Bestimmung von freiem Carnitin und Carnitinestern im Plasma schwangerer Frauen mittels HPLC-MS

Gestationsdiabetes, eine Glucosestoffwechselstörung, wird durch die stetig steigende Prävalenz zu einem immer größeren Problem in der Schwangerschaft. Die Manifestation dieser Stoffwechselerkrankung kann sowohl für die Mutter als auch für das Kind verheerende Folgen haben. Da die Erkrankung meist symptomlos verläuft, erweist sich die Risikoabschätzung als schwierig. Derzeit gilt der orale Glucosetoleranztest als diagnostisches Mittel der Wahl, welcher sich jedoch nach Grenzwerten richtet, die oftmals weder einheitlich, noch evidenzbasiert sind. Die Erforschung neuer Methoden für diagnostische Zwecke auf diesem Gebiet läuft auf Hochtouren, wobei besonders das vitaminähnliche Carnitin immer öfter als bedeutender Faktor diskutiert wird. Ziel dieser Arbeit war die Erarbeitung einer Methode zur Messung von Carnitinestern mittels ESI-HPLC-MS in menschlichem Plasma zur Risikoabschätzung von Schwangerschaftsdiabetes. Dazu wurde mittels Metaanalyse eine geeignete Methode eruiert und als Messsubstanzen dienten Plasmaproben schwangerer Frauen in der Mitte oder am Ende der Schwangerschaft. Die Proben wurden mittels Festphase extrahiert, mit einem eigens hergestellten Reagenz derivatisiert, im Hochdruckflüssigkeitschromatographen getrennt und im Massenspektrometer detektiert. Als Referenzwerte und Mittel zur Quantifizierung der in den Proben enthaltenen Carnitinmenge dienten Standardverbindungen, welche bis unter die erwartete Plasmakonzentration verdünnt wurden. Die Ergebnisse der vorliegenden Arbeit zeigen, dass die Methode an und für sich funktioniert, jedoch jedenfalls noch modifiziert werden muss. Die Messung der Standardverbindungen bis zu einer Konzentration von 2µg/ml, welche deutlich unter der erwarteten Konzentration in den Proben lag, war einwandfrei möglich. Die Wiederfindungsrate von zum Plasma zugesetzten Carnitinen, sowie der direkte Nachweis von freiem Carnitin und Acylcarnitinen im Plasma bereitete jedoch große Schwierigkeiten und war kaum möglich. Abschließend kann also festgestellt werden, dass die in dieser Arbeit entwickelte Methode -in dieser Form- noch kein geeignetes Mittel zur Diagnostik bzw.Risikoabschätzung für Schwangerschaftsdiabetes darstellt. Im Rahmen der Risikoabschätzung ist jedenfalls weitere Forschung notwendig.Gestational diabetes, a disturbance of the glucose metabolism, becomes more and more problematic in pregnancy by the consistently increasing prevalence. The manifestation of this metabolic disease have severe consequences for the mother as well as for the child. As the disease proceeds mostly without symptoms, the risk evaluation turns out to be difficult. At present the oral glucose tolerance test is consulted as diagnostic method, but critical values are neither uniform, nor evidence-based. The investigation of new methods for diagnostic objectives in this area proceeds rapidly and particularly the vitamin-like carnitine is more and more often discussed as an important factor. The aim of this work was the development of a method for the measurement of carnitine ester by ESI-HPLC-MS in human plasma for the risk estimation of gestational diabetes. Therefore a suitable method was investigated by meta-analysis. As measuring substances plasma samples of pregnant women in the middle or at the end of their pregnancy were utilized. The samples were extracted by solid phase extraction, derivatized and separated by high pressure liquid chromatography and detected in the mass spectrometer. For quantification stock solutions of selective acylcarnitines were established and calibration curved of these serial dilutions were measured. The results of the present work show that the method works in general, but needs to be modified. Very low concentrations of the standard solutions (i.e. 2 µg / ml) which are definitively ten times lower than the expected sample concentration can be measured with good reproducibility. But the recovery rate of carnitine (added to the plasma), as well as the direct analysis of free carnitine and acylcarnitine in the plasma however caused great difficulties and was hardly possible. Finally we can discover that the approach compiled in this work still shows no suitable method for the diagnostics or risk evaluation for gestational diabetes; within the scope of the risk evaluation further research is necessary

The Uncertainty of Weighing Data Obtained with Electronic Analytical Balances

Abstract.: Weighing is a common task in any chemical laboratory and weighing data are associated with some uncertainty, as this is common with all other working procedures and their data. This paper presents the influence factors which are part of the combined measurement uncertainty of a mass determination and their interplay, namely the technical specifications of the balance (repeatability, nonlinearity, sensitivity tolerance, and temperature coefficient of the sensitivity) and the effect of air buoyancy. Depending on the net and gross weight, the densities involved (density of air and of the weighing object in relation to the density of the reference weights) and the uncertainties of these densities the relative uncertainty of weighing data is often in the 10−5 to 10−4 range (10 to 100 ppm). It must be kept in mind that such low values can only be obtained with simple weighing goods, i.e. in the absence of disturbances such as electrostatic charges, air drafts, evaporation, or water adsorption phenomen

Fostering preservice teachers’ expectancies and values towards computational thinking

Theory Digital technologies have become an integral part of everyday life that children are exposed to. Therefore, it is important for children to acquire an understanding of these technologies early on by teaching them computational thinking (CT) as a part of STEM. However, primary school teachers are often reluctant to teach CT. Expectancy-value theory suggests that motivational components play an important role in teaching and learning. Thus, one hindrance to teachers’ willingness to teach CT might be their low expectancies of success and high emotional costs, e.g., anxiety towards CT. Aims We investigated whether a specifically designed seminar on CT affected preservice teachers’ expectancies and values towards programming.Method: A total of 311 German primary school and special education preservice teachers took part in the study. The primary school preservice teachers received a seminar on CT and programming with low-threshold programming tasks, while the special education teachers served as a baseline group. The seminar was specifically designed to enhance expectancies and values and decrease emotional costs, following implications of research on expectancy-value theory. Results The preservice teachers who visited the seminar gained higher expectancies and values towards CT and programming compared to the baseline group. Moreover, their emotional costs decreased. CT was positively related to change in expectancies and values and negatively related to emotional costs. Discussion Interventions with low-threshold programming tasks can support primary school preservice teachers in finding trust in their abilities and values towards CT. Moreover, their anxiety towards CT and programming can be alleviated. Thus, first steps in preparing preservice teachers to teach CT in their future classrooms can be taken in university

cGMP kinase I regulates glucagon release

© 2009 Leiss et al; licensee BioMed Central Ltd. Blood glucose levels are tightly controlled by the two peptide hormones glucagon and insulin. At hyperglycaemia, B-cells in the islets of Langerhans secrete insulin, whereas islet A-cells release glucagon at hypoglycaemia to stimulate e.g. glucose production in the liver. Previously, an important role for nitric oxide (NO) in the development of type-1 diabetes mellitus (insulin dependent diabetes mellitus) was reported [1]. The mechanisms are unknown whereby NO modulates islet (mal-)function. We hypothesized that NO signals via the cGMP/cGMP kinase I (cGKI) pathway to modulate the endocrine control of blood glucose levels. Glucose homeostasis was studied in the conventional cGKI knockouts (KOs) and in cGKI rescue mice (RM) [2] in comparison to age- and littermat

Fostering preservice teachers’ expectancies and values towards computational thinking

Theory: Digital technologies have become an integral part of everyday life that children are exposed to. Therefore, it is important for children to acquire an understanding of these technologies early on by teaching them computational thinking (CT) as a part of STEM. However, primary school teachers are often reluctant to teach CT. Expectancy-value theory suggests that motivational components play an important role in teaching and learning. Thus, one hindrance to teachers’ willingness to teach CT might be their low expectancies of success and high emotional costs, e.g., anxiety towards CT. Thus, introducing preservice teachers to CT during their university years might be a promising way to support their expectancies and values, while simultaneously alleviating their emotional costs. Prior CT competences might contribute to these outcomes. Aims: We investigated whether a specifically designed seminar on CT affected preservice teachers’ expectancies and values towards programming. Method: A total of 311 German primary school and special education preservice teachers took part in the study. The primary school preservice teachers received a seminar on CT and programming with low-threshold programming tasks, while the special education teachers served as a baseline group. The seminar was specifically designed to enhance expectancies and values and decrease emotional costs, following implications of research on expectancy-value theory. Results: The preservice teachers who visited the seminar gained higher expectancies and values towards CT and programming compared to the baseline group. Moreover, their emotional costs decreased. CT was positively related to change in expectancies and values and negatively related to emotional costs. Discussion: Interventions with low-threshold programming tasks can support primary school preservice teachers in finding trust in their abilities and values towards CT. Moreover, their anxiety towards CT and programming can be alleviated. Thus, first steps in preparing preservice teachers to teach CT in their future classrooms can be taken in university

Fetal eye movements on magnetic resonance imaging.

OBJECTIVES: Eye movements are the physical expression of upper fetal brainstem function. Our aim was to identify and differentiate specific types of fetal eye movement patterns using dynamic MRI sequences. Their occurrence as well as the presence of conjugated eyeball motion and consistently parallel eyeball position was systematically analyzed. METHODS: Dynamic SSFP sequences were acquired in 72 singleton fetuses (17-40 GW, three age groups [17-23 GW, 24-32 GW, 33-40 GW]). Fetal eye movements were evaluated according to a modified classification originally published by Birnholz (1981): Type 0: no eye movements; Type I: single transient deviations; Type Ia: fast deviation, slower reposition; Type Ib: fast deviation, fast reposition; Type II: single prolonged eye movements; Type III: complex sequences; and Type IV: nystagmoid. RESULTS: In 95.8% of fetuses, the evaluation of eye movements was possible using MRI, with a mean acquisition time of 70 seconds. Due to head motion, 4.2% of the fetuses and 20.1% of all dynamic SSFP sequences were excluded. Eye movements were observed in 45 fetuses (65.2%). Significant differences between the age groups were found for Type I (p = 0.03), Type Ia (p = 0.031), and Type IV eye movements (p = 0.033). Consistently parallel bulbs were found in 27.3-45%. CONCLUSIONS: In human fetuses, different eye movement patterns can be identified and described by MRI in utero. In addition to the originally classified eye movement patterns, a novel subtype has been observed, which apparently characterizes an important step in fetal brainstem development. We evaluated, for the first time, eyeball position in fetuses. Ultimately, the assessment of fetal eye movements by MRI yields the potential to identify early signs of brainstem dysfunction, as encountered in brain malformations such as Chiari II or molar tooth malformations

MR-based morphometry of the posterior fossa in fetuses with neural tube defects of the spine.

OBJECTIVES: In cases of "spina bifida," a detailed prenatal imaging assessment of the exact morphology of neural tube defects (NTD) is often limited. Due to the diverse clinical prognosis and prenatal treatment options, imaging parameters that support the prenatal differentiation between open and closed neural tube defects (ONTDs and CNTDs) are required. This fetal MR study aims to evaluate the clivus-supraocciput angle (CSA) and the maximum transverse diameter of the posterior fossa (TDPF) as morphometric parameters to aid in the reliable diagnosis of either ONTDs or CNTDs. METHODS: The TDPF and the CSA of 238 fetuses (20-37 GW, mean: 28.36 GW) with a normal central nervous system, 44 with ONTDS, and 13 with CNTDs (18-37 GW, mean: 24.3 GW) were retrospectively measured using T2-weighted 1.5 Tesla MR -sequences. RESULTS: Normal fetuses showed a significant increase in the TDPF (r = .956; p<.001) and CSA (r = .714; p<.001) with gestational age. In ONTDs the CSA was significantly smaller (p<.001) than in normal controls and CNTDs, whereas in CNTDs the CSA was not significantly smaller than in controls (p = .160). In both ONTDs and in CNTDs the TDPF was significantly different from controls (p<.001). CONCLUSIONS: The skull base morphology in fetuses with ONTDs differs significantly from cases with CNTDs and normal controls. This is the first study to show that the CSA changes during gestation and that it is a reliable imaging biomarker to distinguish between ONTDs and CNTDs, independent of the morphology of the spinal defect

Sarcopenia in Neurological Patients: Standard Values for Temporal Muscle Thickness and Muscle Strength Evaluation.

Temporal muscle thickness (TMT) was investigated as a novel surrogate marker on MRI examinations of the brain, to detect patients who may be at risk for sarcopenia. TMT was analyzed in a retrospective, normal collective cohort (n = 624), to establish standard reference values. These reference values were correlated with grip strength measurements and body mass index (BMI) in 422 healthy volunteers and validated in a prospective cohort (n = 130) of patients with various neurological disorders. Pearson correlation revealed a strong association between TMT and grip strength (retrospective cohort, ρ = 0.746; p < 0.001; prospective cohort, ρ = 0.649; p < 0.001). A low or no association was found between TMT and age (retrospective cohort, R2 correlation coefficient 0.20; p < 0.001; prospective cohort, ρ = -0.199; p = 0.023), or BMI (retrospective cohort, ρ = 0.116; p = 0.042; prospective cohort, ρ = 0.227; p = 0.009), respectively. Male patients with temporal wasting and unintended weight loss, respectively, showed significantly lower TMT values (p = 0.04 and p = 0.015, unpaired t-test). TMT showed a high correlation with muscle strength in healthy individuals and in patients with various neurological disorders. Therefore, TMT should be integrated into the diagnostic workup of neurological patients, to prevent, delay, or treat sarcopenia