Transcranial direct current stimulation (tDCS) over the auditory cortex modulates GABA and glutamate: a 7 T MR-spectroscopy study.

Transcranial direct current stimulation (tDCS) is one of the most prominent non-invasive electrical brain stimulation method to alter neuronal activity as well as behavioral processes in cognitive and perceptual domains. However, the exact mode of action of tDCS-related cortical alterations is still unclear as the results of tDCS studies often do not comply with the somatic doctrine assuming that anodal tDCS enhances while cathodal tDCS decreases neuronal excitability. Changes in the regional cortical neurotransmitter balance within the stimulated cortex, measured by excitatory and inhibitory neurotransmitter levels, have the potential to provide direct neurochemical underpinnings of tDCS effects. Here we assessed tDCS-induced modulations of the neurotransmitter concentrations in the human auditory cortex (AC) by using magnetic resonance spectroscopy (MRS) at ultra-high-field (7 T). We quantified inhibitory gamma-amino butyric (GABA) concentration and excitatory glutamate (Glu) and compared changes in the relative concentration of GABA to Glu before and after tDCS application. We found that both, anodal and cathodal tDCS significantly increased the relative concentration of GABA to Glu with individual temporal specificity. Our results offer novel insights for a potential neurochemical mechanism that underlies tDCS-induced alterations of AC processing.

Low prevalence of porcine circovirus type 2 infections in farrowing sows and corresponding pre-suckling piglets in southern German pig farms.

Porcine circovirus type 2 (PCV2) is the assumed causative agent of a number of different diseases summarized as porcine circovirus diseases (PCVD). The virus is shed via different se- and excretions of PCV2 infected pigs. Transmission of the virus occurs horizontally and vertically either by oronasal or diaplacental infection. Recent research emphasizes the importance of diaplacental PCV2 infection or the infection in early stages of the piglet's life attributable to excretion of PCV2 by the dams within the suckling period. To estimate the prevalence of intrauterine PCV2 infections under field conditions in Bavaria the PCV2 status of farrowing sows (n=198) and corresponding pre-suckling piglets (n=590) of 20 piglet producing farms was examined. PCV2 viral load and anti-PCV2 antibodies in the serum of the sows and piglets were examined at time of farrowing or before colostrum intake, respectively. PCV2 excretion of the sows via saliva, feces and urine was examined additionally. PCV2 specific antibodies in the serum of the sows were detectable on 11 farms with a mean in herd seroprevalence of 35.5% in these farms. Only 0.65% of all samples collected from 198 sows were positive for PCV2 DNA (serum: 1%; feces: 0.5%; saliva: 0.5%; urine: 0.6%). PCV2 DNA was detectable in sample material from seronegative sows as well as from seropositive sows. In none of the pre-suckling serum samples of the piglets IgG antibodies against PCV2 or PCV2 DNA were present. No correlation between the antibody- and viremia status of the sows and the PCV2 excretion was detectable. In contrast to reports about a high prevalence of viremic pre-suckling piglets in the suckling period in North America, the results of the present study reveal that diaplacental infection with PCV2 is comparatively rare in Southern Germany and infection of piglets within the suckling period seems to be more likely.

[Electromyographic Analysis of Neck Muscles at a Simulated Rear-end Impact in Healthy Subjects]. / Elektromyografische Analyse der Halsmuskulatur bei simulierter Heckkollision an gesunden Probanden.

BACKGROUND: Despite the introduction of safety belts and head restraints, severe neck injuries still occur in traffic accidents. Whether there are anthropometric factors or muscular properties, that affect the reflex times during a rear-end collision, and if they have predictive value for the expected trauma, should be reviewed in this investigation. METHODS: In 32 male volunteers anthropometric data and the maximal strength of their cervical musculature were measured. Thereafter, the volunteers were subjected to a simulated rear-end collision with a speed of 2 km/h. The impending crash was not announced to the subjects during the first test run. The situation was repeated several times to test the effect of warning. During the investigation, the muscle activity of neck and shoulder muscles was derived with surface electromyography (EMG). RESULTS: There was a strong correlation between the reflex time of the anterior neck muscles and the strength of that muscle group (r=-0.75; r²=0.57). In addition, the neck length correlated to the reflex time (r=-0.67; r²=0.45). The warning provided for the volunteers influences the EMG as well. The reflex times of the subjects were shorter (p Alle statistischen Berechnungen wurden mit IBM SPSS Statistics (Version 18; IBM Inc., Armonk, USA), sowie dem Programm Excel, (Microsoft, Redmond, USA) vorgenommen. Die Reflexzeiten wurden den anthropometrischen Daten, sowie der Muskelkraft gegenübergestellt und nach Pearson korreliert. Als eine angemessene Korrelation wurde das Quadrat des Korrelationskoeffizienten bei Werten r²>0,4 festgelegt. Außerdem wurden die Mediane der Reflexzeiten, der verschiedenen Kollisionssituationen miteinander verglichen. Das Signifikanz-Niveau wurde auf p<0,05 festgelegt. 0.05), when they knew about the impending collision. CONCLUSION: A high force capacity of anterior neck muscles has preventive value to reduce the consequences of whiplash accidents. The use and development of early warning systems in cars should be supported.

Implications of Blood Type for Ovarian Reserve and Infertility - Impact on Oocyte Yield in IVF Patients.

Introduction: Diminished ovarian reserve (DOR) has been linked to certain subpopulations and distinct gene polymorphisms. It has even been hypothesized that the AB0 blood group system could be linked to ovarian reserve (OR) as reflected by early follicular phase follicle stimulating hormone (FSH) levels. Although estimation of OR is routinely done using levels of anti-Müllerian hormone (AMH), FSH, estradiol or inhibin B, the diagnostic accuracy of these markers is often limited. The aim of this study was to evaluate whether there is any correlation between IVF patients' AB0 blood group system and ART outcome. Methods: In this retrospective observational single-center study we investigated the outcome of 1889 IVF cycles carried out between 2005 and 2012 with regard to blood type and OR in different age groups (21-36 years and 37-43 years). The number of cumulus oocyte complexes (COCs) and metaphase II oocytes obtained after ovarian stimulation, fertilization rate (FR), pregnancy rate (PR) and birth rate (BR) were evaluated with respect to maternal age (21-36 and 37-43 years, respectively). Results: We found no significant differences in the average number of COCs after ovum pick-up in either of the age groups. Moreover, the mean number of MII oocytes and 2PN stages were similar for all blood type groups. As regards IVF outcome measured in terms of PR and BR, no significant differences were observed between the different blood groups. In conclusion, no correlation was found between blood type and female fertility. Discussion: The most precise definition of OR is determining the number of competent oocytes. Based on the finding of our study, the hypothesis that there is a correlation between OR and AB0 blood group system can be dismissed for Caucasian IVF patients.

Clinical and haematological characterisation of Mycoplasma suis infections in splenectomised and non-splenectomised pigs.

Mycoplasma suis causes infectious anaemia in pigs (IAP), which can manifest in various degrees of severity depending on the virulence and the host's susceptibility. As M. suis cannot be cultured in vitro experimental infections of splenectomised animals play an essential role for pathogenesis research. The aim of the present study was to characterise the course of experimental infection using the highly virulent and red blood cell (RBC-) invasive M. suis strain KI3806, to compare the experimental course in splenectomised and non-splenectomised pigs and to correlate clinical and haematological parameters with M. suis blood loads. All infected splenectomised pigs (n=7) were PCR-positive 2 days post infection (DPI) with maximum mean bacterial loads of 1.61 × 10(10)M. suis/mL on 8 DPI. They developed severe anaemia and massive hypoglycaemia by 8 DPI and had to be euthanised preterm (until 8 DPI) without seroconversion. The non-splenectomised pigs (n=7) became PCR-positive within 23 DPI and reached a maximum mean M. suis load of 1.64 × 10(5)M. suis/mL on 8 DPI. They developed mild anaemia, massive skin alterations with petechiae and haemorrhagic diathesis and seroconverted within 35 DPI. The study demonstrated that experimental infection of splenectomised pigs with the highly virulent M. suis strain KI3806 induces a fulminant course of infection. In contrast, M. suis strain KI3806 induces a mild course of disease in non-splenectomised pigs, which resembles the situation in naturally infected pigs. Therefore, these infection models are valuable for future pathogenesis studies on acute and chronic M. suis infections.

Direct visualization of anatomic subfields within the superior aspect of the human lateral thalamus by MRI at 7T.

BACKGROUND AND PURPOSE: The morphology of the human thalamus shows high interindividual variability. Therefore, direct visualization of landmarks within the thalamus is essential for an improved definition of electrode positions for deep brain stimulation. The aim of this study was to provide anatomic detail in the thalamus by using inversion recovery TSE imaging at 7T. MATERIALS AND METHODS: The MR imaging protocol was optimized on 1 healthy subject to segment thalamic nuclei from one another. Final images, acquired with 0.5(2)-mm2 in-plane resolution and 3-mm section thickness, were compared with stereotactic brain atlases to assign visualized details to known anatomy. The robustness of the visualization of thalamic nuclei was assessed with 4 healthy subjects at lower image resolution. RESULTS: Thalamic subfields were successfully delineated in the dorsal aspect of the lateral thalamus. T1-weighting was essential. MR images had an appearance very similar to that of myelin-stained sections seen in brain atlases. Visualized intrathalamic structures were, among others, the lamella medialis, the external medullary lamina, the reticulatum thalami, the nucleus centre médian, the boundary between the nuclei dorso-oralis internus and externus, and the boundary between the nuclei dorso-oralis internus and zentrolateralis intermedius internus. CONCLUSIONS: Inversion recovery-prepared TSE imaging at 7T has a high potential to reveal fine anatomic detail in the thalamus, which may be helpful in enhancing the planning of stereotactic neurosurgery in the future.

Preattentive mechanisms of change detection in early auditory cortex: a 7 Tesla fMRI study.

The auditory system continuously monitors the environment for irregularities in an automatic, preattentive fashion. This is presumably accomplished by two mechanisms: a sensory mechanism detects a deviant sound on the basis of differential refractoriness of neural populations sensitive to the standard and deviant sounds, whereas the cognitive mechanism reveals deviance by comparing incoming auditory information with a template derived from previous input. Using fast event-related high-resolution functional magnetic resonance imaging at 7 Tesla we show that both mechanisms can be mapped to different parts of the auditory cortex both at the group level and the single-subject level. The sensory mechanism is supported by primary auditory areas in Heschl's gyrus whereas the cognitive mechanism is implemented in more anterior secondary auditory areas. Both mechanisms are equally engaged by simple sine-wave tones and speech-related phonemes indicating that streams of speech and non-speech stimuli are processed in a similar fashion.

Effects of embryo transfer quality on pregnancy and live birth delivery rates.

BACKGROUND: To analyze the effects of embryo transfer (ET) quality on clinical pregnancy (CPR) and live birth delivery rates (LBDR). METHODS: In a retrospective study at a single, private infertility center between November 2005 and December 2009 one thousand fifty-five day-3 and day-5 ETs following IVF/ICSI/IMSI were evaluated. We analyzed the impact of an atraumatic ET with a soft catheter (ET 1), after external guidance (ET 2), after probing of the cervix with a stylet (ET 3), or after grasping the portio vaginalis with a tenaculum (ET 4) on CPR and LBDR. RESULTS: The use of external guidance showed a significantly reduced LBDR as compared to an atraumatic ET (26.0% vs. 32.5%). The lowest CPR and LBDR were found in ET 4. The application of stylets in cases of difficult ETs was superior to the use of external guidance. No differences in miscarriages between ET 1-4 were noted. CONCLUSIONS: Besides embryo culture and patient history, the quality of an ET might also have an important impact on pregnancy outcome. Techniques to ensure an atraumatic ET, such as mechanic uterine cavity length measurements, before starting treatment might help identify patients at risk for a difficult ET and lead to modified treatments, such as the primary use of a stylet. Limitation of study: retrospective analysis.

The impact of physiological noise correction on fMRI at 7 T.

Cognitive neuroimaging studies typically require fast whole brain image acquisition with maximal sensitivity to small BOLD signal changes. To increase the sensitivity, higher field strengths are often employed, since they provide an increased image signal-to-noise ratio (SNR). However, as image SNR increases, the relative contribution of physiological noise to the total time series noise will be greater compared to that from thermal noise. At 7 T, we studied how the physiological noise contribution can be best reduced for EPI time series acquired at three different spatial resolutions (1.1 mm × 1.1 mm × 1.8 mm, 2 mm × 2 mm × 2 mm and 3 mm × 3 mm × 3 mm). Applying optimal physiological noise correction methods improved temporal SNR (tSNR) and increased the numbers of significantly activated voxels in fMRI visual activation studies for all sets of acquisition parameters. The most dramatic results were achieved for the lowest spatial resolution, an acquisition parameter combination commonly used in cognitive neuroimaging which requires high functional sensitivity and temporal resolution (i.e. 3mm isotropic resolution and whole brain image repetition time of 2s). For this data, physiological noise models based on cardio-respiratory information improved tSNR by approximately 25% in the visual cortex and 35% sub-cortically. When the time series were additionally corrected for the residual effects of head motion after retrospective realignment, the tSNR was increased by around 58% in the visual cortex and 71% sub-cortically, exceeding tSNR ~140. In conclusion, optimal physiological noise correction at 7 T increases tSNR significantly, resulting in the highest tSNR per unit time published so far. This tSNR improvement translates into a significant increase in BOLD sensitivity, facilitating the study of even subtle BOLD responses.

High field FMRI reveals thalamocortical integration of segregated cognitive and emotional processing in mediodorsal and intralaminar thalamic nuclei.

Thalamocortical loops, connecting functionally segregated, higher order cortical regions, and basal ganglia, have been proposed not only for well described motor and sensory regions, but also for limbic and prefrontal areas relevant for affective and cognitive processes. These functions are, however, more specific to humans, rendering most invasive neuroanatomical approaches impossible and interspecies translations difficult. In contrast, non-invasive imaging of functional neuroanatomy using fMRI allows for the development of elaborate task paradigms capable of testing the specific functionalities proposed for these circuits. Until recently, spatial resolution largely limited the anatomical definition of functional clusters at the level of distinct thalamic nuclei. Since their anatomical distinction seems crucial not only for the segregation of cognitive and limbic loops but also for the detection of their functional interaction during cognitive-emotional integration, we applied high resolution fMRI on 7 Tesla. Using an event-related design, we could isolate thalamic effects for preceding attention as well as experience of erotic stimuli. We could demonstrate specific thalamic effects of general emotional arousal in mediodorsal nucleus and effects specific to preceding attention and expectancy in intralaminar centromedian/parafascicular complex. These thalamic effects were paralleled by specific coactivations in the head of caudate nucleus as well as segregated portions of rostral or caudal cingulate cortex and anterior insula supporting distinct thalamo-striato-cortical loops. In addition to predescribed effects of sexual arousal in hypothalamus and ventral striatum, high resolution fMRI could extent this network to paraventricular thalamus encompassing laterodorsal and parataenial nuclei. We could lend evidence to segregated subcortical loops which integrate cognitive and emotional aspects of basic human behavior such as sexual processing.

Nanoscale chemical imaging using top-illumination tip-enhanced Raman spectroscopy.

We present a new top-illumination scheme for tip-enhanced Raman spectroscopy (TERS) in a gap-mode configuration with illumination and detection in a straightforward fashion perpendicular to the sample surface. This illumination focuses the light tightly around the tip end, which effectively diminishes far-field background contributions during TERS measurements. The setup maintains the entire functionality range of both the scanning probe microscopy and the confocal optical microscopy of the setup. For the first time, we show large (64 × 64 up to 200 × 200 pixels), high-resolution TERS imaging with full spectral information at every pixel, which is necessary for the chemical identification of sample constituents. With a scanning tunneling microscope tip and feedback, these TERS maps can be recorded with a resolution better than 15 nm (most likely even less, as discussed with Figure 6). An excellent enhancement (∼10(7)×, sufficient for detection of few molecules) allows short acquisition times (<<1 s/pixel) and reasonably low laser power (in the microwatt regime) yielding spectroscopic images with high pixel numbers in reasonable time (128 × 128 pixels in <25 min). To the best of our knowledge, no Raman maps with similar pixel numbers and full spectral information have ever been published.

Description of the iliolumbar ligament for computer-assisted reconstruction.

STUDY DESIGN: The iliolumbar ligament (IL) was examined using morphometric and virtual methods. OBJECTIVES: A macroscopic study was performed to measure the anterior (AIL) and the posterior part of the IL (PIL). SUMMARY OF BACKGROUND DATA: Though being a widely accepted cause of low back pain and lumbosacral instability, the IL is neglected in computer-based biomechanical studies due to the lack of morphometric information. METHODS: Frozen sections prepared from 29 human subjects were measured and 7-tesla MR images made to distinguish the AIL and PIL. Cuboids were designated as geometric figures to both parts of the ligament, allowing computer-based calculations of length, surface, volume and angle of positional relationships. RESULTS: Based on 7-tesla MR imaging, virtual reconstruction was conducted for one male pelvis, including the IL. While left- and right-side parameters varied at a statistically significant level, no gender-dependencies could be determined. Lengths of 30 and 25 mm were measured for the AIL and PIL, as well as heights of 17-19 mm, respectively, and a thickness of 4mm. CONCLUSIONS: Correlations between the side-dependent parameters and the AIL and the PIL of the same side indicate close functional relationships. Additional dependencies suggest that the IL is capable of compensating age-related as well as bone-attributed alterations in lumbosacral morphology. The IL data and the visualised ligament structures contribute to determination of the influence of the IL in spinal and sacroiliac stability by means of computer-assisted biomechanics.

The sacrotuberous and the sacrospinous ligament--a virtual reconstruction.

Little is known about the morphometric properties of the sacrotuberous ligament (ST) and the sacrospinous ligament (SS). The influence of ligaments on pelvic stability and the extent of reconstruction in case of instability are controversially discussed. The ST and the SS of 55 human subjects fixed in alcohol solution and of four fresh cadavers were measured. Both ligaments were defined as geometric figures. The ST was a contorted bifrustum, while the SS was a contorted frustum, both with elliptic planes. In all cases investigated, the ST and the SS fibres were twisted. For men, the ST and the SS had a mean length of 64 and 38 mm. For women, lengths of 70 and 46 mm were measured in the ST and the SS. The ST length, height and cross-sectional area showed gender-specific differences at statistically significant level. The ST and the SS volumes correlated closely, regardless of gender or side. Measurements of fresh ligaments of four unfixed cadavers showed similar results. The data obtained were then used to generate computer-based three-dimensional models of both ligaments, using the Catia software. Conclusively, the virtually generated ST and SS are suitable models to be included in pelvic fracture simulation, using the finite element method.

A new concept of a unified parameter management, experiment control, and data analysis in fMRI: application to real-time fMRI at 3T and 7T.

In functional MRI (fMRI) complex experiments and applications require increasingly complex parameter handling as the experimental setup usually consists of separated soft- and hardware systems. Advanced real-time applications such as neurofeedback-based training or brain computer interfaces (BCIs) may even require adaptive changes of the paradigms and experimental setup during the measurement. This would be facilitated by an automated management of the overall workflow and a control of the communication between all experimental components. We realized a concept based on an XML software framework called Experiment Description Language (EDL). All parameters relevant for real-time data acquisition, real-time fMRI (rtfMRI) statistical data analysis, stimulus presentation, and activation processing are stored in one central EDL file, and processed during the experiment. A usability study comparing the central EDL parameter management with traditional approaches showed an improvement of the complete experimental handling. Based on this concept, a feasibility study realizing a dynamic rtfMRI-based brain computer interface showed that the developed system in combination with EDL was able to reliably detect and evaluate activation patterns in real-time. The implementation of a centrally controlled communication between the subsystems involved in the rtfMRI experiments reduced potential inconsistencies, and will open new applications for adaptive BCIs.

The role of partnership dynamics in determining the acceptability of condoms and microbicides.

Microbicides are a class of substances under development that could reduce the sexual transmission of HIV and other sexually transmitted diseases when applied locally to genital mucosal surfaces. Microbicide acceptability research has largely focused on product characteristics, rather than processes of negotiation within relationships about use. Gender relations, decision-making power and communication within sexual relationships are recognised as important determinants of condom and contraceptive use, and are likely to determine microbicide use also. As part of social science research linked to the Microbicides Development Programme (MDP) we combine relationship-based theories with anthropological work conducted with women and men using a placebo gel. We explore communication and decision-making in gel and condom use, including constructions of risk and trust. During the MDP301 Phase III pilot study, in-depth interviews were conducted at sites in South Africa, Tanzania, Uganda and Zambia. Following four weeks of placebo gel use, women and their partners were asked about gel use and acceptability, partner involvement, sexual practices and condom use. Data from 45 couples at five sites were analysed using a grounded theory approach in NVivo. Participation in the study did not require women to inform their partners, yet our data shows women seeking permission from their partners, negotiating disclosure, exchanging information and persuading or motivating for gel use. Although gel was supposedly 'woman-controlled', men exercised considerable influence in determining whether and how it was used. Despite this, negotiations around use were largely successful, since the gel increased sexual pleasure and provided opportunities for intimate communication and the building of trust. Decisions about condom and microbicide use are made in a dyadic context and involve a complex negotiation of risk and trust. Whilst preferences relating to product characteristics are largely individual, use itself is dependent on partnership dynamics and the broader social context in which sexual risk management occurs.

Tighter focusing with a parabolic mirror.

We demonstrate experimentally and theoretically that a parabolic mirror (PM) with a high numerical aperture (NA) of 1 focuses a radially polarized laser mode to the smallest diffraction-limited spot at a fixed NA and wavelength, having an area of 0.134 lambda(2). The measurements were performed with a confocal microscope, using the PM as a focusing and collecting element. The results stand in accordance with the theoretical calculations presented by Davidson and Bokor [Opt. Lett. 29, 1318 (2004)], who predicted a reduction in the total focal spot size of 43% as compared with an aplanatic lens.

High resolution single-shot EPI at 7T.

OBJECTIVE: Single-shot echo planar imaging (EPI) acquisitions at 7T are challenging due to increased distortions, signal dropouts, RF-power requirements, and reduced T2*. This study developed and tested pulse sequence and protocol modifications required to allow high resolution EPI for whole brain functional neuroimaging. MATERIALS AND METHODS: Using geometric distortion correction methods, modified fat saturation, and parallel imaging, we acquired high resolution single-shot gradient-echo EPI data at 7T with different spatial resolution. The BOLD sensitivity was evaluated and quantified in a breath hold experiment. RESULTS: Single-shot EPI data with isotropic resolution from 3 to 1.1 mm were acquired in human subjects. The RF-power deposition has been reduced to allow up to 22 slices per second. In addition, acoustic noise and helium boil-off have been reduced. A reduction of the fat saturation flip angle resulted in up to 20% signal gain without compromising the fat suppression quality. For the coil used, the BOLD sensitivity is highest for 2 or 1.4 mm isotropic resolution. CONCLUSION: High resolution single-shot EPI in the whole brain can be performed at 7T with high efficiency, low signal dropout, and without major geometric distortions.

Sexual coercion and sexual desire: ambivalent meanings of heterosexual anal sex in Soweto, South Africa.

Anal sex within heterosexual relationships is usually underreported or not reported at all, yet is increasingly recognised as a potential mode of HIV transmission. Understanding the circumstances of anal sex is critical for trials that seek to assess the efficacy of microbicides. This article draws on qualitative data collected during a feasibility study for a clinical trial of microbicides in Soweto, South Africa. Focus groups of women enrolled in the feasibility study discussed the circumstances under which they and other women in the community had anal sex. Their narratives drew attention to the ambivalent meanings of anal sex; often regarded as a form of sexual coercion but also frequently as sexual pleasure. The article explores the reasons for these apparent contradictions.