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

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.

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

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.

Mechanism of adrenergic CaV1.2 stimulation revealed by proximity proteomics.

Increased cardiac contractility during the fight-or-flight response is caused by ß-adrenergic augmentation of CaV1.2 voltage-gated calcium channels1-4. However, this augmentation persists in transgenic murine hearts expressing mutant CaV1.2 α1C and ß subunits that can no longer be phosphorylated by protein kinase A-an essential downstream mediator of ß-adrenergic signalling-suggesting that non-channel factors are also required. Here we identify the mechanism by which ß-adrenergic agonists stimulate voltage-gated calcium channels. We express α1C or ß2B subunits conjugated to ascorbate peroxidase5 in mouse hearts, and use multiplexed quantitative proteomics6,7 to track hundreds of proteins in the proximity of CaV1.2. We observe that the calcium-channel inhibitor Rad8,9, a monomeric G protein, is enriched in the CaV1.2 microenvironment but is depleted during ß-adrenergic stimulation. Phosphorylation by protein kinase A of specific serine residues on Rad decreases its affinity for ß subunits and relieves constitutive inhibition of CaV1.2, observed as an increase in channel open probability. Expression of Rad or its homologue Rem in HEK293T cells also imparts stimulation of CaV1.3 and CaV2.2 by protein kinase A, revealing an evolutionarily conserved mechanism that confers adrenergic modulation upon voltage-gated calcium channels.

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

Context: The influence of co-morbid conditions on the outcome of acute methanol poisoning in mass poisoning outbreaks is not known.Objective: 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.Methods: 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.Results: 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; p = .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; p = .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 p < .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; p = .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 (p = .027) or moderate (p = .020) scores. For the patients who died during follow-up, cancers of different localizations were responsible for 7/15 (47%) of the deaths.Conclusions: 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.

Deep Airway Inflammation and Respiratory Disorders in Nanocomposite Workers.

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 (p ˂ 0.05). Post-shift EBC samples were higher for TNF (p ˂ 0.001), LTB4 (p ˂ 0.001), and LTE4 (p ˂ 0.01) compared with controls. Nanocomposites production was associated with LTB4 (p ˂ 0.001), LTE4 (p ˂ 0.05), and TNF (p ˂ 0.001), in addition to pre-shift LTD4 and LXB4 (both p ˂ 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.

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

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.

Proteolytic cleavage and PKA phosphorylation of α1C subunit are not required for adrenergic regulation of CaV1.2 in the heart.

Calcium influx through the voltage-dependent L-type calcium channel (CaV1.2) rapidly increases in the heart during "fight or flight" through activation of the ß-adrenergic and protein kinase A (PKA) signaling pathway. The precise molecular mechanisms of ß-adrenergic activation of cardiac CaV1.2, however, are incompletely known, but are presumed to require phosphorylation of residues in α1C and C-terminal proteolytic cleavage of the α1C subunit. We generated transgenic mice expressing an α1C 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 ß-adrenergic regulation of CaV1.2 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 ß-adrenergic regulation does not require any combination of potential PKA phosphorylation sites conserved in human, guinea pig, rabbit, rat, and mouse α1C subunits. We separately generated transgenic mice with inducible expression of proteolytic-resistant α1C Prevention of C-terminal cleavage did not alter ß-adrenergic stimulation of CaV1.2 in the heart. These studies definitively rule out a role for all conserved consensus PKA phosphorylation sites in α1C in ß-adrenergic stimulation of CaV1.2, and show that phosphoregulatory sites on α1C are not redundant and do not each fractionally contribute to the net stimulatory effect of ß-adrenergic stimulation. Further, proteolytic cleavage of α1C is not required for ß-adrenergic stimulation of CaV1.2.

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

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 (Cmax) LT concentrations were higher than concentrations in survivors: Cmax 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.

Markers of lipid oxidative damage in the exhaled breath condensate of nano TiO2 production workers.

Nanoscale titanium dioxide (nanoTiO2) is a commercially important nanomaterial. Animal studies have documented lung injury and inflammation, oxidative stress, cytotoxicity and genotoxicity. Yet, human health data are scarce and quantitative risk assessments and biomonitoring of exposure are lacking. NanoTiO2 is classified by IARC as a group 2B, possible human carcinogen. In our earlier studies we documented an increase in markers of inflammation, as well as DNA and protein oxidative damage, in exhaled breath condensate (EBC) of workers exposed nanoTiO2. This study focuses on biomarkers of lipid oxidation. Several established lipid oxidative markers (malondialdehyde, 4-hydroxy-trans-hexenal, 4-hydroxy-trans-nonenal, 8-isoProstaglandin F2α and aldehydes C6-C12) were studied in EBC and urine of 34 workers and 45 comparable controls. The median particle number concentration in the production line ranged from 1.98 × 104 to 2.32 × 104 particles/cm3 with ∼80% of the particles <100 nm in diameter. Mass concentration varied between 0.40 and 0.65 mg/m3. All 11 markers of lipid oxidation were elevated in production workers relative to the controls (p < 0.001). A significant dose-dependent association was found between exposure to TiO2 and markers of lipid oxidation in the EBC. These markers were not elevated in the urine samples. Lipid oxidation in the EBC of workers exposed to (nano)TiO2 complements our earlier findings on DNA and protein damage. These results are consistent with the oxidative stress hypothesis and suggest lung injury at the molecular level. Further studies should focus on clinical markers of potential disease progression. EBC has reemerged as a sensitive technique for noninvasive monitoring of workers exposed to engineered nanoparticles.

Leukotrienes in exhaled breath condensate and fractional exhaled nitric oxide in workers exposed to TiO2 nanoparticles.

Human health data regarding exposure to nanoparticles are extremely scarce and biomonitoring of exposure is lacking in spite of rodent pathological experimental data. Potential markers of the health-effects of engineered nanoparticles were examined in 30 workers exposed to TiO2 aerosol, 22 office employees of the same plant, and 45 unexposed controls. Leukotrienes (LT) B4, C4, E4, and D4 were analysed in the exhaled breath condensate (EBC) and urine via liquid chromatography-electrospray ionization-tandem mass spectrometry (LC-ESI-MS/MS). Fractional exhaled nitric oxide (FeNO) and spirometry was also measured. The median particle number concentration of the aerosol in the production ranged from 1.98 × 10(4) to 2.32 × 10(4) particles cm(-3); about 80% of the particles were <100 nm in diameter. Median total mass concentration varied between 0.4 and 0.65 mg m(-3). All LT levels in workers' EBC were elevated relative to the controls (p < 0.01). LTs in the EBC sample were correlated with titanium levels. Urinary LTs were not elevated in the workers and office employees. Office workers had higher LTB4 in EBC (p < 0.05), and higher levels of FeNO (p < 0.01). FeNO was higher in office employees with allergic diseases and was negatively correlated with smoking (p < 0.01). In spirometry significant impairment in the workers was seen only for %VCIN and %PEF (both p < 0.01). Multiple regression analysis confirmed a significant association between production of TiO2 and all cysteinyl LTs in EBC (p < 0.01) and impaired %VCIN and %PEF (both p < 0.01). LTB4 was also associated with smoking (p < 0.01). LT levels complemented our earlier findings of DNA, protein, and lipid damage in the EBC of workers with nanoTiO2 exposures. Cysteinyl LTs in EBC analysis suggest inflammation and potential fibrotic changes in the lungs; they may be helpful for monitoring the biological effect of (nano)TiO2 on workers. Spirometry was not sensitive enough.

Oxidative stress markers are elevated in exhaled breath condensate of workers exposed to nanoparticles during iron oxide pigment production.

Markers of oxidative stress and inflammation were analysed in the exhaled breath condensate (EBC) and urine samples of 14 workers (mean age 43 ± 7 years) exposed to iron oxide aerosol for an average of 10 ± 4 years and 14 controls (mean age 39 ± 4 years) by liquid chromatography-electrospray ionization-mass spectrometry/mass spectrometry (LC-ESI-MS/MS) after solid-phase extraction. Aerosol exposure in the workplace was measured by particle size spectrometers, a scanning mobility particle sizer (SMPS) and an aerodynamic particle sizer (APS), and by aerosol concentration monitors, P-TRAK and DustTRAK DRX. Total aerosol concentrations in workplace locations varied greatly in both time and space. The median mass concentration was 0.083 mg m(-3) (IQR 0.063-0.133 mg m(-3)) and the median particle concentration was 66 800 particles cm(-3) (IQR 16,900-86,900 particles cm(-3)). In addition, more than 80% of particles were smaller than 100 nm in diameter. Markers of oxidative stress, malondialdehyde (MDA), 4-hydroxy-trans-hexenale (HHE), 4-hydroxy-trans-nonenale (HNE), 8-isoProstaglandin F2α (8-isoprostane) and aldehydes C6-C12, in addition to markers of nucleic acid oxidation, including 8-hydroxy-2-deoxyguanosine (8-OHdG), 8-hydroxyguanosine (8-OHG), 5-hydroxymethyl uracil (5-OHMeU), and of proteins, such as o-tyrosine (o-Tyr), 3-chlorotyrosine (3-ClTyr), and 3-nitrotyrosine (3-NOTyr) were analysed in EBC and urine by LC-ESI-MS/MS. Almost all markers of lipid, nucleic acid and protein oxidation were elevated in the EBC of workers comparing with control subjects. Elevated markers were MDA, HNE, HHE, C6-C10, 8-isoprostane, 8-OHdG, 8-OHG, 5-OHMeU, 3-ClTyr, 3-NOTyr, o-Tyr (all p < 0.001), and C11 (p < 0.05). Only aldehyde C12 and the pH of samples did not differ between groups. Markers in urine were not elevated. These findings suggest the adverse effects of nano iron oxide aerosol exposure and support the utility of oxidative stress biomarkers in EBC. The analysis of urine oxidative stress biomarkers does not support the presence of systemic oxidative stress in iron oxide pigment production workers.

Raman microspectroscopy of exhaled breath condensate and urine in workers exposed to fine and nano TiO2 particles: a cross-sectional study.

The health effects of engineered nanoparticles in humans are not well-understood; however experimental data support the theory of oxidative stress promoting fibrogenesis and carcinogenicity. The aim of this study was to detect TiO2 particles in exhaled breath condensate (EBC) and urine samples to ascertain their presence and potential persistence and excretion in urine.EBC and urine samples were collected from 20 workers exposed to TiO2 aerosol; among them, 16 had a higher risk level of exposure (production workers) and four had medium risk level (research workers); in addition to 20 controls. Titanium levels in EBC and urine were analysed using the inductively coupled plasma mass spectrometry (ICP-MS) method. A Raman microspectroscopic analysis was performed in EBC and urine to identify the phase composition of TiO2 particles observed. Aerosol exposure in the workplaces was measured using SMPS and APS spectrometers and P-TRAK and DustTRAK DRX monitors.The median concentration of TiO2 aerosol was 1.98 × 10(4) particles cm(-3), the interquartile range (IQR) was 1.50 × 10(4) - 3.01 × 10(4) particles cm(-3) and the median mass concentration was 0.65 mg m(-3) (IQR 0.46-.0.83 mg m(-3)); 70-82% of the particles were smaller than 100 nm in diameter. In any part of the plant, the median TiO2 air concentration did not exceed the national airborne exposure limit of 10 mg m(-3) for inert dust. Particles of rutile and/or anatase were found in the EBC of exposed workers in 8/20 (40%) of the pre-shift and 14/20 (70%) of the post-shift samples. In the urine of workers, TiO2 particles were detected in 2/20 post-shift urine samples only. The mean concentration of titanium in the EBC in production workers was 24.1 ± 1.8 µg/l. In the research workers the values were below the limit of quantitation; LOQ = 4.0 ± 0.2 µg/l), as well as in the controls. In the urine samples of all of the subjects, titanium was under the limit of detection (LOD = 1.2 µg/l). Raman microanalysis of EBC in the workers confirmed the presence of TiO2 anatase and/or rutile crystal phases in the pre-shift samples and their persistence from previous shifts in the workers.

Successful Use of Hydroxocobalamin and Sodium Thiosulfate in Acute Cyanide Poisoning: A Case Report with Follow-up.

Hydroxocobalamin is an effective first-line antidote used mainly in monotherapy of cyanide poisonings, while the opinions are different on the effects of its combination with sodium thiosulfate. A 58-year-old male committed a suicide attempt by ingesting of 1200-1500 mg of potassium cyanide; he was unconscious for 1-1.5 min. after ingestion with the episode of generalized seizures. On admission to the ICU, the patient was acidotic (pH 7.28; HCO3 14.0 mmol/L, base excess -12.7 mmol/L, saturation O2 0.999) with high serum lactate (12.5 mmol/L). Hydroxocobalamin was administered 1.5 hr after ingestion in two subsequent intravenous infusions at a total dose of 7.5 g. The infusion was followed by continuous intravenous administration of 1 mL/hr/kg of 10% sodium thiosulfate at a total dose of 12 g. No complications and adverse reactions were registered. Serum lactate decreased to 0.6 mmol/L the same day, and arterial blood gases became normal (pH 7.49; HCO3 27.2 mmol/L, base excess 2.2 mmol/L, saturation O2 0.994). The follow-up examination 5 months later revealed no damage of basal ganglia and cerebellum on magnetic resonance imaging. The neurological examination revealed no pathological findings. On the ocular coherence tomography, the retinal nerve fibres layer was normal. In visual evoked potentials, there was a normal evoked complex on the left eye and minor decrease in amplitude on the right eye. Combination of hydroxocobalamin and sodium thiosulfate can have a positive effect on the survival without long-term neurological and visual sequelae in the cases of massive cyanide poisonings due to the possibility of a potentiation or synergism of hydroxocobalamin effects by sodium thiosulfate. This synergism can be explained by the different time-points of action of two antidotes: the initial and immediate effect of hydroxocobalamin, followed by the delayed, but more persistent effect of sodium thiosulfate.

Positions of the cytoplasmic end of BK α S0 helix relative to S1-S6 and of ß1 TM1 and TM2 relative to S0-S6.

The large-conductance, voltage- and Ca(2+)-gated K(+) (BK) channel consists of four α subunits, which form a voltage- and Ca(2+)-gated channel, and up to four modulatory ß subunits. The ß1 subunit is expressed in smooth muscle, where it slows BK channel kinetics and shifts the conductance-voltage (G-V) curve to the left at [Ca(2+)] > 2 µM. In addition to the six transmembrane (TM) helices, S1-S6, conserved in all voltage-dependent K(+) channels, BK α has a unique seventh TM helix, S0, which may contribute to the unusual rightward shift in the G-V curve of BK α in the absence of ß1 and to a leftward shift in its presence. Such a role is supported by the close proximity of S0 to S3 and S4 in the voltage-sensing domain. Furthermore, on the extracellular side of the membrane, one of the two TM helices of ß1, TM2, is adjacent to S0. We have now analyzed induced disulfide bond formation between substituted Cys residues on the cytoplasmic side of the membrane. There, in contrast, S0 is closest to the S2-S3 loop, from which position it is displaced on the addition of ß1. The cytoplasmic ends of ß1 TM1 and TM2 are adjacent and are located between the S2-S3 loop of one α subunit and S1 of a neighboring α subunit and are not adjacent to S0; i.e., S0 and TM2 have different trajectories through the membrane. In the absence of ß1, 70% of disulfide bonding of W43C (S0) and L175C (S2-S3) has no effect on V50 for activation, implying that the cytoplasmic end of S0 and the S2-S3 loop move in concert, if at all, during activation. Otherwise, linking them together in one state would obstruct the transition to the other state, which would certainly change V50.

Fomepizole in the treatment of acute methanol poisonings: experience from the Czech mass methanol outbreak 2012-2013.

OBJECTIVE: During an outbreak of mass methanol poisonings in the Czech Republic in 2012-2013, fomepizole was applied as an alternative antidote to ethanol. We present the laboratory data, clinical features, adverse reactions, and treatment outcomes in all patients treated with fomepizole. METHODS: Combined retrospective and prospective case series study in 25 patients, median age 50 (16-73) years, 18 males and 7 females. RESULTS: There were 24% fatalities, 36% survivors without health impairment, and 40% survivors with sequelae. All the patients who died were comatose on admission; the mortality was 50% among patients in a coma. The median intensive care unit length of stay was six (2-22) days. The median total dose of fomepizole was 2 (1-9) g. Complications were observed in 7/25 cases: aspiration pneumonia (4), sepsis (2), bleeding (2), malignant arrhythmia (1), delirium tremens (1), and rebound of acidosis (1). The patients who survived without impairment were less acidotic than those who died or survived with sequelae (P<0.01). No difference in serum methanol and formate was found between the three groups. CONCLUSION: There is no evidence whether fomepizole is a more efficient antidote than ethanol with regards to the hospital mortality. The possibility of delirium tremens in the patients with a history of chronic alcohol abuse has to be taken in consideration. The benefits of fomepizole were indirect: no need to monitor serum ethanol's level during the hemodialysis in severely poisoned patients and less working overload on ICU doctors treating several poisoned patients simultaneously.

[Emergency reserve of life-saving anti-infective drugs]. / Pohotovostni zasoba zivot zachranujicich antiinfektiv.

OBJECTIVES: Problems with importing non-registered medicines for treating rare life-threatening infectious diseases led to establishment of the Emergency Anti-Infective Drug Reserve (EAIDR) for the Czech Republic. METHODS: Thirteen anti-infective drugs are included in the project: antisera against rabies virus, varicella-zoster virus, and botulinum toxin; antituberculosis drugs (intravenous rifampicin and isoniazid; capreomycin, cycloserine, and clofazimine); antiparasitics (intravenous quinine, primaquine, meglumine antimoniate, and praziquantel); and pentamidine. These drugs are imported according to the Czech drug legislation (specific drug availability programs). Realization: The project, approved by the Czech Ministry of Health in September 2013, was started in January 2014. The anti-infective drugs sufficient for 2-4 patients are permanently available in the Toxicological Information Center (TIC) in Prague. The medicines can be applied in any hospital throughout the Czech Republic within several hours. CONCLUSIONS: All but three drugs are available at present; the remaining ones will be imported after new batches of these drugs are released.

Occupational asthma follow-up--which markers are elevated in exhaled breath condensate and plasma?

OBJECTIVES: To search for optimal markers in the exhaled breath condensate (EBC), plasma and urine that would reflect the activity/severity of occupational asthma (OA) after the withdrawal from the exposure to the allergen. MATERIAL AND METHODS: Markers of oxidative stress: 8-iso-prostaglandin F2α (8-isoprostane, 8-ISO), malondialdehyde (MDA), 4-hydroxy-trans-2-nonenale (HNE), cysteinyl leukotrienes (LT) and LTB4 were determined using liquid chromatography and mass spectrometry in 43 subjects with immunological OA (49.3 ± 11.8 years), removed from the exposure to the sensitizing agent 10.5 ± 6.5 years ago; and in 20 healthy subjects (49.0 ± 14.9 years). EBC was harvested both before and after the methacholine challenge test. In parallel, identical markers were collected in plasma and urine. The results were analyzed together with forced expiratory volume in one second (FEV1), blood eosinophils, immunoglobulin E (IgE) and eosinophilic cationic protein (ECP) and statistically evaluated (Spearman rank correlation rS, two- or one-sample t tests and alternatively Kruskal Wallis or pair Wilcoxon tests). RESULTS: Several parameters of lung functions were lower in the patients (FEV1% predicted, MEF25% and MEF50%, Rtot%, p < 0.001). Shorter time interval since the removal from the allergen exposure correlated with higher ECP (rS = 0.375) and lower FEV1%, MEF25% and MEF50% after methacholine challenge (rS = -0.404, -0.425 and -0.532, respectively). In the patients, IgE (p < 0.001) and ECP (p = 0.009) was increased compared to controls. In EBC, 8-ISO and cysteinyl LTs were elevated in the asthmatics initially and after the challenge. Initial 8-ISO in plasma correlated negatively with FEV1 (rS = -0.409) and with methacholine PD20 (rS = -0.474). 8-ISO in plasma after the challenge correlated with IgE (rS = 0.396). CONCLUSIONS: The improvement in OA is very slow and objective impairments persist years after removal from the exposure. Cysteinyl LTs and 8-ISO in EBC and 8-ISO in plasma might enrich the spectrum of useful objective tests for the follow-up of OA.

Orientations and proximities of the extracellular ends of transmembrane helices S0 and S4 in open and closed BK potassium channels.

The large-conductance potassium channel (BK) α subunit contains a transmembrane (TM) helix S0 preceding the canonical TM helices S1 through S6. S0 lies between S4 and the TM2 helix of the regulatory ß1 subunit. Pairs of Cys were substituted in the first helical turns in the membrane of BK α S0 and S4 and in ß1 TM2. One such pair, W22C in S0 and W203C in S4, was 95% crosslinked endogenously. Under voltage-clamp conditions in outside-out patches, this crosslink was reduced by DTT and reoxidized by a membrane-impermeant bis-quaternary ammonium derivative of diamide. The rate constants for this reoxidation were not significantly different in the open and closed states of the channel. Thus, these two residues are approximately equally close in the two states. In addition, 90% crosslinking of a second pair, R20C in S0 and W203C in S4, had no effect on the V50 for opening. Taken together, these findings indicate that separation between residues at the extracellular ends of S0 and S4 is not required for voltage-sensor activation. On the contrary, even though W22C and W203C were equally likely to form a disulfide in the activated and deactivated states, relative immobilization by crosslinking of these two residues favored the activated state. Furthermore, the efficiency of recrosslinking of W22C and W203C on the cell surface was greater in the presence of the ß1 subunit than in its absence, consistent with ß1 acting through S0 to stabilize its immobilization relative to α S4.

Positions of ß2 and ß3 subunits in the large-conductance calcium- and voltage-activated BK potassium channel.

Large-conductance voltage- and Ca(2+)-gated K(+) channels are negative-feedback regulators of excitability in many cell types. They are complexes of α subunits and of one of four types of modulatory ß subunits. These have intracellular N- and C-terminal tails and two transmembrane (TM) helices, TM1 and TM2, connected by an ∼100-residue extracellular loop. Based on endogenous disulfide formation between engineered cysteines (Cys), we found that in ß2 and ß3, as in ß1 and ß4, TM1 is closest to αS1 and αS2 and TM2 is closest to αS0. Mouse ß3 (mß3) has seven Cys in its loop, one of which is free, and this Cys readily forms disulfides with Cys substituted in the extracellular flanks of each of αS0-αS6. We identified by elimination mß3-loop Cys152 as the only free Cys. We inferred the disulfide-bonding pattern of the other six Cys. Using directed proteolysis and fragment sizing, we determined this pattern first among the four loop Cys in ß1. These are conserved in ß2-ß4, which have four additional Cys (eight in total), except that mß3 has one fewer. In ß1, disulfides form between Cys at aligned positions 1 and 8 and between Cys at aligned positions 5 and 6. In mß3, the free Cys is at position 7; position 2 lacks a Cys present in all other ß2-ß4; and the disulfide pattern is 1-8, 3-4, and 5-6. Presumably, Cys 2 cross-links to Cys 7 in all other ß2-ß4. Cross-linking of mß3 Cys152 to Cys substituted in the flanks of αS0-S5 attenuated the protection against iberiotoxin (IbTX); cross-linking of Cys152 to K296C in the αS6 flank and close to the pore enhanced protection against IbTX. In no case was N-type inactivation by the N-terminal tail of mß3 perturbed. Although the mß3 loop can move, its position with Cys152 near αK296, in which it blocks IbTX binding, is likely favored.

Location of modulatory beta subunits in BK potassium channels.

Large-conductance voltage- and calcium-activated potassium (BK) channels contain four pore-forming alpha subunits and four modulatory beta subunits. From the extents of disulfide cross-linking in channels on the cell surface between cysteine (Cys) substituted for residues in the first turns in the membrane of the S0 transmembrane (TM) helix, unique to BK alpha, and of the voltage-sensing domain TM helices S1-S4, we infer that S0 is next to S3 and S4, but not to S1 and S2. Furthermore, of the two beta1 TM helices, TM2 is next to S0, and TM1 is next to TM2. Coexpression of alpha with two substituted Cys's, one in S0 and one in S2, and beta1 also with two substituted Cys's, one in TM1 and one in TM2, resulted in two alphas cross-linked by one beta. Thus, each beta lies between and can interact with the voltage-sensing domains of two adjacent alpha subunits.