State-of-the-art model for derivation of analytical performance specifications: how to define the highest level of analytical performance technically achievable.

To be accurate and equivalent among assays, laboratory results should be traceable to higher-order references and their quality should fulfill maximum allowable measurement uncertainty (MU) as defined to fit the intended clinical use. Accordingly, laboratory professionals should estimate and validate MU of performed tests using appropriate analytical performance specifications (APS). Current consensus supports the derivation of APS by using one of the three models established by the European Federation of Clinical Chemistry and Laboratory Medicine (EFLM) Strategic Conference held in Milan in 2014. It is recognized that some models are better suited for certain measurands than for others and the attention should be primarily directed towards their biological and clinical characteristics. Among others, model 3 should reflect the state of the art of the measurements that can be defined as the best analytical performance that is technically achievable. Taking serum C-reactive protein and ferritin as examples, here we describe the theoretical premises and the experimental protocol to be used to derive APS for MU when a measurand is allocated to this model. Although the model lacks a direct relationship with clinical outcomes, useful information about the in vitro diagnostic medical device performance and the average quality of provided results may be obtained.

Nasal exudate for diagnosis of stroke: fundamental studies through iron fractionation, total iron, and targeted protein determinations.

During the last years, there has been an increasing research interest in the analysis of biological fluids requiring non-invasive sampling for biomedical and clinical applications. In this work, we have focused on the nasal exudate with the aim of investigating the potential use of this fluid to know the role of iron in stroke and also for diagnosis. Potential differences in the nasal exudate, collected in swabs, from diagnosed hemorrhagic stroke, ischemic stroke, and control groups were investigated with regard to total iron by inductively coupled plasma-mass spectrometry, iron fractionation studies by size exclusion chromatography together with post-column isotope dilution analysis, and four proteins containing iron (ferritin, transferrin, lactoferrin, and ferroportin) with ELISA kits. All these analyses represent an analytical challenge, considering the rather limited amount of sample (10-40 mg) available, being the nasal exudate extracted from the swab with 300 µL 10 mM Tris/HCl, pH = 7.4. Studies to obtain reliable analytical information, such as the blank contribution of the sampling step, evaluation of the extraction efficiency of the nasal exudate from the swab, and normalization strategies for data treatment, have been carried out. Results showed that despite the limited number of investigated samples, fractionation studies as well as the concentrations of ferritin and ferroportin obtained with ELISA kits showed a differential behavior between the different cohorts.

Iron deficiency and fatigue among adolescents with bleeding disorders.

Iron deficiency anemia is associated with heavy menstrual bleeding (HMB) and, by extension, a bleeding disorder (BD). It is unknown if iron deficiency without anemia is associated with a BD in adolescents. Moreover, the threshold of ferritin associated with fatigue in adolescents with HMB is unclear. In this multicenter study, we enrolled adolescents with HMB without BD. Participants underwent BD and anemia work-up in Young Women's Hematology Clinics and completed the Peds QL™ fatigue scale. BDs were defined as von Willebrand Disease, platelet function defect, clotting factor deficiencies, and hypermobility syndrome. Two hundred and fifty consecutive adolescents were enrolled, of whom 196 met eligibility criteria. Overall, 43% (95% confidence interval: 36%-50%) were diagnosed with BD. A total of 61% (n = 119) had serum ferritin levels < 15 ng/mL, 23.5% (n = 46) had iron deficiency only, and 37% (n = 73) had iron deficiency anemia. Low ferritin or ferritin dichotomized as < 15 or ≥ 15 ng/mL was not associated with BD on univariable analysis (p = .24) or when accounting for age, race, ethnicity, body mass index, and hemoglobin (p = .35). A total of 85% had total fatigue score below the population mean of 80.5, and 52% (n = 102) were > 2 SD (or < 54) below the mean, the cut-off associated with severe fatigue. A ferritin threshold of < 6 ng/mL had a specificity of 79.8% but a sensitivity of 36% for severe fatigue. In conclusion, iron deficiency without anemia is not a predictor of BD in adolescents with HMB in a specialty setting. Severe fatigue, especially sleep fatigue, is prevalent in adolescents with BD. Ferritin of < 6 ng/mL has ~80% specificity for severe fatigue in adolescents with HMB.

Excess iron promotes emergence of foamy macrophages that overexpress ferritin in the lungs of silicosis patients.

BACKGROUND AND OBJECTIVE: Inhalation of high concentrations of respirable crystalline silica (RCS) can lead to silicosis. RCS contains varying levels of iron, which can cause oxidative stress and stimulate ferritin production. This study evaluated iron-related and inflammatory markers in control and silicosis patients. METHODS: A cohort of stone benchtop industry workers (n = 18) were radiologically classified by disease severity into simple or complicated silicosis. Peripheral blood and bronchoalveolar lavage (BAL) were collected to measure iron, ferritin, C-reactive protein, serum amyloid A and serum silicon levels. Ferritin subunit expression in BAL and transbronchial biopsies was analysed by reverse transcription quantitative PCR. Lipid accumulation in BAL macrophages was assessed by Oil Red O staining. RESULTS: Serum iron levels were significantly elevated in patients with silicosis, with a strong positive association with serum ferritin levels. In contrast, markers of systemic inflammation were not increased in silicosis patients. Serum silicon levels were significantly elevated in complicated disease. BAL macrophages from silicosis patients were morphologically consistent with lipid-laden foamy macrophages. Ferritin light chain (FTL) mRNA expression in BAL macrophages was also significantly elevated in simple silicosis patients and correlated with systemic ferritin. CONCLUSION: Our findings suggest that elevated iron levels during the early phases of silicosis increase FTL expression in BAL macrophages, which drives elevated BAL and serum ferritin levels. Excess iron and ferritin were also associated with the emergence of a foamy BAL macrophage phenotype. Ferritin may represent an early disease marker for silicosis, where increased levels are independent of inflammation and may contribute to fibrotic lung remodelling.

Clinical and prognostic significance of elevated ferritin levels in hospitalised adults.

PURPOSE OF THE STUDY: Elevated ferritin levels are associated with a variety of infectious, malignant and inflammatory diseases. We aimed to investigate the prognostic value of markedly elevated ferritin levels in hospitalised patients with various medical conditions. STUDY DESIGN: Retrospective analysis of patients with a ferritin level higher than 2000 ng/mL hospitalised in Sheba Medical Center between 1 January 2007 and 31 December 2015. Medical conditions of these patients were recorded. In-hospital, 30-day and 1-year mortality rates were evaluated according to ferritin ranges and clinical categories. RESULTS: The study included 722 patients (63.4% men) with a mean age of 63.9±16.7 years. The most common clinical conditions associated with markedly elevated ferritin were infectious diseases and malignancies. The highest mean ferritin levels were associated with rheumatological/inflammatory conditions (16 241.3 ng/dL), particularly in patients with macrophage activation syndrome (MAS) (96 615.5 ng/dL). In-hospital, 30-day and 1-year mortality rates were 32.3%, 46.7% and 70.8%, respectively. The highest in-hospital, 30-day and 1-year mortality rates were observed among patients with solid malignancies (40.1%, 64.7% and 90.3%, respectively), whereas the lowest rates were found among patients with rheumatological/inflammatory conditions, including MAS (21.4%, 38.1% and 45.2%, respectively). Ferritin levels were not associated with mortality. CONCLUSIONS: In hospitalised patients, ferritin levels higher than 2000 ng/mL are mainly associated with infectious and malignant diseases but do not predict mortality.

Can ferritin/lymphocyte percentage ratio, a new indicator, predict the clinical course of COVID-19 cases?

OBJECTIVES: COVID-19 maintains its seriousness as a global emergency with its rapid distribution worldwide. Ferritin / lymphocyte percentage ratio (FLPR) may appear as a prognostic value at the initial evaluation stage and thus can be used as a simple, effective, and reliable parameter in critical patient identification with COVID-19. METHODS: In this retrospective cohort study, we evaluated patients over 18 years old, who were hospitalized after being evaluated as COVID-19 and whose PCR results were positive. We calculated FLPRs from complete blood counts taken during emergency department admissions and classified disease severity due to emergency initial evaluation. The relationship between the severity of the thoracic tomography findings, hospitalization, and intensive care needs, and 28-day mortality with the FLPR were evaluated. RESULTS: The difference between the groups classified according to COVID-19 severity and the FLPR means was statistically significant (x2=148.284; SD=3; p=0.000). FLPR levels were found to be high in critical and serious groups. In the ROC analysis for the FLPR level, the area under the curve (AUC) value was found to be 0.909 (95% CI 0.857-0.961). When the cut off value of FLPR was 9.80, the sensitivity was found to be 97.6 %, and the specificity was 65.2 %, whereas, when the cut off value for FLPR was found to be 21.11, the sensitivity was 82.9 % and the specificity was 82.8 %. CONCLUSION: The FLPR, a new parameter, can be used as a significant marker to predict the 28-day mortality in patients (Tab. 5, Fig. 1, Ref. 25).

Measuring the iron content of dopaminergic neurons in substantia nigra with MRI relaxometry.

In Parkinson's disease, the depletion of iron-rich dopaminergic neurons in nigrosome 1 of the substantia nigra precedes motor symptoms by two decades. Methods capable of monitoring this neuronal depletion, at an early disease stage, are needed for early diagnosis and treatment monitoring. Magnetic resonance imaging (MRI) is particularly suitable for this task due to its sensitivity to tissue microstructure and in particular, to iron. However, the exact mechanisms of MRI contrast in the substantia nigra are not well understood, hindering the development of powerful biomarkers. In the present report, we illuminate the contrast mechanisms in gradient and spin echo MR images in human nigrosome 1 by combining quantitative 3D iron histology and biophysical modeling with quantitative MRI on post mortem human brain tissue. We show that the dominant contribution to the effective transverse relaxation rate (R2*) in nigrosome 1 originates from iron accumulated in the neuromelanin of dopaminergic neurons. This contribution is appropriately described by a static dephasing approximation of the MRI signal. We demonstrate that the R2* contribution from dopaminergic neurons reflects the product of cell density and cellular iron concentration. These results demonstrate that the in vivo monitoring of neuronal density and iron in nigrosome 1 may be feasible with MRI and provide directions for the development of biomarkers for an early detection of dopaminergic neuron depletion in Parkinson's disease.

Identification of novel yolk ferritins unique to planarians: planarians supply aluminum rather than iron to vitellaria in egg capsules.

All animals, other than Platyhelminthes, produce eggs containing yolk, referred to as "entolecithal" eggs. However, only Neoophora, in the phylum Platyhelminthes, produce "ectolecithal" eggs (egg capsules), in which yolk is stored in the vitelline cells surrounding oocytes. Vitelline cells are derived from vitellaria (yolk glands). Vitellaria are important reproductive organs that may be studied to elucidate unique mechanisms that have been evolutionarily conserved within Platyhelminthes. Currently, only limited molecular level information is available on vitellaria. The current study identified major vitellaria-specific proteins in a freshwater planarian, Dugesia ryukyuensis, using peptide mass fingerprinting (PMF) and expression analyses. Amino acid sequence analysis and orthology analysis via OrthoFinder ver.2.3.8 indicated that the identified major vitellaria-specific novel yolk ferritins were conserved in planarians (Tricladida). Because ferritins play an important role in Fe (iron) storage, we examined the metal elements contained in vitellaria and ectolecithal eggs, using non-heme iron histochemistry, elemental analysis based on inductively coupled plasma mass spectrometry and transmission electron microscopy- energy-dispersive X-ray spectroscopy analysis. Interestingly, vitellaria and egg capsules contained large amounts of aluminum (Al), but not Fe. The knockdown of the yolk ferritin genes caused a decrease in the volume of egg capsules, abnormality in juveniles, and increase in Al content in vitellaria. Yolk ferritins of D. ryukyuensis may regulate Al concentration in vitellaria via their pooling function of Al and protect the egg capsule production and normal embryogenesis from Al toxicity.

Demographic, clinical, and biochemical predictors of pica in a large cohort of blood donors.

BACKGROUND: Pica is characterized as repeatedly eating or chewing a non-nutritious substance including, but not limited to ice, clay and dirt, starch, raw pasta, chalk, coal, paint, or paper. Pica symptoms can be intense and addiction-like and disrupt quality of life. It is strongly linked to iron deficiency. Since substantial iron loss occurs during blood donation, blood donors may be susceptible to development of pica behaviors. METHODS: We investigated demographic, clinical, hematological, and biochemical factors associated with pica using univariable and multivariable logistic regression analysis in a cohort of 11,418 racially diverse blood donors. Pica was defined by questionnaire responses as consuming at least 8 oz of ice daily and/or consumption of non-ice substances regardless of the amount and frequency. RESULTS: Pica was present in 2.2% of the donors. The sensitivity and specificity of pica in iron-deficient donors were 36% and 82%, respectively. Lower ferritin (p = .001), non-Asian race (p < .001), higher red cell distribution width (p < .001), younger age, and restless legs syndrome (p = .008) were independently associated with pica. Female sex is associated with iron deficiency but was not an independent predictor of pica suggesting that iron deficient males and females were equally susceptible to the development of pica behaviors. Donors with normal ferritin levels also reported pica, reinforcing the role of non-iron related factors in its presentation. CONCLUSIONS: We have identified demographic, clinical, and biochemical predictors of pica that help identify those most at risk for developing pica behaviors, and thereby assist in its clinical diagnosis and treatment.

The effect of curcumin on serum copper, zinc, and zinc/copper ratio in patients with ß-thalassemia intermedia: a randomized double-blind clinical trial.

Thalassemia intermedia is a subgroup of ß-thalassemia which originates from mutations in the beta-globin gene. Zinc and copper play important roles in the metabolism. Due to its significant therapeutic effects, curcumin has led many studies to focus on curcumin. In a double-blind clinical trial study, 30 patients with beta-thalassemia intermedia with an age range of 20 to 35 years were randomly selected 1:1 to receive either curcumin or placebo for 3 months. Before and after the intervention period, 5 ml of blood was taken to determine the serum levels of zinc and copper. The laboratory tests were checked at baseline and at the end of the treatment. While the serum levels of zinc and zinc/copper significantly increased, the serum levels of copper decreased after 3 months of curcumin intake. In addition, on the basis of baseline characteristics, a negative correlation was found between zinc and body mass index and positive correlations were identified between copper with triglyceride and high-density lipoprotein. Also, the level of ferritin protein in the curcumin group compared to the placebo group showed a significant decrease after 3 months of curcumin use. Therefore, it could be concluded that curcumin might exert a net protective effect on copper toxicity in thalassemia intermedia patients. The investigation also implicated that curcumin represents an approach to regulating zinc homeostasis and may be useful as a complementary treatment of patients with thalassemia intermedia, especially in patients with zinc deficiency or low serum zinc/copper ratio. Clinical Trial Registration Number: IRCT20190902044668N1.

Extracellular vesicles from thalassemia patients carry iron-containing ferritin and hemichrome that promote cardiac cell proliferation.

Extracellular vesicles (EVs) are bioactive, submicron-sized membrane vesicles released from all cell types upon activation or apoptosis. EVs including microparticles (MPs) and exosomes have emerged as important mediators of cell-to-cell communication in both normal and pathological states including thalassemia (thal). However, the role of EVs derived from ß-thal patients with iron overload (+ IO) and without iron overload (-IO) on cardiac cells is unclear. We hypothesized plasma EVs in thal patients containing ferritin (iron storage protein) and a denaturated hemoglobin-hemichrome that induce cardiac cell proliferation. The origins and numbers of EVs isolated from plasma of normal, thal (+ IO), and (- IO) patients were compared and determined for their iron and iron-containing proteins along with their effects on cardiac and endothelial cells. Data shows that MPs were originated from many cell sources with marked numbers of platelet origin. Only the number of RBC-derived MPs in thal (+ IO) patients was significantly high when compared to normal controls. Although MPs derived from both normal and thal patients promoted cardiac cell proliferation in a dose-dependent manner, only exosomes from thal patients promoted cardiac cell proliferation compared to the untreated. Moreover, the exosomes from thal (+ IO) potentially induce higher cardiac cell proliferation and angiogenesis in terms of tube number than thal (- IO) and normal controls. Interestingly, ferritin content in the exosomes isolated from thal (+ IO) was higher than that found in the MPs isolated from the same patient. The exosomes of thal patients with higher serum ferritin level also contained greater level of ferritin inside the exosomes. Apart from ferritin, there were trends of increasing hemichrome and iron presented in the plasma EVs and EV-treated H9C2 cells. Findings from this study support the hypothesis that EVs from ß-thal patients carry iron-load proteins that leads to the induction of cardiac cell proliferation.

Post-transplant ferritin level predicts outcomes after allogeneic hematopoietic stem cell transplant, independent from pre-transplant ferritin level.

Allogeneic hematopoietic stem cell transplantation (HCT) is associated with significant morbidity and mortality. Elevated pre-transplant ferritin level (ferritinPre-HCT) is reported to be associated with increased mortality following HCT. The present study attempted to determine whether post-transplant ferritin level (ferritinPost-HCT) is associated with outcomes post-HCT, especially in the subgroups which developed acute or chronic graft-versus-host disease (GVHD). Out of 229 patients with serum ferritin level measured post-HCT, median ferritinPost-HCT was 2178 ng/mL. Patients were stratified into low- or high-risk groups using recursive partitioning, based on ferritinPost-HCT (≤ 3169 vs > 3169 ng/mL) and ferritinPre-HCT (≤ 669 vs > 669 ng/mL). Compared to the low ferritinPost-HCT group, the high ferritinPost-HCT group had lower 3-year overall survival (OS) (40.0% vs 66.7%, p < 0.001) and higher non-relapse mortality (NRM) (48.6% vs 17.8%, p < 0.001), but no difference in relapse (10.5% vs 19.7%, p = 0.079). Multivariate analysis confirmed ferritinPost-HCT as an independent prognostic factor for OS (p = 0.001, HR = 2.323) and NRM (p < 0.001, HR = 3.905). However, ferritinPre-HCT did not stratify well for OS or NRM. FerritinPost-HCT was also found to be an independent prognostic marker for OS and NRM in the subgroups which developed GVHD. In our cohort, high ferritinPost-HCT levels were significantly associated with decreased OS and increased NRM independent of ferritinPre-HCT or GVHD. Additional studies including larger sample sizes and prospective investigation are warranted to clarify the prognostic significance and pathophysiology of pre- and post-transplant hyperferritinemia.

Prevalence, correlates and outcomes of absolute and functional iron deficiency anemia in nondialysis-dependent chronic kidney disease.

BACKGROUND: Anemia is associated with adverse outcomes in those with chronic kidney disease (CKD). We examined the association of absolute and functional iron deficiency anemia (IDA) with adverse outcomes (cardiovascular hospitalization, dialysis and mortality) in those with nondialysis-dependent CKD. METHODS: Nondialysis-dependent CKD patients followed in the US Veterans Administration with hemoglobin level measured within 90 days of the date of the second estimated glomerular filtration rate <60 mL/min/1.73 m2 were included. Logistic regression, multivariate Cox proportional hazards and Poisson regression models adjusted for demographics and comorbidities were used to assess the prevalence and correlates of absolute [transferrin saturation (TSAT) ≤20%, ferritin <100 ng/mL] and functional (TSA T≤20%, ferritin >100-500 ng/mL) IDA and the associations of absolute and functional IDA with mortality, dialysis and cardiovascular hospitalization. RESULTS: Of 933 463 patients with CKD, 20.6% had anemia. Among those with anemia, 23.6% of patients had both TSAT and ferritin level measured, of whom 30% had absolute IDA and 19% had functional IDA. Absolute IDA in CKD was not associated with an increased risk of mortality or dialysis but was associated with a higher risk of 1-year {risk ratio [RR] 1.20 [95% confidence interval (CI) 1.12-1.28]} and 2-year cardiovascular hospitalization [RR 1.11 (95% CI 1.05-1.17)]. CKD patients with functional IDA had a higher risk of mortality [hazard ratio (HR) 1.11 (95% CI 1.07-1.14)] along with a higher risk of 1-year [RR 1.21 (95% CI 1.1-1.30)] and 2-year cardiovascular hospitalization [RR 1.13 (95% CI 1.07-1.21)]. Ferritin >500 ng/mL (treated as a separate category) was only associated with an increased risk of mortality [HR 1.38 (95% CI 1.26-1.51)]. CONCLUSIONS: In a large population of CKD patients with anemia, absolute and functional IDA were associated with various clinical covariates. Functional IDA was associated with an increased risk of mortality and cardiovascular hospitalization, but absolute IDA was associated only with a higher risk of hospitalization.

Myelodysplastic syndromes with ring sideroblasts (MDS-RS) and MDS/myeloproliferative neoplasm with RS and thrombocytosis (MDS/MPN-RS-T) - "2021 update on diagnosis, risk-stratification, and management".

DISEASE OVERVIEW: Ring sideroblasts (RS) are erythroid precursors with abnormal perinuclear mitochondrial iron accumulation. Two myeloid neoplasms defined by the presence of RS, include myelodysplastic syndromes with RS (MDS-RS) and MDS/myeloproliferative neoplasm with RS and thrombocytosis (MDS/MPN-RS-T). DIAGNOSIS: MDS-RS is a lower risk MDS, with single or multilineage dysplasia (MDS-RS-SLD/MLD), <5% bone marrow (BM) blasts, <1% peripheral blood blasts and ≥15% BM RS (≥5% in the presence of SF3B1 mutations). MDS/MPN-RS-T, now a formal entity in the MDS/MPN overlap syndromes, has diagnostic features of MDS-RS-SLD, along with a platelet count ≥450 × 109 /L and large atypical megakaryocytes. MUTATIONS AND KARYOTYPE: Mutations in SF3B1 are seen in ≥80% of patients with MDS-RS-SLD and MDS/MPN-RS-T, and strongly correlate with the presence of BM RS; MDS/MPN-RS-T patients also demonstrate JAK2V617F (50%), DNMT3A, TET2 and ASXL1 mutations. Cytogenetic abnormalities are uncommon in both. RISK STRATIFICATION: Most patients with MDS-RS-SLD are stratified into lower risk groups by the revised-IPSS. Disease outcome in MDS/MPN-RS-T is better than that of MDS-RS-SLD, but worse than that of essential thrombocythemia (MPN). Both diseases are associated with a low risk of leukemic transformation. TREATMENT: Anemia and iron overload are complications seen in both and are managed similar to lower risk MDS and MPN. Luspatercept, a first-in-class erythroid maturation agent is now approved for the management of anemia in patients with MDS-RS and MDS/MPN-RS-T. Aspirin therapy is reasonable in MDS/MPN-RS-T, especially in the presence of JAK2V617F, but the value of platelet-lowering drugs remains to be defined.

JAK/STAT Pathway Inhibition May Be a Promising Therapy for COVID-19-Related Hyperinflammation in Hematologic Patients.

COVID-19 has rapidly become a major concern for the health systems worldwide. Its high contagiousness and associated mortality demand the discovery of helpful interventions with promising safety profile. Here, we report 3 severe COVID-19 cases, which achieved rapid and sustained improvement in outcome with the use of ruxolitinib, a JAK/STAT pathway inhibitor.

A cutoff value for the Systemic Immune-Inflammation Index in determining activity of Behçet disease.

BACKGROUND: Behçet disease (BD) is an immune-mediated vasculitis-like syndrome characterized by recurrent aphthous lesions and various systemic manifestations. Inflammatory markers may be useful to assess disease severity. The Systemic Immune-Inflammation Index (SII) (neutrophils × platelets/lymphocytes) has been widely used in oncology since 2014, with promising results. AIM: To assess the efficiency of the SII in determining activity of BD. METHODS: This retrospective cohort study was conducted on patients with BD who were admitted to the outpatient clinic of the Department of Dermatology and Venereology, Ufuk University Hospital, between 1 January 2010 and 31 December 2019. Patients were divided into two groups based on their disease status upon admission: (i) active BD (n = 103), and (ii) inactive BD (n = 63). Clinical characteristics, demographic features, type of medications, full blood count parameters, erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), ferritin and SII were compared between the groups. Furthermore, receiver operating characteristic curve analysis was performed to assess the performance of the SII in determining disease severity upon admission to hospital. RESULTS: Higher numbers of white blood cells, platelets and neutrophils, greater red cell distribution width, higher levels of ESR, CRP and ferritin, and higher SII were observed in the active disease group (P < 0.001). The cutoff value of 552 × 103 /mm3 was found to have 81% sensitivity and 82% specificity. CONCLUSION: The SII may be used as an additional indicator for the assessment of BD status and physicians should be cautious in patients with SII levels of > 552 × 103 /mm3 ) at the initial evaluation of the patients.

Longitudinal and Transverse Relaxivity Analysis of Native Ferritin and Magnetoferritin at 7 T MRI.

Magnetite mineralization in human tissue is associated with various pathological processes, especially neurodegenerative disorders. Ferritin's mineral core is believed to be a precursor of magnetite mineralization. Magnetoferritin (MF) was prepared with different iron loading factors (LFs) as a model system for pathological ferritin to analyze its MRI relaxivity properties compared to those of native ferritin (NF). The results revealed that MF differs statistically significantly from NF, with the same LF, for all studied relaxation parameters at 7 T: r1, r2, r2*, r2/r1, r2*/r1. Distinguishability of MF from NF may be useful in non-invasive MRI diagnosis of pathological processes associated with iron accumulation and magnetite mineralization (e.g., neurodegenerative disorders, cancer, and diseases of the heart, lung and liver). In addition, it was found that MF samples possess very strong correlation and MF's relaxivity is linearly dependent on the LF, and the transverse and longitudinal ratios r2/r1 and r2*/r1 possess complementary information. This is useful in eliminating false-positive hypointensive artefacts and diagnosis of the different stages of pathology. These findings could contribute to the exploitation of MRI techniques in the non-invasive diagnosis of iron-related pathological processes in human tissue.

Predicting the Shapes of Protein Complexes through Collision Cross Section Measurements and Database Searches.

In structural biology, collision cross sections (CCSs) from ion mobility mass spectrometry (IM-MS) measurements are routinely compared to computationally or experimentally derived protein structures. Here, we investigate whether CCS data can inform about the shape of a protein in the absence of specific reference structures. Analysis of the proteins in the CCS database shows that protein complexes with low apparent densities are structurally more diverse than those with a high apparent density. Although assigning protein shapes purely on CCS data is not possible, we find that we can distinguish oblate- and prolate-shaped protein complexes by using the CCS, molecular weight, and oligomeric states to mine the Protein Data Bank (PDB) for potentially similar protein structures. Furthermore, comparing the CCS of a ferritin cage to the solution structures in the PDB reveals significant deviations caused by structural collapse in the gas phase. We then apply the strategy to an integral membrane protein by comparing the shapes of a prokaryotic and a eukaryotic sodium/proton antiporter homologue. We conclude that mining the PDB with IM-MS data is a time-effective way to derive low-resolution structural models.

Three-Dimensional Chemical Mapping of a Single Protein in the Hydrated State with Atom Probe Tomography.

Unravelling the three-dimensional structures and compositions of biological macromolecules sheds light on their functions and also contributes to the design of future biochemical compounds and processes. Atom probe tomography (APT) is demonstrated in this research as a new and effective approach to explore the structure and chemical composition of a single protein in the hydrated state. By introducing graphene encapsulation, proteins in solution can be immobilized on a metal specimen tip, with an end radius in the range of 50 nm to allow field ionization and evaporation. Using a ferritin particle as an example, analysis of the mass spectrum and reconstructed 3D chemical maps at near-atomic resolution acquired from APT reveals the core consisting of iron and iron oxides, the peptide shell containing amino acids, and the interior interface between the iron core and the peptide shell. The quantitative distribution and proportion of iron isotopes from a single ferritin core have been determined for the first time, as well as identification of the possible sites of amino acids inside the protein shell. The complete experimental protocol is straightforward and lays a foundation for future exploration of various macromolecules in a controlled environment.

Detection of iron deficiency in children with Down syndrome.

PURPOSE: Current American Academy of Pediatrics guidelines for children with Down syndrome (DS) recommend a complete blood count (CBC) at birth and hemoglobin annually to screen for iron deficiency (ID) and ID anemia (IDA) in low-risk children. We aimed to determine if macrocytosis masks the diagnosis of ID/IDA and to evaluate the utility of biochemical and red blood cell indices for detecting ID/IDA in DS. METHODS: We reviewed data from 856 individuals from five DS specialty clinics. Data included hemoglobin, mean corpuscular volume, red cell distribution width (RDW), percent transferrin saturation (TS), ferritin, and c-reactive protein. Receiver operating characteristic curves were calculated. RESULTS: Macrocytosis was found in 32% of the sample. If hemoglobin alone was used for screening, all individuals with IDA would have been identified, but ID would have been missed in all subjects. RDW had the highest discriminability of any single test for ID/IDA. The combination of RDW with ferritin or TS led to 100% sensitivity, and RDW combined with ferritin showed the highest discriminability for ID/IDA. CONCLUSION: We provide evidence to support that a CBC and ferritin be obtained routinely for children over 1 year old with DS rather than hemoglobin alone for detection of ID.