Publications by authors named "Sergey Zakharov"

86 Publications

Adrenergic Ca1.2 Activation via Rad Phosphorylation Converges at α I-II Loop.

Circ Res 2021 Jan 22;128(1):76-88. Epub 2020 Oct 22.

Division of Cardiology, Department of Medicine (A.P., J.K., J.A.H., A.N.K., S.I.Z., B.-x.C., L.Y., R.L., S.L., G.L., D.R., X.L., V.T., S.O.M.), Columbia University, Vagelos College of Physicians and Surgeons, New York, NY.

Rationale: Changing activity of cardiac Ca1.2 channels under basal conditions, during sympathetic activation, and in heart failure is a major determinant of cardiac physiology and pathophysiology. Although cardiac Ca1.2 channels are prominently upregulated via activation of PKA (protein kinase A), essential molecular details remained stubbornly enigmatic.

Objective: The primary goal of this study was to determine how various factors converging at the Ca1.2 I-II loop interact to regulate channel activity under basal conditions, during β-adrenergic stimulation, and in heart failure.

Methods And Results: We generated transgenic mice with expression of Ca1.2 α subunits with (1) mutations ablating interaction between α and β-subunits, (2) flexibility-inducing polyglycine substitutions in the I-II loop (GGG-α), or (3) introduction of the alternatively spliced 25-amino acid exon 9* mimicking a splice variant of α upregulated in the hypertrophied heart. Introducing 3 glycine residues that disrupt a rigid IS6-α-interaction domain helix markedly reduced basal open probability despite intact binding of Caβ to α I-II loop and eliminated β-adrenergic agonist stimulation of Ca1.2 current. In contrast, introduction of the exon 9* splice variant in the α I-II loop, which is increased in ventricles of patients with end-stage heart failure, increased basal open probability but did not attenuate stimulatory response to β-adrenergic agonists when reconstituted heterologously with β and Rad or transgenically expressed in cardiomyocytes.

Conclusions: Ca channel activity is dynamically modulated under basal conditions, during β-adrenergic stimulation, and in heart failure by mechanisms converging at the α I-II loop. Caβ binding to α stabilizes an increased channel open probability gating mode by a mechanism that requires an intact rigid linker between the β-subunit binding site in the I-II loop and the channel pore. Release of Rad-mediated inhibition of Ca channel activity by β-adrenergic agonists/PKA also requires this rigid linker and β-binding to α.
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http://dx.doi.org/10.1161/CIRCRESAHA.120.317839DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7790865PMC
January 2021

Fibroblast growth factor homologous factors tune arrhythmogenic late NaV1.5 current in calmodulin binding-deficient channels.

JCI Insight 2020 10 2;5(19). Epub 2020 Oct 2.

Division of Cardiology, Department of Medicine.

The Ca2+-binding protein calmodulin has emerged as a pivotal player in tuning Na+ channel function, although its impact in vivo remains to be resolved. Here, we identify the role of calmodulin and the NaV1.5 interactome in regulating late Na+ current in cardiomyocytes. We created transgenic mice with cardiac-specific expression of human NaV1.5 channels with alanine substitutions for the IQ motif (IQ/AA). The mutations rendered the channels incapable of binding calmodulin to the C-terminus. The IQ/AA transgenic mice exhibited normal ventricular repolarization without arrhythmias and an absence of increased late Na+ current. In comparison, transgenic mice expressing a lidocaine-resistant (F1759A) human NaV1.5 demonstrated increased late Na+ current and prolonged repolarization in cardiomyocytes, with spontaneous arrhythmias. To determine regulatory factors that prevent late Na+ current for the IQ/AA mutant channel, we considered fibroblast growth factor homologous factors (FHFs), which are within the NaV1.5 proteomic subdomain shown by proximity labeling in transgenic mice expressing NaV1.5 conjugated to ascorbate peroxidase. We found that FGF13 diminished late current of the IQ/AA but not F1759A mutant cardiomyocytes, suggesting that endogenous FHFs may serve to prevent late Na+ current in mouse cardiomyocytes. Leveraging endogenous mechanisms may furnish an alternative avenue for developing novel pharmacology that selectively blunts late Na+ current.
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http://dx.doi.org/10.1172/jci.insight.141736DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7566708PMC
October 2020

Efficiency of I-ioflupane SPECT as the marker of basal ganglia damage in acute methanol poisoning: 6-year prospective study.

Clin Toxicol (Phila) 2021 Mar 7;59(3):235-245. Epub 2020 Aug 7.

Department of Occupational Medicine, First Faculty of Medicine, Charles University, Prague, Czech Republic.

Context: Investigate whether I-ioflupane SPECT (DaT SPECT) has the potential as a marker of basal ganglia damage in acute methanol poisoning.

Methods: Prospective, single-centre, cohort study of patients with confirmed methanol poisoning was conducted. DaT SPECT was performed twice with semi-quantification using DaTQUANT and MRI-based volumetry was calculated. Specific binding ratios (SBR) of striatum, caudate nucleus, and putamen were correlated with laboratory parameters of outcome, volumetric data, and retinal nerve fibres layer (RNFL) thickness measurements.

Results: Forty-two patients (mean age 46.3 ± 4.2 years; 8 females), including 15 with MRI-detected putamen lesions (group I) and 27 patients with intact putamen (group II), underwent DaT SPECT. Volumetry was calculated in 35 of the patients assessed. SBR values for the left putamen correlated with putamen volume ( = 0.665;  < 0.001). Decreased bilateral SBR values were determined for the striatum and the putamen, but not for the nucleus caudate, in group I ( < 0.05). Significant correlation was observed between the SBR of the posterior putamen and arterial blood pH ( = 0.574;  < 0.001) and other toxicological parameters of severity of poisoning/outcome including serum lactate, glucose, and creatinine concentrations ( < 0.05). The SBR of the posterior putamen positively correlated with the global RNFL thickness ( < 0.05). ROC analysis demonstrated a significant discriminatory ability of SBR of the posterior putamen with AUC = 0.753 (95%CI 0.604-0.902;  = 0.007). The multivariate regression model demonstrated that arterial blood pH, age, and gender were the most significant factors associated with SBR of the posterior putamen.

Conclusion: DaT SPECT demonstrates significant potential for the diagnosis of methanol-induced basal ganglia damage.
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http://dx.doi.org/10.1080/15563650.2020.1802033DOI Listing
March 2021

MRI-based brain volumetry and retinal optical coherence tomography as the biomarkers of outcome in acute methanol poisoning.

Neurotoxicology 2020 09 15;80:12-19. Epub 2020 Jun 15.

Toxicological Information Centre, General University Hospital, Prague, Czech Republic; Department of Occupational Medicine, First Faculty of Medicine, Charles University, Prague, Czech Republic.

Background: Basal ganglia lesions are typical findings on magnetic resonance imaging (MRI) of the brain in survivors of acute methanol poisoning. However, no data are available on the association between the magnitude of damaged brain regions, serum concentrations of markers of acute methanol toxicity, oxidative stress, neuroinflammation, and the rate of retinal nerve ganglion cell loss.

Objectives: To investigate the association between MRI-based volumetry of the basal ganglia, retinal nerve fibre layer (RNFL) thickness and prognostic laboratory markers of outcomes in acute methanol poisoning.

Methods: MRI-based volumetry of putamen, nucleus caudatus and globus pallidus was performed and compared with laboratory parameters of severity of poisoning and acute serum markers of oxidative damage of lipids (8-isoprostan, MDA, HHE, HNE), nucleic acids (8-OHdG, 8-OHG, 5-OHMU), proteins (o-Thyr, NO-Thyr, Cl-Thyr) and leukotrienes (LTC4, LTD4, LTE4, LTB4), as well as with the results of RNFL measurements by optic coherence tomography (OCT) in 16 patients with acute methanol poisoning (Group I) and in 28 survivors of poisoning two years after discharge with the same markers measured within the follow-up examination (Group II). The control group consisted of 28 healthy subjects without methanol poisoning.

Results: The survivors of acute methanol poisoning had significantly lower volumes of basal ganglia than the controls. The patients with MRI signs of methanol-induced toxic brain damage had significantly lower volumes of basal ganglia than those without these signs. A positive correlation was found between the volume of putamen and arterial blood pH on admission (r = 0.45; p = 0.02 and r = 0.44; p = 0.02 for left and right putamen, correspondingly). A negative correlation was present between the volumes of putamen and acute serum lactate (r = -0.63; p < 0.001 and r = -0.59; p = 0.01), creatinine (r = -0.53; p = 0.01 and r = -0.47; p = 0.01) and glucose (r = -0.55; p < 0.001 and r = -0.50; p = 0.01) concentrations. The volume of basal ganglia positively correlated with acute concentrations of markers of lipoperoxidation (8-isoprostan: r = 0.61; p < 0.05 and r = 0.59; p < 0.05 for left and right putamen, correspondingly) and inflammation (leukotriene LTB4: r = 0.61; p < 0.05 and r = 0.61; p < 0.05 for left and right putamen, correspondingly). The higher the volume of the basal ganglia, the higher the thickness of the RNFL, with the strongest positive association between global RNFL and the volume of putamen bilaterally (all p < 0.01). In the follow-up markers of oxidative stress and inflammation, only o-Thyr concentration negatively correlated with the volume of putamen bilaterally (r = -0.39; p < 0.05 and r = -0.37; p < 0.05 for left and right putamen, correspondingly).

Conclusion: In survivors of acute methanol poisoning with signs of toxic brain damage, the magnitude of affected areas correlated with acute parameters of severity of poisoning, markers of oxidative stress and neuroinflammation. There was a positive association between the basal ganglia volume and the thickness of RNFL, making OCT an important screening test and MRI-based volumetry the confirmative diagnostic method for the detection of CNS sequelae of methanol poisoning.
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http://dx.doi.org/10.1016/j.neuro.2020.06.006DOI Listing
September 2020

Peripheral polyneuropathy after acute methanol poisoning: Six-year prospective cohort study.

Neurotoxicology 2020 07 5;79:67-74. Epub 2020 May 5.

Toxicological Information Centre, General University Hospital, Prague, Czech Republic; Department of Occupational Medicine, 1st Faculty of Medicine, Charles University, Prague, Czech Republic.

Background: Methanol is a widely used industrial short-chain aliphatic alcohol with known neurotoxic properties. Mass poisoning outbreaks due to the consumption of methanol-adulterated alcoholic drinks present a challenge to healthcare providers due to the high mortality and serious central nervous system (CNS) damage in survivors. However, the impact of methanol exposure on the peripheral nervous system is unknown.

Objectives: To investigate the role of acute methanol exposure in the development of peripheral polyneuropathy (PNP) during the years following discharge from the hospital.

Methods: A total of 55 patients with confirmed methanol poisoning (mean age of 47.9 ± 3.6 years; 9 females) were examined 4 times within a 6-year prospective longitudinal cohort study. The program included neurological and electromyographic examinations, visual evoked potentials, ocular examinations with retinal nerve fibre layer thickness measurements, brain magnetic resonance imaging, and a series of biochemical and toxicological tests.

Results: PNP was observed in 20/55 (36 %) patients, which, in most of the cases, was mild axonal sensorimotor neuropathy. In 8/55 (15 %) patients, worsening of electromyographic findings was registered during the follow-up period, including 5 cases with newly diagnosed PNP and 3 cases of PNP progression. In one subject, complete reversal of PNP was registered after cessation of alcohol intake. The patients with PNP were significantly older (57.3 ± 5.3 versus 42.5 ± 3.9 years; p < 0.001), with higher blood glucose (5.93 ± 0.97 versus 4.81 ± 0.32 mmol/L; p = 0.035) and lower vitamin B (45.5 ± 7.4 versus 57.5 ± 5.2 ug/L; p = 0.015) concentrations. The number of chronic alcohol abusers was significantly higher in the PNP group (17/20 versus 20/35; p = 0.034). No associations between PNP prevalence/ dynamics and acute parameters of poisoning severity, arterial blood pH (7.26 ± 0.07 with PNP versus 7.18 ± 0.09 without PNP; p = 0.150), or serum methanol (1320.0 ± 700.0 with PNP versus 1430.0 ± 510.0 mg/L without PNP; p = 0.813) and ethanol (460.0 ± 560.0 with PNP versus 340.0 ± 230.0 mg/L without PNP; p = 0.675) concentrations at admission were found. No difference in the number of patients with visual (9/20 with PNP versus 12/35 patients without PNP; p = 0.431) and CNS sequelae (9/20 with PNP versus 15/35 patients without PNP; p = 0.877) of poisoning was present.

Discussion: Despite the relatively high number of PNP cases, no association was found between the severity of acute methanol poisoning and the prevalence of PNP and its dynamics during six years of observation. We did not find an association between methanol-induced visual/ brain damage and the prevalence of PNP in survivors of poisoning. A high prevalence of PNP and its progression might be attributed to other causes, mainly a history of chronic alcohol abuse and insufficiently treated diabetes mellitus. Our results highlight the importance of complete cessation of alcohol consumption and better control of glycaemia in diabetic patients in the prevention and treatment of peripheral PNP.
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http://dx.doi.org/10.1016/j.neuro.2020.04.010DOI Listing
July 2020

Formaldehyde Reacts with Amino Acids and Peptides with a Potential Role in Acute Methanol Intoxication.

J Anal Toxicol 2020 Dec;44(8):880-885

Charles University, First Faculty of Medicine and General University Hospital, Department of Occupational Medicine, Na Bojisti 1, 120 00 Prague, Czech Republic.

Methanol, an aliphatic alcohol widely used in the industry, causes acute and chronic intoxications associated with severe long-term health damage, including permanent visual impairment, brain damage, mainly necrosis of the basal ganglia and high mortality due to cancer. However, the role of formaldehyde, an intermediate metabolite of methanol oxidation, in methanol toxicity remains unclear. Thus, we studied the reactivity of several amino acids and peptides in the presence of formaldehyde by identifying products by direct infusion electrospray high-resolution mass spectrometry (MS) and matrix-assisted laser desorption-ionization MS. Cysteine, homocysteine and two peptides, CG and CGAG, provided cyclic products with a +12 amu mass shift with respect to the original compounds. The proposed structures of the products were confirmed by high-resolution tandem MS. Moreover, the formation of the products with +12 amu mass shift was also shown for two biologically relevant peptides, fragments of ipilimumab, which is a human IgG1 monoclonal antibody against cytotoxic T-lymphocyte-associated protein 4. Overall, our experimental results indicate that formaldehyde reacts with some amino acids and peptides, yielding covalently modified structures. Such chemical modifications may induce undesirable changes in the properties and function of vital biomolecules (e.g., hormones, enzymes) and consequently pathogenesis.
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http://dx.doi.org/10.1093/jat/bkaa039DOI Listing
December 2020

Acute exposures to e-cigarettes and heat-not-burn products reported to the Czech Toxicological Information Centre over a 7-year period (2012-2018).

Basic Clin Pharmacol Toxicol 2020 Jul 19;127(1):39-46. Epub 2020 Mar 19.

Toxicological Information Centre, General University Hospital, Prague, Czech Republic.

E-cigarettes and heat-not-burn cigarettes (HNBC) present new health risks due to their rising popularity, high content of nicotine and serious adverse effects. The objective of the study was to analyse the cases of acute exposure to e-cigarettes, e-liquids and HNBC products containing nicotine that led to toxicological consultations at our poisons control centre during a 7-year period (2012-2018) and identify the categories of special concern that require further investigation and intervention. The demographic, toxicological and clinical data were analysed by descriptive statistics. Poisoning severity score (PSS) was estimated. From 119 229 consultations, 148 cases concerned acute exposure to e-cigarettes. Children and adolescents were exposed in 91 (61%) cases, including exposure of neonates and infants in 54 (36%) cases. The main route of exposure was ingestion in 129 (87%), inhalation in nine (6%), ocular in six (4%) and intravenous administration in three (2%) cases. The source of exposure was the cartridge with e-liquid (107; 72%), refillable tank in 29 (20%) and HNBC refill in nine (6%) cases. The reason for exposure was accidental in 110 (74%), incorrect application of the device in 10 (7%), abuse in six (4%), suicide attempt in six (4%) and other/unknown in 16 (11%) cases. The dose estimation was severe/lethal in 6 (4%), toxic in 53 (36%), low-to-moderate in 35 (24%) and unknown in 54 (36%) cases. Vomiting was observed in 38 (26%) patients; 72% of patients were hospitalised. In symptomatic cases, 41 patient had PSS 1, 12 patients had PSS 2, and one patient had PSS 3. Activated charcoal was applied in 57 (39%) patients, and symptomatic treatment was recommended in 75 (51%) patients. Cases of unintentional exposure of children demonstrate the need for preventive risk reduction measures.
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http://dx.doi.org/10.1111/bcpt.13393DOI Listing
July 2020

Mechanism of adrenergic Ca1.2 stimulation revealed by proximity proteomics.

Nature 2020 01 22;577(7792):695-700. Epub 2020 Jan 22.

Division of Cardiology, Department of Medicine, Columbia University, Vagelos College of Physicians and Surgeons, New York, NY, USA.

Increased cardiac contractility during the fight-or-flight response is caused by β-adrenergic augmentation of Ca1.2 voltage-gated calcium channels. However, this augmentation persists in transgenic murine hearts expressing mutant Ca1.2 α and β subunits that can no longer be phosphorylated by protein kinase A-an essential downstream mediator of β-adrenergic signalling-suggesting that non-channel factors are also required. Here we identify the mechanism by which β-adrenergic agonists stimulate voltage-gated calcium channels. We express α or β subunits conjugated to ascorbate peroxidase in mouse hearts, and use multiplexed quantitative proteomics to track hundreds of proteins in the proximity of Ca1.2. We observe that the calcium-channel inhibitor Rad, a monomeric G protein, is enriched in the Ca1.2 microenvironment but is depleted during β-adrenergic stimulation. Phosphorylation by protein kinase A of specific serine residues on Rad decreases its affinity for β subunits and relieves constitutive inhibition of Ca1.2, observed as an increase in channel open probability. Expression of Rad or its homologue Rem in HEK293T cells also imparts stimulation of Ca1.3 and Ca2.2 by protein kinase A, revealing an evolutionarily conserved mechanism that confers adrenergic modulation upon voltage-gated calcium channels.
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http://dx.doi.org/10.1038/s41586-020-1947-zDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7018383PMC
January 2020

Health-related quality of life determinants in survivors of a mass methanol poisoning outbreak: six-year prospective cohort study.

Clin Toxicol (Phila) 2020 09 8;58(9):870-880. Epub 2020 Jan 8.

Department of Occupational Medicine, First Faculty of Medicine, Charles University, Prague, Czech Republic.

The effect of acute methanol poisoning on the follow-up quality of life of survivors in mass poisoning outbreaks is not known. The objective of this is to study the impact of visual and central nervous system (CNS) sequelae of methanol poisoning on long-term health-related quality of life (QoL) of survivors, its clinical determinants, and dynamics. A total of 54 patients with confirmed methanol poisoning (mean age 46.7 ± 13.4 years, 9 females) were examined consequently three times within six-year prospective cohort study and compared to 23 controls with the history of chronic alcohol abuse. The following tests were performed: SF-36 QoL questionnaire, visual evoked potentials (VEP) of optic nerve, ocular examination with retinal nerve fiber layer (RNFL) thickness measurement, brain magnetic resonance imaging (MRI), and biochemical and toxicological tests. Acute methanol poisoning led to significant decrease in physical component summary (PCS) compared to PCS of age-adjusted controls (mean score with SD 46.8 ± 11.0 versus 52.3 ± 9.4 points;  = .003). In 17/40 (42.5%) patients with three rounds of examination, signs of severe disability (≤30 points in at least one score) were present six years after discharge, with negative dynamics of PCS score during the observation period. The patients with abnormal RNFL thickness had lower PCS (mean difference 10.5 points; 95%CI 3.5-17.5,  = .004) and mental component summary score (9.5 points; 95%CI 1.9-17.1,  = .015) compared to the patients with normal RNFL. Signs of physical and mental adaptation to long-term visual sequelae were registered with gradual reduction of difference in most of physical and mental components scores compared to the patients with normal RNFL during six years of observation. Signs of hemorrhagic brain lesions were associated with permanent decrease of PCS score (mean difference 7.4 points; 95%CI 0.6-14.0;  = .033), bodily pain (8.7 points; 95%CI 1.6-17.6;  = .018), and social functioning (8.2 points; 95%CI 3.0-17.4;  = .005) six years after discharge. No effect of type of antidote (fomepizole versus ethanol) and extracorporeal enhanced elimination modality (intermittent hemodialysis versus continuous renal replacement therapy) applied in hospital on long-term QoL was found (all  > .05). Acute methanol poisoning was associated with a significant decrease of health-related quality of life of survivors persisting for at least six years after discharge. The more pronounced decrease in QoL scores was observed in the patients with hemorrhagic brain lesions and visual sequelae of poisoning with abnormal RNFL thickness.
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http://dx.doi.org/10.1080/15563650.2019.1702994DOI Listing
September 2020

Consensus statements on the approach to patients in a methanol poisoning outbreak.

Clin Toxicol (Phila) 2019 12 22;57(12):1129-1136. Epub 2019 Jul 22.

The Norwegian CBRNE Centre of Medicine, Department of Acute Medicine, Oslo University Hospital, Oslo, Norway.

Methanol poisoning is an important cause of mortality and morbidity worldwide. Although it often occurs as smaller sporadic events, epidemic outbreaks are not uncommon due to the illicit manufacture and sale of alcoholic beverages. We aimed to define methanol poisoning outbreak (MPO), outline an approach to triaging an MPO, and define criteria for prioritizing antidotes, extracorporeal elimination treatments (i.e., dialysis), and indications for transferring patients in the context of an MPO. We convened a group of experts from across the world to explore geographical, socio-cultural and clinical considerations in the management of an MPO. The experts answered specific open-ended questions based on themes aligned to the goals of this project. This project used a modified Delphi process. The discussion continued until there was condensation of themes. We defined MPO as a sudden increase in the number of cases of methanol poisoning during a short period of time above what is normally expected in the population in that specific geographic area. Prompt initiation of an antidote is necessary in MPOs. Scarce hemodialysis resources require triage to identify patients most likely to benefit from this treatment. The sickest patients should not be transferred unless the time for transfer is very short. Transporting extracorporeal treatment equipment and antidotes may be more efficient. We have developed consensus statements on the response to a methanol poisoning outbreak. These can be used in any country and will be most effective when they are discussed by health authorities and clinicians prior to an outbreak.
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http://dx.doi.org/10.1080/15563650.2019.1636992DOI Listing
December 2019

The impact of co-morbidities on a 6-year survival after methanol mass poisoning outbreak: possible role of metabolic formaldehyde.

Clin Toxicol (Phila) 2020 04 12;58(4):241-253. Epub 2019 Jul 12.

Department of Occupational Medicine, First Faculty of Medicine, Charles University, Prague, Czech Republic.

The influence of co-morbid conditions on the outcome of acute methanol poisoning in mass poisoning outbreaks is not known. The objective of this is to study the impact of burden of co-morbidities, complications, and methanol-induced brain lesions on hospital, follow-up, and total mortality. All patients hospitalized with methanol poisoning during a mass poisoning outbreak were followed in a prospective cohort study until death or final follow-up after 6 years. The age-adjusted Charlson co-morbidity index (ACCI) score was calculated for each patient. A multivariate Cox regression model was used to calculate the adjusted hazards ratio (HR) for death. The survival was modeled using the Kaplan-Meier method. Of 108 patients (mean age with SD 50.9 ± 2.6 years), 24 (54.4 ± 5.9 years) died during hospitalization (mean survival with SD 8 ± 4 days) and 84 (49.9 ± 3.0 years;  = .159) were discharged, including 27 with methanol-induced brain lesions. Of the discharged patients, 15 (56.3 ± 6.8 years) died during the follow-up (mean survival 37 ± 11 months) and 69 (48.5 ± 3.3 years;  = .044) survived. The hospital mortality was 22%, the follow-up mortality was 18%; the total mortality was 36%. Cardiac/respiratory arrest, acute respiratory failure, multiorgan failure syndrome, and arterial hypotension increased the HR for hospital and total (but not follow-up) mortality after adjustment for age, sex, and arterial pH (all  < .05). All patients who died in the hospital had at least one complication. A higher ACCI score was associated with greater total mortality (HR 1.22; 1.00-1.48 95% CI;  = .046). Of those who died, 35 (90%) had a moderate-to-high ACCI. The Kaplan-Meier curve demonstrated that patients with a high ACCI had greater follow-up mortality compared to ones with low ( = .027) or moderate ( = .020) scores. For the patients who died during follow-up, cancers of different localizations were responsible for 7/15 (47%) of the deaths. The character and number of complications affected hospital but not follow-up mortality, while the burden of co-morbidities affected follow-up mortality. Methanol-induced brain lesions did not affect follow-up mortality. Relatively high cancer mortality rate may be associated with acute exposure to metabolic formaldehyde produced by methanol oxidation.
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http://dx.doi.org/10.1080/15563650.2019.1637525DOI Listing
April 2020

Methanol Poisoning as an Acute Toxicological Basal Ganglia Lesion Model: Evidence from Brain Volumetry and Cognition.

Alcohol Clin Exp Res 2019 07 28;43(7):1486-1497. Epub 2019 May 28.

Department of Neurology and Centre of Clinical Neuroscience, First Faculty of Medicine and General University Hospital, Charles University, Prague, Czech Republic.

Background: Acute methanol poisoning leads to optic neuropathy and necrotic lesions of basal ganglia (BG) and subcortical white matter. Survivors of methanol poisoning exhibit long-term executive and memory deficits. Associations between brain volumetry parameters and cognitive sequelae of methanol poisoning are not known. The aim of our study was to identify long-term associations between the cognitive performance of survivors of methanol poisoning and the volume of the brain structures that are selectively vulnerable to methanol.

Methods: We conducted a cross-sectional follow-up study on a sample of patients (n = 33, age 50 ± 14 years, 82% males) who survived acute methanol poisoning during methanol mass poisoning outbreak from September 2012 till January 2013 in the Czech Republic. A battery of neuropsychological tests and brain magnetic resonance imaging were included in the clinical examination protocol. Specific brain structures (putamen, globus pallidus, nucleus caudatus, and frontal white matter) were selected as regions of interest, and their volumes were estimated using the MorphoBox prototype software.

Results: In robust multiple regression models, sustained visual attention performance (as assessed by Trail Making Test and Prague Stroop Test) was positively associated with BG structures and frontal white matter volumes (Wald = 9.03 to 85.50, p < 0.01), sensitivity to interference (as assessed by Frontal Battery Assessment) was negatively associated with frontal white matter volume (Wald = 35.44 to 42.25, p < 0.001), and motor performance (as assessed by Finger Tapping Test) was positively associated with globus pallidus and frontal white matter volumes (Wald = 9.66 to 13.29, p < 0.01).

Conclusions: Our results demonstrate that smaller volumes of elements of BG-thalamocortical circuitry, namely the BG and frontal white matter, relate to attention and motor performance in methanol poisoning from a long-term perspective. Disruption of those functional circuits may underlie specific cognitive deficits observed in methanol poisoning.
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http://dx.doi.org/10.1111/acer.14077DOI Listing
July 2019

Heterogeneity of the action potential duration is required for sustained atrial fibrillation.

JCI Insight 2019 04 25;5. Epub 2019 Apr 25.

Division of Cardiology, Department of Medicine, Vagelos College of Physicians and Surgeons, Columbia University, New York, New York, USA.

Atrial fibrillation (AF) is the most common cardiac arrhythmia and accounts for substantial morbidity and mortality. Recently, we created a mouse model with spontaneous and sustained AF caused by a mutation in the NaV1.5 channel (F1759A) that enhances persistent Na+ current, thereby enabling the investigation of molecular mechanisms that cause AF and the identification of novel treatment strategies. The mice have regional heterogeneity of action potential duration of the atria similar to observations in patients with AF. In these mice, we found that the initiation and persistence of the rotational reentrant AF arrhythmias, known as spiral waves or rotors, were dependent upon action potential duration heterogeneity. The centers of the rotors were localized to regions of greatest heterogeneity of the action potential duration. Pharmacologically attenuating the action potential duration heterogeneity reduced both spontaneous and pacing-induced AF. Computer-based simulations also demonstrated that the action potential duration heterogeneity is sufficient to generate rotors that manifest as AF. Taken together, these findings suggest that action potential duration heterogeneity in mice and humans is one mechanism by which AF is initiated and that reducing action potential duration heterogeneity can lessen the burden of AF.
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http://dx.doi.org/10.1172/jci.insight.128765DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6629142PMC
April 2019

Clinical and genetic determinants of chronic visual pathway changes after methanol - induced optic neuropathy: four-year follow-up study.

Clin Toxicol (Phila) 2019 06 17;57(6):387-397. Epub 2018 Nov 17.

a Toxicological Information Centre, Department of Occupational Medicine, First Faculty of Medicine , Charles University and General University Hospital , Prague , Czech Republic.

Context: Methanol poisoning induces acute optic neuropathy with possible long-term visual damage.

Objective: To study the dynamics and key determinants of visual pathway functional changes during 4 years after acute methanol poisoning.

Methods: A total of 42 patients with confirmed methanol poisoning (mean age 45.7 ± 4.4 years) were examined 4.9 ± 0.6, 25.0 ± 0.6, and 49.9 ± 0.5 months after discharge. The following tests were performed: visual evoked potential (VEP), retinal nerve fiber layer (RNFL) measurement, brain magnetic resonance imaging (MRI), complete ocular examination, biochemical tests, and apolipoprotein E (ApoE) genotyping.

Results: Abnormal VEP P1 latency was registered in 18/42 right eyes (OD) and 21/42 left eyes (OS), abnormal N1P1 amplitude in 10/42 OD and OS. Mean P1 latency shortening during the follow-up was 15.0 ± 2.0 ms for 36/42 (86%) OD and 14.9 ± 2.4 ms for 35/42 (83%) OS, with maximum shortening up to 35.0 ms. No significant change of mean N1P1 amplitude was registered during follow-up. A further decrease in N1P1 amplitude ≥1.0 mcV in at least one eye was observed in 17 of 36 patients (47%) with measurable amplitude (mean decrease -1.11 ± 0.83 (OD)/-2.37 ± 0.66 (OS) mcV versus -0.06 ± 0.56 (OD)/-0.83 ± 0.64 (OS) mcV in the study population; both p < .001). ApoE4 allele carriers had lower global and temporal RNFL thickness and longer initial P1 latency compared to the non-carriers (all p < .05). The odds ratio for abnormal visual function was 8.92 (3.00-36.50; 95%CI) for ApoE4 allele carriers (p < .001). The presence of ApoE4 allele was further associated with brain necrotic lesions (r = 0.384; p = .013) and brain hemorrhages (r = 0.395; p = .011).

Conclusions: Improvement of optic nerve conductivity occurred in more than 80% of patients, but evoked potential amplitude tended to decrease during the 4 years of observation. ApoE4 allele carriers demonstrated lower RNFL thickness, longer P1 latency, and more frequent methanol-induced brain damage compared to non-carriers.
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http://dx.doi.org/10.1080/15563650.2018.1532083DOI Listing
June 2019

Cardiac CaV1.2 channels require β subunits for β-adrenergic-mediated modulation but not trafficking.

J Clin Invest 2019 02 7;129(2):647-658. Epub 2019 Jan 7.

Division of Cardiology, Department of Medicine, Columbia University.

Ca2+ channel β-subunit interactions with pore-forming α-subunits are long-thought to be obligatory for channel trafficking to the cell surface and for tuning of basal biophysical properties in many tissues. Unexpectedly, we demonstrate that transgenic expression of mutant α1C subunits lacking capacity to bind CaVβ can traffic to the sarcolemma in adult cardiomyocytes in vivo and sustain normal excitation-contraction coupling. However, these β-less Ca2+ channels cannot be stimulated by β-adrenergic pathway agonists, and thus adrenergic augmentation of contractility is markedly impaired in isolated cardiomyocytes and in hearts. Similarly, viral-mediated expression of a β-subunit-sequestering peptide sharply curtailed β-adrenergic stimulation of WT Ca2+ channels, identifying an approach to specifically modulate β-adrenergic regulation of cardiac contractility. Our data demonstrate that β subunits are required for β-adrenergic regulation of CaV1.2 channels and positive inotropy in the heart, but are dispensable for CaV1.2 trafficking to the adult cardiomyocyte cell surface, and for basal function and excitation-contraction coupling.
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http://dx.doi.org/10.1172/JCI123878DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6355231PMC
February 2019

Deep Airway Inflammation and Respiratory Disorders in Nanocomposite Workers.

Nanomaterials (Basel) 2018 Sep 16;8(9). Epub 2018 Sep 16.

UMass, Lowell, Department of Biomedical and Nutritional Sciences, Zuckerberg College of Health Sciences, Lowell, MA 01854, USA.

Thousands of researchers and workers worldwide are employed in nanocomposites manufacturing, yet little is known about their respiratory health. Aerosol exposures were characterized using real time and integrated instruments. Aerosol mass concentration ranged from 0.120 mg/m³ to 1.840 mg/m³ during nanocomposite machining processes; median particle number concentration ranged from 4.8 × 10⁴ to 5.4 × 10⁵ particles/cm³. The proportion of nanoparticles varied by process from 40 to 95%. Twenty employees, working in nanocomposite materials research were examined pre-shift and post-shift using spirometry and fractional exhaled nitric oxide (FeNO) in parallel with 21 controls. Pro-inflammatory leukotrienes (LT) type B4, C4, D4, and E4; tumor necrosis factor (TNF); interleukins; and anti-inflammatory lipoxins (LXA4 and LXB4) were analyzed in their exhaled breath condensate (EBC). Chronic bronchitis was present in 20% of researchers, but not in controls. A significant decrease in forced expiratory volume in 1 s (FEV1) and FEV1/forced vital capacity (FVC) was found in researchers post-shift ( ˂ 0.05). Post-shift EBC samples were higher for TNF ( ˂ 0.001), LTB4 ( ˂ 0.001), and LTE4 ( ˂ 0.01) compared with controls. Nanocomposites production was associated with LTB4 ( ˂ 0.001), LTE4 ( ˂ 0.05), and TNF ( ˂ 0.001), in addition to pre-shift LTD4 and LXB4 (both ˂ 0.05). Spirometry documented minor, but significant, post-shift lung impairment. TNF and LTB4 were the most robust markers of biological effects. Proper ventilation and respiratory protection are required during nanocomposites processing.
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http://dx.doi.org/10.3390/nano8090731DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6164906PMC
September 2018

Markers of Oxidative Stress in the Exhaled Breath Condensate of Workers Handling Nanocomposites.

Nanomaterials (Basel) 2018 Aug 10;8(8). Epub 2018 Aug 10.

Department of Biomedical and Nutritional Sciences, Zuckerberg College of Health Sciences, Lowell, MA 01854, USA.

Researchers in nanocomposite processing may inhale a variety of chemical agents, including nanoparticles. This study investigated airway oxidative stress status in the exhaled breath condensate (EBC). Nineteen employees (42.4 ± 11.4 y/o), working in nanocomposites research for 18.0 ± 10.3 years were examined pre-shift and post-shift on a random workday, together with nineteen controls (45.5 ± 11.7 y/o). Panels of oxidative stress biomarkers derived from lipids, nucleic acids, and proteins were analyzed in the EBC. Aerosol exposures were monitored during three major nanoparticle generation operations: smelting and welding (workshop 1) and nanocomposite machining (workshop 2) using a suite of real-time and integrated instruments. Mass concentrations during these operations were 0.120, 1.840, and 0.804 mg/m³, respectively. Median particle number concentrations were 4.8 × 10⁴, 1.3 × 10⁵, and 5.4 × 10⁵ particles/cm³, respectively. Nanoparticles accounted for 95, 40, and 61%, respectively, with prevailing Fe and Mn. All markers of nucleic acid and protein oxidation, malondialdehyde, and aldehydes C₆⁻C were elevated, already in the pre-shift samples relative to controls in both workshops. Significant post-shift elevations were documented in lipid oxidation markers. Significant associations were found between working in nanocomposite synthesis and EBC biomarkers. More research is needed to understand the contribution of nanoparticles from nanocomposite processing in inducing oxidative stress, relative to other co-exposures generated during welding, smelting, and secondary oxidation processes, in these workshops.
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http://dx.doi.org/10.3390/nano8080611DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6116291PMC
August 2018

The Hypothesis of Circulus Hypoxicus and Its Clinical Relevance in Patients With Methanol Poisoning - An Observational Study of 35 Patients.

Basic Clin Pharmacol Toxicol 2018 Dec 23;123(6):749-755. Epub 2018 Jul 23.

Department of Acute Medicine, Division of Medicine, Oslo University Hospital, Oslo, Norway.

Methanol mass poisoning is a global problem with high fatality rates and often severe sequelae in survivors. Patients typically present late to the hospital with severe metabolic acidosis followed by a rapid deterioration in their clinical status. The hypothesis 'Circulus hypoxicus' describes the metabolic acidosis following methanol poisoning as a self-enhancing hypoxic circle responsible for methanol toxicity. We wanted to test the validity of this hypothesis by an observational study based on 35 patients from the methanol outbreaks in Norway (2004) and the Czech Republic (2012). Comprehensive laboratory values, including S(serum)-methanol, S-formate, S-lactate, arterial blood gases, anion and osmolal gaps, were used in the calculations. Laboratory values and calculated gaps were compared to each other using linear regression. S-lactate and S-formate correlated better with the increased base deficit and anion gap than did S-formate alone. Base deficit rose to about 20 mmol/L and S-formate rose to 12 mmol/L prior to a significant rise in S-lactate - most likely caused by formate inhibition of mitochondrial respiration (type B lactacidosis). The further rise in S-lactate was not linear to S-formate most likely due to the self-enhancing pathophysiology, but may also be associated with hypotension in critically ill patients and variable ethanol drinking habits. Our study suggests that the primary metabolic acidosis leads to a secondary lactic acidosis mainly due to the toxic effects of formate. The following decline in pH will further increase this toxicity. As such, a vicious and self-enhancing acidotic circle may explain the pathophysiology in methanol poisoning, namely the 'Circulus hypoxicus'.
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http://dx.doi.org/10.1111/bcpt.13074DOI Listing
December 2018

Neuroinflammation markers and methyl alcohol induced toxic brain damage.

Toxicol Lett 2018 Dec 4;298:60-69. Epub 2018 May 4.

Toxicological Information Centre, General University Hospital, Na Bojisti 1, 12000, Prague, Czech Republic; Department of Biomimetic Electrochemistry, J. Heyrovský Institute of Physical Chemistry of the AS CR, v.v.i, Dolejskova 2155/3, 18200, Prague, Czech Republic.

Methyl alcohol intoxication is a global problem with high mortality and long-term visual sequelae and severe brain damage in survivors. The role of neuroinflammation in the mechanisms of methyl alcohol-induced toxic brain damage has not been well studied. We measured the acute concentrations and dynamics of lipoxins LxA4 and LxB4 and the interleukins IL-4, IL-5, IL-9, IL-10, and IL-13 in the serum of patients treated with methyl alcohol poisoning and the follow-up concentrations in survivors two years after discharge from the hospital. A series of acute measurements was performed in 28 hospitalized patients (mean age 54.2 ± 5.2 years, mean observation time 88 ± 20 h) and the follow-up measurements were performed in 36 subjects who survived poisoning (including 12/28 survivors from the acute group). Visual evoked potentials (VEP) and magnetic resonance imaging of the brain (MRI) were performed to detect long-term visual and brain sequelae of intoxication. The acute concentrations of inflammatory mediators were higher than the follow-up concentrations: LxA4, 62.0 ± 6.0 vs. 30.0 ± 5.0 pg/mL; LxB4, 64.0 ± 7.0 vs. 34.0 ± 4.0 pg/mL; IL-4, 29.0 ± 4.0 vs. 15.0 ± 1.0 pg/mL; IL-5, 30.0 ± 4.0 vs. 13.0 ± 1.0 pg/mL; IL-9, 30.0 ± 4.0 vs. 13.0 ± 1.0 pg/mL; IL-10, 38.0 ± 5.0 vs. 16.0 ± 1.0 pg/mL; IL-13, 35.0 ± 4.0 vs. 14.0 ± 1.0 pg/mL (all p < 0.001). The patients with higher follow-up IL-5 concentration had prolonged latency P1 (r = 0.413; p = 0.033) and lower amplitude N1P1 (r = -0.498; p = 0.010) of VEP. The higher follow-up IL-10 concentration was associated with MRI signs of brain necrotic damage (r = 0.533; p = 0.001) and brain hemorrhage (r = 0.396; p = 0.020). Our findings suggest that neuroinflammation plays an important role in the mechanisms of toxic brain damage in acute methyl alcohol intoxication.
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http://dx.doi.org/10.1016/j.toxlet.2018.05.001DOI Listing
December 2018

Progressive Chronic Retinal Axonal Loss Following Acute Methanol-induced Optic Neuropathy: Four-Year Prospective Cohort Study.

Am J Ophthalmol 2018 07 28;191:100-115. Epub 2018 Apr 28.

Toxicological Information Centre, Department of Occupational Medicine, First Faculty of Medicine, Charles University and General University Hospital, Prague, Czech Republic. Electronic address:

Purpose: To study the dynamics and clinical determinants of chronic retinal nerve fiber layer thickness (RNFL) loss after methanol-induced optic neuropathy.

Design: Prospective cohort study.

Methods: All patients underwent complete ophthalmic evaluation including spectral-domain optical coherence tomography 3 times during 4 years of observation: 4.9 (±0.6), 25.0 (±0.6), and 49.9 (±0.5) months after discharge.

Participants: Eighty-four eyes of 42 survivors of methanol poisoning, mean age (standard deviation) of 45.7 (±4.4) years; and 82 eyes of 41 controls, mean age 44.0 (±4.2) years.

Main Outcome Measures: Global and temporal RNFL loss.

Results: Abnormal RNFL thickness was registered in 13 of 42 (31%) survivors of methanol poisoning and chronic axonal loss in 10 of 42 (24%) patients. Significant decrease of global/temporal RNFL thickness during the observation period was found in the study population compared to the controls (P < .001). The risk estimate of chronic global RNFL loss for arterial blood pH < 7.3 at admission was 11.65 (95% confidence interval 1.91-71.12) after adjusting for age and sex. The patients with chronic axonal degeneration demonstrated progressive visual loss in 7 of 10 cases. The patients with abnormal RNFL thickness had magnetic resonance signs of brain damage in 10 of 13 vs 8 of 29 cases with normal RNFL thickness (P = .003). Signs of brain hemorrhages were present in 7 of 13 patients with abnormal RNFL thickness vs 5 of 29 cases with normal RNFL thickness (P = .015).

Conclusions: Methanol-induced optic neuropathy may lead to chronic retinal axonal loss during the following years. Arterial blood pH on admission is the strongest predictor of chronic RNFL thickness decrease. Chronic retinal neurodegeneration is associated with the progressive loss of visual functions and necrotic brain lesions.
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http://dx.doi.org/10.1016/j.ajo.2018.04.015DOI Listing
July 2018

Role of activation of lipid peroxidation in the mechanisms of acute methanol poisoning

Clin Toxicol (Phila) 2018 10 2;56(10):893-903. Epub 2018 Apr 2.

a Toxicological Information Centre , General University Hospital in Prague , Prague , Czech Republic.

Context: The role of activation of lipid peroxidation in the mechanisms of acute methanol poisoning has not been studied.

Objective: We measured the concentrations of lipid peroxidation markers in acutely intoxicated patients with known serum concentrations of methanol and leukotrienes.

Methods: Blood serum samples were collected from 28 patients hospitalized with acute intoxication and from 36 survivors 2 years after discharge. In these samples, concentrations of 4-hydroxy-trans-2-hexenal (HHE), 4-hydroxynonenal (HNE), and malondialdehyde (MDA) were measured using the method of liquid chromatography-electrospray ionization-tandem mass spectrometry.

Results: The maximum acute serum concentrations of all three lipid oxidative damage markers were higher than the follow-up serum concentrations: HNE 71.7 ± 8.0 ng/mL versus 35.4 ± 2.3 ng/mL; p < .001; HHE 40.1 ± 6.7 ng/mL versus 17.7 ± 4.1 ng/mL; p < .001; MDA 80.0 ± 7.2 ng/mL versus 40.9 ± 1.9 ng/mL; p < .001. The survivors without methanol poisoning sequelae demonstrated higher acute serum concentrations of the markers than the patients with sequelae. A correlation between measured markers and serum leukotrienes was present: HNE correlated with LTC4 (r = 0.663), LTD4 (r = 0.608), LTE4 (r = 0.771), LTB4 (r = 0.717), HHE correlated with LTC4 (r = 0.713), LTD4 (r = 0.676), LTE4 (r = 0.819), LTB4 (r = 0.746), MDA correlated with LTC4 (r = 0.785), LTD4 (r = 0.735), LTE4 (r = 0.814), LTB4 (r = 0.674); all p < .001. Lipid peroxidation markers correlated with anion gap (r= -0.428, -0.388, -0.334; p = .026, .045, .080 for HNE, HHE, MDA, respectively). The follow-up serum concentrations of lipid oxidation markers measured in survivors with and without visual/neurological sequelae 2 years after discharge did not differ.

Conclusion: Our results demonstrate that lipid peroxidation plays a significant role in the mechanisms of acute methanol poisoning. The acute concentrations of three measured biomarkers were elevated in comparison with the follow-up concentrations. Neuronal membrane lipid peroxidation seems to activate leukotriene-mediated inflammation as a part of the neuroprotective mechanisms. No cases of persistent elevation were registered among the survivors 2 years after discharge.
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http://dx.doi.org/10.1080/15563650.2018.1455980DOI Listing
October 2018

Neurological and Neurophysiological Findings in Workers with Chronic 2,3,7,8-Tetrachlorodibenzo-p-Dioxin Intoxication 50 Years After Exposure.

Basic Clin Pharmacol Toxicol 2018 Feb 27;122(2):271-277. Epub 2017 Sep 27.

Department of Occupational Medicine, First Faculty of Medicine, Charles University and General University Hospital in Prague, Prague, Czech Republic.

The last eight survivors of 80 workers accidentally exposed to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) during production of herbicides based on trichlorophenoxyacetic acid in 1965-1967 in a chemical factory were followed. All were men, mean age 72.4 ± 1.3 years. Their current median TCDD blood level was 112 (46-390) pg/g lipids. Neurological examination revealed central nervous system impairment in all individuals and signs of polyneuropathy in 87.5%, which was confirmed by a nerve conduction study (NCS) in 75%. A Lanthony test demonstrated acquired dyschromatopsia in 87.5% of the patients, with deterioration of mean colour confusion index (CCI) from 1.52 ± 0.39 in 2010 to 1.73 ± 0.41 in 2016. Single-photon emission computer tomography (SPECT) of the brain showed focal reduction of perfusion in various brain locations in all patients and worsening in six patients. Visual-evoked potentials (VEP) was abnormal in 62.6% of individuals. Most patients complained of psychological problems. The neuropsychological test battery showed most positive impairments in the Trail Making Test evaluating processing speed (average level in the range of mild neurocognitive impairment), which correlated with mean CCI (p < 0.05).

Conclusion: Fifty years after exposure, blood levels of TCDD are still 10 times higher than the general population. NCS, VEP, Lanthony test and SPECT findings deteriorated from examination of these patients in 2004 and in 2010. The total of abnormal tests per patient in 2016 is very high. Minor differences among patients and their reduced count may explain why the number of impairments in 2016 does not correlate with TCDD blood level.
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http://dx.doi.org/10.1111/bcpt.12899DOI Listing
February 2018

Proteolytic cleavage and PKA phosphorylation of α subunit are not required for adrenergic regulation of Ca1.2 in the heart.

Proc Natl Acad Sci U S A 2017 08 7;114(34):9194-9199. Epub 2017 Aug 7.

Division of Cardiology, Department of Medicine, College of Physicians and Surgeons, Columbia University, New York, NY 10032;

Calcium influx through the voltage-dependent L-type calcium channel (Ca1.2) rapidly increases in the heart during "fight or flight" through activation of the β-adrenergic and protein kinase A (PKA) signaling pathway. The precise molecular mechanisms of β-adrenergic activation of cardiac Ca1.2, however, are incompletely known, but are presumed to require phosphorylation of residues in α and C-terminal proteolytic cleavage of the α subunit. We generated transgenic mice expressing an α with alanine substitutions of all conserved serine or threonine, which is predicted to be a potential PKA phosphorylation site by at least one prediction tool, while sparing the residues previously shown to be phosphorylated but shown individually not to be required for β-adrenergic regulation of Ca1.2 current (17-mutant). A second line included these 17 putative sites plus the five previously identified phosphoregulatory sites (22-mutant), thus allowing us to query whether regulation requires their contribution in combination. We determined that acute β-adrenergic regulation does not require any combination of potential PKA phosphorylation sites conserved in human, guinea pig, rabbit, rat, and mouse α subunits. We separately generated transgenic mice with inducible expression of proteolytic-resistant α Prevention of C-terminal cleavage did not alter β-adrenergic stimulation of Ca1.2 in the heart. These studies definitively rule out a role for all conserved consensus PKA phosphorylation sites in α in β-adrenergic stimulation of Ca1.2, and show that phosphoregulatory sites on α are not redundant and do not each fractionally contribute to the net stimulatory effect of β-adrenergic stimulation. Further, proteolytic cleavage of α is not required for β-adrenergic stimulation of Ca1.2.
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http://dx.doi.org/10.1073/pnas.1706054114DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5576811PMC
August 2017

Intermittent versus continuous renal replacement therapy in acute methanol poisoning: comparison of clinical effectiveness in mass poisoning outbreaks.

Ann Intensive Care 2017 Dec 20;7(1):77. Epub 2017 Jul 20.

The Norwegian CBRNE Centre of Medicine, Department of Acute Medicine, Oslo University Hospital, Oslo, Norway.

Background: Intermittent hemodialysis (IHD) is the modality of choice in the extracorporeal treatment (ECTR) of acute methanol poisoning. However, the comparative clinical effectiveness of intermittent versus continuous modalities (CRRT) is unknown. During an outbreak of mass methanol poisoning, we therefore studied the effect of IHD versus CRRT on mortality and the prevalence of visual/central nervous system (CNS) sequelae in survivors.

Methods: The study was designed as prospective observational cohort study. Patients hospitalized with a diagnosis of acute methanol poisoning were identified for the study. Exploratory factor analysis and multivariate logistic regression were applied to determine the effect of ECTR modality on the outcome.

Results: Data were obtained from 41 patients treated with IHD and 40 patients with CRRT. The follow-up time in survivors was two years. Both groups of patients were comparable by age, time to presentation, laboratory data, clinical features, and other treatment applied. The CRRT group was more acidemic (arterial blood pH 6.96 ± 0.08 vs. 7.17 ± 0.07; p < 0.001) and more severely poisoned (25/40 vs. 9/41 patients with Glasgow Coma Scale (GCS) ≤ 8; p < 0.001). The median intensive care unit length of stay (4 (range 1-16) days vs. 4 (1-22) days; p = 0.703) and the number of patients with complications during the treatment (11/41 vs. 13/40 patients; p = 0.576) did not differ between the groups. The mortality was higher in the CRRT group (15/40 vs. 5/41; p = 0.008). The number of survivors without sequelae of poisoning was higher in the IHD group (23/41 vs. 10/40; p = 0.004). There was a significant association of ECTR modality with both mortality and the number of survivors with visual and CNS sequelae of poisoning, but this association was not present after adjustment for arterial blood pH and GCS on admission (all p > 0.05).

Conclusions: In spite of the faster correction of the acidosis and the quicker removal of the toxic metabolite in intermittent dialysis, we did not find significant differences in the treatment outcomes between the two groups after adjusting for the degree of acidemia and the severity of poisoning on admission. These findings support the strategy of "use what you have" in situations with large outbreaks and limited dialysis capacity.
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http://dx.doi.org/10.1186/s13613-017-0300-7DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5519513PMC
December 2017

Positive serum ethanol concentration on admission to hospital as the factor predictive of treatment outcome in acute methanol poisoning.

Monatsh Chem 2017 25;148(3):409-419. Epub 2016 Oct 25.

Toxicological Information Centre, General University Hospital in Prague, Na Bojisti 1, 120 00 Prague 2, Czech Republic.

Abstract: Mass methanol poisonings present a serious problem for health systems worldwide, with poor outcome associated with delayed treatment. Positive pre-hospital serum ethanol concentration may have predictive value as the prognostic factor of the treatment outcome. We studied the effect of positive serum ethanol level on admission to hospital on survival in patients treated during the Czech methanol outbreak during 2012-2014. Cross-sectional cohort study was performed in 100 hospitalized patients with confirmed methanol poisoning. Pre-hospital ethanol was administered in 42 patients (by paramedic/medical staff to 30 patients and self-administered by 12 patients before admission); 58 patients did not receive pre-hospital ethanol. Forty-two patients had detectable serum ethanol concentration on admission to hospital [median 18.3 (IQR 6.6-32.2) mmol dm]. Pre-hospital ethanol administration by paramedic/medical staff had a significant effect on survival without visual and CNS sequelae when adjusted for arterial blood pH on admission (OR 8.73; 95 % CI 3.57-21.34;  < 0.001). No patients receiving pre-hospital ethanol died compared with 21 not receiving ( < 0.001). Positive serum ethanol concentration on admission to hospital was a predictor for survival without health sequelae when adjusted for arterial blood pH (OR 8.10; 95 % CI 2.85-23.02;  < 0.001). The probability of visual and CNS sequelae in survivors reduced with increasing serum ethanol concentration on admission.

Graphical Abstract:
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http://dx.doi.org/10.1007/s00706-016-1846-zDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5346122PMC
October 2016

Cost-effectiveness of hospital treatment and outcomes of acute methanol poisoning during the Czech Republic mass poisoning outbreak.

J Crit Care 2017 06 6;39:190-198. Epub 2017 Mar 6.

Department of Occupational Medicine, 1st Faculty of Medicine, Charles University and General University Hospital, Toxicological Information Centre, Na Bojisti 1, 120 00 Prague 2, Czech Republic. Electronic address:

Purpose: During an outbreak of mass methanol poisoning in the Czech Republic in 2012-2014, we compared the total hospital costs and one-year medical costs in the patients treated with different antidotes (fomepizole versus ethanol) and modalities of hemodialysis (intermittent hemodialysis, IHD, versus continuous renal replacement therapy, CRRT).

Methods: Cross-sectional study in 106 patients with confirmed diagnosis treated in 30 ICU settings. For each patient, the following data were analyzed: admission laboratory data, GCS, PSS, ICU length of stay, organ failures, treatment, outcome, and total hospital costs. Of 83 survivors, in 54 (65%) patients the follow-up examination, quality of life measurement with SF36 questionnaire two years after discharge, and one-year medical costs analysis were performed.

Results: The median total hospital costs were 7200 (IQR 1500-10,900) euros and the median one-year medical costs were 1447 (IQR 133-1163) euros in the study population. The total hospital costs were higher in the patients treated with fomepizole comparing to ethanol: 12,890 (IQR 6910-16,210) versus 5590 (IQR 1430-6940) euros (p<0.001). The hospital costs in the patients treated with IHD were 5400 (IQR 1520-6910) versus 12,410 (IQR 5380-16,960) euros in the patients with CRRT (p=0.317). The geometric mean ratio for increased hospital costs in the patients treated with fomepizole versus ethanol adjusted for the severity of poisoning was 3.30 (1.70-3.80 CI 95%), p<0.001, and in the patients treated with IHD versus CRRT - 0.70 (0.60-0.99 CI 95%), p=0.047. The patients with visual sequelae had higher total hospital costs than those without sequelae: 10,419 (IQR 2984-14,355) versus 4605 (IQR 1303-4505) euros (p=0.009). The patients with GCS≤13 on admission had higher one-year medical costs as well (p<0.001). No difference was found in physical and mental condition scores in the patients treated with different antidotes and modalities of hemodialysis two years after discharge (both p>0.05).

Conclusion: The total hospital costs in the patients with acute methanol poisoning were more than three times higher in the patients treated with fomepizole than in the patients treated with ethanol after adjustment for the severity of poisoning. The dialysis modality did not affect the total hospital costs, but the trend to lower costs was present in IHD-group.
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http://dx.doi.org/10.1016/j.jcrc.2017.03.001DOI Listing
June 2017

Markers of nucleic acids and proteins oxidation among office workers exposed to air pollutants including (nano)TiO2 particles.

Neuro Endocrinol Lett 2016 Dec;37(Suppl1):13-16

Charles University and General University Hospital in Prague, 1st Faculty of Medicine, Department of Occupational Medicine, Prague, Czech Republic.

Objectives: Experimental studies using nanoscale TiO2 have documented lung injury, inflammation, oxidative stress, and genotoxicity. Human health data are extremely scarce.

Methods: In exhaled breath condensate (EBC) and urine of 22 office employees occupationally exposed to TiO2 during their visit in the production workshops for average 14±9 min/day a panel of biomarkers of nucleic acids and proteins oxidation was studied, specifically 8-hydroxy-2-deoxyguanosine (8-OHdG), 8-hydroxyguanosine (8-OHG), 5-hydroxymethyl uracil (5-OHMeU), o-tyrosine (o-Tyr), 3-chlorotyrosine (3-ClTyr), and 3-nitrotyrosine (3-NOTyr). Examination was performed also in 14 comparable controls.

Results: The median respirable TiO2 mass concentration in the workshops was 0.40 mg/m3, median number concentration was 2.32×104 particles/cm3 with 80% of the particles being <100 nm in diameter. All 6 markers of oxidation were elevated in EBC in factory office employees relative to controls (p<0.01). Significant association was found between their job in TiO2 production plant and 5 markers of oxidation (except 3-NOTyr) in the EBC in multivariate analysis. No elevation of markers was detected in the urine.

Conclusion: This pilot study suggests that even short nanoTiO2 exposure may lead to pulmonary oxidative stress; however this effect may be short-term and reversible. The clinical significance of these findings is unclear and more studies are needed.
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December 2016

Reply to "Letter in response to efficiency of acidemia correction on intermittent versus continuous hemodialysis in acute methanol poisoning".

Clin Toxicol (Phila) 2017 04;55(4):306-307

c The Norwegian CBRNe Centre of Medicine, Department of Acute Medicine , Oslo University Hospital , Oslo , Norway.

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http://dx.doi.org/10.1080/15563650.2017.1284338DOI Listing
April 2017

Leukotriene-mediated neuroinflammation, toxic brain damage, and neurodegeneration in acute methanol poisoning.

Clin Toxicol (Phila) 2017 Apr 6;55(4):249-259. Epub 2017 Feb 6.

a Department of Occupational Medicine, First Faculty of Medicine , Charles University , Prague , Czech Republic.

Context: The role of neuroinflammation in methanol-induced toxic brain damage has not been studied.

Objective: We studied acute concentrations and the dynamics of leukotrienes (LT) in serum in hospitalized patients with acute methanol poisoning and in survivors.

Methods: Series of acute cysteinyl-LT and LTB4 concentration measurements were performed in 28/101 hospitalized patients (mean observation time: 88 ± 20 h). In 36 survivors, control LT measurements were performed 2 years after discharge.

Results: The acute maximum (C) LT concentrations were higher than concentrations in survivors: C for LTC4 was 80.7 ± 5.6 versus 47.9 ± 4.5 pg/mL; for LTD4, 51.0 ± 6.6 versus 23.1 ± 2.1 pg/mL; for LTE4, 64.2 ± 6.0 versus 26.2 ± 3.9 pg/mL; for LTB4, 59.8 ± 6.2 versus 27.2 ± 1.4 pg/mL (all p < 0.001). The patients who survived had higher LT concentrations than those who died (all p < 0.01). Among survivors, patients with CNS sequelae had lower LTE4 and LTB4 than did those without sequelae (both p < 0.05). The LT concentrations increased at a rate of 0.4-0.5 pg/mL/h and peaked 4-5 days after admission. The patients with better outcomes had higher cys-LTs (all p < 0.01) and LTB4 (p < 0.05). More severely poisoned patients had lower acute LT concentrations than those with minor acidemia. The follow-up LT concentrations in survivors with and without CNS sequelae did not differ (all p > 0.05). The mean decrease in LT concentration was 30.9 ± 9.0 pg/mL for LTC4, 26.3 ± 8.6 pg/mL for LTD4, 37.3 ± 6.4 pg/mL for LTE4, and 32.0 ± 8.8 pg/mL for LTB4.

Conclusions: Our findings suggest that leukotriene-mediated neuroinflammation may play an important role in the mechanisms of toxic brain damage in acute methanol poisoning in humans. Acute elevation of LT concentrations was moderate, transitory, and was not followed by chronic neuroinflammation in survivors.
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http://dx.doi.org/10.1080/15563650.2017.1284332DOI Listing
April 2017