Population Pharmacokinetic Model of Linezolid and Probability of Target Attainment in Patients with COVID-19-Associated Acute Respiratory Distress Syndrome on Veno-Venous Extracorporeal Membrane Oxygenation—A Step toward Correct Dosing

During veno-venous extracorporeal membrane oxygenation (vv ECMO) therapy, antimicrobial drugs are frequently used, and appropriate dosing is challenging due to there being limited data to support the dosage. Linezolid is effective against multidrug-resistant Gram-positive pathogens frequently isolated in ECMO patients. In total, 53 steady-state linezolid levels were obtained following 600 mg intravenous (IV) injections every 8 h, and these were used to develop a population pharmacokinetic (PopPK) model in patients with COVID-19-associated acute respiratory distress syndrome (CARDS) on vv ECMO. The data were analyzed using a nonlinear mixed-effects modelling approach. Monte Carlo simulation generated 5000 patients’ individual PK parameters and corresponding concentration–time profiles using the PopPK model, following the administration of 600 mg/8 h (a higher-than-standard dosing) and 600 mg/12 h (standard). The probabilities of pharmacokinetic/pharmacodynamic (PK/PD) target attainment (PTA) and the cumulative fraction of responses (CFR) for three pathogens were calculated and compared between the two dosing scenarios. Linezolid 600 mg/8 h was predicted to achieve greater than or equal to 85%Tf>MIC in at least 90% of the patients with CARDS on vv ECMO compared to only approximately two thirds of the patients after dosing every 12 h at a minimal inhibitory concentration (MIC) of 2 mg/L. In addition, for the same MIC, fAUC24/MIC ≥ 80 was achieved in almost three times the number of patients following an 8-h versus a 12-h interval. PopPK simulation predicted that a significantly higher proportion of the patients with CARDS on vv ECMO would achieve the PK/PD targets following the 8-h dosing interval compared to standard linezolid dosing. Nevertheless, the safety concern, in particular, for thrombocytopenia, with higher-than-standard linezolid dosage is reasonable, and consequently, monitoring is essential

Direct Estimation of Reference Intervals for Thyroid Parameters in the Republic of Srpska

Background: The aim of this study was to determine the reference values for thyrotropin (TSH), thyroid hormones (total and free thyroxine, T4 and fT4; total and free triiodothyronine, T3 and fT3), thyroglobulin (Tg) and thyroid antibodies (thyroid peroxidase, TPOAb and thyroglobulin antibody, TgAb) in the population of the Republic of Srpska. Methods: A total of 250 euthyroid subjects were enrolled in this study. A direct method for choosing reference subjects was used to establish reference intervals. The hormones and thyroid antibodies were measured by an electrochemiluminescence immunoassay method (ECLIA, Roche Diagnostics, Mannheim, Germany). We calculated the re f erence intervals by MedCalc, version 12.1.4.0 (MedCalc software, Belgium) as recommended by the IFCC (CLSI C28-A3). Results: Using guidelines recommended by the National Academy of Clinical Biochemistry (NACB) and based on standard statistical approaches, the reference intervals derived for TSH, fT4, T4, fT3, T3 were 0.75-5.32 mIU/L, 12.29-20.03 pmol/L, 73.49-126,30 nmol/L, 4.11-6.32 pmol/L, 1.15-2.32 nmol/L and for Tg, TPOAb, TgAb were 3.63-26.00 mu g/L, lt 18.02 mIU/L, lt 98.00 mIU/L, respe ctively. We found a significant difference (p lt 0.05) in TSH and fT3 values between different age groups as well as in T4, fT4 and fT3 values between ge nder groups. Conclusions: The established reference values for the population of the Republic of Srpska were significantly different from the values recommended by the manufacturer of reagents (Roche Diagnostics). Our results showed that a laboratory needs to establish its own reference values in order to set up a proper diagnosis, as well as to treat patients successfully

The Pleiotropic Effects of Atorvastatin on Stable Angina Patients: Evidence by Analysis of High-Density Lipoprotein Size and Subclasses, and Plasma mRNA

Background: High-density lipoproteins (HDL) have atheroprotective biological properties: antioxidative, anti-apoptotic, anti-inflammatory, and they have the efflux capacity of cellular cholesterol. Plasma mRNA analysis can be used to investigate statin pleiotropy in vivo as a new analytical tool for non-invasive assessment of gene expression in vascular beds. The aim of this study was to assess the pleiotropic effects of atorvastatin in stable angina patients with highrisk values (group A) as compared with patients who had borderline and desirable HDL-cholesterol (HDL-C) values (group B). Methods: The atorvastatin therapy (20 mg/day) was given to forty-three patients with stable angina for 10 weeks. We investigated three statin pleiotropy-targeted genes: intercellular adhesion molecule-1, chemokine (C-C motif) ligand 2 and cathepsin S and assessed by gel electrophoresis gradient the effects of atorvastatin on HDL size and subclasses. Results: In group A, after therapy, HDL-C concentration was significantly increased but not in group B. Atorvastatin lowered plasma chemokine (C-C motif) ligand 2 and intercellular adhesion molecule-1 mRNA levels in both groups, but did not change the plasma cathepsin S mRNA levels. In group A only, baseline total bilirubin showed negative cor relations with the genes of cathepsin S (r=-0.506; p = 0.023) and significantly increased after therapy. Conclusions: HDL-C and bilirubin can be promising therapeutic targets in the treatment of cardiovascular diseases. Analysis of cell-free mRNA in plasma might become a useful tool for estimating statin pleiotropy

The genetic architecture of the human cerebral cortex

The cerebral cortex underlies our complex cognitive capabilities, yet little is known about the specific genetic loci that influence human cortical structure. To identify genetic variants that affect cortical structure, we conducted a genome-wide association meta-analysis of brain magnetic resonance imaging data from 51,665 individuals. We analyzed the surface area and average thickness of the whole cortex and 34 regions with known functional specializations. We identified 199 significant loci and found significant enrichment for loci influencing total surface area within regulatory elements that are active during prenatal cortical development, supporting the radial unit hypothesis. Loci that affect regional surface area cluster near genes in Wnt signaling pathways, which influence progenitor expansion and areal identity. Variation in cortical structure is genetically correlated with cognitive function, Parkinson's disease, insomnia, depression, neuroticism, and attention deficit hyperactivity disorder

Indirektna procjena referentnih intervala za parametre štitne žlijezde upotrebom advia centaur XP analizatora

Background: The aim of this study was to determine the reference intervals (RIs) for thyroid stimulating hormone (TSH), free thyroxine (FT4), free triiodothyronine (FT3) and FT3/FT4 ratio using indirect methods. Methods: We analyzed 1256 results TSH, FT4 and FT3 collected from a laboratory information system between 2017 and 2021. All measurements were performed on a Siemens ADVIA Centaur XP analyzer using the chemiluminescent immunoassay. We calculated the values of the 2.5th and 97.5th percentiles as recommended by the IFCC (CLSI C28-A3). Results: The RIs derived for TSH, FT4, FT3 and FT3/FT4 ratio were 0.34–4.10 mIU/L, 11.3–20.6 pmol/L, 3.5–6.32 pmol/L and 0.21–0.47, respectively. We found a significant difference between calculated RIs for the TSH and FT4 and those recommended by the manufacturer. Also, FT3 values were significantly higher in the group younger than 30 years relative to the fourth decade (5.26 vs. 5.02, p=0.005), the fifth decade (5.26 vs. 4.94, p=0.001), the sixth decade (5.26 vs. 4.87, p<0.001), the seventh decade (5.26 vs. 4.79, p<0.001) and the group older than 70 years old (5.26 vs. 4.55, p<0.001). Likewise, we found for TSH values and FT3/FT4 ratio a significant difference (p <0.001) between different age groups. Conclusions: The establishing RIs for the population of the Republic of Srpska were significantly differed from the recommended RIs by the manufacturer for TSH and FT4. Our results encourage other laboratories to develop their own RIs for thyroid parameters by applying CLSI recommendations.Uvod: Cilj ove studije bio je da se odrede referentni intervali (RI) tireotropnog hormona (TSH), slobodnog tiroksina (FT4), slobodnog trijodotironina (FT3) i odnosa FT3/FT4 indirektnom metodom procene referentnih intervala. Metode: Analizirali smo 1256 dobijenih vrednosti TSH, FT4 i FT3 u periodu između 2017. i 2021. godine. Rezultate smo uzeli iz laboratorijskog informacionog sistema. Sva merenja su izvedena na Siemens ADVIA Centaur XP analizatoru pomo}u hemiluminiscentnih imunohemijskih testova. Izračunali smo vrednosti 2,5-og i 97,5-og percentila prema preporuci IFCC-a (CLSI C28-A3). Rezultati: Procenjeni RI za TSH, FT4, FT3 i odnos FT3/FT4 bili su 0,34-4,10 mIU/L; 11,3-20,6 pmol/L; 3,5-6,32 pmol/L i 0,21-0,47. Utvrdili smo značajnu razliku između izračunatih RI za TSH i FT4 i onih koje preporučuje proizvođač. Takođe, vrednosti FT3 bile su značajno ve}e u grupi mlađoj od 30 godina u odnosu na četvrtu deceniju (5,26 vs. 5,02; p = 0,005), petu deceniju (5,26 vs. 4,94; p = 0,001), šestu deceniju (5,26 vs. 4,87; p<0,001), sedmu deceniju (5,26 vs. 4,79; p<0,001) i grupu stariju od 70 godina (5,26 vs. 4,55; p<0,001). Isto tako, za vrednosti TSH i odnos FT3/FT4 pronašli smo značajnu razliku (p <0,001) između različitih dobnih grupa. Zaključak: Procenjene vrednosti referentnih intervala za TSH i FT4 za stanovništvo Republike Srpske značajno su se razlikovale od preporučenih RI od strane proizvođača. Naši rezultati podstiču druge laboratorije da izrade sopstvene RI za parametre štitne žlezde primenom CLSI preporuka

Population pharmacokinetic model of Vancomycin based on therapeutic drug monitoring data in critically ill septic patients

Purpose: The present study aimed to establish a population pharmacokinetic model of vancomycin, including adult critically ill septic patients, with normal and impaired renal function. Materials and methods: A prospective analysis of 146 concentrations from 73 adult critically ill septic patients treated with 1-h intravenous infusion of vancomycin were included in the study. A nonlinear mixed effects modeling (NONMEM) approach was applied for data analysis and evaluation of the final model. The influence of creatinine clearance calculated by the Cockcroft-Gault equation (CrCl), and other potential covariates on vancomycin clearance (CL) were evaluated. Results: The final one-compartment pharmacokinetic model includes the effect of CrCl on CL. Population pharmacokinetic values for a typical subject were estimated at 0.024 l/h for CL dependent on renal function (CLCrCl), 1.93 l/h for residual portion of CL (not dependent on renal function), and 0.511 l/kg for volume of distribution (V). According to the final model, for patients with CrCl = 120 ml/min, the median vancomycin total CL is 4.81 l/h, while CrCl-dependent fraction accounts for approximately 60% of CL. Conclusions: The developed population vancomycin model may be used in estimating individual CL for adult critically ill septic patients, and could be applied for individualizing dosage regimens taking into account the continuous effect of CrCl