Measurement of Atmospheric Mercury: Current Limitations and Suggestions for Paths Forward.

Mercury (Hg) researchers have made progress in understanding atmospheric Hg, especially with respect to oxidized Hg (HgII) that can represent 2 to 20% of Hg in the atmosphere. Knowledge developed over the past ∼10 years has pointed to existing challenges with current methods for measuring atmospheric Hg concentrations and the chemical composition of HgII compounds. Because of these challenges, atmospheric Hg experts met to discuss limitations of current methods and paths to overcome them considering ongoing research. Major conclusions included that current methods to measure gaseous oxidized and particulate-bound Hg have limitations, and new methods need to be developed to make these measurements more accurate. Developing analytical methods for measurement of HgII chemistry is challenging. While the ultimate goal is the development of ultrasensitive methods for online detection of HgII directly from ambient air, in the meantime, new surfaces are needed on which HgII can be quantitatively collected and from which it can be reversibly desorbed to determine HgII chemistry. Discussion and identification of current limitations, described here, provide a basis for paths forward. Since the atmosphere is the means by which Hg is globally distributed, accurately calibrated measurements are critical to understanding the Hg biogeochemical cycle.

Fatal hyperacute left main thrombosis after aortic root surgery.

Acute aortic root thrombosis is a potentially lethal condition due to the possibility of thrombosis into the ascending aorta branches, resulting in various clinical manifestations. A 29-year-old male patient was admitted to our center with hyperacute left main thrombosis after elective Bentall procedure. Due to massive left ventricular infarction, the patient was supported by extracorporeal membrane oxygenation, but without success to recovery. The patient's blood analyses revealed a high level of the Factor VIII. In conclusion, Factor VIII levels in the blood are elevated by genetic abnormalities, infectious diseases such as severe acute respiratory syndrome-coronavirus 2 infection, and vascular inflammation. This pathological condition may be a reason for hyperacute thrombosis.

Traceable Calibration of Atmospheric Oxidized Mercury Measurements.

Most previous measurements of oxidized mercury were collected using a method now known to be biased low. In this study, a dual-channel system with an oxidized mercury detection limit of 6-12 pg m-3 was deployed alongside a permeation tube-based automated calibrator at a mountain top site in Steamboat Springs Colorado, USA, in 2021 and 2022. Permeation tubes containing elemental mercury and mercury halides were characterized via an International System of Units (SI)-traceable gravimetric method and gas chromatography/mass spectrometry before deployment in the calibrator. The dual-channel system recovered 97 ± 4 and 100 ± 8% (±standard deviation) of injected elemental mercury and HgBr2, respectively. Total Hg permeation rates and Hg speciation from the gravimetric method, the chromatography system, the dual-channel system, and an independent SI-traceable measurement method performed at the Jozef Stefan Institute laboratory were all comparable within the respective uncertainties of each method. These are the first measurements of oxidized mercury at low environmental concentrations that have been verified against an SI-traceable calibration system in field conditions while sampling ambient air, and they show that accurate, routinely calibrated oxidized mercury measurements are achievable.

Exploring mechanisms of mupirocin resistance and hyper-resistance.

Mupirocin is a broad-spectrum antibiotic that acts predominantly against Gram-positive bacteria. It is produced by Pseudomonas fluorescens NCIMB 10586 and has been clinically used to treat primary and secondary skin infections and to eradicate nasal colonisation of methicillin-resistant Staphylococcus aureus strains. Mupirocin inhibits protein synthesis by blocking the active site of isoleucyl-tRNA synthetase (IleRS), which prevents the enzyme from binding isoleucine and ATP for Ile-tRNAIle synthesis. Two types of IleRS are found in bacteria - while IleRS1 is susceptible to mupirocin inhibition, IleRS2 provides resistance to cells. These two types belong to distinct evolutionary clades which likely emerged from an early gene duplication in bacteria. Resistance in IleRS2 is based on the loss of interactions that govern mupirocin binding to IleRS1, such as hydrogen bonding to the carboxylate moiety of mupirocin. IleRS2 enzymes with Ki in the millimolar range have recently been discovered. These hyper-resistant IleRS2 variants surprisingly have a non-canonical version of the catalytic motif, which serves as a signature motif of class I aminoacyl-tRNA synthetases to which IleRS belongs. The non-canonical motif, in which the 1st and 3rd positions are swapped, is key for hyper-resistance and can be accommodated without abolishing enzyme activity in IleRS2 but not in IleRS1. Clinical use of mupirocin led to the emergence of resistance in S. aureus. Low-level resistance arises by mutations of the housekeeping IleRS1, while high-level resistance develops by the acquisition of the resistant IleRS2 on a plasmid. There is no evidence that hyper-resistant variants have been found in clinical isolates.

Case Report: Giant cholesterol granuloma in the anterior mediastinum.

Cholesterol granuloma is a rare entity, which can develop in many regions of the body, accounting at most 1% of all mediastinal tumors. Etiology of this granuloma is still not clearly understood. The gold standard choice of treatment for cholesterol granuloma is total surgical resection. Symptomatic mediastinum granuloma can be easily diagnosed, but if mass effect is not evident then diagnosis of this tumor is really challenging. We present a rare case of huge cholesterol granuloma in the anterior mediastinum of the patient who underwent on elective coronary artery graft bypass surgery.

Comparison of active measurements, lichen biomonitoring, and passive sampling for atmospheric mercury monitoring.

The number of atmospheric mercury (Hg) monitoring stations is growing globally. However, there are still many regions and locations where Hg monitoring is limited or non-existent. Expansion of the atmospheric Hg monitoring network could be facilitated by the use of cost-effective monitoring methods. As such, biomonitoring and passive monitoring offer a unique alternative to well-established monitoring by active measurements, since they do not require a power supply and require minimal workload to operate. The use of biomonitoring (lichens and mosses) and passive air samplers (PASs) (various designs with synthetic materials) has been reported in the literature, and comparisons with active measurement methods have also been made. However, these studies compared either biomonitoring or PASs (not both) to only one type of active measurement. In our work, we used transplanted (7 sampling sites) and in situ lichens (8 sampling sites) for biomonitoring, two PASs from different producers (3 sampling sites), and two different active measurement types (continuous and discontinuous active measurements, 1 and 8 sampling sites, respectively) to evaluate their effectiveness as monitoring methods. In the 9-month sampling campaign, 3 sampling locations with different characteristics (unpolluted, vicinity of a cement plant, and vicinity of a former Hg mine) were used. The results obtained with lichens and PASs clearly distinguished between sampling locations with different Hg concentrations; using both PASs and lichens together increased the confidence of our observations. The present work shows that biomonitoring and passive sampling can be effectively used to identify areas with elevated atmospheric Hg concentrations. The same can be said for discontinuous active measurements; however, the discrepancy between atmospheric Hg concentrations derived from PASs and discontinuous active measurements should be further investigated in the future.

Surgical treatment of a left ventricular pseudoaneurysm with an extracellular matrix patch.

Left ventricle pseudoaneurysm is a rare and life-threatening complication of myocardial infarction that is formed as a result of left ventricle free wall rupture contained by the overlying pericardium. Urgent surgical repair is crucial, and in most reports, left ventricle was reconstructed with a Dacron or bovine pericardial patch. We present a case of a 66-year-old female with left ventricle pseudoaneurysm which was successfully repaired with an extracellular matrix patch. Supplementary Information: The online version contains supplementary material available at 10.1007/s12055-023-01669-3.

Application of traceable calibration for gaseous oxidized mercury in air.

BACKGROUND: The current speciation methods for mercury (Hg) measurements are fraught with considerable uncertainty, from sample collection to calibration. High reactivity of gaseous oxidized Hg (GOM) species and their ultra-trace level presence makes them difficult to sample and calibrate. Given that improper calibration may lead to measurement biases, reliable and metrologically traceable calibration methods are required for accurately quantifying GOM in air. In the present study, we applied the recently developed calibration method based on non-thermal plasma oxidation of elemental Hg, to a commercially available Hg air speciation system for actual environmental measurements of GOM for the first time. RESULTS: Hg species such as HgO, HgCl2, and HgBr2 were produced with trace amounts of reactant gases (oxygen and electrolytically produced chlorine and bromine) and the production was driven by plasma-assisted oxidation. The plasma oxidation efficiency of elemental Hg with oxygen was 98.5 ± 7.5 % (k = 2), while that for chlorine and bromine was 96.8 ± 6.9 % (k = 2) and 97.4 ± 9.6 % (k = 2), respectively. The calibration method was tested against the internal permeation (Hg0) source of the Tekran 2537B Hg analyzer on-field by loading HgO to different KCl-coated denuders using the plasma. GOM concentrations were measured using the Tekran speciation system. With internal calibration, concentrations were up to 9.1 % lower than those in plasma calibration, thereby emphasizing the importance of the calibration strategy. Measurement uncertainty (k = 2) further emphasizes this distinction. Internal calibration measurement uncertainty was 36.8 %, while plasma calibration boasted lower uncertainty at 13.8 %. SIGNIFICANCE: The non-thermal plasma calibration strategy, as a unique and discrete calibration method traceable to the NIST SRM 3133 for ambient air GOM measurements, provide a higher level of confidence in the accuracy of GOM measurements with several advantages over other methods. Calibrations at extreme low concentrations (<100 pg) are possible with this method relevant to ambient air GOM concentrations.

Optimization of a pre-concentration method for the analysis of mercury isotopes in low-concentration foliar samples.

Hg isotope analysis in samples from background regions is constrained by the presence of low Hg concentration and therefore requires a pre-concentration method. Existing Hg pre-concentration methods are constrained by long sample processing time and limited sample loading capacity. Using foliar samples as a test case, an optimized Hg pre-concentration method is presented that involves the microwave-assisted digestion of samples for Hg isotope analysis with the addition of a pre-digestion step. Microwave-digested foliar samples and CRMs were transferred to an impinger, reduced with SnCl2, and collected in a 2.25 mL concentrated inverse aqua regia (3:1 HNO3:HCl, v/v). This resulted in an optimal acid concentration in the solution ideal for analysis on MC-ICP-MS. The time for purging with Hg-free N2 was optimized to 30 min and the efficiency of the pre-concentration method was tested using a combination of approaches. Tests performed on pure reagents and matrix of foliar samples spiked with 197Hg radiotracer showed recoveries averaging 99 ± 1.7% and 100 ± 3.0%, respectively. Mercury at concentrations as low as 1.83 ng g-1 was pre-concentrated by digesting aliquots of foliage samples in individual digestion vessels. Recoveries following their pre-concentration averaged 99 ± 6.0%, whereas recoveries of 95 ± 4.7% and 95 ± 2.5% were achieved for NIST SRM 1575a (pine needle) and reagents spiked with NIST SRM 3133, respectively. Analysis using multicollector-ICP-MS showed low fractionation of δ202Hg during sample pre-concentration with no significant mass-independent fractionation. The proposed method is a relatively simple and robust way to prepare Hg samples for Hg isotopic analysis and is suitable even for complex biological matrices.

Clinical Impact of Patient-Prosthesis Mismatch After Aortic Valve Replacement With a Mechanical or Biological Prosthesis.

BACKGROUND: Patient-prosthesis mismatch (PPM) may impair functional capacity and survival after aortic valve replacement. This study aimed to investigate the impact of PPM on long-term survival and quality of life after mechanical and biological aortic valve replacement. METHODS: This study included 595 consecutive patients who had undergone isolated aortic valve replacement. Patients were divided into 2 groups according to prosthesis type. The baseline and operative characteristics, survival rates, complications, and quality of life of the groups with and without PPM were compared for up to 6 years. The PPM calculation was performed using the effective orifice area value provided by the manufacturer divided by the patient's body surface area. RESULTS: The moderate to severe PPM rates were 69.8% and 3.7% after biological and mechanical prosthesis implantation, respectively. Mean survival for patients in the biological group who had PPM was statistically significantly shorter (50.2 months [95% CI, 45.2-55.3]) than for patients in the biological group without PPM (60.1 months [95% CI, 55.7-64.4]; P = .04). In the mechanical prosthesis group, there was no difference in mean survival between the subgroup with PPM (66.6 months [95% CI, 58.3-74.9]) and the subgroup without PPM (64.9 months [95% CI, 62.6-67.2]; P = .50). A quality-of-life questionnaire's scores did not differ between the groups. CONCLUSION: Mismatch is common after biological valve implantation and statistically significantly affects long-term survival and quality of life. If the risk of PPM after implantation of a biological prosthesis is suspected, adopting strategies to avoid PPM at the time of surgery is warranted.

Assessing comparability and uncertainty of analytical methods for methylated mercury species in seawater.

BACKGROUND: The relative distribution and importance of monomethylmercury (MMHg) and dimethylmercury (DMHg) in seawater is still under debate. A lack of comparability between measurements at sub-picomolar levels hampered the further understanding of the biogeochemical Hg cycle. To overcome this, we assessed the relative standard measurement uncertainties (Uex,r) for direct measurements of MMHg and DMHg by species-specific isotope dilution ICP-MS and cryo-focusing GC-ICP-MS at femtomolar concentrations. Furthermore, Uex,r was determined for the indirect determination of DMHg (DMHgcalc = MeHg - MMHg) and MeHg (MeHgcalc = MMHg + DMHg) to compare the two methodologies. RESULTS: Expanded Uex,r (confidence interval of 95%) for cryo-focusing GC-ICP-MS was 14.4 (<50 fM) and 14.2% (>50 fM) and for SS-ID GC-ICP-MS 5.6 (<50 fM) and 3.7% (>50 fM). For concentrations above 50 fM, Uex,r for DMHgcalc was always lower than for direct measurements (14.2%). For MeHgcalc, on the other hand, Uex,r was always higher for concentrations above 115 fM (range: 3.7-13.9%) than for direct measurements (3.7%). We evaluated the comparability of directly measured and calculated DMHg and MeHg concentrations based on Hg speciation measurements for two vertical profiles in the Mediterranean Sea. We show that directly measured and indirectly determined DMHg and MeHg concentrations yield comparable results. SIGNIFICANCE: Our results validate the application of the indirect method for the determination of DMHg if a direct measurement method with a low Uex,r such as isotope dilution is used for MMHg and MeHg measurements. The validation of the indirect measurement approach opens new possibilities to generate more precise and accurate DMHg data in the global ocean.

Optimisation of distillation as an isolation method for the determination of low methylmercury concentrations in urine samples.

Methylmercury (MeHg) speciation in urine requires a robust, reproducible and sensitive technique that enables reliable measurements in limited sample volumes. Conventional MeHg extraction by acid digestion allows for processing of only small amounts of urine digest, making accurate MeHg determination in low-concentration samples virtually impossible. Distillation has been proven as an efficient isolation method with very low detection limits for measuring MeHg in water samples; therefore, in this study, it was optimised for urine samples. Combined with aqueous phase ethylation, purging with nitrogen, preconcentration on Tenax trap, isothermal gas chromatography and cold vapour atomic fluorescence detection, distillation achieved high and repeatable urine spike recoveries of 94% ± 7%. Larger measured aliquot volume led to a significantly lower limit of detection (LOD) for distillation compared with acid digestion (1.1 versus 5.5 pg g-1 urine). Thirty-two general population urine samples were analysed using both methods, and the results were compared. Distillation led to better separation of MeHg from inorganic Hg and the matrix. Good correlation was observed between the results obtained by the two methods for samples with MeHg concentrations above 10 pg g-1 urine (slope = 0.9492, R2 = 0.9879). For samples below this MeHg concentration, distillation was superior, enabling the measurement of MeHg in 9 out of 12 urine samples that were below the LOD of acid digestion. Distillation had significantly lower measurement uncertainty, particularly in the low-concentration samples, where the expanded combined standard uncertainty of the acid digestion method reached as high as 43.2% (k = 2), predominantly owing to poor sample repeatability.

Surgical treatment of right ventricle thrombus in a patient with iron-deficiency anaemia.

Right ventricle organized thrombus is a rare pathological condition diagnosed in patients with a risk factor. The most common are right ventricle (RV) failure, autoimmune disease (Behcet disease), hypercoagulable disorder, anaemia, RV pacing leads, pulmonary artery catheters, RV infarction, and ventricular arrhythmogenic cardiomyopathy. The literature describes the impact of iron-deficiency anaemia on thrombosis. We described surgical extirpation of the organized right ventricle outflow tract (RVOT) thrombus in a patient with iron-deficiency anaemia. Supplementary Information: The online version contains supplementary material available at 10.1007/s12055-022-01460-w.

First-in-Human µCAB™ Coronary Revascularization Surgery.

Less invasive coronary artery bypass grafting surgery is underused despite more than 25 years of interest from surgeons and growing patient demands for less pain and rapid full recovery. New approaches may offer surgeons additional options to provide enhanced clinical results through reliable subxiphoid bilateral internal thoracic artery harvesting and the creation of durable anastomoses through very small thoracotomy incisions. This first-in-human case report describes 2 patients who received surgical coronary revascularization using the µCAB™ technology and techniques. The encouraging early results indicate that the µCAB™ approach may offer a new ergonomic, affordable method for coronary revascularization with less surgical trauma.

Influence of Three Different Surgical Techniques on Microscopic Damage of Saphenous Vein Grafts-A Randomized Study.

Background and Objectives: The saphenous vein is one of the most common used grafts (SVG) for surgical revascularization. The mechanism of the SVGs occlusion is still unknown. Surgical preparation techniques have an important role in the early and late graft occlusion. Our study analyzed the influence of the three different surgical techniques on the histological and immunohistochemical characteristics of the vein grafts. Methods: Between June 2019 and December 2020, 83 patients who underwent surgical revascularization were prospectively randomly assigned to one of the three groups, according to saphenous vein graft harvesting (conventional (CVH), no-touch (NT) and endoscopic (EVH)) technique. The vein graft samples were sent on the histological (hematoxylin-eosin staining) and immunohistochemical (CD31, Factor VIII, Caveolin and eNOS) examinations. Results: The CVH, NT, and EVH groups included 27 patients (mean age 67.66 ± 5.6), 31 patients (mean age 66.5 ± 7.4) and 25 patients (mean age 66 ± 5.5), respectively. Hematoxylin-eosin staining revealed a lower grade of microstructural vein damage in the NT group (2, IQR 1-2) in comparison with CVH and EVH (3, IQR 2-4), (4, IQR 2-4) respectively (p < 0.001). Immunohistochemical examination revealed a high grade of staining in the NT group compared to the CVH and EVH group (CD 31 antibody p = 0.02, FVIII, p < 0.001, Caveolin, p = 0.001, and eNOS, p = 0.003). Conclusion: The best preservation of the structural vein integrity was in the NT group, while the lowest rate of leg wound complication was in the EVH group. These facts increase the interest in developing and implementing the endoscopic no-touch technique.

Surgical Reconstruction of the Anomalous Left Coronary Artery From the Pulmonary Artery.

The anomalous left coronary artery from the pulmonary artery is a rare congenital disease. Early surgical reconstruction is mandatory to prevent adverse cardiac events. Direct coronary button transfer, vein graft interposition, ligation, and coronary artery bypass construction are the most commonly used techniques. This case report presents a modified technique of Dacron graft interposition and reimplantation anomalous left coronary artery from the pulmonary artery on the ascending aorta.

Same-Day Carotid Artery Stenting and Coronary Artery Bypass Surgery.

BACKGROUND: The optimal treatment strategy for patients with severe carotid artery disease undergoing coronary artery bypass grafting is still problematic. The important question is whether it is necessary to treat significant carotid disease in patients who have undergone coronary artery bypass grafting. This study analyzed short- and midterm results after same-day carotid artery stenting and coronary artery bypass grafting. METHODS: From 2013 to 2020, a total of 69 patients were enrolled in the study. Same-day carotid artery stenting and coronary artery bypass grafting were performed in all patients. The study's primary end points were the evaluation rate of stroke, myocardial infarction, and death within short- and midterm periods after the procedures. RESULTS: The 30-day mortality was 0%. The occurrences of perioperative adverse events, namely stroke, myocardial infarction, and transient ischemic attack, were 1 (1.4%), 1 (1.4%), and 4 (5.8%), respectively. Mean (IQR) follow-up time was 28 (IQR, 17-43) months. Six (8.8%) patients died during this period. Fatal stroke was registered in 2 cases, and 1 patient experienced a disabling stroke with a fatal outcome. The other 3 patients died because of chronic renal disease, a traffic accident, and for an unknown reason, respectively. Midterm survival in the group was 91.2%. CONCLUSION: The study showed that same-day carotid artery stenting and coronary artery bypass grafting for concomitant carotid and coronary disease treatment could be a promising and feasible therapeutic strategy.

Economic Justification Analysis of Minimally Invasive versus Conventional Aortic Valve Replacement.

There is no definitive consensus about the cost-effectiveness of minimally invasive aortic valve replacement (AVR) (MI-AVR) compared to conventional AVR (C-AVR). The aim of this study was to compare the rate of postoperative complications and total hospital costs of MI-AVR versus C-AVR overall and by the type of aortic prosthesis (biological or mechanical). Our single-center retrospective study included 324 patients over 18 years old who underwent elective isolated primary AVR with standard stented AV prosthesis at the Institute for Cardiovascular Diseases "Dedinje" between January 2019 and December 2019. Reintervention, emergencies, combined surgical interventions, and patients with sutureless valves were excluded. In both MI-AVR and C-AVR, mechanical valve implantation contributed to overall reduction of hospital costs with equal efficacy. The cost-effectiveness ratio indicated that C-AVR is cheaper and yielded a better clinical outcome with mechanical valve implantation (67.17 vs. 69.5). In biological valve implantation, MI-AVR was superior. MI-AVR patients had statistically significantly higher LVEF and a lower Euro SCORE than C-AVR patients (Mann-Whitney U-test, p = 0.002 and p = 0.002, respectively). There is a slight advantage to MI-AVR vs. C-AVR, since it costs EUR 9.44 more to address complications that may arise. Complications (mortality, early reoperation, cerebrovascular insult, pacemaker implantation, atrial fibrillation, AV block, systemic inflammatory response syndrome, wound infection) were less frequent in the MI-AVR, making MI-AVR more economically justified than C-AVR (18% vs. 22.1%).