Multi-omics for studying and understanding polar life.

Polar ecosystems are experiencing amongst the most rapid rates of regional warming on Earth. Here, we discuss 'omics' approaches to investigate polar biodiversity, including the current state of the art, future perspectives and recommendations. We propose a community road map to generate and more fully exploit multi-omics data from polar organisms. These data are needed for the comprehensive evaluation of polar biodiversity and to reveal how life evolved and adapted to permanently cold environments with extreme seasonality. We argue that concerted action is required to mitigate the impact of warming on polar ecosystems via conservation efforts, to sustainably manage these unique habitats and their ecosystem services, and for the sustainable bioprospecting of novel genes and compounds for societal gain.

DTI/DXI interferences with global coagulation tests in emergency hospital admissions - Results of the prospective Dresden NOAC Registry (NCT01588119).

BACKGROUND: Depending on test assays and the time of last DOAC intake, direct thrombin inhibitors (DTI) and direct FXa inhibitors (DXI) may or may not affect prothrombin time (PT), international normalized ratio (INR) or activated thromboplastin time (aPTT) but the clinical impact is unknown. METHODS: Using data from the Dresden NOAC Registry, we evaluated the impact of DOAC on first PT, INR or aPTT tests during emergency hospitalizations of DTI/DXI patients and the assay performance across 50 coagulation laboratories. RESULTS: In 724 emergency admissions (77 DTI; 647 DXI), 490 cases (67.7%) had a reported last DOAC intake within 12 h before blood sampling. INR and PT were elevated above the upper limit of normal (ULN) in >65% of all cases and aPTT was elevated in 45%. On the other hand, >30% of all cases had normal values of INR, PR and aPTT despite a DOAC intake within the last 12 h. Assay performance for detecting or ruling out therapeutic DOAC levels was highly variable and, overall, insufficient to guide clinical decisions. DOAC specific testing was performed in <10% of all cases. CONCLUSION: Many DOAC recipients present with elevated PT, INR or aPTT during emergency admissions but false negative values within 12 h of last intake as well as elevated values beyond 24 h after last DOAC intake are common. Both scenarios may result in clinical misinterpretation and, potentially, in patient harm, also because DOAC specific testing is rarely performed in emergency settings.

Evaluation of micro tip pressure transducers for the measurement of intracerebral pressure transients induced by fluid percussion.

We describe the application of MIKRO TIP miniature pressure transducers (MPT) for the in vivo measurement of intracerebral stresses induced by traumatic brain injury (TBI). In order to test the linearity of these transducers pressure pulses of different amplitudes (duration approximately 10ms) were generated in a closed calibration chamber. A piezoelectric pressure transducer (PPT) served as the reference measure. A linear correlation was found within the pressure range between 0.57 and 5.09 bar (R2 = 0.998). The frequency transmission characteristics of the MPTs are comparable to the PPT. In three juvenile swines (6 weeks of age) pressures within the brain tissue were induced by fluid percussion (FP) and were measured in the anterior, middle, and posterior cranial cavity as well as in the extracranial part of the medulla oblongata. The data obtained in our experiments agree with the basic biomechanics of FP known from studies in cats and rabbits. Due to their small size, MPTs can be applied in living animals. Stereotaxic positioning of these catheters at any site of the brain and spinal cord requires only minimal surgery. Therefore, MPTs are useful in evaluating animal models of brain injury and in generating input data for computational models of head injury as well as to validate the mathematical results of such models with experimental data.

Lead reduces depolarization-induced calcium entry in cultured DRG neurons without crossing the cell membrane: fura-2 measurements.

1. Cultured dorsal root ganglion of rat pups were depolarized by exposure to 50 mM K+ and the rise of [Ca2+]i was measured using fura-2 as an indicator. 2. Lead in the extracellular solution reduced the rise of [Ca2+]i in a concentration-dependent manner, with a threshold concentration of 0.25 microM. More than 80% of the calcium entry was prevented by approximately 5 microM lead. The IC50 and the Hill coefficient were 3.1 microM and 1, respectively. 3. This effect was considered to be due to a reduction of VACCCs, since applications of NMDA did not result in any rise of [Ca2+]i. 4. Since Pb2+ itself changes the fura-2 signal in a typical and characteristic manner, fura-2 is also an indicator for Pb2+. No changes in fura-2 signals were detected when lead (5 microM) was applied for several minutes in the absence of calcium, indicating that Pb2+ did not enter the cells. 5. Thus it is concluded that lead prevents calcium entry by reducing VACCCs but does not cross the cell membrane itself.

Histamine H1 receptors in C6 glial cells are coupled to calcium-dependent potassium channels via release of calcium from internal stores.

We investigated the action of histamine on C6-astroglioma cells using patch clamp recording and intracellular calcium measurement. Application of 100 microM histamine hyperpolarized the resting membrane potential and increased free intracellular calcium. Membrane hyperpolarization was accompanied by a decrease in input resistance. The effect of histamine was reversible and responses persisted following repeated applications. In voltage clamp experiments histamine elicited an outward current associated with a conductance increase and a reversal potential near the Nernst potential for potassium. The action of histamine was blocked by mepyramine but not by cimetidine or thioperamide suggesting that a H1 receptor mediated the response. Quinidine and charybdotoxin, but not apamin, blocked the hyperpolarization. Buffering internal calcium with BAPTA diminished the activation of the potassium channel, suggesting a calcium-dependent K(+)-channel, which was also found to be regulated by protein kinase C and phosphatases. The increase in intracellular calcium was not dependent on external calcium or sensitive to pertussis toxin, cholera toxin, forskolin or 8-bromo-cAMP. Both the hyperpolarization and the increase in intracellular calcium were blocked by thapsigargin or the phospholipase C inhibitor U73122. These results indicate that histamine liberates calcium from internal stores by activation of phospholipase C which in turn leads to an increase of intracellular Ca2+ and thereby to the activation of a calcium-dependent potassium channel in C6 glial cells.

Acute and repeated administration of fluphenazine-N-mustard alters levels of tyrosine hydroxylase mRNA in subsets of mesencephalic dopaminergic neurons.

Changes in striatal dopamine turnover and levels of tyrosine hydroxylase messenger RNA were examined in mice injected with D2 selective doses of fluphenazine-N-mustard, an irreversible blocker of dopaminergic receptors. The animals were killed at different times after acute and repeated injections of the drug and dopamine turnover was assessed by measuring dopamine and its metabolite, dihydroxyphenylalanine, in the striatum. Tyrosine hydroxylase mRNA was measured at the single-cell level in neurons of the substantia nigra pars compacta and the ventral tegmental area with quantitative in situ hybridization histochemistry. Acute treatment with fluphenazine-N-mustard induced an increase in both striatal dopamine turnover and the level of tyrosine hydroxylase mRNA in the substantia nigra but not the ventral tegmental area. After two days of repeated drug injections (twice daily), tyrosine hydroxylase mRNA was decreased in the substantia nigra despite the persistence of an elevated dopamine turnover in the striatum. The decrease in mRNA was still observed after four days of repeated treatment while, at that time, turnover values were not different from control. No changes were observed in the ventral tegmental area. The initial increase in tyrosine hydroxylase mRNA in substantia nigra pars compacta suggests that activation of nigrostriatal neurons triggers a very rapid increase in genomic expression of the enzyme. The following decrease in mRNA levels precedes desensitization to the effects of the drug on dopamine turnover, further illustrating a lack of correspondence between increased neurotransmission and levels of tyrosine hydroxylase mRNA in catecholaminergic neurons of the central nervous system.

Subpopulations of mesencephalic dopaminergic neurons express different levels of tyrosine hydroxylase messenger RNA.

Subpopulations of mesencephalic dopamine containing neurons possess different electrophysiological, pharmacological, biochemical, and anatomical properties. In order to determine whether such differences are related to the regulation of tyrosine hydroxylase, the rate limiting enzyme in the synthesis of catecholamines, the regional distribution of tyrosine hydroxylase messenger RNA in these neurons was examined using in situ hybridization histochemistry. In the mouse, labelling for tyrosine hydroxylase messenger RNA associated with individual neurons was significantly less in the lateral substantia nigra pars compacta than in the medial substantia nigra pars compacta and the ventral tegmental area. A similar pattern of labelling was observed in the rat. Labelling for tyrosine hydroxylase messenger RNA was significantly less in the lateral substantia nigra pars compacta than in medial pars compacta (a densely cellular region), the area dorsal to the medial substantia nigra pars compacta (a less cell dense region), and the ventral tegmental area. Differences in levels of labelling for messenger RNA in mesencephalic dopamine neurons were not related to differences in cell size as measured in sections processed for tyrosine hydroxylase immunohistochemistry. The results suggest that tyrosine hydroxylase messenger RNA is differentially regulated in subpopulations of mesencephalic dopamine neurons, supporting the view that these neurons are physiologically distinct.

Heterogeneous distribution of cytochrome oxidase activity in the rat substantia nigra: correlation with tyrosine hydroxylase and dynorphin immunoreactivities.

Cytochrome oxidase (COase) activity, an endogenous marker of neuronal activity, was examined in the substantia nigra of the adult rat at the light-microscopic level. In addition, the pattern of histochemical staining observed for COase activity was correlated with immunohistochemistry for tyrosine hydroxylase (a marker of dopaminergic neurons) and for dynorphin (a peptide present in afferents from the striatum). Differential oxidative metabolic activity was revealed in subregions of the substantia nigra by COase histochemistry. Neurons of the substantia nigra pars compacta (SNc), ventral tegmental area, and ventrally displaced dopaminergic neurons were characterized by little or no staining for COase. In contrast, the substantia nigra pars reticulata (SNr) possessed a heterogeneous distribution of COase activity that was characterized by denser staining in the ventrolateral than the dorsomedial part of the nucleus throughout its rostrocaudal extent, with the exception of the most rostral levels. This pattern of COase activity was inversely correlated with the density of ventrally descending tyrosine hydroxylase-positive dendrites arising from the medial portion of the SNc, as well as with the density of dynorphin immunoreactivity. The results suggest that the SNc and SNr possess distinct levels of oxidative metabolic activity. Furthermore, within the SNr itself, different levels of COase activity characterize subpopulations of neurons which may be differentially regulated by both striatal and dopaminergic influences.

A method for the biocybernetic physiological investigation of postural motor control and its disorders in children.

On a biocybernetic basis, a method for the investigation of human postural motor control with optimal multifrequent binary test-signals is described. The examinations presented demonstrate that a comprehensive and quantitative characterization of normal postural motor control and its disorders is possible by means of this method in children. The examination time is short, the motor task used is simple, and the load is physiologically adequate and standardized.

[Autonomic reflexes, EEG and partial arousal reaction in the near-threshold region to acoustic stimuli in the newborn]. / Vegetative Reflexe, EEG und partielle Arousalreaktion im schwellennahen Bereich auf akustische Reize bei Neugeborenen.

A sample of 19 neonates were exposed to sub- and suprathreshold acoustic stimuli. The experiment was performed with sleeping subjects. Stimuli, tones of 125, 250, 500 and 750 cps, third sounds of the same middle frequency and white noise, were applied only, if periods with no REM activity occurred. Stimulus intensity was varied from the subthreshold level (70-80 dB) to the suprathreshold level (80-100 dB). Polygraphic variables were recorded (EEG, EOG, instantaneous heart rate, respiration movements, actogram, motoric reactions and psychogalvanic reflex). The results showed, that with increasing stimulus intensity irregularities of respiratory parameters occurred. With further increase of stimulus intensity systematic changes in respiratory parameters and heart rate occurred. In addition to these changes, EEG activity and motoric reactions were obtained, when stimulus intensity reached a critical level. These data are consistent with the idea that at low stimulus intensities irregular vegetative reactions occur whereas systematic responses can be observed only, if stimulus intensity is above threshold. We conclude that with increasing stimulus intensity subcortical activity decreases whereas cortical activation increases.