Detection of metals and metalloproteins in the plasma of stroke patients by mass spectrometry methods

Metalloproteins and metalloproteomics in health and disease

Metalloproteins represents more than one third of human proteome, with huge variation in physiological functions and pathological implications, depending on the metal/metals involved and tissue context. Their functions range from catalysis, bioenergetics, redox, to DNA repair, cell proliferation, signaling, transport of vital elements, and immunity. The human metalloproteomic studies revealed that many families of metalloproteins along with individual metalloproteins are dysregulated under several clinical conditions. Also, several sorts of interaction between redox- active or redox- inert metalloproteins are observed in health and disease. Metalloproteins profiling shows distinct alterations in neurodegenerative diseases, cancer, inflammation, infection, diabetes mellitus, among other diseases. This makes metalloproteins -either individually or as families- a promising target for several therapeutic approaches. Inhibitors and activators of metalloenzymes, metal chelators, along with artificial metalloproteins could be versatile in diagnosis and treatment of several diseases, in addition to other biomedical and industrial applications.

Facets of ICP-MS and their potential in the medical sciences-Part 1: fundamentals, stand-alone and hyphenated techniques

Since its inception in the early 80s, inductively coupled plasma-mass spectrometry has developed to the method of choice for the analysis of elements in complex biological systems. High sensitivity paired with isotopic selectivity and a vast dynamic range endorsed ICP-MS for the inquiry of metals in the context of biomedical questions. In a stand-alone configuration, it has optimal qualities for the biomonitoring of major, trace and toxicologically relevant elements and may further be employed for the characterisation of disrupted metabolic pathways in the context of diverse pathologies. The on-line coupling to laser ablation (LA) and chromatography expanded the scope and application range of ICP-MS and set benchmarks for accurate and quantitative speciation analysis and element bioimaging. Furthermore, isotopic analysis provided new avenues to reveal an altered metabolism, for the application of tracers and for calibration approaches. In the last two decades, the scope of ICP-MS was further expanded and inspired by the introduction of new instrumentation and methodologies including novel and improved hardware as well as immunochemical methods. These additions caused a paradigm shift for the biomedical application of ICP-MS and its impact in the medical sciences and enabled the analysis of individual cells, their microenvironment, nanomaterials considered for medical applications, analysis of biomolecules and the design of novel bioassays. These new facets are gradually recognised in the medical communities and several clinical trials are underway. Altogether, ICP-MS emerged as an extremely versatile technique with a vast potential to provide novel insights and complementary perspectives and to push the limits in the medical disciplines. This review will introduce the different facets of ICP-MS and will be divided into two parts. The first part will cover instrumental basics, technological advances, and fundamental considerations as well as traditional and current applications of ICP-MS and its hyphenated techniques in the context of biomonitoring, bioimaging and elemental speciation. The second part will build on this fundament and describe more recent directions with an emphasis on nanomedicine, immunochemistry, mass cytometry and novel bioassays.

Serum/Plasma Zinc Is Apparently Increased in Ischemic Stroke: a Meta-analysis

Zinc (Zn) is found in many neuronal pathways in the brain and has implications for neuromodulation and cerebrovascular disease. However, the association between Zn levels and stroke risk remains controversial. Therefore, we conducted a meta-analysis to explore these relationships. A systematic literature search using PubMed, EMBASE database, and Google Scholar was performed for relevant articles from inception to August 2020. Standardized mean differences (SMDs) and 95% confidence intervals (CIs) were considered the effect sizes and statistical analyses were performed using Stata 12.0. A total of 12 studies involving 1878 cases of stroke and 1754 controls were enrolled. Overall, the meta-analysis demonstrated no significant difference in Zn levels between the stroke group and control group (SMD =-0.18, 95% CI =-0.69 to 0.32, P = 0.480). Subgroup analysis showed that type of stroke had an influence on the Zn levels. A meta-analysis of nine ischemic stroke (IS) studies, which included 1645 cases and 1585 controls, revealed that the Zn levels were significantly higher in IS patients than in controls (SMD (95% CI): 0.61(0.04, 1.19), P = 0.036), but no significant association was found between Zn levels and risk of hemorrhagic stroke (P = 0.113). Egger's test indicated no significant publication bias. This meta-analysis indicates that higher Zn levels may be associated with increased risk of IS; however, these findings should be further confirmed.

Quantification of human plasma metalloproteins in multiple sclerosis, ischemic stroke and healthy controls reveals an association of haptoglobin-hemoglobin complexes with age

Advanced analytical methods play an important role in quantifying serum disease biomarkers. The problem of separating thousands of proteins can be reduced by analyzing for a ‘sub-proteome’, such as the ‘metalloproteome’, defined as all proteins that contain bound metals. We employed size exclusion chromatography (SEC) coupled to an inductively coupled plasma atomic emission spectrometer (ICP-AES) to analyze plasma from multiple sclerosis (MS) participants (n = 21), acute ischemic stroke (AIS) participants (n = 17) and healthy controls (n = 21) for Fe, Cu and Zn-metalloproteins. Using ANOVA analysis to compare the mean peak areas among the groups revealed no statistically significant differences for ceruloplasmin (p = 0.31), α2macroglobulin (p = 0.51) and transferrin (p = 0.31). However, a statistically significant difference was observed for the haptoglobin-hemoglobin (Hp-Hb) complex (p = 0.04), being driven by the difference between the control group and AIS (p = 0.012), but not with the MS group (p = 0.13), based on Dunnes test. A linear regression model for Hp-Hb complex with the groups now adjusted for age found no statistically significant differences between the groups (p = 0.95), but was suggestive for age (p = 0.057). To measure the strength of association between the Hp-Hb complex and age without possible modifications due to disease, we calculated the Spearman rank correlation in the healthy controls. The latter revealed a positive association (r = 0.39, 95% Confidence Interval = (-0.05, 0.83), which suggests that either the removal of Hp-Hb complexes from the blood circulation slows with age or that the release of Hb from red blood cells increases with age. We also observed that the Fe-peak corresponding to the Hp-Hb complex eluted ~100 s later in ~14% of all study samples, which was not correlated with age or disease diagnosis, but is consistent with the presence of the smaller Hp (1–1) isoform in 15% of the population.

Neuroprotective effect of CuATSM in mice stroke model by ameliorating oxidative stress

Cu-diacetyl-bis (N4-methylthiosemicarbazone) (CuATSM) has both anti-oxidative and anti-inflammatory activities, but its therapeutic efficacy for oxidative stress has not been thoroughly investigated in acute ischemic stroke. Here, the present study was designed to assess the efficacies of CuATSM in acute ischemic stroke by comparing with the standard neuroprotective reagent edaravone. Mice were subjected to transient middle cerebral occlusion (tMCAO) for 60 min, and then intravenously administrated with CuATSM (1.5 mg/kg) or edaravone (3 mg/kg) just after the reperfusion, and examined at 1 and 3 d. Compared with the vehicle group, CuATSM treatment decreased infarct volumes and oxidative stress at 3d after tMCAO, which was further enhanced by combined CuATSM + edaravone treatment as compared with single CuATSM group, but not improve neurobehaviors. The present study demonstrated that CuATSM showed strong antioxidative and neuroprotective effects in acute ischemic stroke, which was enhanced by the combination with edaravone.

Sample preparation of blood plasma enables baseline separation of iron metalloproteins by SEC-GFAAS

The analysis of human plasma for biomarkers holds promise to revolutionize disease diagnosis, but is hampered by the inherent complexity of the plasma proteome. One way to overcome this problem is to analyze plasma for a sub-proteome, such as the metalloproteome. Previous studies employing size-exclusion chromatography (SEC) coupled on-line to an inductively coupled plasma-atomic emission spectrometer (ICP-AES) have revealed that plasma contains ~12 copper, iron and zinc metalloproteins. This included the iron metalloproteins transferrin (Tf) and a recently identified haptoglobin-hemoglobin (Hp-Hb) complex, which is formed in plasma when red blood cells rupture. Since this SEC-ICP-AES method required a sample volume of 500 µL to generate diagnostically useful results, we sought to develop an alternative SEC-based hyphenated approach using a smaller SEC column (150 × 5 mm I.D.) and a graphite furnace atomic absorption spectrometer (GFAAS) as the iron-specific detector. A designed interface enabled the integration of the SEC system with the GFAAS. Baseline separation between the Hp-Hb complex and Tf was achieved by developing a sample preparation procedure which involved the chelating agent-based mobilization of Fe from Tf to a small molecular weight Fe complex. Spiking of human plasma (1.0 mL) with red blood cell lysate (1-2 µL) increased only the intensity of the Fe peak corresponding to the Hp-Hb complex, but not that of Tf. Since the developed SEC-GFAAS method requires only 50 µL of plasma for analysis, it can now be employed for the cost-effective quantification of the clinically relevant Hb-Hp complex in human plasma in <50 min.

Comparison of blood lead concentrations in patients with acute ischemic stroke and healthy subjects

BACKGROUND AND OBJECTIVES

Stroke is the main cause of mortality and long-term disability in the general population. With the increased application of metals in industries and human environment, lead has become a health hazard. In this study, we aimed to evaluate the relationship between the blood concentration of lead and the incidence of acute stroke.

MATERIALS AND METHODS

We performed this study during 2016-17 at Vali-e-Asr Hospital in Birjand, Iran, among 80 ischemic stroke patients visiting the hospital and 80 healthy gender- and age-matched controls. Blood lead concentration (BLC) was measured using graphite furnace atomic absorption spectrometry.

RESULTS

BLC medians in the case and control groups were 20.65 [5.37-34.87] μg/dL and 2.65 [1.75-13.85] μg/dL, respectively (p < 0.05). The case group had significantly lower mean levels of HDL and phosphors, whereas the mean levels of white blood cells and uric acid were higher in this group. After adjusting for lipid profile and fasting blood sugar, multiple logistic regression indicated that the serum levels of uric acid and BLC were significant for predicting ischemic stroke. It is estimated that the odds ratio of ischemic stroke increases by 1.04 per 1 μg/dl increase in BLC.

CONCLUSION

This study showed that lead can be a risk factor for ischemic stroke. Since it does not have any beneficial effects on the health of individuals, screening serum concentrations of lead can be considered as a preventive strategy for those at risk of stroke.

Identification of a haptoglobin-hemoglobin complex in human blood plasma

Blood plasma metalloproteins that contain copper (Cu), iron (Fe), zinc (Zn) and/or other metals/metalloids are potential disease biomarkers because the bloodstream is in permanent contact with organs. Their quantification and/or the presence of additional metal-entities or the absence of certain metalloproteins in blood plasma (e.g. in Wilson's disease) may provide insight into the dyshomeostasis of the corresponding metal (s) to gain insight into disease processes. The first step in investigating if the determination of plasma metalloproteins is useful for the diagnosis of diseases is their definitive qualitative identification. To this end, we have added individual highly pure Cu, Fe or Zn-containing metalloproteins to plasma (healthy volunteer) and analyzed this mixture by size-exclusion chromatography (SEC) coupled to an inductively coupled plasma atomic spectrometer (ICP-AES), simultaneously monitoring the emission lines of Cu, Fe and Zn. The results clearly identified ceruloplasmin (Cp), holo-transferrin (hTf), and α₂-macroglobulin (α₂M), which verifies our previous assignments. Interestingly, another major Fe-peak in plasma was identified as a haptoglobin (Hp)-hemoglobin (Hb) complex. This Hp-Hb complex is formed after Hb, which is released during the hemolysis of erythrocytes, binds to the plasma protein Hp. The Hp-Hb complex formation is known to be one of the strongest interactions in biochemistry (K_d≈1pmol/L) and is critical because it prevents kidney toxicity of free Hb. Hence, the simultaneous determination of Cp, hTf, α₂M and the Hp-Hb complex in plasma in <25min has the potential to provide new insight into disease processes associated with the bioinorganic chemistry of Cu, Fe and Zn.

Exploiting His-Tags for Absolute Quantitation of Exogenous Recombinant Proteins in Biological Matrices: Ruthenium as a Protein Tracer

Metal labeling and ICP MS detection offer an alternative to commonly accepted techniques that are currently used to quantitate exogenous proteins in vivo, but modifying the protein surface with metal-containing groups inevitably changes its biophysical properties and is likely to affect trafficking and biodistribution. The approach explored in this work takes advantage of the presence of hexa-histidine tags in many recombinant proteins, which have high affinity toward a range of metals. While many divalent metals bind to poly histidine sequences reversibly, oxidation of imidazole-bound Co^II or Ru^II is known to result in a dramatic increase of the binding strength. In order to evaluate the feasibility of using imidazole-bound metal oxidation as a means of attaching permanent tags to polyhistidine segments, a synthetic peptide YPDFEDYWMKHHHHHH was used as a model. Ru^II can be oxidized under ambient (aerobic) conditions, allowing any oxidation damage to the peptide beyond the metal-binding site to be avoided. The resulting peptide-Ru^III complex is very stable, with the single hexa-histidine segment capable of accommodating up to three metal ions. Localization of Ru^III within the hexa-histidine segment of the peptide was confirmed by tandem mass spectrometry. The Ru^III/peptide binding appears to be irreversible, with both low- and high-molecular weight biologically relevant scavengers failing to strip the metal from the peptide. Application of this protocol to labeling a recombinant form of an 80 kDa protein transferrin allowed Ru^III to be selectively placed within the His-tag segment. The metal label remained stable in the presence of ubiquitous scavengers and did not interfere with the receptor binding, while allowing the protein to be readily detected in serum at sub-nM concentrations. The results of this work suggest that ruthenium lends itself as an ideal metal tag for selective labeling of His-tag containing recombinant proteins to enable their sensitive detection and quantitation with ICP MS.

Prognostic Value of Serum Copper for Post-Stroke Clinical Recovery: A Pilot Study

The clinical course after ischemic stroke can vary considerably despite similar lesions and clinical status at the onset of symptoms, suggesting that individual factors modulate clinical recovery. Here, we sought to test the working hypothesis that elevated copper values provide prognostic information, and specifically predict worse clinical recovery. We further sought to support previous findings regarding metal metabolism in acute stroke. We assessed total antioxidant status, oxidative stress factors (peroxides) and metal metabolism markers (iron, copper, ceruloplasmin concentration and activity, ferritin, and transferrin) in the acute phase (2–10 days from symptom onset) in 30 patients affected by unilateral middle cerebral artery (MCA) stroke. A longitudinal assessment of clinical deficit was performed in the acute and stabilized phases (typically 6 months post-stroke) using the National Institutes of Health Stroke Scale (NIHSS). In identifying recovery-related factors, we considered effective recovery (ER), calculated as the ratio between actual NIHSS recovery and the total potential recovery. This allows an estimation of the actual recovery adjusted for the patient’s initial condition. In the acute phase, clinical severity was correlated with increased peroxide concentrations, and lower iron levels. Less successful clinical recovery was correlated with increased acute copper levels, which entered a multiple regression model that explained 24% of ER variance. These pilot data suggest that, in the acute phase of an ischemic stroke, copper may provide useful information about clinical recovery.

Serum trace elements are interrelated with hormonal imbalance in men with acute ischemic stroke

The objective of the present study was to assess hormonal and trace element status in men suffering from acute ischemic stroke.

METHODS

21 acute ischemic stroke patients and 21 age- and body mass index-matched healthy volunteers were enrolled in the study. Serum trace elements were assessed using inductively coupled plasma mass spectrometry. Serum hormones and brain damage markers were estimated using enzyme-linked immunosorbent assay.

RESULTS

Ischemic stroke patients are characterized by significantly higher levels of total and free triiodothyronine (T₃), anti-thyroid peroxidase antibodies (Anti-TPO-Ab), prolactin, and cortisol, whereas the level of thyroid stimulating hormone (TSH) was decreased. Serum B, Cu, Li, Mn, Ni, Pb, Se, V, and Zn in stroke significantly exceeded the control values, whereas the level of Co and Fe was decreased. Correlation analysis revealed a significant association between serum B and T₃, Anti-TPO-Ab, and iodine concentration; serum Li and Sr levels - with circulating TSH, free T3, and Anti-TPO-Ab; and V concentration - with total T₃ and I levels. The following positive relationships were also revealed: Co - TSH, Mn - free T₃, Zn - free T₃. Multiple linear regression demonstrated that Co, I, and Li were directly related to circulating TSH levels, whereas V concentration was negatively interrelated. In turn, only serum Li levels were characterized by a significant direct relationship with free T3 values.

CONCLUSION

Generally, the obtained data demonstrate that altered serum trace elements are associated with thyroid dysfunction in acute ischemic stroke patients. However, the causal relationship should be estimated.

The metal and metalloprotein profile of human plasma as biomarkers for stroke diagnosis

Stroke, a major cause of disability and mortality, affects someone in the United States every 40s. Stroke biomarkers, including those that could be used as a blood test for diagnosis of stroke, have been particularly elusive. We performed a double blind study to identify human plasma biomarkers for the diagnosis of stroke, including acute ischemic stroke (AIS) and intracerebral hemorrhage (ICH). We utilized a three-track approach based on the total metal profile, the metal cofactor levels among metalloproteins, and the identification of stroke-related metalloproteins. The study included 14 case-control pairs of AIS and 23 case-control pairs of ICH. Controls were matched to cases based on gender, ethnicity, and age (±5 years). AIS cases were statistically higher from their respective controls for protein bound co-factors Se and Cd, while unique correlations of metal cofactor concentrations among metalloproteins were identified between Pb-W, Sr-W, Pb-V, and Cu-V. ICH cases were statistically higher from their respective controls for Se and Co cofactors, whereas Cd and Pb were statistically lower. Unique correlations between metal cofactors for ICH cases were identified between Pb-W, Sr-W, Pb-V, and Cu-V. Stroke-related metalloproteins were identified, including calpain-15, protein-activated inward rectifier potassium channel 1, tau-tubulin kinase 1, and voltage-dependent L-type calcium channel subunit beta-3. Linear discriminant analysis (LDA) was able to classify patients between stroke cases or controls with 93% accuracy as well as classify patients with one of the four stroke groups with 85% accuracy. Additionally, this study found utmost importance in vanadium (V) and tungsten (W) correlations for both bound and total metal concentrations, suggestive of binding to transferrin or inhibition of oxidoreductases. Future work in stroke patients will seek to quantify varying selenoproteins, including selenoprotein P and glutathione peroxidase and identified zinc finger tissue leakage proteins, and further explore the role of trace metal fluctuations with transferrin.

Serum trace elements are associated with hemostasis, lipid spectrum and inflammatory markers in men suffering from acute ischemic stroke

The primary objective of the study is investigation of the association between trace elements status and hemostasis, lipid spectrum and inflammatory markers in acute ischemic stroke (AIS). A total of 30 men suffering from AIS and 30 healthy controls were involved in the current survey. Blood count, serum lipid spectrum, complement components C4 and C3a, vascular endothelial growth factor (VEGF), S100B protein, NR2 antibodies (NR2Ab), and total antioxidant status (TAS), as well as plasma fibrinogen, and D-dimer levels and activated partial thromboplastin time (APTT) were assessed. Serum trace elements were analyzed using inductively coupled plasma mass spectrometry. AIS patients were characterized by significantly increased fibrinogen, D-dimer, TG, C3a, C4, NR2Ab, and VEGF levels. The leukocyte count, erythrocyte sedimentation rate and serum atherogenic index were also increased in stroke patients. Oppositely, TAS and APTT values, bleeding and blood coagulation time were decreased. AIS patients were characterized by significantly decreased serum Fe and Co concentrations, whereas the level of Cu, I, Li, Mn, Se, Zn, As, Pb, Ni, and especially V and B in serum was significantly increased. Serum V and B tightly correlated with the procoagulant state and inflammatory markers. Multiple regression analysis revealed a significant inverse association between serum Se levels and stroke markers after adjustment for covariates. Therefore, it is hypothesized that elements like vanadium and boron may be closely involved in stroke pathogenesis by modulation of hemostasis and inflammation, whereas the observed increase in Se levels may be considered as a compensatory reaction.

The Copper bis(thiosemicarbazone) Complex CuII(atsm) Is Protective Against Cerebral Ischemia Through Modulation of the Inflammatory Milieu

Developing new therapies for stroke is urgently needed, as this disease is the leading cause of death and disability worldwide, and the existing treatment is only available for a small subset of patients. The interruption of blood flow to the brain during ischemic stroke launches multiple immune responses, characterized by infiltration of peripheral immune cells, the activation of brain microglial cells, and the accumulation of immune mediators. Copper is an essential trace element that is required for many critical processes in the brain. Copper homeostasis is disturbed in chronic neurodegenerative diseases and altered in stroke patients, and targeted copper delivery has been shown to be protective against chronic neurodegeneration. This study was undertaken to assess whether the copper bis(thiosemicarbazone) complex, CuII(atsm), is beneficial in acute brain injury, in preclinical mouse models of ischemic stroke. We demonstrate that the copper complex CuII(atsm) protects neurons from excitotoxicity and N2a cells from OGD in vitro, and is protective in permanent and transient ischemia models in mice as measured by functional outcome and lesion size. Copper delivery in the ischemic brains modulates the inflammatory response, specifically affecting the myeloid cells. It reduces CD45 and Iba1 immunoreactivity, and alters the morphology of Iba1 positive cells in the ischemic brain. CuII(atsm) also protects endogenous microglia against ischemic insult and reduces the proportion of invading monocytes. These results demonstrate that the copper complex CuII(atsm) is an inflammation-modulating compound with high therapeutic potential in stroke and is a strong candidate for the development of therapies for acute brain injury.

Serum Trace Element Profiles, Prolactin, and Cortisol in Transient Ischemic Attack Patients

The primary aim of the present study was to assess the association between trace element status, brain damage biomarkers, cortisol, and prolactin levels in transient ischemic attack (TIA) patients. Ten male and 10 female TIA patients were involved in this study. Age, gender, and BMI-matched volunteers served as the respective control group. Serum samples were examined for complement components C4 and C3a, vascular endothelial growth factor (VEGF), S100B, NR2 antibodies (NR2Ab), total antioxidant status (TAS), cortisol, and prolactin. Trace element concentration in serum samples was assessed using inductively coupled plasma mass spectrometry at NexION 300D. The obtained data indicate that both male and female TIA patients were characterized by the increased C4 and prolactin concentrations. At the same time, serum VEGF levels were elevated in only men, whereas TAS values were decreased in women with TIA. Serum cortisol concentrations were significantly increased only in female TIA patients. Men and women with TIA were characterized by a 32 and 44 % decrease in serum Fe content. A two- and threefold increase in serum V content was observed in TIA females and males, respectively. Women with TIA had 60 % higher values of serum B, whereas male patients were characterized by a sevonfold increase in boron content in comparison to the control values. TIA also resulted in decreased serum Cu content in women and elevation of I, Li, Mn, Se, Zn, As, Pb, Ni, and Sr levels in men. Correlation analysis revealed a significant association between trace elements concentration and the studied parameters.

Proteomic studies with a novel nano-magnetic chelating system to capture metalloproteins and its application in the preliminary study of monocyte and macrophage sub-secretome

A new chelating chromatography method was developed based in the use of magnetic iron oxide nanoparticles functionalized with EDTA-TMS ((N-(trimethoxysilylpropyl)ethylenediaminetriacetate trisodium salt). These particles combine a high surface area, biocompatibility and magnetic removal from solution, with the chelating affinity towards metal ions. The particles were used to selectively capture metallo-dependant proteins in secretome obtained from human monocytes and mouse macrophages. Secreted metallo-dependant proteins are highly important sources of information since they are involved in several pathological processes. The identification of secreted proteins involved in these processes is highly important for diagnosis or monitoring the progression of a disease. In this multiple-approach study it was possible to not only selectively capture several secreted metallo-dependant proteins, but also to significantly avoid masking proteins such as the highly abundant albumin form the fetal bovine serum used to supplement the cell culture medium. Overall, the magnetic nanoparticle-based chelating chromatography method developed here has proved to be a sensitive, low cost, and a quick tool for sample treatment in order to selectively enrich metalloproteins while overcoming the contamination of highly abundant proteins.

Apolipoprotein A-I and Paraoxonase-1 Are Potential Blood Biomarkers for Ischemic Stroke Diagnosis

BACKGROUND

Blood biomarkers for ischemic and hemorrhagic stroke diagnosis remain elusive. Recent investigations suggested that apolipoprotein (Apo), matrix metalloproteinase (MMP), and paraoxonase-1 may be associated with stroke. We hypothesized that Apo A-I, Apo C-I, Apo C-III, MMP-3, MMP-9, and paraoxonase-1 are differentially expressed in ischemic stroke, hemorrhagic stroke, and controls.

METHODS

In a single-center prospective observational study, consecutive stroke cases were enrolled if blood samples were obtainable within 12 hours of symptom onset. Age- (±5 years), race-, and sex-matched controls were recruited. Multiplex assays were used to measure protein levels. The Wilcoxon signed-rank test and the Mann-Whitney U-test were used to compare biomarker values between ischemic stroke patients and controls, hemorrhagic stroke patients and controls, and ischemic and hemorrhagic stroke patients. The 95% confidence intervals (CIs) for the difference of 2 medians were calculated.

RESULTS

Fourteen ischemic stroke case-control pairs and 23 intracerebral hemorrhage (ICH) case-control pairs were enrolled. Median Apo A-I levels were lower in ischemic stroke cases versus controls (140 mg/dL versus 175 mg/dL, difference of 35 mg/dL, 95% CI -54 to -16) and in ischemic stroke versus ICH cases (140 mg/dL versus 180 mg/dL, difference of 40 mg/dL, 95% CI -57 to -23). Median paraoxonase-1 was lower in ischemic stroke cases than in both ICH cases and matched controls. Median Apo C-I was slightly lower in ischemic stroke cases than in ICH cases. There were no differences between groups for MMP-3, MMP-9, and Apo C-III.

CONCLUSION

Apo A-I and paraoxonase-1 levels may be clinically useful for ischemic stroke diagnosis and for differentiating between ischemic and hemorrhagic strokes.

Small Molecule Copper and Its Relative Metabolites in Serum of Cerebral Ischemic Stroke Patients

BACKGROUND

Copper is a strong pro-oxidant. The most important pro-oxidative form in serum is small molecule copper (SMC), which is copper that is loosely bound to small molecules, such as amino acids and polypeptides. The association between copper and atherosclerotic diseases has been confirmed, but that between SMC and cerebral ischemic stroke (CIS), one of the most principal manifestations and causes of death of atherosclerotic disease, is not yet clear.

METHODS

We recruited 45 CIS patients and 25 age- and gender-matched healthy controls. We detected their serum levels of SMC, total copper, homocysteine (Hcy), and ceruloplasmin (CP), as well as urinary total copper, and analyzed the relationship of SMC with these aforementioned metabolites or compounds in CIS patients.

RESULTS

SMC was 4.2 ± .5 µg/L and 2.1 ± .9 µg/L; total copper in sera was 1345.5 ± 308.2 µg/L and 1180.3 ± 134.0 µg/L; and total copper in urine was 27.6 ± 9.3 µg/L and 18.8 ± 8.1 µg/L in patients and controls, respectively (all P < .05). Serum CP activity in CIS patients was 59.92 ± 12.11 U/L versus 37.76 ± 5.71 U/L in controls (P = .0001). The concentration of SMC was positively correlated with CP activity, Hcy concentration in sera, and urinary total copper.

CONCLUSION

The serum level of SMC and total copper is remarkably elevated, and SMC positively correlates with Hcy, CP activity, and urinary total copper in CIS patients.

High urinary tungsten concentration is associated with stroke in the National Health and Nutrition Examination Survey 1999-2010

BACKGROUND

In recent years there has been an exponential increase in tungsten demand, potentially increasing human exposure to the metal. Currently, the toxicology of tungsten is poorly understood, but mounting evidence suggests that both the elemental metal and its alloys have cytotoxic effects. Here, we investigate the association between tungsten and cardiovascular disease (CVD) or stroke using six waves of the National Health and Nutrition Examination Survey (NHANES).

METHODS

We investigated associations using crude and adjusted logistic regression models in a cohort of 8614 adults (18-74 years) with 193 reported stroke diagnoses and 428 reported diagnoses of CVD. We also stratified our data to characterize associations in a subset of younger individuals (18-50 years).

RESULTS

Elevated tungsten concentrations were strongly associated with an increase in the prevalence of stroke, independent of typical risk factors (Odds Ratio (OR): 1.66, 95% Confidence Interval (95% CI): 1.17, 2.34). The association between tungsten and stroke in the young age category was still evident (OR: 2.17, 95% CI: 1.33, 3.53).

CONCLUSION

This study represents the most comprehensive analysis of the human health effects of tungsten to date. Individuals with higher urinary tungsten concentrations have double the odds of reported stroke. We hypothesize that the pathological pathway resulting from tungsten exposure may involve oxidative stress.