Maximally informative feature selection using Information Imbalance: Application to COVID-19 severity prediction.

Clinical databases typically include, for each patient, many heterogeneous features, for example blood exams, the clinical history before the onset of the disease, the evolution of the symptoms, the results of imaging exams, and many others. We here propose to exploit a recently developed statistical approach, the Information Imbalance, to compare different subsets of patient features and automatically select the set of features that is maximally informative for a given clinical purpose, especially in minority classes. We adapt the Information Imbalance approach to work in a clinical framework, where patient features are often categorical and are generally available only for a fraction of the patients. We apply this algorithm to a data set of ∼ 1300 patients treated for COVID-19 in Udine hospital before October 2021. Using this approach, we find combinations of features which, if used in combination, are maximally informative of the clinical fate and of the severity of the disease. The optimal number of features, which is determined automatically, turns out to be between 10 and 15. These features can be measured at admission. The approach can be used also if the features are available only for a fraction of the patients, does not require imputation and, importantly, is able to automatically select features with small inter-feature correlation. Clinical insights deriving from this study are also discussed.

Chronic kidney disease and orthostatic hypotension in hospitalised older adults.

PURPOSE: Orthostatic hypotension (OH) may predispose older adults to health complications leading to functional impairment. Despite the central role of the kidney in blood pressure control, the contribution of renal function in orthostatic hypotension is poorly investigated. To verify the association between Chronic Kidney Disease (CKD) and OH a population of hospitalised elderly patients with comorbidities was studied. MATERIALS AND METHODS: 174 patients were consecutively admitted to Acute Geriatric Wards. On admission, patients underwent postural systolic (SBP) and diastolic (DBP) blood pressure evaluation by automatic oscillometric device after 10 min rest in lying position, and in standing position at time 0, 1, 3 and 5 min. CKD was assumed for estimated glomerular filtration rate (e-GFR) less than 60 mL/min/1.73 m2. RESULTS: The mean age of the population enrolled was 74.4 ± 7.0. OH was found in 46.0% and CKD in 56.3% of patients, respectively. A lower e-GFR was observed in patients with (56.1 ± 16.7 mL/min/1.73 m2) than in those without OH (61.1 ± 15.9 mL/min/1.73 m2) (p < 0.05). A greater fall in SBP at 0-min (12.8 ± 6.3 vs. 7.7 ± 3.2 mmHg) and at 1-min (8.4 ± 4.5 vs. 5.7 ± 2.8 mmHg) was found in CKD patients in respect to patients without CKD during active standing test (p < 0.05). Similarly, a DBP reduction at 0-min and at 1-min was observed in CKD patients in respect to patients without CKD (p < 0.05). A multivariate logistic regression analysis showed that CKD was associated to OH (OR 2.426; 95%CI 1.192-4.937; p = 0.014). CONCLUSIONS: CKD is associated to OH in hospitalised older adults.

Antibody response and risk of reinfection over 2 years among the patients with first wave of COVID-19.

OBJECTIVES: To describe the dynamics and factors related to natural and hybrid humoral response against the SARS-CoV-2 and risk of reinfection among first-wave patients. METHODS: A prospective longitudinal study with periodic serological follow-up after acute onset of all recovered patients with SARS-CoV-2 infection cared in Udine Hospital (March-May 2020). Nucleocapsid (N) protein and spike receptor-binding domain (S-RBD) antibody tests were used to distinguish natural and vaccine-induced response. RESULTS: Overall, 153 patients (66 men, mean age 56 years) were followed for a median of 27.3 (interquartile range 26.9-27.8) months. Seroreversion was 98.5% (95% CI: 96.8-99.4) for SARS-CoV-2-N IgM at 1 year and 57.4% (95% CI: 51.5-63.5) for SARS-CoV-2-N IgG at 2 years. Initial serological response (hazard ratio [HR]: 0.99, 95% CI: 0.99-0.99, p 0.002 for IgM and HR: 0.97, 95% CI: 0.97-0.98, p < 0.001 for IgG) and severity of acute infection (HR: 0.62, 95% CI: 0.39-0.96, p 0.033 for IgM and HR: 0.60, 95% CI: 0.37-0.99, p < 0.001 for IgG) were independently associated with persistent SARS-CoV-2-N IgM/IgG response. Older age and smoker status were associated with long-term SARS-CoV-2-N IgM and SARS-CoV-2-N IgG, respectively (HR: 0.75, 95% CI: 0.57-0.98, p 0.038; HR: 1.77, 95% CI: 1.19-2.61, p 0.004 respectively). All patients maintained SARS-CoV-2-S-RBD IgG response at 24-month follow-up. Reinfections occurred in 25 of 153 (16.3%) patients, mostly during the omicron circulation. Reinfection rates did not differ significantly between SARS-CoV-2-N IgG seronegative and seropositive patients (14/89, 15.7% vs. 10/62, 16.1%, p 0.947). Unvaccinated patients had higher risk of reinfection (4/7, 57.1% vs. vaccinated 21/146, 14.4%, p 0.014). DISCUSSION: First-wave patients had durable natural humoral immunity in 40% and anti-S-RBD response in 100% up to 2 years after infection. Natural humoral response alone was not protective against reinfections with omicron SARS-CoV-2 variants, whereas vaccination was effective to reduce the risk of a new infection.

Extracellular vesicle features are associated with COVID-19 severity.

COVID-19 is heterogeneous; therefore, it is crucial to identify early biomarkers for adverse outcomes. Extracellular vesicles (EV) are involved in the pathophysiology of COVID-19 and have both negative and positive effects. The objective of this study was to identify the potential role of EV in the prognostic stratification of COVID-19 patients. A total of 146 patients with severe or critical COVID-19 were enrolled. Demographic and comorbidity characteristics were collected, together with routine haematology, blood chemistry and lymphocyte subpopulation data. Flow cytometric characterization of the dimensional and antigenic properties of COVID-19 patients' plasma EVs was conducted. Elastic net logistic regression with cross-validation was employed to identify the best model for classifying critically ill patients. Features of smaller EVs (i.e. the fraction of EVs smaller than 200 nm expressing either cluster of differentiation [CD] 31, CD 140b or CD 42b), albuminemia and the percentage of monocytes expressing human leukocyte antigen DR (HLA-DR) were associated with a better outcome. Conversely, the proportion of larger EVs expressing N-cadherin, CD 34, CD 56, CD31 or CD 45, interleukin 6, red cell width distribution (RDW), N-terminal pro-brain natriuretic peptide (NT-proBNP), age, procalcitonin, Charlson Comorbidity Index and pro-adrenomedullin were associated with disease severity. Therefore, the simultaneous assessment of EV dimensions and their antigenic properties complements laboratory workup and helps in patient stratification.

Brain Endothelial Cells Activate Neuroinflammatory Pathways in Response to Early Cerebral Small Vessel Disease (CSVD) Patients' Plasma.

The pathogenesis of cerebral small vessel disease (CSVD) is largely unknown. Endothelial disfunction has been suggested as the turning point in CSVD development. In this study, we tested the effect of plasma from CSVD patients on human cerebral microvascular endothelial cells with the aim of describing the pattern of endothelial activation. Plasma samples from three groups of young subjects have been tested: PTs (subjects affected by early stage CSVD); CTRLs (control subjects without abnormalities at MRI scanning); BDs (blood donors). Human Brain Endothelial Cells 5i (HBEC5i) were treated with plasma and total RNA was extracted. RNAs were pooled to reduce gene expression-based variability and NGS analysis was performed. Differentially expressed genes were highlighted comparing PTs, CTRLs and BDs with HBEC5i untreated cells. No significantly altered pathway was evaluated in BD-related treatment. Regulation of p38 MAPK cascade (GO:1900744) was the only pathway altered in CTRL-related treatment. Indeed, 36 different biological processes turned out to be deregulated after PT treatment of HBEC5i, i.e., the cytokine-mediated signaling pathway (GO:0019221). Endothelial cells activate inflammatory pathways in response to stimuli from CSVD patients' plasma, suggesting the pathogenetic role of neuroinflammation from the early asymptomatic phases of cerebrovascular disease.

Recurrent reflex syncope in idiopathic intracranial hypertension patient resolved after lumbar puncture: pathogenetic implications.

BACKGROUND: Idiopathic intracranial hypertension is a disease characterized by increased intracranial cerebrospinal fluid volume and pressure without evidence of other intracranial pathology. Dural sinuses are rigid structures representing a privileged low-pressure intracranial compartment. Rigidity of dural sinus ensures that the large physiologic fluctuations of cerebrospinal fluid pressure associated with postural changes or to Valsalva effect cannot be transmitted to the sinus. An abnormal dural sinus collapsibility, especially when associated with various anatomical sinus narrowing, has been proposed as a key factor in the pathogenesis of idiopathic intracranial hypertension. This pathogenetic model is based on an excessive collapsibility of the dural sinuses that leads to the triggering of a self-limiting venous collapse positive feedback-loop between the cerebrospinal fluid pressure, that compresses the sinus, and the increased dural sinus pressure upstream, that reduces the cerebrospinal fluid reabsorption rate, increasing cerebrospinal fluid volume and pressure at the expense of intracranial compliance and promoting further sinus compression. Intracranial compliance is the ability of the craniospinal space to accept small volumetric increases of one of its compartments without appreciable intracranial pressure rise. In idiopathic intracranial hypertension, a condition associated with a reduced rate of CSF reabsorption leading to its volumetric expansion, a pathologically reduced IC precedes and accompanies the rise of ICP. Syncope is defined as a transient loss of consciousness due to a transient cerebral hypoperfusion characterized by rapid onset, short duration, and spontaneous complete recovery. A transient global cerebral hypoperfusion represents the final mechanism of syncope determined by cardiac output and/or total peripheral resistance decrease. There are many causes determining low cardiac output including reflex bradycardia, arrhythmias, cardiac structural disease, inadequate venous return, and chronotropic and inotropic incompetence. Typically, syncopal transient loss of consciousness is mainly referred to an extracranial mechanism triggering a decrease in cardiac output and/or total peripheral resistance. Conversely, the association of syncope with a deranged control of intracranial compliance related to cerebral venous outflow disorders has been only anecdotally reported. CASE PRESENTATION: We report on a 57-year-old woman with daily recurrent orthostatic hypotension syncope and idiopathic intracranial hypertension-related headaches, which resolved after lumbar puncture with cerebrospinal fluid subtraction. CONCLUSIONS: A novel mechanism underlying the triggering of orthostatic syncope in the presence of intracranial hypertension-dependent reduced intracranial compliance is discussed.

Potential role of IgM-enriched immunoglobulin as adjuvant treatment in severe SARS-CoV-2 infection.

BACKGROUND: Severe COVID-19 patients are characterized by a dysregulated host response to an infection, with uncontrolled pro- and anti- inflammatory pathway activation. Consistent proportion of patients require admission in intensive care units and are at risk of progression to severe forms of disease. These patients are generally admitted during later stages of the disease, when effective antiviral and monoclonal antibody are not indicated. We aimed to assess the potential role of IgM-enriched intra venous immunoglobulins (IGAM) preparations in this setting. METHODS: This retrospective, observational case-controlled study was conducted at a single-center University Hospital of Udine in the Friuli Venezia Giulia Region of Italy. Patients referring to the center between March 2020 and April 2021 was included. During the study period, patient who received Pentaglobin® IGAM treatment (N.=56), administered as compassionate use, was compared with a control group (N.=169) to assess, by propensity score analysis, clinical outcome. RESULTS: Untreated controls required, respect to patient treated with IGAM therapy, longer time to hospitalization with no significant differences in death and orotracheal intubation requirement. Significant differences in the two cohort were in: SOFA was higher in treated, while D-dimer and P/F ratio was better in the treatment cohort. Multivariate logistic regression analysis performed on the "matched sample," obtained by a weighting propensity score approach, identify, as significant protective factor for death outcome, the Pentaglobin® treatment (0.820 [0.698-0.963], P=0.016) and low C-reactive protein (1.001 [1.000-1.002], P=0.031) value while the delay of onset hospitalization is associate with a worst outcome (0.983 [0.967-0.999], P=0.041). CONCLUSIONS: The present study offers a significant insight concerning the use of IgM-enriched immunoglobulin preparations in patients with SARS-CoV-2 severe infection and also could identifying the specific immunological and biochemical profile of the patient who can more benefit from this therapeutic option.

Mycophenolate Interruption Restores Anti-SARS-CoV-2 Vaccine Immunogenicity in Unresponsive Liver Transplant Recipients.

BACKGROUND & AIMS: The fourth dose of anti-SARS-CoV-2 vaccine slightly improved the humoral response among previously seronegative liver transplant (LT) recipients. Mycophenolate (MMF) treatment worsens the vaccination response. This study aimed to evaluate whether temporary MMF interruption might improve the immunogenicity of the fourth anti-SARS-CoV-2 BNT16b2 vaccine dose in nonresponsive LT recipients. METHODS: LT recipients negative for anti-spike glycoprotein-specific immunoglobulin G receptor-binding domain (s-RBD) antibodies after the third vaccine dose were enrolled. Anti-SARS-CoV-2 spike-specific T-cell responses were measured before and 2 months following the fourth vaccine dose, and anti-SARS-CoV-2 s-RBD antibodies also 6 months thereafter. MMF was suspended two weeks before and after vaccination. RESULTS: Five LT recipients were enrolled. After a mean of 78 days after vaccination, all patients tested positive for anti-SARS-CoV-2 s-RBD antibodies. The mean antibody titer was 8944 UI/mL. The positive antibody response was maintained during a mean of 193 days of follow-up. Three patients developed a positive T-cell response. Two patients (one positive for T-cell response) developed a self-limited SARS-CoV-2 infection. CONCLUSIONS: Suspending MMF prior to the fourth dose of the anti-SARS-CoV-2 mRNA vaccine seems feasible and safe. This procedure could restore vaccine-induced immunogenicity in a large portion of previously nonresponsive LT recipients.

Post-COVID-19 Syndrome 2 Years After the First Wave: The Role of Humoral Response, Vaccination and Reinfection.

Background: The aim of this study was to describe the long-term evolution of post-COVID-19 syndrome over 2 years after the onset of severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2) in survivors of the first wave. Methods: This prospective study was based on interviews and investigated post-COVID-19 syndrome 6, 12, and 24 months after the disease onset in all adult in- and outpatients with COVID-19 followed at Udine Hospital (Italy) during the first wave (March-May 2020). Humoral response, vaccination status, and reinfection were assessed. Results: Overall, 230 patients (53.5% female; mean age 54.7 years) were interviewed 2.3 years (standard deviation = 0.11) after acute onset. Post-COVID-19 syndrome was observed in 36.1% of patients (n = 83) at 2 years. The most common persistent symptoms were fatigue (14.4%), rheumatological (14.4%), and psychiatric symptoms (9.6%). Overall, 55.4% (46 of 83) of long haulers searched for healthcare system support and 21 (45.7%) were visited by a specialist. Female gender (odds ratio [OR] = 2.50, P = .005), a proportional increase in the number of symptoms during acute COVID-19 (OR = 1.40, P = .001), and the presence of comorbidities (OR = 1.57, P = .004) were all independent risk factors for post-COVID-19 syndrome. Vaccination and reinfection had no impact on post-COVID-19 syndrome dynamics. The presence of receptor-binding domain (RBD) SARS-CoV-2 immunoglobulin G (IgG) and non-RBD SARS-CoV-2 IgG titers were not associated with the occurrence of post-COVID-19 syndrome. Conclusions: Two years after COVID-19, the burden of persistent symptoms remains high among in- and outpatients' population infected during the first wave. Post-COVID-19 dynamic does not seem to be influenced by SARS-CoV-2 immunization status and reinfection.

Ceramide releases exosomes with a specific miRNA signature for cell differentiation.

Exosomes are well established effectors of cell-cell communication. Their role on maturation of embryonic cells located in hippocampus, seat of memory, is unknown. Here we show that ceramide facilitates release of exosomes from HN9.10e cells extending information for cell differentiation to neighboring cells. We found only 38 miRNAs differentially expressed in exosomes derived from ceramide-treated cells in comparison with control cells (including 10 up-regulated and 28 down-regulated). Some overexpressed miRNAs (mmu-let-7f-1-3p, mmu-let-7a-1-3p, mmu-let-7b-3p, mmu-let-7b-5p, mmu-miR-330-3p) regulate genes encoding for protein involved in biological, homeostatic, biosynthetic and small molecule metabolic processes, embryo development and cell differentiation, all phenomena relevant for HN9.10e cell differentiation. Notably, the overexpressed mmu-let-7b-5p miRNA appears to be important for our study based on its ability to regulate thirty-five gene targets involved in many processes including sphingolipid metabolism, sphingolipid-related stimulation of cellular functions and neuronal development. Furthermore, we showed that by incubating embryonic cells with exosomes released under ceramide treatment, some cells acquired an astrocytic phenotype and others a neuronal phenotype. We anticipate our study to be a start point for innovative therapeutic strategies to regulate the release of exosomes useful to stimulate delayed brain development in the newborn and to improve the cognitive decline in neurodegenerative disorders.

The role of asymmetric dimethylarginine (ADMA) in COVID-19: association with respiratory failure and predictive role for outcome.

We aimed to assess the potential role of Asymmetric dimethylarginine (ADMA) in conditioning respiratory function and pulmonary vasoregulation during Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV2) infection. Within 72 h from admission, samples from 90 COVID-19 patients were assessed for ADMA, SDMA, L-arginine concentrations. In addition to classical statistics, patients were also clustered by a machine learning approach according to similar features. Multivariable analysis showed that C-reactive protein (OR 1.012), serum ADMA (OR 4.652), white blood cells (OR = 1.118) and SOFA (OR = 1.495) were significantly associated with negative outcomes. Machine learning-based clustering showed three distinct clusters: (1) patients with low severity not requiring invasive mechanical ventilation (IMV), (2) patients with moderate severity and respiratory failure whilst not requiring IMV, and (3) patients with highest severity requiring IMV. Serum ADMA concentration was significantly associated with disease severity and need for IMV although less pulmonary vasodilation was observed by CT scan. High serum levels of ADMA are indicative of high disease severity and requirement of mechanical ventilation. Serum ADMA at the time of hospital admission may therefore help to identify COVID-19 patients at high risk of deterioration and negative outcome.

Ampicillin and Ceftobiprole Combination for the Treatment of Enterococcus faecalis Invasive Infections: "The Times They Are A-Changin".

BACKGROUND: Enterococcus faecalis is responsible for a large variety of severe infections. This study is a case series reporting our experience in the treatment of E. faecalis invasive infections with ampicillin in combination with ceftobiprole (ABPR). METHODS: We retrospectively analyzed all the medical records of patients admitted to the University Hospital of Udine from January to December 2020 with a diagnosis of infective endocarditis or primary or non-primary complicated or uncomplicated bacteremia caused by E. faecalis. RESULTS: Twenty-one patients were included in the final analysis. The clinical success rate was very high, accounting for 81% of patients, and microbiological cure was obtained in 86% of patients. One relapse was recorded in one patient who did not adhere to the partial oral treatment prescribed. Therapeutic drug monitoring (TDM) was always performed for ampicillin and ceftobiprole, and serum concentrations of both drugs were compared to the MICs of the different enterococcal isolates. CONCLUSIONS: ABPR is a well-tolerated antimicrobial regimen with anti-E. faecalis activity. TDM can help clinicians optimize medical treatments to achieve the best possible efficacy with fewer side effects. ABPR might be a reasonable option for the treatment of severe invasive infections caused by E. faecalis due to the high level of enterococcal penicillin-binding protein (PBP) saturation.

A Novel Mix of Polyphenols and Micronutrients Reduces Adipogenesis and Promotes White Adipose Tissue Browning via UCP1 Expression and AMPK Activation.

Background: Obesity is a pandemic disease characterized by excessive severe body comorbidities. Reduction in fat accumulation represents a mechanism of prevention, and the replacement of white adipose tissue (WAT) with brown adipose tissue (BAT) has been proposed as one promising strategy against obesity. In the present study, we sought to investigate the ability of a natural mixture of polyphenols and micronutrients (A5+) to counteract white adipogenesis by promoting WAT browning. Methods: For this study, we employed a murine 3T3-L1 fibroblast cell line treated with A5+, or DMSO as control, during the differentiation in mature adipocytes for 10 days. Cell cycle analysis was performed using propidium iodide staining and cytofluorimetric analysis. Intracellular lipid contents were detected by Oil Red O staining. Inflammation Array, along with qRT-PCR and Western Blot analyses, served to measure the expression of the analyzed markers, such as pro-inflammatory cytokines. Results: A5+ administration significantly reduced lipids' accumulation in adipocytes when compared to control cells (p < 0.005). Similarly, A5+ inhibited cellular proliferation during the mitotic clonal expansion (MCE), the most relevant stage in adipocytes differentiation (p < 0.0001). We also found that A5+ significantly reduced the release of pro-inflammatory cytokines, such as IL-6 and Leptin (p < 0.005), and promoted fat browning and fatty acid oxidation through increasing expression levels of genes related to BAT, such as UCP1 (p < 0.05). This thermogenic process is mediated via AMPK-ATGL pathway activation. Conclusion: Overall, these results demonstrated that the synergistic effect of compounds contained in A5+ may be able to counteract adipogenesis and then obesity by inducing fat browning.

Antibody, cell-mediated response and infection susceptibility in allogeneic hematopoietic stem cell recipients after COVID-19 mRNA vaccination.

BACKGROUND: Patients undergoing allogeneic stem-cell transplantation (allo-SCT) have reduced responses to vaccines due to immunosuppressive status linked to GvHD prophylaxis and treatment. In our study, we compared humoral responses to anti-SARS-CoV-2 mRNA vaccine, and infection onset, according to patients and transplant features; we also evaluated cellular response in patients without seroconversion. METHODS: We tested antibodies titer after second and third vaccine doses. Antibodies were detected through an immune-enzymatic assay. In a patients' subgroup without seroconversion, we tested cell-mediated responses evaluating interferon-gamma release by T-lymphocytes exposed to virus spike protein. RESULTS: Seroconversion rate increased from 66% at 30 days to 81% at 90 days after the second dose; it was 97% at 150 days after the third dose. We found a significant association between seroconversion after the second dose and two variables: shorter interval between allo-SCT and vaccination; ongoing immunosuppression. Twelve of 19 patients (63%) without antibodies after the second dose did not show cellular responses. Nineteen percent of patients developed SARS-CoV-2 infection after the third dose, with favorable outcome in all cases. Patients within 12 months after allo-SCT showed a significantly higher infection risk. CONCLUSIONS: Our study suggests that an interval shorter than 12 months between allo-SCT and first vaccine dose and/or ongoing immunosuppression were associated with humoral and cellular response deficiency after two doses. Third dose induced an increased and sustained humoral response in the majority of patients. However, patients within 1 year after allo-SCT remained at higher infection risk and may be candidate for prophylaxis with anti-SARS-CoV-2 monoclonal antibodies.

Humoral and T-Cell Mediated Response after the Third Dose of mRNA Vaccines in Patients with Systemic Lupus Erythematosus on Belimumab.

OBJECTIVE: To evaluate humoral and T-cell cellular-mediated immune response after three doses of SARS-CoV-2 mRNA vaccines in patients with systemic lupus erythematosus (SLE) under Belimumab. PATIENTS AND METHODS: 12 patients on Belimumab and 13 age-matched healthy volunteers were recruited. Patients were in remission or in low disease activity, and they were taking no corticosteroids or only low doses. None of the patients and controls had detectable anti-SARS-CoV-2 antibodies due to previous exposure to the virus. All the patients received three doses of mRNA anti-SARS-CoV-2 vaccines and the humoral and cellular-mediated response were tested 4 weeks after the second dose (T0), 6 months after the second dose (T1) and 4 weeks after the third dose (T2). Comparison with the control group was performed at time T0 (i.e., 4 weeks after the second dose). Total anti-SARS-CoV-2 RBD antibodies were analyzed using a diagnostic assay, while cellular-mediated response was evaluated using the interferon-gamma release assay (IGRA). RESULTS: A humoral response was documented in all the patients at T0 (median 459; IQR 225.25-758.5), but the antibody titer significantly declined from T0 to T1 (median 44.7; IQR: 30.3-202; p = 0.0066). At T2, the antibody titer significantly increased from T1 (median 2500; IQR: 2500-2500), and it was not different from T0 (respectively p < 0.0001, p = 0.66). Cellular-mediated response significantly declined from T0 to T1 (p = 0.003) but not from T0 to T2 (p = 0.3). No differences were found between patients and controls at T0 as regards both humoral and cellular responses (p = 1.0 and p = 0.09 for humoral and cellular responses, respectively). CONCLUSION: The third dose of mRNA COVID-19 vaccine can restore both humoral and cellular immune response in SLE patients on Belimumab.

The impact of different calibration matrices on the determination of insulin-like growth factor 1 by high-resolution-LC-MS in acromegalic and growth hormone deficient patients.

OBJECTIVES: Calibration is an important source of variability in liquid chromatography mass spectrometry (LC-MS) methods for insulin-like growth factor 1 (IGF-1). This study investigated the impact of different calibrator matrices on IGF-1 measurements by LC-MS. Moreover, the comparability of immunoassays and LC-MS was assessed. DESIGN & METHODS: Calibrators from 12.5 to 2009 ng/ml were prepared by spiking WHO international Standard (ID 02/254 NIBSC, UK) into the following matrices: native human plasma, fresh charcoal-treated human plasma (FCTHP), old charcoal-treated human plasma, deionized water, bovine serum albumin (BSA), and rat plasma (RP). A validated in-house LC-MS method was calibrated repeatedly with these calibrators. Then, serum samples from 197 growth hormone excess and deficiency patients were analysed with each calibration. RESULTS: The seven calibration curves had different slopes leading to markedly different patient results. The largest differences in IGF-1 concentration from the median (interquartile range) was observed with the calibrator in water and the calibrator in RP (336.4 [279.6-417.0] vs. 112.5 [71.2-171.2], p < 0.001). The smallest difference was observed with calibrators in FCTHP and BSA (141.8 [102.0-198.5] vs. 127.9 [86.9-186.0], p < 0.049). Compared to LC-MS with calibrators in FCTHP, immunoassays showed relevant proportional bias (range: -43% to -68%), constant bias (range: 22.84 to 57.29 ng/ml) and pronounced scatter. Comparing the immunoassays with each other revealed proportional bias of up to 24%. CONCLUSIONS: The calibrator matrix is critical for the measurement of IGF-1 by LC-MS. Regardless of the calibrator matrix, LC-MS shows poor agreement with immunoassays. Also, the agreement between different immunoassays is variable.

Immunogenicity and safety of a third dose of anti-SARS-CoV-2 BNT16b2 vaccine in liver transplant recipients.

BACKGROUND & AIMS: A strategy to improve the low rate of anti-SARS-CoV-2 mRNA vaccine-induced immunogenicity in liver transplant recipients (LTs) is urgently needed. METHODS: We analysed the rate of positive (≥0.8 U/ml) anti-SARS-CoV-2 receptor domain-binding protein (RBD) antibody response 2 months after a third dose of the BNT16b2 vaccine in 107 LTs who completed the second vaccine dose 7 months earlier. RESULTS: A positive anti-SARS-CoV-2-s-RBD antibody response after the third vaccine dose was detected in 98 (91.6%) LTs compared to 82 (76.6%) after the second vaccine dose (p = .003). The median of anti-SARS-CoV-2 RBD antibody titres increased from 22.9 U/ml 6 months after the second to 3500 U/ml 2 months after the third vaccine dose (p < .001). Fourteen (14.3%) responder patients presented antibody titres <100 U/ml, 57 (58.2%) between 100 and 9999 U/ml and 27 (27.6%) ≥10 000 U/ml. Seropositivity after the second dose was maintained after the third dose. Independent predictors of antibody response failure after the third vaccine dose were taking a higher daily dose of mycophenolate mofetil (MMF, p < .001) and had a lower (<60 ml/min/1.73 m2 ) estimated glomerular filtration rate (p = .007). Nine (9.1%) LTs experienced symptomatic SARS-CoV-2 infection after the third vaccine dose. Median antibody titres were not statistically different between infected and not infected LTs (1325 vs 3515 U/ml, p = .678). CONCLUSIONS: The third dose of the BNT16b2 vaccine increased the number of LTs who developed a positive anti-SARS-CoV-2 s-RBD antibody response. A proportion of patients remained unresponsive, mainly for modifiable factors, such as the use of MMF or multiple immunosuppressants.