International Patient Summary Terminology.

SNOMED CT is a comprehensive medical ontology used in health care sectors across the world covering a wide range of concepts that support diversity at the point of healthcare. However, not all these concepts are needed for every use case; it is better to concentrate on those parts that apply to the particular application while preserving the meaning of relevant concepts. This paper considers the application of a novel subontology extraction method to create a new resource, called the IPS terminology, which functions as a standalone ontology with the same features as SNOMED CT, but is designed for cross-border patient care. The IPS terminology has been released for free use under an open license, with the intention of promoting interoperability of health information worldwide.

Immunodeficiency is prevalent in congenital heart disease and associated with increased risk of emergency admissions and death.

AIMS: To provide population-based data on the prevalence and clinical significance of immune deficiency syndromes (IDS) associated with congenital heart disease (CHD). METHODS AND RESULTS: Utilizing administrative German Health System data the prevalence of increased susceptibility to infection (ISI) or confirmed IDS was assessed in CHD patients and compared with an age-matched non-congenital control group. Furthermore, the prognostic significance of IDS was assessed using all-cause mortality and freedom from emergency hospital admission. A total of 54 449 CHD patients were included. Of these 14 998 (27.5%) had ISI and 3034 (5.6%) had a documented IDS (compared with 2.9% of the age-matched general population). During an observation period of 394 289 patient-years, 3824 CHD patients died, and 31 017 patients experienced a combined event of all-cause mortality or emergency admission. On multivariable Cox proportional-hazard analysis, the presence of ISI [hazard ratio (HR): 2.14, P < 0.001] or documented IDS (HR: 1.77, P = 0.035) emerged as independent predictors of all-cause mortality. In addition, ISI and confirmed IDS were associated with a significantly higher risk of emergency hospital admission (P = 0.01 for both on competing risk analysis) during follow-up. CONCLUSION: Limited immune competence is common in CHD patients and associated with an increased risk of morbidity and mortality. This highlights the need for structured IDS screening and collaboration with immunology specialists as immunodeficiency may be amenable to specific therapy. Furthermore, studies are required to assess whether IDS patients might benefit from intensified antibiotic shielding or tailored prophylaxis.

Palliative care on the radiation oncology ward-improvements in clinical care through interdisciplinary ward rounds.

INTRODUCTION: Palliative care is essential for patients with terminal diseases and aims at effective symptom control. This may stand in opposition to radiation treatment as an oncological treatment modality. The hereby presented work demonstrates the successful integration of a palliative care service in the radiation oncology ward. METHODS: Since 2015, 1018 patients were seen by the palliative care service on the radiation oncology ward and have been analyzed in this single center study. To assess teaching efficacy of the consultation service, a survey was conducted among 15 radiation oncology residents. RESULTS: Cooperation between the two departments proved to be efficient with rising patient numbers. Palliative care was able to guide appropriate postdischarge care with the number of patients dying on the radiation oncology ward decreasing significantly (p = 0.009). The main topics for consultation were pain medication (92.3%), organization of postdischarge care (92.3%), and psycho-oncological support (84.6%). Most residents had a positive image of the palliative care service and consented on adjectives like "enriching", "empathic", "collegial", "professionally founded", and a "low threshold for consultation". All participants agreed that cooperation deepened their knowledge on palliative care. CONCLUSION: A synergistic cooperation between a palliative care consultation service and a radiation oncology department addresses patient symptoms on an individual level. It confers advanced knowledge on palliative care which is essential for resident education and patient treatment.

Maternal and neonatal complications in women with congenital heart disease: a nationwide analysis.

AIMS: The aim of this study was to provide population-based data on maternal and neonatal complications and outcome in the pregnancies of women with congenital heart disease (CHD). METHODS AND RESULTS: Based on administrative data from one of the largest German Health Insurance Companies (BARMER GEK, ∼9 million members representative for Germany), all pregnancies in women with CHD between 2005 and 2018 were analysed. In addition, an age-matched non-CHD control group was included for comparison and the association between adult CHD (ACHD) and maternal or neonatal outcomes investigated. Overall, 7512 pregnancies occurred in 4015 women with CHD. The matched non-CHD control group included 6502 women with 11 225 pregnancies. Caesarean deliveries were more common in CHD patients (40.5% vs. 31.5% in the control group; P < 0.001). There was no excess mortality. Although the maternal complication rate was low in absolute terms, women with CHD had a significantly higher rate of stroke, heart failure and cardiac arrhythmias during pregnancy (P < 0.001 for all). Neonatal mortality was low but also significantly higher in the ACHD group (0.83% vs. 0.22%; P = 0.001) and neonates to CHD mothers had low/extremely low birth weight or extreme immaturity (<0.001) or required resuscitation and mechanical ventilation more often compared to non-CHD offspring (P < 0.001 for both). On multivariate logistic regression maternal defect complexity, arterial hypertension, heart failure, prior fertility treatment, and anticoagulation with vitamin K antagonists emerged as significant predictors of adverse neonatal outcome (P < 0.05 for all). Recurrence of CHD was 6.1 times higher in infants to ACHD mothers compared to controls (P < 0.0001). CONCLUSIONS: This population-based study illustrates a reassuringly low maternal mortality rate in a highly developed healthcare system. Nevertheless, maternal morbidity and neonatal morbidity/mortality were significantly increased in women with ACHD and their offspring compared to non-ACHD controls highlighting the need of specialized care and pre-pregnancy counselling.

Lack of specialist care is associated with increased morbidity and mortality in adult congenital heart disease: a population-based study.

AIMS: The aim of this study was to provide population-based data on the healthcare provision for adults with congenital heart disease (ACHD) and the impact of cardiology care on morbidity and mortality in this vulnerable population. METHODS AND RESULTS: Based on administrative data from one of the largest German Health Insurance Companies, all insured ACHD patients (<70 years of age) were included. Patients were stratified into those followed exclusively by primary care physicians (PCPs) and those with additional cardiology follow-up between 2014 and 2016. Associations between level of care and outcome were assessed by multivariable/propensity score Cox analyses. Overall, 24 139 patients (median age 43 years, 54.8% female) were included. Of these, only 49.7% had cardiology follow-up during the 3-year period, with 49.2% of patients only being cared for by PCPs and 1.1% having no contact with either. After comprehensive multivariable and propensity score adjustment, ACHD patients under cardiology follow-up had a significantly lower risk of death [hazard ratio (HR) 0.81, 95% confidence interval (CI) 0.67-0.98; P = 0.03) or major events (HR 0.85, 95% CI 0.78-0.92; P < 0.001) compared to those only followed by PCPs. At 3-year follow-up, the absolute risk difference for mortality was 0.9% higher in ACHD patients with moderate/severe complexity lesions cared by PCPs compared to those under cardiology follow-up. CONCLUSION: Cardiology care compared with primary care is associated with superior survival and lower rates of major complications in ACHD. It is alarming that even in a high resource setting with well-established specialist ACHD care approximately 50% of contemporary ACHD patients are still not linked to regular cardiac care. Almost all patients had at least one contact with a PCP during the study period, suggesting that opportunities to refer patients to cardiac specialists were missed at PCP level. More efforts are required to alert PCPs and patients to appropriate ACHD care.

Unlocking big data doubled the accuracy in predicting the grain yield in hybrid wheat.

The potential of big data to support businesses has been demonstrated in financial services, manufacturing, and telecommunications. Here, we report on efforts to enter a new data era in plant breeding by collecting genomic and phenotypic information from 12,858 wheat genotypes representing 6575 single-cross hybrids and 6283 inbred lines that were evaluated in six experimental series for yield in field trials encompassing ~125,000 plots. Integrating data resulted in twofold higher prediction ability compared with cases in which hybrid performance was predicted across individual experimental series. Our results suggest that combining data across breeding programs is a particularly appropriate strategy to exploit the potential of big data for predictive plant breeding. This paradigm shift can contribute to increasing yield and resilience, which is needed to feed the growing world population.

Mortality and morbidity in patients with congenital heart disease hospitalised for viral pneumonia.

OBJECTIVES: Data on the clinical outcome of patients with congenital heart disease (CHD) affected by severe viral pneumonia are limited. We analysed morbidity and mortality of viral pneumonia and evaluated the association between medical conditions, medication, vaccination and outcome specifically in patients with CHD requiring hospitalisation for viral pneumonia. METHODS: Based on data from one of Germany's largest health insurers, all cases of viral pneumonia requiring hospital admission (2005-2018) were studied. Mortality, and composites of death, transplantation, mechanical circulatory support, ventilation or extracorporeal lung support served as endpoints. RESULTS: Overall, 26 262 viral pneumonia cases occurred in 24 980 patients. Of these, 1180 cases occurred in patients with CHD. Compared with patients without CHD, mortality rate was elevated in patients with CHD. As a group, patients with CHD aged 20-59 years even exceeded mortality rates in patients without CHD aged >60 years. No mortality was observed in patients with CHD with simple defects <60 years of age without associated cardiovascular risk factors. On multivariable logistic regression analysis, age, CHD complexity, chromosomal anomalies, cardiac medication, use of immunosuppressants and absence of vaccination for influenza emerged as risk factors of adverse outcome. CONCLUSIONS: We present timely data on morbidity and mortality of severe viral pneumonia requiring hospital admission in patients with CHD. Need for mechanical ventilation and risk of death in CHD increase early in life, reaching a level equivalent to non-CHD individuals >60 years of age. Our data suggest that except for patients with isolated simple defects, patients with CHD should be considered higher-risk individuals when faced with severe viral pneumonia.

Selecting Closely-Linked SNPs Based on Local Epistatic Effects for Haplotype Construction Improves Power of Association Mapping.

Genome-wide association studies (GWAS) have gained central importance for the identification of candidate loci underlying complex traits. Single nucleotide polymorphism (SNP) markers are mostly used as genetic variants for the analysis of genotype-phenotype associations in populations, but closely linked SNPs that are grouped into haplotypes are also exploited. The benefit of haplotype-based GWAS approaches vs. SNP-based approaches is still under debate because SNPs in high linkage disequilibrium provide redundant information. To overcome some constraints of the commonly-used haplotype-based GWAS in which only consecutive SNPs are considered for haplotype construction, we propose a new method called functional haplotype-based GWAS (FH GWAS). FH GWAS is featured by combining SNPs into haplotypes based on the additive and epistatic effects among SNPs. Such haplotypes were termed functional haplotypes (FH). As shown by simulation studies, the FH GWAS approach clearly outperformed the SNP-based approach unless the minor allele frequency of the SNPs making up the haplotypes is low and the linkage disequilibrium between them is high. Applying FH GWAS for the trait flowering time in a large Arabidopsis thaliana population with whole-genome sequencing data revealed its potential empirically. FH GWAS identified all candidate regions which were detected in SNP-based and two other haplotype-based GWAS approaches. In addition, a novel region on chromosome 4 was solely detected by FH GWAS. Thus both the results of our simulation and empirical studies demonstrate that FH GWAS is a promising method and superior to the SNP-based approach even if almost complete genotype information is available.

Reinterpreting Dependency Schemes: Soundness Meets Incompleteness in DQBF.

Dependency quantified Boolean formulas (DQBF) and QBF dependency schemes have been treated separately in the literature, even though both treatments extend QBF by replacing the linear order of the quantifier prefix with a partial order. We propose to merge the two, by reinterpreting a dependency scheme as a mapping from QBF into DQBF. Our approach offers a fresh insight on the nature of soundness in proof systems for QBF with dependency schemes, in which a natural property called 'full exhibition' is central. We apply our approach to QBF proof systems from two distinct paradigms, termed 'universal reduction' and 'universal expansion'. We show that full exhibition is sufficient (but not necessary) for soundness in universal reduction systems for QBF with dependency schemes, whereas for expansion systems the same property characterises soundness exactly. We prove our results by investigating DQBF proof systems, and then employing our reinterpretation of dependency schemes. Finally, we show that the reflexive resolution path dependency scheme is fully exhibited, thereby proving a conjecture of Slivovsky.

Haplotype-Based Genome-Wide Prediction Models Exploit Local Epistatic Interactions Among Markers.

Genome-wide prediction approaches represent versatile tools for the analysis and prediction of complex traits. Mostly they rely on marker-based information, but scenarios have been reported in which models capitalizing on closely-linked markers that were combined into haplotypes outperformed marker-based models. Detailed comparisons were undertaken to reveal under which circumstances haplotype-based genome-wide prediction models are superior to marker-based models. Specifically, it was of interest to analyze whether and how haplotype-based models may take local epistatic effects between markers into account. Assuming that populations consisted of fully homozygous individuals, a marker-based model in which local epistatic effects inside haplotype blocks were exploited (LEGBLUP) was linearly transformable into a haplotype-based model (HGBLUP). This theoretical derivation formally revealed that haplotype-based genome-wide prediction models capitalize on local epistatic effects among markers. Simulation studies corroborated this finding. Due to its computational efficiency the HGBLUP model promises to be an interesting tool for studies in which ultra-high-density SNP data sets are studied. Applying the HGBLUP model to empirical data sets revealed higher prediction accuracies than for marker-based models for both traits studied using a mouse panel. In contrast, only a small subset of the traits analyzed in crop populations showed such a benefit. Cases in which higher prediction accuracies are observed for HGBLUP than for marker-based models are expected to be of immediate relevance for breeders, due to the tight linkage a beneficial haplotype will be preserved for many generations. In this respect the inheritance of local epistatic effects very much resembles the one of additive effects.

A quantitative genetic framework highlights the role of epistatic effects for grain-yield heterosis in bread wheat.

Increasing wheat yield is a key global challenge to producing sufficient food for a growing human population. Wheat grain yield can be boosted by exploiting heterosis, the superior performance of hybrids compared with midparents. Here we present a tailored quantitative genetic framework to study the genetic basis of midparent heterosis in hybrid populations derived from crosses among diverse parents. We applied this framework to an extensive data set assembled for winter wheat. Grain yield was assessed for 1,604 hybrids and their 135 parental elite breeding lines in 11 environments. The hybrids outperformed the midparents by 10% on average, representing approximately 15 years of breeding progress in wheat, thus further substantiating the remarkable potential of hybrid-wheat breeding. Genome-wide prediction and association mapping implemented through the developed quantitative genetic framework showed that dominance effects played a less prominent role than epistatic effects in grain-yield heterosis in wheat.

Extracting genotype information of Arabidopsis thaliana recombinant inbred lines from transcript profiles established with high-density oligonucleotide arrays.

KEY MESSAGE: Polymorphic probes identified via a sequence-based approach are suitable to infer the genotypes of recombinant inbred lines from hybridisation intensities of GeneChip ® transcript profiling experiments. The sequences of the probes of the ATH1 GeneChip® exactly match transcript sequences of the Arabidopsis thaliana reference genome Col-0, whereas nucleotide differences and/or insertions/deletions may be observed for transcripts of other A. thaliana accessions. Individual probes of the GeneChip® that show sequence polymorphisms between different A. thaliana accessions may serve as single-feature polymorphism (SFP) markers, provided that the sequence changes cause differences in hybridisation intensity for the accessions of interest. A sequence-based approach identified features on the high-density oligonucleotide array that showed sequence polymorphisms between A. thaliana accessions Col-0 and C24. Hybridisation intensities of polymorphic probes were extracted from genome-wide transcript profiles of Col-0/C24 and C24/Col-0 recombinant inbred lines and assessed after standardisation via sliding window analyses to identify SFP markers. The genotypes of the recombinant inbred lines were determined with the SFP markers and the resulting data were integrated with information, which had been established previously with single nucleotide polymorphism and insertion/deletion markers, to enrich the linkage map of the Col-0/C24 and C24/Col-0 recombinant inbred populations. Congruence between the molecular marker map and the sequence maps of the A. thaliana Col-0 chromosomes proved the reliability of the genotype information which was deduced from the transcript profiles of the Col-0/C24 and C24/Col-0 recombinant inbred lines.

Tailoring high-density oligonucleotide arrays for transcript profiling of different Arabidopsis thaliana accessions using a sequence-based approach.

KEY MESSAGE: Excluding polymorphic probes from GeneChip ® transcript profiling experiments via a sequence-based approach results in improved detection of differentially expressed genes in developing seeds of Arabidopsis thaliana accessions Col-0 and C24. GeneChip® arrays represent a powerful tool for transcript profiling experiments. The ATH1 GeneChip® has been designed based on the sequence of the Arabidopsis thaliana reference genome Col-0, hence the features on the array exactly match the sequences of Col-0 transcripts. In contrast, transcripts of other A. thaliana accessions or related species may show nucleotide differences and/or insertions/deletions when compared to the corresponding Col-0 transcripts, therefore, comparisons of transcript abundance involving different A. thaliana accessions or related species may be compromised for a certain number of transcripts. To tackle this limitation, a sequence-based strategy was developed. Only features on the array that were identical in sequence for the specimen to be compared were considered for transcript profiling. The impact of the proposed strategy was evaluated for transcript profiles that were established for developing seeds of A. thaliana accessions Col-0 and C24.

Genetic dissection of metabolite variation in Arabidopsis seeds: evidence for mQTL hotspots and a master regulatory locus of seed metabolism.

To gain insight into genetic factors controlling seed metabolic composition and its relationship to major seed properties, an Arabidopsis recombinant inbred line (RIL) population, derived from accessions Col-0 and C24, was studied using an MS-based metabolic profiling approach. Relative intensities of 311 polar primary metabolites were used to identify associated genomic loci and to elucidate their interactions by quantitative trait locus (QTL) mapping. A total of 786 metabolic QTLs (mQTLs) were unequally distributed across the genome, forming several hotspots. For the branched-chain amino acid leucine, mQTLs and candidate genes were elucidated in detail. Correlation studies displayed links between metabolite levels, seed protein content, and seed weight. Principal component analysis revealed a clustering of samples, with PC1 mapping to a region on the short arm of chromosome IV. The overlap of this region with mQTL hotspots indicates the presence of a potential master regulatory locus of seed metabolism. As a result of database queries, a series of candidate regulatory genes, including bZIP10, were identified within this region. Depending on the search conditions, metabolic pathway-derived candidate genes for 40-61% of tested mQTLs could be determined, providing an extensive basis for further identification and characterization of hitherto unknown genes causal for natural variation of Arabidopsis seed metabolism.

Chromosome identification for the carnivorous plant Genlisea margaretae.

Genlisea margaretae, subgenus Genlisea, section Recurvatae (184 Mbp/1C), belongs to a plant genus with a 25-fold genome size difference and an extreme genome plasticity. Its 19 chromosome pairs could be distinguished individually by an approach combining optimized probe pooling and consecutive rounds of multicolor fluorescence in situ hybridization (mcFISH) with bacterial artificial chromosomes (BACs) selected for repeat-free inserts. Fifty-one BACs were assigned to 18 chromosome pairs. They provide a tool for future assignment of genomic sequence contigs to distinct chromosomes as well as for identification of homeologous chromosome regions in other species of the carnivorous Lentibulariaceae family, and potentially of chromosome rearrangements, in cases where more than one BAC per chromosome pair was identified.

Risk of Pregnancy in Moderate and Severe Aortic Stenosis: From the Multinational ROPAC Registry.

BACKGROUND: Controversial results on maternal risk and fetal outcome have been reported in women with aortic stenosis (AS). OBJECTIVES: The authors sought to investigate maternal and fetal outcomes in patients with AS in a large cohort. METHODS: The Registry on Pregnancy and Cardiac Disease (ROPAC) is a global, prospective observational registry of women with structural heart disease, providing a uniquely large study population. Data of women with moderate (peak gradient 36 to 63 mm Hg) and severe AS (peak gradient ≥64 mm Hg) were analyzed. RESULTS: Of 2,966 pregnancies in ROPAC, the authors identified 96 women who had at least moderate AS (34 with severe AS). No deaths were observed during pregnancy and in the first week after delivery. However, 20.8% of women were hospitalized for cardiac reasons during pregnancy. This was significantly more common in severe AS compared with moderate AS (35.3% vs. 12.9%; p = 0.02), and reached the highest rate (42.1%) in severe, symptomatic AS. Pregnancy was complicated by heart failure in 6.7% of asymptomatic and 26.3% of symptomatic patients, but could be managed medically, except for 1 patient who was symptomatic before pregnancy and underwent balloon valvotomy. Children of patients with severe AS had a significantly higher percentage of low birth weight (35.0% vs. 6.0%; p = 0.006). CONCLUSIONS: Mortality in pregnant women with AS, including those with severe AS, appears to be close to zero in the current era. Symptomatic and severe AS does, however, carry a substantial risk of heart failure and is associated with high rates of hospitalization for cardiac reasons, although heart failure can nearly always be managed medically. The results highlight the importance of appropriate pre-conceptional patient evaluation and counseling.

Selective Irreversible Inhibition of Neuronal and Inducible Nitric-oxide Synthase in the Combined Presence of Hydrogen Sulfide and Nitric Oxide.

Citrulline formation by both human neuronal nitric-oxide synthase (nNOS) and mouse macrophage inducible NOS was inhibited by the hydrogen sulfide (H2S) donor Na2S with IC50 values of ∼2.4·10(-5) and ∼7.9·10(-5) m, respectively, whereas human endothelial NOS was hardly affected at all. Inhibition of nNOS was not affected by the concentrations of l-arginine (Arg), NADPH, FAD, FMN, tetrahydrobiopterin (BH4), and calmodulin, indicating that H2S does not interfere with substrate or cofactor binding. The IC50 decreased to ∼1.5·10(-5) m at pH 6.0 and increased to ∼8.3·10(-5) m at pH 8.0. Preincubation of concentrated nNOS with H2S under turnover conditions decreased activity after dilution by ∼70%, suggesting irreversible inhibition. However, when calmodulin was omitted during preincubation, activity was not affected, suggesting that irreversible inhibition requires both H2S and NO. Likewise, NADPH oxidation was inhibited with an IC50 of ∼1.9·10(-5) m in the presence of Arg and BH4 but exhibited much higher IC50 values (∼1.0-6.1·10(-4) m) when Arg and/or BH4 was omitted. Moreover, the relatively weak inhibition of nNOS by Na2S in the absence of Arg and/or BH4 was markedly potentiated by the NO donor 1-(hydroxy-NNO-azoxy)-l-proline, disodium salt (IC50 ∼ 1.3-2.0·10(-5) m). These results suggest that nNOS and inducible NOS but not endothelial NOS are irreversibly inhibited by H2S/NO at modest concentrations of H2S in a reaction that may allow feedback inhibition of NO production under conditions of excessive NO/H2S formation.

Combining C-arm CT with a new remote operated positioning and guidance system for guidance of minimally invasive spine interventions.

OBJECTIVE: To report our experience using C-arm cone beam CT (C-arm CBCT) combined with the new remote operated positioning and guidance system, iSYS1, for needle guidance during spinal interventions. METHODS: A C-arm CBCT with a flat panel angiography system was acquired (Artis Zeego; Siemens Healthcare Sector, Forchheim, Germany). Reconstruction of CT-like images and planning of the needle path were performed using a common workstation. The needle holder of iSYS1 acted as a guide during insertion of Kirschner (K) wires. 20 percutaneous K wires were placed in the pedicles at T2-T3, T7-T12, and L1-L2 in a cadaver specimen. Postprocedure C-arm CBCT scans were obtained to confirm the accuracy of the K wire placement. RESULTS: All K wire placements were successfully performed. Mean planning time with Syngo iGuide was 4:16 min, mean positioning time of iSYS1 was 3:35 min, and mean placement time of the K wires was 2:22 min. Mean total intervention time was 10:13 min per pedicle. A mean deviation of 0.35 mm between the planned path and the placed K wire with a mean path length of 6.73 cm was documented. CONCLUSIONS: Our results demonstrate the potential of combining C-arm CBCT with iSYS1 for safe and accurate percutaneous placement of pedicle K wires in spinal interventions.

Aerobic nitric oxide-induced thiol nitrosation in the presence and absence of magnesium cations.

Although different routes for the S-nitrosation of cysteinyl residues have been proposed, the main in vivo pathway is unknown. We recently demonstrated that direct (as opposed to autoxidation-mediated) aerobic nitrosation of glutathione is surprisingly efficient, especially in the presence of Mg(2+). In the present study we investigated this reaction in greater detail. From the rates of NO decay and the yields of nitrosoglutathione (GSNO) we estimated values for the apparent rate constants of 8.9 ± 0.4 and 0.55 ± 0.06 M(-1)s(-1) in the presence and absence of Mg(2+). The maximum yield of GSNO was close to 100% in the presence of Mg(2+) but only about half as high in its absence. From this observation we conclude that, in the absence of Mg(2+), nitrosation starts by formation of a complex between NO and O2, which then reacts with the thiol. Omission of superoxide dismutase (SOD) reduced by half the GSNO yield in the absence of Mg(2+), demonstrating O2(-) formation. The reaction in the presence of Mg(2+) seems to involve formation of a Mg(2+)•glutathione (GSH) complex. SOD did not affect Mg(2+)-stimulated nitrosation, suggesting that no O2(-) is formed in that reaction. Replacing GSH with other thiols revealed that reaction rates increased with the pKa of the thiol, suggesting that the nucleophilicity of the thiol is crucial for the reaction, but that the thiol need not be deprotonated. We propose that in cells Mg(2+)-stimulated NO/O2-induced nitrosothiol formation may be a physiologically relevant reaction.