodically. X-ray reflectivity (XRR), X-ray photoelectron spectroscopy (XPS), and inductively coupled plasma mass spectrometry (ICP-MS) were combined to afford a precise picture of the grafting density, chemical composition, and catalyst loadings of the surfaces investigated here. We report that the control of the terpyridine density and thus the control of catalytic loadings can be achieved through a fine modification of silanization concentrations, which affords surfaces with tunable catalytic activity.

Acute kidney injury following acute liver failure: potential role of systemic cadmium mobilization?

OBJECTIVE: A significant fraction of patients with acute liver failure (ALF) suffer from a concomitant acute kidney injury (AKI), the mechanism of which is probably multifactorial. Cadmium (Cd) is a widespread environmental pollutant and a tubulotoxic metal that accumulates in the liver. We tested the hypothesis that a release of Cd during ALF may cause a redistribution of Cd from the liver to the kidneys and play a role in the occurrence of ALF-associated AKI. METHODS: Twenty patients with ALF (ALF-patients), 20 patients from the ICU with no liver damage at admission (ICU-controls) and 20 healthy controls were recruited to compare the 24-h urinary excretion rate of Cd with that of lead (Pb), a nephrotoxic metal that does not accumulate in the liver, and zinc (Zn), a non-nephrotoxic element found in high amounts in the liver. The excretion rates of the low-molecular-weight proteins (LMWPs) were monitored. RESULTS: ALF-patients excreted markedly more Cd than the healthy controls and ICU-controls. In ALF-patients, the four urinary LMWPs (RBP, ß2-MG, CC16 and α1-MG) increased as a function of Cd excretion, with high correlation coefficients. The prevalence of patients excreting a high amount of LMWPs also increased with increasing Cd excretion. No relationship was found between the other elements investigated and the LMWPs, with the exception of copper, which shares close toxicokinetic similarities with Cd. CONCLUSIONS: This study shows a strong association between urinary Cd levels and the excretion rates of LMWPs in patients with ALF. A causal relationship is possible but could not be fully demonstrated in this study.

Occupational exposure to indium: what does biomonitoring tell us?

BACKGROUND: The industrial uses of indium, a rare metal with no known physiological role in humans, have increased dramatically over the past 15 years. The results of animal toxicity studies showing pulmonary and systemic effects as well as some reports in workers have created a growing concern about the possible occurrence of toxic effects in exposed workers. Validated biomarkers to assess exposure to indium are not available. OBJECTIVES: This work aimed at investigating the kinetics of indium in urine (In-U) and plasma (In-Pl) in workers manufacturing In ingots and mainly exposed to hardly water-soluble In compounds. All nine workers from the In department of a large metallurgical concern participated in the study as well as 5 retired workers and 20 controls. METHODS: Personal breathing zone air was collected throughout the work shift on Monday and Friday. Blood and urine samples were collected, before and after the shift, on the same day as the air sampling and on preshift the next Monday after a non-working week-end. Moreover, rats were given either InCl(3) by intraperitoneal injection or In(2)O(3) by pharyngeal aspiration, In was followed in plasma during 120 days and measured in tissues 120 days after exposure. RESULTS: Higher In-Pl and In-U concentrations were found in both current (range 0.32-12.61 µg/L plasma; 0.22-3.50 µg/g creat) and former (0.03-4.38 µg/L plasma; 0.02-0.69 µg/g creat) workers compared with controls (<0.03 µg/L plasma; <0.02 µg/g creat). Both biological parameters were highly correlated but no correlation was found between In-air (10-1030 µg/m(3)) and In-Pl or In-U. Normalizing In-U by the urinary creatinine concentration reduced the inter- (from 90% to 70%) and intra-individual variability (from 54% to 35%). In-Pl remained remarkably stable along the working week (inter- and intra-individual variability: 89% and 10%, respectively). Neither In-U nor In-Pl significantly increased during the day or the week. A week-end without occupational exposure was not sufficient to reach the background In-Pl and In-U levels measured in controls. The results of the experimental investigations confirmed the hypothesis that inhalation of hardly soluble In compounds may cause accumulation of In in the body leading to a prolonged "endogenous exposure" from both a lung depot of "insoluble" particles that are progressively absorbed and from a retention depot in other internal organs. CONCLUSION: This study shows that in workers exposed to hardly soluble In compounds, In-U and In-Pl are very sensitive to detect exposure and mainly reflect long-term exposure. In-Pl levels are particularly stable for a given individual. In-U might be more influenced than In-Pl by recent exposure. Both parameters remained high years after withdrawal from exposure, indicating a possible endogenous exposure and a prolonged risk of pulmonary and systemic diseases even after work exposure has ceased.

Manganese in plasma: a promising biomarker of exposure to Mn in welders. A pilot study.

BACKGROUND: There is raising concern about the potential neurotoxic effects of manganese (Mn) inhalation exposure in welders. Because most of the airborne particles in welding fume are in the respirable fraction, their bioavailability is likely to be higher than for coarser dust exposure. No well-validated biomarker for Mn exposure is available. OBJECTIVES: To investigate the interest of measuring Mn in plasma (Mn-P) and urine (Mn-U) as biomarkers of exposure in a group of 28 welders whose tasks were only welding-related. METHODS: Ambient air exposure to Mn (Mn-air) was determined by personal full-shift measurements on Monday and Tuesday. On the same days, blood and urine samples were collected before and after the shift. RESULTS: Mn-air varied from 1.3 to 729 µg/m(3) (GM 27.7). For Mn-U 65% of the values in welders were below the LOQ (0.20 µg/L). Compared to controls, the welders' Mn-P averaged 33% higher (1.5 vs 2.0 µg/L). In welders, the after-shift Mn-P values correlated well with Mn-air above 10 µg/m(3). In spite of similar Mn-air exposure on Monday and Tuesday, the relationships between Mn-air and after-shift Mn-P strikingly differed on Tuesday in that the inflection in the relationship was less obvious and the slope of the regression line (Mn-P after-shift/logMn-air) for a doubling of logMn-air was 2.3 times lower than on Monday. On Monday (the first day of the workweek), a Mn-P value of 2 µg/L could distinguish Mn-air exposure above or below 20 µg/m(3) with a sensitivity of 69% and a specificity of 82%. CONCLUSIONS: This preliminary study indicates that Mn-P is a promising biomarker of current exposure to Mn in welders and lends biological plausibility to the intended change for the Mn TLV-TWA of 20 µg/m(3) proposed by ACGIH for respirable Mn particulate.

Stearoyl-CoA desaturase is an essential enzyme for the parasitic protist Trypanosoma brucei.

Trypanosoma brucei, the etiologic agent of sleeping sickness, is exposed to important changes in nutrients and temperature during its life cycle. To adapt to these changes, the fluidity of its membranes plays a crucial role. This fluidity, mediated by the fatty-acid composition, is regulated by enzymes named desaturases. We have previously shown that the oleoyl desaturase is essential for Trypanosoma cruzi and T. brucei. In this work, we present experimental support for the relevance of stearoyl-CoA desaturase (SCD) for T. brucei's survival, in both its insect or procyclic-form (PCF) and bloodstream-form (BSF) stages. We evaluated this essentiality in two different ways: by generating a SCD knocked-down parasite line using RNA interference, and by chemical inhibition of the enzyme with two compounds, Isoxyl and a thiastearate with the sulfur atom at position 10 (10-TS). The effective concentration for 50% growth inhibition (EC(50)) of PCF was 1.0 ± 0.2 µM for Isoxyl and 5 ± 2 µM for 10-TS, whereas BSF appeared more susceptible with EC(50) values 0.10 ± 0.03 µM (Isoxyl) and 1.0 ± 0.6 µM (10-TS). RNA interference showed to be deleterious for both stages of the parasite. In addition, T. brucei-infected mice were fed with Isoxyl, causing a reduction of the parasitemia and an increase of the rodents' survival.

Glycosomal ABC transporters of Trypanosoma brucei: characterisation of their expression, topology and substrate specificity.

Metabolism in trypanosomatids is compartmentalised with major pathways, notably glycolysis, present in peroxisome-like organelles called glycosomes. To date, little information is available about the transport of metabolites through the glycosomal membrane. Previously, three ATP-binding cassette (ABC) transporters, called GAT1-3 for Glycosomal ABC Transporters 1 to 3, have been identified in the glycosomal membrane of Trypanosoma brucei. Here we report that GAT1 and GAT3 are expressed both in bloodstream and procyclic form trypanosomes, whereas GAT2 is mainly or exclusively expressed in bloodstream-form cells. Protease protection experiments showed that the nucleotide-binding domain of GAT1 and GAT3 is exposed to the cytosol, indicating that these transporters mediate the ATP-dependent uptake of solutes from the cytosol into the glycosomal lumen. Depletion of GAT1 and GAT3 by RNA interference in procyclic cells grown in glucose-containing medium did not affect growth. Surprisingly, GAT1 depletion enhanced the expression of the very different GAT3 protein. Expression knockdown of GAT1, but not GAT3, in procyclic cells cultured in glucose-free medium was lethal. Depletion of GAT1 in glucose-grown procyclic cells caused a modification of the total cellular fatty-acid composition. No or only minor changes were observed in the levels of most fatty acids, including oleate (C18:1), nevertheless the linoleate (C18:2) abundance was significantly increased upon GAT1 silencing. Furthermore, glycosomes purified from procyclic wild-type cells incorporate oleoyl-CoA in a concentration- and ATP-dependent manner, whilst this incorporation was severely reduced in glycosomes from cells in which GAT1 levels had been decreased. Together, these results strongly suggest that GAT1 serves to transport primarily oleoyl-CoA, but possibly also other fatty acids, from the cytosol into the glycosomal lumen and that its depletion results in a cellular linoleate accumulation, probably due to the presence of an active oleate desaturase. The role of intraglycosomal oleoyl-CoA and its essentiality when the trypanosomes are grown in the absence of glucose, are discussed.

Genetic and chemical evaluation of Trypanosoma brucei oleate desaturase as a candidate drug target.

BACKGROUND: Trypanosomes can synthesize polyunsaturated fatty acids. Previously, we have shown that they possess stearoyl-CoA desaturase (SCD) and oleate desaturase (OD) to convert stearate (C18) into oleate (C18:1) and linoleate (C18:2), respectively. Here we examine if OD is essential to these parasites. METHODOLOGY: Cultured procyclic (insect-stage) form (PCF) and bloodstream-form (BSF) Trypanosoma brucei cells were treated with 12- and 13-thiastearic acid (12-TS and 13-TS), inhibitors of OD, and the expression of the enzyme was knocked down by RNA interference. The phenotype of these cells was studied. PRINCIPAL FINDINGS: Growth of PCF T. brucei was totally inhibited by 100 µM of 12-TS and 13-TS, with EC(50) values of 40±2 and 30±2 µM, respectively. The BSF was more sensitive, with EC(50) values of 7±3 and 2±1 µM, respectively. This growth phenotype was due to the inhibitory effect of thiastearates on OD and, to a lesser extent, on SCD. The enzyme inhibition caused a drop in total unsaturated fatty-acid level of the cells, with a slight increase in oleate but a drastic decrease in linoleate level, most probably affecting membrane fluidity. After knocking down OD expression in PCF, the linoleate content was notably reduced, whereas that of oleate drastically increased, maintaining the total unsaturated fatty-acid level unchanged. Interestingly, the growth phenotype of the RNAi-induced cells was similar to that found for thiastearate-treated trypanosomes, with the former cells growing twofold slower than the latter ones, indicating that the linoleate content itself and not only fluidity could be essential for normal membrane functionality. A similar deleterious effect was found after RNAi in BSF, even with a mere 8% reduction of OD activity, indicating that its full activity is essential. CONCLUSIONS/SIGNIFICANCE: As OD is essential for trypanosomes and is not present in mammalian cells, it is a promising target for chemotherapy of African trypanosomiasis.

Influence of pancreatic status and sex on polyunsaturated fatty acid profiles in cystic fibrosis.

BACKGROUND: Some but not all studies have reported abnormal polyunsaturated fatty acid composition in cystic fibrosis (CF) patients. We investigated the influence of pancreatic status and sex on the fatty acid profile in plasma and erythrocyte membranes in patients with CF. METHODS: After a 1-step transesterification with acetyl chloride on plasma and washed erythrocyte membranes, we quantified fatty acid methyl esters by use of GC-MS in 124 CF patients and 80 age-matched healthy controls. In the CF group, mean (SD) age was 17.5 (11.3) years, and 51.6% were male. Pancreatic insufficiency was diagnosed in 78% of the CF population. RESULTS: A decrease in docosahexaenoic acid concentrations was observed in CF patients independently of pancreatic status. Pancreatic insufficient CF patients displayed lower concentrations of linoleic acid and arachidonic acid and higher concentrations of dihomo-gamma-linolenic acid and eicosatrienoic acid (mead acid) in plasma and erythrocyte membranes compared with healthy controls and pancreatic sufficient CF patients. Male CF patients had significantly lower docosahexaenoic acid and higher eicosatrienoic acid in plasma and erythrocyte membranes compared with female CF patients. CONCLUSIONS: These results support the concept that multiple abnormalities of polyunsaturated fatty acid composition participate in the CF disease phenotype and that pancreatic status plays a major role in such abnormalities. Moreover, patient sex influences the polyunsaturated fatty acid spectrum in CF, with more marked abnormalities in males.