Therapeutic drug monitoring of once daily aminoglycoside dosing: comparison of two methods and investigation of the optimal blood sampling strategy.

PURPOSE Therapeutic drug monitoring of patients receiving once daily aminoglycoside therapy can be performed using pharmacokinetic (PK) formulas or Bayesian calculations. While these methods produced comparable results, their performance has never been checked against full PK profiles. We performed a PK study in order to compare both methods and to determine the best time-points to estimate AUC0-24 and peak concentrations (C max). METHODS We obtained full PK profiles in 14 patients receiving a once daily aminoglycoside therapy. PK parameters were calculated with PKSolver using non-compartmental methods. The calculated PK parameters were then compared with parameters estimated using an algorithm based on two serum concentrations (two-point method) or the software TCIWorks (Bayesian method). RESULTS For tobramycin and gentamicin, AUC0-24 and C max could be reliably estimated using a first serum concentration obtained at 1 h and a second one between 8 and 10 h after start of the infusion. The two-point and the Bayesian method produced similar results. For amikacin, AUC0-24 could reliably be estimated by both methods. C max was underestimated by 10-20% by the two-point method and by up to 30% with a large variation by the Bayesian method. CONCLUSIONS The ideal time-points for therapeutic drug monitoring of once daily administered aminoglycosides are 1 h after start of a 30-min infusion for the first time-point and 8-10 h after start of the infusion for the second time-point. Duration of the infusion and accurate registration of the time-points of blood drawing are essential for obtaining precise predictions.

Determination of Ethyl glucuronide and Ethyl sulfate from dried blood spots

BACKGROUND: Ethyl glucuronide (EtG) and ethyl sulfate (EtS) are non-oxidative minor metabolites of ethanol. They are detectable in various body fluids shortly after initial consumption of ethanol and have a longer detection time frame than the parent compound. They are regarded highly sensitive and specific markers of recent alcohol uptake. This study evaluates the determination of EtG and EtS from dried blood spots (DBS), a simple and cost-effective sampling method that would shorten the time gap between offense and blood sampling and lead to a better reflectance of the actual impairment. METHODS: For method validation, EtG and EtS standard and quality control samples were prepared in fresh human heparinized blood and spotted on DBS cards, then extracted and measured by an LC-ESI-MS/MS method. Additionally, 76 heparinized blood samples from traffic offense cases were analyzed for EtG and EtS as whole blood and as DBS specimens. The results from these measurements were then compared by calculating the respective mean values, by a matched-paired t test, by a Wilcoxon test, and by Bland-Altman and Mountain plots. RESULTS AND DISCUSSION: Calibrations for EtG and EtS in DBS were linear over the studied calibration range. The precision and accuracy of the method met the requirements of the validation guidelines that were employed in the study. The stability of the biomarkers stored as DBS was demonstrated under different storage conditions. The t test showed no significant difference between whole blood and DBS in the determination of EtG and EtS. In addition, the Bland-Altman analysis and Mountain plot confirmed that the concentration differences that were measured in DBS specimens were not relevant.

Evaluation of a bolus/infusion protocol for 11C-ABP688, a PET tracer for mGluR5

(11)C-ABP-688 is a selective tracer for the mGluR5 receptor. Its kinetics is fast and thus favourable for an equilibrium approach to determine receptor-related parameters. The purpose of this study was to test the hypothesis that the pattern of the (11)C-ABP688 uptake using a bolus-plus-infusion (B/I) protocol at early time points corresponds to the perfusion and at a later time point to the total distribution volume. METHODS: A bolus and a B/I study (1 h each) was performed in five healthy male volunteers. With the B/I protocol, early and late scans were normalized to gray matter, cerebellum and white matter. The same normalization was done on the maps of the total distribution volume (Vt) and K(1) which were calculated in the study with bolus only injection and the Logan method (Vt) and a two-tissue compartment model (K(1)). RESULTS: There was an excellent correlation close to the identity line between the pattern of the late uptake in the B/I study and Vt of the bolus-only study for all three normalizations. The pattern of the early uptake in the B/I study correlated well with the K(1) maps, but only when normalized to gray matter and cerebellum, not to white matter. CONCLUSION: It is demonstrated that with a B/I protocol the (11)C-ABP688 distribution in late scans reflects the pattern of the total distribution volume and is therefore a measure for the density pattern of mGluR5. The early scans following injection are related to blood flow, although not in a fully quantitative manner. The advantage of the B/I protocol is that no arterial blood sampling is required, which is advantageous in clinical studies.

Formation of Phosphatidylethanol and Its Subsequent Elimination During an Extensive Drinking Experiment Over 5 Days

BACKGROUND: For almost 30 years, phosphatidylethanol (PEth) has been known as a direct marker of alcohol consumption. This marker stands for consumption in high amounts and for a longer time period, but it has been also detected after 1 high single intake of ethanol (EtOH). The aim of this study was to obtain further information about the formation and elimination of PEth 16:0/18:1 by simulating extensive drinking. METHODS: After 3 weeks of alcohol abstinence, 11 test persons drank an amount of EtOH leading to an estimated blood ethanol concentration of 1 g/kg on each of 5 successive days. After the drinking episode, they stayed abstinent for 16 days with regular blood sampling. PEth 16:0/18:1 analysis was performed using liquid chromatography-tandem mass spectrometry (high-performance liquid chromatography 1100 system and QTrap 2000 triple quadrupole linear ion trap mass spectrometer. Values of blood alcohol were obtained using a standardized method with headspace gas chromatography flame ionization detector. RESULTS: Maximum measured concentrations of EtOH were 0.99 to 1.83 g/kg (mean 1.32 g/kg). These values were reached 1 to 3 hours after the start of drinking (mean 1.9 hours). For comparison, 10 of 11 volunteers had detectable PEth 16:0/18:1 values 1 hour after the start of drinking, ranging from 45 to 138 ng/ml PEth 16:0/18:1. Over the following days, concentrations of PEth 16:0/18:1 increased continuously and reached the maximum concentrations of 74 to 237 ng/ml between days 3 and 6. CONCLUSIONS: This drinking experiment led to measurable PEth concentrations. However, PEth 16:0/18:1 concentrations stayed rather low compared with those of alcohol abusers from previous studies.

Serum leptin and C-reactive protein levels in the physiological spontaneous menstrual cycle in reproductive age women

OBJECTIVE: Only a few studies have investigated variations of different markers for inflammatory processes during the physiological menstrual cycle. The results are conflicting, particularly concerning the correlation between the marker leptin and steroid hormones. The aim of the study was to investigate the inflammatory markers C-reactive protein (CRP) and leptin in the serum of healthy, normally ovulating women and to correlate these with each other and with the hormones of the gonadal axis. A cycle-dependence of the markers studied would imply an exact timing of the blood sampling for clinical needs. DESIGN: Observational study investigating the two inflammatory markers CRP and leptin in relation to the hormonal pattern of the gonadal axis during the normal cycle. METHODS: Ovulatory cycles of 36 healthy, young, normo-androgenic women, having a normal body mass index were evaluated. Serum concentrations of leptin and CRP, as well as of follicle-stimulating hormone, luteinising hormone, 17beta-oestradiol, progesterone, prolactin (PRL) and free testosterone were measured every 1-2 days during one full cycle. RESULTS: Serum levels of leptin and CRP behaved differently during ovulatory cycles, with higher concentrations for leptin only during certain phases. Significant correlations were found in the follicular phase between leptin and PRL and leptin and free testosterone. CONCLUSIONS: Leptin levels change during the menstrual cycle. Leptin levels are more stable on cycle days 1-5 than later in the cycle. For precise cycle-independent measurements, these fluctuations have to be taken into account. There is no similar cyclic pattern for CRP.

First trimester markers for pre-eclampsia: placental vs. non-placental protein serum levels

BACKGROUND/AIM: Parallel investigation, in a matched case-control study, of the association of different first-trimester markers with the risk of subsequent pre-eclampsia (PE). METHOD: The levels of different first trimester serum markers and fetal nuchal translucency thickness were compared between 52 cases of PE and 104 control women by non-parametric two-group comparisons and by calculating matched odds ratios. RESULTS: In univariable analysis increased concentrations of inhibin A and activin A were associated with subsequent PE (p < 0.02). Multivariable conditional logistic regression models revealed an association between increased risk of PE and increased inhibin A and translucency thickness and respectively reduced pregnancy-associated plasma protein A (PAPP-A) and placental lactogen . However, these associations varied with the gestational age at sample collection. For blood samples taken in pregnancy weeks 12 and 13 only, increased levels of activin A, inhibin A and nuchal translucency thickness, and lower levels of placenta growth factor and PAPP-A were associated with an increased risk of PE. CONCLUSIONS: Members of the inhibin family and to some extent PAPP-A and placental growth factor are superior to other serum markers, and the predictive value of these depends on the gestational age at blood sampling. The availability of a single, early pregnancy 'miracle' serum marker for PE risk assessment seems unlikely in the near future.

Increased circulating placental growth factor during percutaneous coronary intervention is associated with applied radiocontrast agent

BACKGROUND AND AIM OF THE STUDY: Recent studies have suggested placental growth factor (PlGF) and vascular endothelial growth factor (VEGF) as promising new biomarkers for risk stratification in acute coronary syndromes (ACS). However, little is known about the influence of percutaneous coronary intervention (PCI) on circulating PlGF and VEGF levels. METHODS: Thirty-five patients with ACS, 27 patients with stable coronary artery disease (sCAD), and nine healthy controls were enrolled in the study. Although all patients with ACS and 14 patients with stable angina pectoris underwent PCI, 13 patients with coronary artery disease required no revascularization (sCAD). PlGF and VEGF plasma concentrations were measured by immunoassay during and at the end of PCI and coronary angiography. RESULTS: Plasma PlGF levels were comparable in patients with ACS and sCAD on admission. Although coronary angiography or heparin alone did not alter PlGF and VEGF levels, immediately after PCI a dramatic increase was seen in circulating PlGF and a decrease in VEGF, which was independent of the clinical presentation of the patients, heparin administration, or the angiographic procedure itself, but was associated with the extent of coronary artery disease and the amount of the injected contrast media. In-vitro experiments revealed that radiocontrast agents induced the release of PlGF from endothelial cells without altering PlGF mRNA expression. CONCLUSION: Patients undergoing PCI exhibit an increase in circulating PlGF, probably caused by posttranslational modifications of radiocontrast agents in endothelial cells. Therefore, analysis of plasma PlGF and VEGF levels may consider the timing of blood sampling with respect to PCI and contrast media exposure.

Nighttime vagal cardiac control and plasma fibrinogen levels in a population of working men and women

BACKGROUND: Elevated plasma fibrinogen levels have prospectively been associated with an increased risk of coronary artery disease in different populations. Plasma fibrinogen is a measure of systemic inflammation crucially involved in atherosclerosis. The vagus nerve curtails inflammation via a cholinergic antiinflammatory pathway. We hypothesized that lower vagal control of the heart relates to higher plasma fibrinogen levels. METHODS: Study participants were 559 employees (age 17-63 years; 89% men) of an airplane manufacturing plant in southern Germany. All subjects underwent medical examination, blood sampling, and 24-hour ambulatory heart rate recording while kept on their work routine. The root mean square of successive differences in RR intervals during the night period (nighttime RMSSD) was computed as the heart rate variability index of vagal function. RESULTS: After controlling for demographic, lifestyle, and medical factors, nighttime RMSSD explained 1.7% (P = 0.001), 0.8% (P = 0.033), and 7.8% (P = 0.007), respectively, of the variance in fibrinogen levels in all subjects, men, and women. Nighttime RMSSD and fibrinogen levels were stronger correlated in women than in men. In all workers, men, and women, respectively, there was a mean +/- SEM increase of 0.41 +/- 0.13 mg/dL, 0.28 +/- 0.13 mg/dL, and 1.16 +/- 0.41 mg/dL fibrinogen for each millisecond decrease in nighttime RMSSD. CONCLUSIONS: Reduced vagal outflow to the heart correlated with elevated plasma fibrinogen levels independent of the established cardiovascular risk factors. This relationship seemed comparably stronger in women than men. Such an autonomic mechanism might contribute to the atherosclerotic process and its thrombotic complications.

Myoglobin as a prognostic indicator for outcome in dogs with gastric dilatation-volvulus

OBJECTIVE: To determine whether myoglobin (Mb) is a useful prognostic indicator for outcome and to investigate any relationship between Mb and mortality in dogs with gastric dilatation-volvulus (GDV). DESIGN: Prospective study. SETTING: Veterinary teaching hospital. ANIMALS: Seventy-two dogs with GDV. INTERVENTIONS: Blood sampling. MEASUREMENTS AND MAIN RESULTS: Mb levels were measured at the time of diagnosis (Mbt0), 24 hours (Mbt1), and 48 hours (Mbt2) after signs of GDV were recognized. Fifty-seven dogs survived (group I) and 15 dogs did not survive (group II). Mbt0 differed significantly between groups (P=0.04). Mbt0 in group I ranged from <30 to >700 ng/mL (n=57, median 74 ng/mL), and in group II from 34 to >700 ng/mL (n=15, median 238 ng/mL). Analysis of a receiver operating characteristic curve of Mbt0 suggested that the best single cutpoint would be 168 ng/mL (sensitivity 60.0%, specificity 84.2%). Fifty percent of dogs with Mbt0>168 ng/mL were euthanized, while 88.9% with Mbt0<168 ng/mL survived. Mbt1 and Mbt2 differed significantly between groups I and II. Mbt1 in group I ranged from 32 to >700 ng/mL (n=55, median 123 ng/mL), and Mbt1 in group II ranged from 131 to 643 ng/mL (n=7, median 343 ng/mL) (P=0.006). Mbt2 in group I ranged from 30 to 597 ng/mL (n=54, median 101 ng/mL), and in group II from 141 to >700 ng/mL (n=8, median 203 ng/mL) (P=0.02). CONCLUSIONS: In this study, Mbt0 is a moderately sensitive and specific prognostic indicator. Almost 90% of the dogs below the cutpoint survived to discharge, whereas 50% with Mbt0 above the cutpoint did not survive.

Effects of thermal environment on hypothalamic-pituitary-adrenal axis hormones, oxytocin, and behavioral activity in periparturient sows

Provision of additional floor heating (33 to 34 degrees C) at birth and during the early postnatal hours is favorable for newborn piglets of domestic sows (Sus scrofa). We investigated whether this relatively high temperature influenced sow behavior and physiology around farrowing. One-half of 28 second-parity pregnant sows were randomly chosen to be exposed to floor heating 12 h after onset of nest building and until 48 h after birth of the first piglet (heat treatment), whereas the rest of the sows entered the control group (control treatment) with no floor heating. Hourly blood sampling from 8 h before and until 24 h after the birth of the first piglet was used for investigation of temporal changes in plasma concentrations of oxytocin, cortisol, and ACTH. In addition, occurrence and duration of sow postures were recorded -8 to +48 h relative to the birth of the first piglet. There was a clear temporal development in sow behavior and hormone concentrations (ACTH, cortisol, and oxytocin) across parturition (P < 0.001), independent of treatment. In general, hormone concentrations increased from the start to the end of farrowing. The observed oxytocin increase and peak late in farrowing coincided with the passive phase where sows lie laterally with an overall reduced activity. Floor heating increased the mean concentration of cortisol (P = 0.02; estimated as 29% greater than in controls) and tended to increase the mean concentration of ACTH (P = 0.08; estimated as 17% greater than in controls), but we did not find any treatment effect on mean oxytocin concentrations, the course of parturition, or the behavior of sows. Behavioral thermoregulation may, however, have lost some function for the sows because the floor was fully heated in our study. In addition, exposure to heat decreased the between-sow variation of plasma oxytocin (approximately 31% less relative to control) and ACTH (approximately 46% less relative to control). Whether this decreased variation may be indicative of acute stress or linked to other biological events is unclear. In conclusion, inescapable floor heating (around 33.5 degrees C) may be considered a stressor for sows around farrowing, giving rise to elevated plasma concentrations of cortisol, but without concurrent changes in oxytocin or behavioral activity.

Factor XIII Deficiency: An Update

Confirmation of suspected congenital factor XIII (FXIII) deficiency still represents a diagnostic challenge in the field of rare bleeding disorders. Because of the lack of awareness and difficulties associated with timing of blood sampling, FXIII laboratory assays, and interpretation of laboratory results, diagnoses of FXIII deficiency are still missed all over the world with potentially fatal consequences from severe bleeding complications. Better knowledge of FXIII biochemical properties and function and understanding of the principles and limitations of FXIII laboratory assays can prevent missed diagnoses, and patients will benefit from better care. This review gives a detailed overview and update about congenital FXIII deficiency, its epidemiology, and molecular genetics. It highlights the importance of newer specific FXIII assays and their principles to avoid any missed diagnosis of FXIII deficiency. This review also gives an update on the therapeutic options for patients suffering from this rare but life-threatening disease.

An In Vitro Method to Investigate the Microbicidal Potential of Human Macrophages for Use in Psychosomatic Research

OBJECTIVE: Psychological states relate to changes in circulating immune cells, but associations with immune cells in peripheral tissues such as macrophages have hardly been investigated. Here, we aimed to implement and validate a method for measuring the microbicidal potential of ex vivo isolated human monocyte-derived macrophages (HMDMs) as an indicator of macrophage activation. METHODS: The method was implemented and validated for two blood sampling procedures (short-term cannula insertion versus long-term catheter insertion) in 79 participants (34 women, 45 men) aged between 18 and 75 years. The method principle is based on the reduction of 2-(4-iodophenyl)-3-(4-nitrophenyl)-5-(2,4-dis-ulfophenyl)-2H-tetrazolium, monosodium salt (WST-1) by superoxide anions, the first in a series of pathogen-killing reactive oxygen species produced by phorbol myristate acetate-activated HMDM. Cytochrome c reduction and current generation were measured as reference methods for validation purposes. We further evaluated whether depressive symptom severity (Beck Depression Inventory) and chronic stress (Chronic Stress Screening Scale) were associated with macrophage microbicidal potential. RESULTS: The assay induced superoxide anion responses by HMDM in all participants. Assay results depended on blood sampling procedure (cannula versus catheter insertion). Interassay variability as a measure for assay reliability was 10.92% or less. WST-1 reduction scores correlated strongly with results obtained by reference methods (cytochrome c: r = 0.57, p = .026; current generation: r values ≥ 0.47, p values <.033) and with psychological factors (depressive symptom severity: r = 0.35 [cannula insertion] versus r = -0.54 [catheter insertion]; chronic stress: r = 0.36 [cannula insertion]; p values ≤ .047). CONCLUSIONS: Our findings suggest that the implemented in vitro method investigates microbicidal potential of HMDM in a manner that is valid and sensitive to psychological measures.

The energy expenditure of 2 Holstein cow strains in an organic grazing system

Until recently, measurements of energy expenditure (EE; herein defined as heat production) in respiration chambers did not account for the extra energy requirements of grazing dairy cows on pasture. As energy is first limiting in most pasture-based milk production systems, its efficient use is important. Therefore, the aim of the present study was to compare EE, which can be affected by differences in body weight (BW), body composition, grazing behavior, physical activity, and milk production level, in 2 Holstein cow strains. Twelve Swiss Holstein-Friesian (HCH; 616 kg of BW) and 12 New Zealand Holstein-Friesian (HNZ; 570 kg of BW) cows in the third stage of lactation were paired according to their stage of lactation and kept in a rotational, full-time grazing system without concentrate supplementation. After adaption, the daily milk yield, grass intake using the alkane double-indicator technique, nutrient digestibility, physical activity, and grazing behavior recorded by an automatic jaw movement recorder were investigated over 7d. Using the (13)C bicarbonate dilution technique in combination with an automatic blood sampling system, EE based on measured carbon dioxide production was determined in 1 cow pair per day between 0800 to 1400 h. The HCH were heavier and had a lower body condition score compared with HNZ, but the difference in BW was smaller compared with former studies. Milk production, grass intake, and nutrient digestibility did not differ between the 2 cow strains, but HCH grazed for a longer time during the 6-h measurement period and performed more grazing mastication compared with the HNZ. No difference was found between the 2 cow strains with regard to EE (291 ± 15.6 kJ) per kilogram of metabolic BW, mainly due to a high between-animal variation in EE. As efficiency and energy use are important in sustainable, pasture-based, organic milk production systems, the determining factors for EE, such as methodology, genetics, physical activity, grazing behavior, and pasture quality, should be investigated and quantified in more detail in future studies.

Association between thyroid dysfunction and venous thromboembolism in the elderly: a prospective cohort study.

BACKGROUND Venous thromboembolism (VTE) and subclinical thyroid dysfunction (SCTD) are both common in elderly patients. SCTD has been related to a hypercoagulable state and increased thromboembolic risk. However, prospective data on the relationship between SCTD and VTE are lacking. OBJECTIVES To investigate the relationship between SCTD and recurrent VTE (rVTE), all-cause mortality, and thrombophilic biomarkers. PATIENTS Elderly participants with VTE. METHODS In a prospective multicenter cohort, thyroid hormones and thrombophilic biomarkers were measured 1 year after acute VTE, as both may be influenced by acute thrombosis. We defined subclinical hypothyroidism (SHypo) as elevated thyroid stimulating hormone levels (TSH=4.50-19.99 mIU/l), and subclinical hyperthyroidism (SHyper) as TSH<0.45, both with normal free thyroxine levels. Outcomes were incidence of rVTE and overall mortality during follow-up starting after the 1-year blood sampling. RESULTS Of 561 participants (58% with anticoagulation), 6% had SHypo and 5% SHyper. After 20.8 months of mean follow-up, 9% developed rVTE and 10% died. rVTE incidence rate was 7.2 (95% confidence interval:2.7-19.2) per 100 patient-years in SHypo, 0.0 (0.0-7.6) in SHyper and 5.9 (4.4-7.8) in euthyroid participants. In multivariate analyses, the sub-hazard ratio [SHR] for rVTE was 0.00 (0.00-0.58) in SHyper and 1.50 (0.52-4.34) in SHypo compared to euthyroids, without increased thrombophilic biomarkers. SHyper (HR 0.80,0.23-2.81) and SHypo (HR 0.99,0.30-3.29) were not associated with mortality. CONCLUSION In elderly patients, SHyper may be associated with lower rVTE risks. SHypo showed a non-statistically significant pattern of an association with rVTE, without increased mortality or differences in thrombophilic biomarkers. This article is protected by copyright. All rights reserved.

Hematology, serum chemistry, and serum protein electrophoresis ranges for free-ranging roe deer (Capreolus capreolus) in Sweden.

We present the first reference ranges for hematology (n = 35 animals), serum biochemistry (n = 62), and serum protein electrophoresis (n = 32) in physically restrained free-ranging roe deer (Capreolus capreolus). Animals were captured in box traps and physically restrained for blood sampling during the winter in Sweden, 2011-13. No clinically significant sex or age differences were found.