Stage-associated risk of transmission of the lyme disease spirochete by EuropeanIxodes ticks

To more closely define the risk of infection by the agent of Lyme disease in Europe, we determined whether spirochetal prevalence increases throughout the development of theIxodes ricinus vector tick. Of all ticks that could be flagged from vegetation,I. ricinus were by far the most abundant. Spirochetal infection rates in the adult stage of this tick (15%) are no higher than those in nymphs (18%) but greatly exceed those in larvae (0.7%). This tick therefore appears to attain infection mainly from the host of its larval stage, generally feeds on hosts that are noncompetent as reservoirs in its nymphal stage, and rarely inherits infection. Risk of human infection mainly derives from contact with the nymphal stage of the vector tick because the larva is rarely infected and the adult is large enough to be noticed and promptly removed.This work was supported in part by grant AI 19693 from the National Institute of Allergy and Infectious Disease and by grants from the city of Berlin     

Frühe intra- und postoperative Komplikationen der C1-C2-Fixation nach Goel-Harms

Die Unfallchirurgie - Densfrakturen zählen zu den häufigsten Verletzungen der Wirbelsäule. Neben den klassischen Verfahren kann die dorsale C1-C2-Fusion nach Goel-Harms als...     

Chemical shift sodium imaging in a mouse model of thromboembolic stroke at 9.4 T

Purpose:

To estimate changes in the ²³Na density and in the ²³Na relaxation time T₂* in the anatomically small murine brain after stroke.

Materials and Methods:

Three‐dimensional acquisition weighted chemical shift imaging at a resolution of 0.6 × 0.6 × 1.2 mm³ was used for sodium imaging and relaxation parameter mapping. In vivo measurements of the mouse brain (n = 4) were performed 24 hours after stroke, induced by microinjection of purified murine thrombin into the right middle cerebral artery. The measurement time was 14 minutes in one mouse and 65 minutes in the other three. An exponential fit estimation of the free induction decay was calculated for each voxel enabling the reconstruction of locally resolved relaxation parameter maps.

Results:

The infarcted areas showed an increase in sodium density between 160% and 250%, while the T₂* relaxation time increased by 5%–72% compared to unaffected contralateral brain tissue.

Conclusion:

²³Na chemical shift imaging at a resolution of 0.6 × 0.6 × 1.2 mm³ enabled sodium imaging of the anatomical small mouse brain and the acquired data allowed calculating relaxation parameter maps and hence a more exact evaluation of sodium signal changes after stroke. J. Magn. Reson. Imaging 2011;. © 2011 Wiley‐Liss, Inc.     

Comparison of selective arterial spin labeling using 1D and 2D tagging RF pulses

Generic arterial spin labeling (ASL) techniques label all brain feeding arteries. In this work, we used two different selective ASL (SASL) methods to show the perfusion of one single artery. A slice selective inversion of an area including the desired vessel was compared to a multidimensional RF pulse with Gaussian profile to label only the artery of interest. Perfusion images with a resolution of 2 x 2 x 5 mm³ are shown that were acquired after tagging only the internal carotid artery of healthy volunteers. In addition, both techniques were applied to a patient with an extra-intracranial bypass to illustrate its perfusion territory. These perfusion images are consistent with a standard angiography. SASL imaging with a resolution of 2 x 2 x 5 mm³ is possible in a total scan time of 5 min. The presented MR techniques may in part replace the assessment of revascularization success by conventional angiography.     

Capacity of European animals as reservoir hosts for the Lyme disease spirochete.

The abundance of spirochete-infected Ixodes ricinus ticks naturally derived from endemic rodents was compared to identify the reservoir hosts of the agent of Lyme disease at a series of enzootic sites in Central Europe. Black-striped mice appear to be the most important rodent host for the tick and infect more ticks with Borrelia burgdorferi than do other mice and voles tested. Although rodents infect about half of the ticks that feed on them, lizards infect none. These spirochete-incompetent hosts dilute the force of transmission because many nymphal ticks feed on them. Older male hosts are more heavily infested by subadult ticks than are younger or female hosts. The intensity of transmission of the agent of Lyme disease at particular Central European sites appears to correlate directly with the presence of black-striped mice and inversely with that of lizards.     

Severe mood dysregulation: in the "light" of circadian functioning

Severe affective and behavioral dysregulation, labeled as severe mood dysregulation (SMD), is a widely spread phenomenon among adolescent psychiatric patients. This phenotype constitutes severe impairment across multiple settings, including various symptoms, such as non-episodic anger, mood instability, and hyperarousal. Moreover, SMD patients often show depression and reduced need for sleep. Despite a lifetime prevalence of 3.3%, systematic research is still scarce, and treatments that have been established do not account for the range of symptoms present in SMD. Considering the circadian dysfunctions, two hormones, melatonin and cortisol, are essential. When these hormones are dysregulated, the circadian rhythm gets out of synchrony. Since evidence is emerging showing that the worse the sleep-wake cycle is entrained, the worse the psychiatric symptoms are depicted, the importance of proper circadian functioning becomes clear.Chronotherapy as the controlled exposure to environmental stimuli (e.g. light) acting on biological rhythms has shown therapeutic effects. In both seasonal and major depression chronotherapy has been implemented, decreasing depressive symptoms and stabilizing circadian rhythms. Preliminary evidence from SMD related disorders, namely attention-deficit/hyperactivity disorder and pediatric bipolar depression, indicates that morning light therapy elicits positive influences on other symptoms as well. Hence, light therapy might not only be effective for depressive symptoms and circadian rhythms, but might also be beneficial for symptoms including inattention and irritability.We hypothesize that light therapy might be a helpful adjunctive treatment enhancing affective and circadian functioning, and eliciting positive influences on behavior. Physiologically, changes of both cortisol levels and melatonin production are expected.     

Correction of metabolic alkalosis by HCl and acetazolamide: effects on extracellular and intracellular acid-base status in rats in vivo

Extracellular plasma pH (pHe) of nephrectomized male or female Sprague-Dawley rats was changed by infusion of either sodium bicarbonate or HCl to predetermined values in the pH range of 7.53-7.14, and then held constant for 2 h. Intracellular pH (pHi) of the liver, heart, brain, and two skeletal muscle groups as calculated from the distribution of 14C-labelled DMO (5.5-dimethyl-2,4-oxazolidinedione) was compared to corresponding tissues of a control group and rats treated with the carbonic anhydrase inhibitor acetazolamide (Diamox). When compared to control, changes of the extracellular pH in male or female rats were followed by similar effects on pHi in the investigated tissues. At the same extracellular pH there were no statistical differences between pHi values of HCl or acetazolamide treated rats, though the arterial PCO2 following acetazolamide administration was significantly increased when compared to control or the corresponding HCl group. This study shows that administration of acetazolamide or HCl results in a dose-dependent decrease of plasma and tissue pH, and that both agents may be used as a logical and safe therapy during severe metabolic alkalosis in rats.