Efficacy and safety of platelet additive solution-E stored platelet concentrates.

INTRODUCTION: In 2018, platelet (PLT) additive solution-E (PAS-E) was introduced. The implementation of PAS-E was expected to diminish the number of allergic reactions in recipients following a PLT transfusion. Here, we evaluated the efficacy and safety of transfusions with PLTs stored in PAS-E. STUDY DESIGN AND METHODS: After implementation of PAS-E, data were collected from 2 cohorts of patients with hematological disorders as well as oncology patients, receiving PLTs in PAS-E. A similar patient group in a recent RCT, receiving PLTs in plasma, was used as a historical control group for both cohorts. Endpoints were corrected count increments (CCIs), bleeding scores (only reported in cohort 1), and the incidence of adverse reactions. RESULTS: In cohort 1, the mean 1-h CCI was 14.3 ± 6.9, and the 24-h CCI was 8.7 ± 5.6. In cohort 2, the 1-h CCI was 11.6 ± 7.8 and the 24-h CCI was 7.0 ± 6.1. In the control group, the 1-h CCI was 15.4 ± 5.5 and 24-h CCI 8.7 ± 4.8. Bleeding complications of WHO grade ≥2 occurred in 40% of patients in cohort 1 compared to 44% in plasma PCs. The incidence of adverse reactions was 1.2% in the two PAS-E cohorts, compared to 3.0% in plasma PCs. National hemovigilance data showed a significant reduction in allergic reactions with PAS-E PC transfusions as compared to plasma PCs with an odds ratio of 0.46 (CI 95% 0.37-0.58). CONCLUSION: The CCIs of PLTs in PAS-E were decreased compared to plasma PCs, but clinically acceptable. Allergic transfusion reactions were decreased in PAS-E PCs compared to plasma PCs.

Intravenous Iron in a Prehabilitation Program for Older Surgical Patients: Prospective Cohort Study.

BACKGROUND: Older patients often have iron deficiency anemia before surgery, which can be effectively treated with intravenous iron supplementation (IVIS). Anemia and blood transfusions are associated with an increased risk of delirium. The aim of this research was to assess the effectiveness and safety of using IVIS in a prehabilitation program. MATERIAL AND METHODS: Patients ≥70 y who underwent abdominal surgery between November 2015 and June 2018 were included in this single-center prospective cohort study. All patients were prehabilitated; however, only anemic patients received a single dose of 1000 mg intravenous iron (ferric carboxymaltose) to increase preoperative hemoglobin levels (IVIS group). Nonanemic patients received standard care (SC). The hemoglobin levels (primary outcome) were assessed at the outpatient clinic visit, at admission, and at discharge. Secondary outcomes were postoperative delirium, postoperative anemia, blood transfusion, complications other than delirium, and length of hospital stay. All outcomes were compared between the IVIS group and SC group. RESULTS: Of all patients (n = 248), 97 anemic patients received IVIS (39%). Of the anemic patients, 50 patients (52%) had iron deficiency. Initial differences in hemoglobin concentrations between the IVIS group and SC group at T1 and T2 (7.2 versus 8.8; P < 0.001 and 7.4 versus 8.6; P = 0.023, respectively) were no longer present at discharge (6.6 versus 7.2; P = 0.35). No statistically significant differences were observed for all secondary outcomes between the IVIS group and the SC group. No infusion-related adverse events occurred. CONCLUSIONS: Adding IVIS to prehabilitation programs is safe and diminishes differences in these concentrations between preoperatively anemic and nonanemic patients. IVIS may be worthwhile as an additional component of prehabilitation programs. Results merit further investigation.

An Unusual Compound Heterozygosity for Hb O-Arab (HBB: c.364G>A) and Hb D-Los Angeles (HBB: c.364G>C).

We report a newborn with a compound heterozygosity for Hb O-Arab (HBB: 364G>A) and Hb D-Los Angeles (HBB: 364G>C). To the best of our knowledge, the combination of these two hemoglobin (Hb) variants has not been identified and reported before. The variants of the proband and parents were identified by high-performance liquid chromatography (HPLC) and capillary electrophoresis (CE). DNA analysis was performed to confirm the variants. The levels of Hb variants of the proband were determined post-partum, at 3 months and 1 year after birth. Blood count analysis after 1 year revealed that the proband had a mild microcytic anemia. Furthermore, HPLC and CE analysis revealed an equal distribution of Hb D-Los Angeles compared to Hb O-Arab at the age of 1 year. The follow-up of the patient, suggested that the Hb combination is clinically silent or mild.

A national Transfusion Register of Irregular Antibodies and Cross (X)-match Problems: TRIX, a 10-year analysis.

BACKGROUND: The Transfusion Register of Irregular Antibodies and Cross-match Problems (TRIX) is a unique national database in the Netherlands that was launched in 2007. Transfusion laboratories register the presence of irregular RBC alloantibodies for their patients and can consult the database for information that is relevant for pretransfusion testing, unknown in their own laboratory information system. STUDY DESIGN AND METHODS: Data from the TRIX database 10 years after implementation have been analyzed to demonstrate the added value of TRIX for transfusion practice. TRIX antibody registration, antibody disappearance likelihood, and differences between men and women have been analyzed and evaluated. RESULTS: In the 10-year period 2007 to 2016, a total of 80,164 alloantibodies have been identified and registered in 62,110 individuals. Of the antibodies, 81% were reported in women and 19% in men (female:male, 4.3:1). Rh (DCcEe and Cw ), K, Fya , and Jka antibodies account for 65.6% of all antibody registrations. M and Lewis antibodies account for 18.6% of all antibodies. Antibody disappearance likelihood is relatively high for the clinically relevant antibodies directed against Jkb , s, Fyb , and e. Antibodies directed against D, Fya , and K have a relatively low antibody disappearance likelihood. CONCLUSION: TRIX is a unique and useful tool for transfusion laboratories for timely and up-to-date information on the presence of erythrocyte antibodies, which improves pretransfusion testing and compatible blood selection. TRIX also provides macro data on the prevalence of individual antibodies and antibody disappearance likelihoods that can be used for developing blood type matching strategies for patient groups at risk. © 2019 AABB.

Analytical variation in factor VIII one-stage and chromogenic assays: Experiences from the ECAT external quality assessment programme.

BACKGROUND: Both one-stage (OSA) and chromogenic substrate assays (CSA) are used to measure factor VIII (FVIII) activity. Factors explaining analytical variation in FVIII activity levels are still to be completely elucidated. AIM: The aim of this study was to investigate and quantify the analytical variation in OSA and CSA. METHODS: Factors determining analytical variation were studied in sixteen lyophilized plasma samples (FVIII activity <0.01-1.94 IU/mL) and distributed by the ECAT surveys. To elucidate the causes of OSA variation, we exchanged deficient plasma between three company set-ups. RESULTS: On average, 206 (range 164-230) laboratories used the OSA to measure FVIII activity and 30 (range 12-51) used CSA. The coefficient of variation of OSA and CSA increased with lower FVIII levels (FVIII <0.05 IU/mL). This resulted in misclassification of a severe haemophilia A sample into a moderate or mild haemophilia A sample in 4/30 (13.3%) of CSA measurements, while this was 37/139 (26.6%) for OSA. OSA measurements performed with reagents and equipment from Werfen showed slightly lower FVIII activity (0.93, IQR 0.88-0.98 IU/mL) compared to measurements with Stago (1.07, IQR 1.02-1.14 IU/mL) and Siemens (1.03, IQR 0.97-1.07 IU/mL). Part of this difference is explained by the value of the calibrator. For CSA, the measured FVIII levels were similar using the different kits. CONCLUSIONS: In the lower range (<0.05 IU/mL), analytical variation of FVIII measurements is high in both OSA and CSA measurements. The variation in FVIII activity levels was partly explained by specific manufacturers. Further standardization of FVIII measurements and understanding of analytical variation is required.

A multicomponent prehabilitation pathway to reduce the incidence of delirium in elderly patients in need of major abdominal surgery: study protocol for a before-and-after study.

BACKGROUND: Due to the increase in elderly patients who undergo major abdominal surgery there is a subsequent increase in postoperative complications, prolonged hospital stays, health-care costs and mortality rates. Delirium is a frequent and severe complication in the 'frail' elderly patient. Different preoperative approaches have been suggested to decrease incidence of delirium by improving patients' baseline health. Studies implementing these approaches are often heterogeneous, have a small sample and do not provide high-quality or successful strategies. The aim of this study is to prevent postoperative delirium and other complications by implementing a unique multicomponent and multidisciplinary prehabilitation program. METHODS: This is a single-center controlled before-and-after study. Patients aged ≥70 years in need of surgery for colorectal cancer or an abdominal aortic aneurysm are considered eligible. Baseline characteristics (such as factors of frailty, physical condition and nutritional state) are collected prospectively. During 5 weeks prior to surgery, patients will follow a prehabilitation program to optimize overall health, which includes home-based exercises, dietary advice and intravenous iron infusion in case of anaemia. In case of frailty, a geriatrician will perform a comprehensive geriatric assessment and provide additional preoperative interventions when deemed necessary. The primary outcome is incidence of delirium. Secondary outcomes are length of hospital stay, complication rate, institutionalization, 30-day, 6- and 12-month mortality, mental health and quality of life. Results will be compared to a retrospective control group, meeting the same inclusion and exclusion criteria, operated on between January 2013 and October 2015. Inclusion of the prehabilitation cohort started in November 2015; data collection is ongoing. DISCUSSION: This is the first study to investigate the effect of prehabilitation on postoperative delirium. The aim is to provide evidence, based on a large sample size, for a standardized multicomponent strategy to improve patients' preoperative physical and nutritional status in order to prevent postoperative delirium and other complications. A multimodal intervention was implemented, combining physical, nutritional, mental and hematinic optimization. This research involves a large cohort, including patients most at risk for postoperative adverse outcomes. TRIAL REGISTRATION: The protocol is retrospectively registered at the Netherlands National Trial Register (NTR) number: NTR5932 . Date of registration: 05-04-2016.

Storage time of platelet concentrates and all-cause bacteremia in hematologic patients.

BACKGROUND: Extension of storage time of platelet (PLT) concentrates may result in an increased risk of bacteremia, directly via transfusion of contaminated products or indirectly via transfusion-related immunomodulation. We aimed to quantify the association of storage time of PLT concentrates and all-cause bacteremia in hematologic patients. STUDY DESIGN AND METHODS: We established a cohort of hematologic patients who received a PLT transfusion between 2005 and 2015. Cases were defined as patients with a bacteremia the day after transfusion and matched to as many controls as possible. A conditional logistic regression was performed, stratified by storage medium. RESULTS: Among 3514 patients receiving 36,032 PLT concentrates stored in plasma, 613 cases of bacteremia were found. The relative risk of all-cause bacteremia the day after transfusion was 0.80 (95% confidence interval [CI], 0.58-1.12) for PLT concentrates stored 3 to 4 days and 0.67 (95% CI, 0.49-0.92) for at least 5 days, compared to no more than 2 days. Among 1527 patients receiving 11,822 PLT concentrates stored in PLT additive solution, 182 cases of bacteremia were found. The relative risk of all-cause bacteremia was 1.14 (95% CI, 0.70-1.84) for PLT concentrates stored for 3 to 4 days and 1.19 (95% CI, 0.70-2.01) for at least 5 days, compared to not more than 2 days. CONCLUSION: Storage time of PLT concentrates was not associated with increased occurrence of all-cause bacteremia the day after transfusion. If anything, fewer cases of bacteremia occurred with increasing storage time of PLT concentrates in plasma. These bacteremias are not directly caused by transfusion of a contaminated product and the underlying mechanism warrants further research.

Defining trimester-specific reference intervals for carbohydrate deficient transferrin in pregnant women.

OBJECTIVES: Extensive consumption of alcohol during pregnancy can lead to severe complications for the unborn child. Carbohydrate-deficient transferrin (CDT) levels in serum have become a common biomarker for excessive alcohol intake. However, during pregnancy CDT levels can rise to levels above commonly used cut-off values, for reasons unrelated to alcohol intake. The aim of this study is to investigate the changes in CDT values during pregnancy and to determine accurate, trimester dependent reference intervals. METHODS: 439 serum samples of 147 healthy pregnant women were obtained for trimester 1, 2, 3, and post-partum and were analysed by high-performance liquid chromatography (HPLC) and an N-Latex immunonephelometric assay. New trimester-specific reference intervals were established. RESULTS: This study demonstrates there is a trimester-dependent increase of %CDT, as up to 39.4% of the population exceeded the previously established upper reference limit of 1.7%. In our study the estimated upper reference limit for %DST/%CDT were 1.55%, 1.96%, 2.05% and 1.35% for trimester 1, 2, 3 and post-partum for the HPLC-method and 2.02%, 2.19%, 2.19% and 1.96% for the N-Latex immunoassay. CONCLUSIONS: We demonstrate that CDT levels rise during pregnancy. The magnitude of the increase is method-dependent and needs to be taken into account. We have established method- and trimester-specific reference intervals to prevent false-positive results in alcohol abuse screening tests during pregnancy.

Association of Altered Plasma Lipidome with Disease Severity in COVID-19 Patients.

The severity of COVID-19 is linked to an imbalanced immune response. The dysregulated metabolism of small molecules and bioactive lipids has also been associated with disease severity. To promote understanding of the disease biochemistry and provide targets for intervention, we applied a range of LC-MS platforms to analyze over 100 plasma samples from patients with varying COVID-19 severity and with detailed clinical information on inflammatory responses (>30 immune markers). This is the third publication in a series, and it reports the results of comprehensive lipidome profiling using targeted LC-MS/MS. We identified 1076 lipid features across 25 subclasses, including glycerophospholipids, sterols, glycerolipids, and sphingolipids, among which 531 lipid features were dramatically changed in the plasma of intensive care unit (ICU) patients compared to patients in the ward. Patients in the ICU showed 1.3-57-fold increases in ceramides, (lyso-)glycerophospholipids, diglycerides, triglycerides, and plasmagen phosphoethanolamines, and 1.3-2-fold lower levels of a cyclic lysophosphatidic acid, sphingosine-1-phosphates, sphingomyelins, arachidonic acid-containing phospholipids, lactosylceramide, and cholesterol esters compared to patients in the ward. Specifically, phosphatidylinositols (PIs) showed strong fatty acid saturation-dependent behavior, with saturated fatty acid (SFA)- and monosaturated fatty acid (MUFA)-derived PI decreasing and polystaturated (PUFA)-derived PI increasing. We also found ~4000 significant Spearman correlations between lipids and multiple clinical markers of immune response with |R| ≥ 0.35 and FDR corrected Q < 0.05. Except for lysophosphatidic acid, lysophospholipids were positively associated with the CD4 fraction of T cells, and the cytokines IL-8 and IL-18. In contrast, sphingosine-1-phosphates were negatively correlated with innate immune markers such as CRP and IL-6. Further indications of metabolic changes in moderate COVID-19 disease were demonstrated in recovering ward patients compared to those at the start of hospitalization, where 99 lipid species were altered (6 increased by 30-62%; 93 decreased by 1.3-2.8-fold). Overall, these findings support and expand on early reports that dysregulated lipid metabolism is involved in COVID-19.

Severe COVID-19 Is Characterised by Perturbations in Plasma Amines Correlated with Immune Response Markers, and Linked to Inflammation and Oxidative Stress.

The COVID-19 pandemic raised a need to characterise the biochemical response to SARS-CoV-2 infection and find biological markers to identify therapeutic targets. In support of these aims, we applied a range of LC-MS platforms to analyse over 100 plasma samples from patients with varying COVID-19 severity and with detailed clinical information on inflammatory responses (>30 immune markers). The first publication in a series reports the results of quantitative LC-MS/MS profiling of 56 amino acids and derivatives. A comparison between samples taken from ICU and ward patients revealed a notable increase in ten post-translationally modified amino acids that correlated with markers indicative of an excessive immune response: TNF-alpha, neutrophils, markers for macrophage, and leukocyte activation. Severe patients also had increased kynurenine, positively correlated with CRP and cytokines that induce its production. ICU and ward patients with high IL-6 showed decreased levels of 22 immune-supporting and anti-oxidative amino acids and derivatives (e.g., glutathione, GABA). These negatively correlated with CRP and IL-6 and positively correlated with markers indicative of adaptive immune activation. Including corresponding alterations in convalescing ward patients, the overall metabolic picture of severe COVID-19 reflected enhanced metabolic demands to maintain cell proliferation and redox balance, alongside increased inflammation and oxidative stress.

TRB sequences targeting ORF1a/b are associated with disease severity in hospitalized COVID-19 patients.

The potential protective or pathogenic role of the adaptive immune response to SARS-CoV-2 infection has been vigorously debated. While COVID-19 patients consistently generate a T lymphocyte response to SARS-CoV-2 antigens, evidence of significant immune dysregulation in these patients continues to accumulate. In this study, next generation sequencing of the T cell receptor beta chain (TRB) repertoire was conducted in hospitalized COVID-19 patients to determine if immunogenetic differences of the TRB repertoire contribute to disease course severity. Clustering of highly similar TRB CDR3 amino acid sequences across COVID-19 patients yielded 781 shared TRB sequences. The TRB sequences were then filtered for known associations with common diseases such as EBV and CMV. The remaining sequences were cross-referenced to a publicly accessible dataset that mapped COVID-19 specific TCRs to the SARS-CoV-2 genome. We identified 158 SARS-CoV-2 specific TRB sequences belonging to 134 clusters in our COVID-19 patients. Next, we investigated 113 SARS-CoV-2 specific clusters binding only one peptide target in relation to disease course. Distinct skewing of SARS-CoV-2 specific TRB sequences toward the nonstructural proteins (NSPs) encoded within ORF1a/b of the SARS-CoV-2 genome was observed in clusters associated with critical disease course when compared to COVID-19 clusters associated with a severe disease course. These data imply that T-lymphocyte reactivity towards peptides from NSPs of SARS-CoV-2 may not constitute an effective adaptive immune response and thus may negatively affect disease severity.

Plasma Oxylipins and Their Precursors Are Strongly Associated with COVID-19 Severity and with Immune Response Markers.

COVID-19 is characterised by a dysregulated immune response, that involves signalling lipids acting as mediators of the inflammatory process along the innate and adaptive phases. To promote understanding of the disease biochemistry and provide targets for intervention, we applied a range of LC-MS platforms to analyse over 100 plasma samples from patients with varying COVID-19 severity and with detailed clinical information on inflammatory responses (>30 immune markers). The second publication in a series reports the results of quantitative LC-MS/MS profiling of 63 small lipids including oxylipins, free fatty acids, and endocannabinoids. Compared to samples taken from ward patients, intensive care unit (ICU) patients had 2−4-fold lower levels of arachidonic acid (AA) and its cyclooxygenase-derived prostanoids, as well as lipoxygenase derivatives, exhibiting negative correlations with inflammation markers. The same derivatives showed 2−5-fold increases in recovering ward patients, in paired comparison to early hospitalisation. In contrast, ICU patients showed elevated levels of oxylipins derived from poly-unsaturated fatty acids (PUFA) by non-enzymatic peroxidation or activity of soluble epoxide hydrolase (sEH), and these oxylipins positively correlated with markers of macrophage activation. The deficiency in AA enzymatic products and the lack of elevated intermediates of pro-resolving mediating lipids may result from the preference of alternative metabolic conversions rather than diminished stores of PUFA precursors. Supporting this, ICU patients showed 2-to-11-fold higher levels of linoleic acid (LA) and the corresponding fatty acyl glycerols of AA and LA, all strongly correlated with multiple markers of excessive immune response. Our results suggest that the altered oxylipin metabolism disrupts the expected shift from innate immune response to resolution of inflammation.

Exploratory analysis of interleukin-38 in hospitalized COVID-19 patients.

INTRODUCTION: A major contributor to coronavirus disease 2019 (COVID-19) progression and severity is a dysregulated innate and adaptive immune response. Interleukin-38 (IL-38) is an IL-1 family member with broad anti-inflammatory properties, but thus far little is known about its role in viral infections. Recent studies have shown inconsistent results, as one study finding an increase in circulating IL-38 in COVID-19 patients in comparison to healthy controls, whereas two other studies report no differences in IL-38 concentrations. METHODS: Here, we present an exploratory, retrospective cohort study of circulating IL-38 concentrations in hospitalized COVID-19 patients admitted to two Dutch hospitals (discovery n = 148 and validation n = 184) and age- and sex-matched healthy subjects. Plasma IL-38 concentrations were measured by enzyme-linked immunosorbent assay, disease-related proteins by proximity extension assay, and clinical data were retrieved from hospital records. RESULTS: IL-38 concentrations were stable during hospitalization and similar to those of healthy control subjects. IL-38 was not associated with rates of intensive care unit admission or mortality. Only in men in the discovery cohort, IL-38 concentrations were positively correlated with hospitalization duration. A positive correlation between IL-38 and the inflammatory biomarker d-dimer was observed in men of the validation cohort. In women of the validation cohort, IL-38 concentrations correlated negatively with thrombocyte numbers. Furthermore, plasma IL-38 concentrations in the validation cohort correlated positively with TNF, TNFRSF9, IL-10Ra, neurotrophil 3, polymeric immunoglobulin receptor, CHL1, CD244, superoxide dismutase 2, and fatty acid binding protein 2, and negatively with SERPINA12 and cartilage oligomeric matrix protein. CONCLUSIONS: These data indicate that IL-38 is not associated with disease outcomes in hospitalized COVID-19 patients. However, moderate correlations between IL-38 concentrations and biomarkers of disease were identified in one of two cohorts. While we demonstrate that IL-38 concentrations are not indicative of COVID-19 severity, its anti-inflammatory effects may reduce COVID-19 severity and should be experimentally investigated.

Targeted proteomics identifies circulating biomarkers associated with active COVID-19 and post-COVID-19.

The ongoing Coronavirus Disease 2019 (COVID-19) pandemic is caused by the highly infectious Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2). There is an urgent need for biomarkers that will help in better stratification of patients and contribute to personalized treatments. We performed targeted proteomics using the Olink platform and systematically investigated protein concentrations in 350 hospitalized COVID-19 patients, 186 post-COVID-19 individuals, and 61 healthy individuals from 3 independent cohorts. Results revealed a signature of acute SARS-CoV-2 infection, which is represented by inflammatory biomarkers, chemokines and complement-related factors. Furthermore, the circulating proteome is still significantly affected in post-COVID-19 samples several weeks after infection. Post-COVID-19 individuals are characterized by upregulation of mediators of the tumor necrosis (TNF)-α signaling pathways and proteins related to transforming growth factor (TGF)-ß. In addition, the circulating proteome is able to differentiate between patients with different COVID-19 disease severities, and is associated with the time after infection. These results provide important insights into changes induced by SARS-CoV-2 infection at the proteomic level by integrating several cohorts to obtain a large disease spectrum, including variation in disease severity and time after infection. These findings could guide the development of host-directed therapy in COVID-19.

The effect of acidification and oxalate concentration on urine calcium measurements in EQAS materials and patient samples.

BACKGROUND: An increase in urine calcium compared to the consensus value was observed in some urine samples of the Dutch External Quality Assessment Scheme (EQAS). It appeared that the increase was due to the addition of oxalate by the EQAS organizers and preanalytical acidification of the samples by some of the participants. Because of this observation, the effect of urine acidification on urine calcium level in EQAS and patient samples with added oxalate was investigated. METHODS: Twenty-four EQAS urine samples and 20 patient urine samples were subject to recovery measurements of urine calcium before and after addition of sodium oxalate and acidification. RESULTS: Differences in urine calcium between acidified and non-acidified samples up to 30.9% have been observed in EQAS samples with added oxalate. Patient samples show differences up to 80%. Differences between acidified and non-acidified samples are minimal for low calcium oxalate levels but increase with higher levels. Samples without added oxalate show equal urine calcium results between acidified and non-acidified samples. CONCLUSIONS: Urine calcium results are decreased in non-acidified samples with an excess of oxalate. In case of hyperoxaluria, acidification of patient urine collections and EQAS samples is recommended for correct urine calcium values.

Cyanosis, hemolysis, decreased HbA1c and abnormal co-oximetry in a patient with hemoglobin M Saskatoon [HBB:c.190C > T p.His64Tyr].

We describe a first Dutch case of Hb M Saskatoon (HBB:c.190C > T p.His64Tyr) in a 47-year-old female Dutch patient who presented with cyanosis, hemolysis, and abnormal co-oximetry. A mean corpuscular volume (MCV) of 105 fL caused by reticulocytosis (160 × 109/L) and low red blood cell count (3.6 × 1012/L) suggested an increased erythrocyte turnover. An HPLC glyco-globin analysis revealed a decreased HbA1c fraction of 12.3 mmol/mmol, HbA0 of 93.3% and an additional unidentified fraction at 1.2 min. DNA sequencing revealed a missense mutation in the HBB gene, (HBB:c.190C > T p.His64Tyr), known as Hb M Saskatoon, a variant which has been previously identified as an unstable hemoglobin variant leading to methemoglobinemia and anemia. In this report, we describe the clinical and remarkable laboratory aspects of our patient with Hb M Saskatoon, and the consequences for treatment and drug use.

Nuclear magnetic resonance secondary shifts of a light-harvesting 2 complex reveal local backbone perturbations induced by its higher-order interactions.

Protein nuclear magnetic resonance (NMR) secondary chemical shifts are widely used to predict the secondary structure, and in solid-state NMR, they are often the only unambiguous structural parameters available. However, the employed prediction methods are empirical in nature, relying on the assumption that secondary shifts are only affected by shielding effects of neighboring atoms. We analyzed the secondary shifts of a photosynthetic membrane protein with a high density of chromophores and very tight packing, the light-harvesting 2 (LH2) complex of Rhodopseudomonas acidophila. A relation was found between secondary shift anomalies and protein-protein or pigment-protein tertiary and quaternary contacts. For several residues, including the bacteriochlorophyll-coordinating histidines (alphaH31 and betaH30) and the phenylalanine alphaF41 that has strongly twisted C(b)-C(a)-C and C(a)-C-N conformations in the LH2 crystal structure, the perturbing effects on the backbone chemical shifts were tested by density functional theory (DFT) calculations. We propose that higher-order interactions in the tightly packed complex can induce localized perturbations of the backbone conformation and electronic structure, related to functional pigment-protein or protein-protein interactions.