Percutaneous left and right heart catheterization in fully anticoagulated patients utilizing the radial artery and forearm vein: a two-center experience

BACKGROUND: Stopping oral anticoagulants prior to cardiac catheterization is associated with an increased risk of thromboembolism. Performing the procedures via the femoral artery and vein without interruption of anticoagulation is associated with a high rate of major access site complications. The transradial technique for left heart catheterization is safe in fully anticoagulated patients but few data are available on the percutaneous right and left heart catheterization utilizing a combination of the radial artery and antecubital vein in this group of patients. METHODS: We report our experience in 28 consecutive patients that underwent left and right heart catheterizations via this percutaneous arm approach without interruption of anticoagulation. These were compared to 31 consecutive non-anticoagulated patients that underwent the procedure via a conventional femoral artery and vein approach. RESULTS: Arterial and venous accesses were achieved and complete angiographic and hemodynamic data obtained in all patients. There were no access site complications in the anticoagulated patients despite an International normalized ratio (INR) of 2.5 +/- 0.5. Procedural duration was longer in the anticoagulated group of patients, but fluoroscopy time and patient radiation dose were similar in both groups. CONCLUSION: Our experience suggests that left and right heart catheterization can be safely performed in most fully anticoagulated patients using this technique with a low bleeding and thromboembolic risk and no increase in radiation exposure.     

New approaches to drug-DNA interactions based on graphical representation and numerical characterization of DNA sequences

Graphical representations of DNA sequences is a new field of analysis of the DNA and RNA sequences that have the potential to be of utility in determination of drug-DNA interaction sites and also yield indexation schemes to quantify levels of potency or toxicity of various chemicals and drugs. In this paper we explain the new techniques of analysis and briefly review some of the applications that have been made relevant to the field of drug design and chemical toxicity measures specifically in relation to DNA and RNA sequences. The review concludes with some remarks on the future directions that could be taken in development and applications of this nascent technique.     

Maturation of luminance- and motion-defined form perception beyond adolescence: a combined ERP and fMRI study

Abilities to discriminate forms defined by motion continue to develop throughout childhood. To investigate late development of the visual motion system, we measured brain activity with event-related EEG potentials (ERPs) and functional magnetic resonance imaging (fMRI) in groups of adolescents (15-17 years) and adults (20-30 years) during a visual form discrimination task--with forms being either defined by motion or luminance contrast. We further explored whether possible developmental changes varied with the degree of motion coherence reflecting maturation specific to global motion processing. Both the fMRI activation patterns and ERP topographies were very similar between adolescents and adults, suggesting that the basic visual networks for processing motion and form are established by the age of 15-17. The ERP response to luminance- and motion-defined forms was dominated by a posterior negativity (N1: 120-270 ms). The N1 of the motion contrast was delayed in adolescents, whereas the N1 of the static condition did not differ between groups. Since the motion-evoked N1 is thought to arise in the middle temporal area MT/V5, our results indicate that visual motion processing in MT continues to get faster, becoming still more efficient during late development. Neither the ERP nor the fMRI results revealed maturation effects specific to motion coherence. This indicates that the specific mechanisms to process global dot motion are already mature in adolescence. The present findings support the view that static perception matures earlier than dynamic perception, and that these visual systems have different developmental courses.     

Evidence for developmental changes in the visual word processing network beyond adolescence

Late development of specialization in the visual word processing system was examined using event-related potentials (ERP) and functional magnetic resonance imaging (fMRI) of word and symbol string processing in groups of adolescents (15.2-17.3 years) and adults (19.8-30.8 years). We focused our ERP analyses on fast visual activity: the occipital P1 (82-131 ms) modulated by physical stimulus characteristics and the occipito-temporal N1 (132-256 ms) reflecting visual tuning for print. Our fMRI analyses concentrated on basal occipito-temporal activations in the visual word form area VWFA. For words, the correlation of fMRI activation in the VWFA and N1 amplitude confirmed the close relationship of the electrophysiological N1 with metabolic activity in the VWFA. Further support for this relationship came from low resolution electromagnetic tomography localizing the word-specific N1 near the VWFA. Both imaging techniques revealed age-independent differences between words and symbol strings. Late development, however, was preferentially detected with ERPs. Decreases of P1 and N1 amplitudes with age were not limited to words and suggested further maturation of the underlying brain microstructure and function. Following adolescence, decreasing N1 latencies specific to words point to continued specialization of the visual word processing system. Both N1 and fMRI measures correlated with reading performance. In summary, the similarity of global fMRI activation patterns between groups suggests a fully established distribution of the reading network in adolescence, while the decreasing N1 latencies for words indicate protracted fine tuning after adolescence.     

Exploring structural requirements of aurone derivatives as antimalarials by validated DFT-based QSAR, HQSAR, and COMFA–COMSIA approach

Chloroquine resistance is nowadays a great problem in malaria. Aurone derivatives were effective against chloroquine resistant parasite. Validated density functional theory (DFT)-based chemometric modeling, hologram QSAR (HQSAR), comparative molecular field analysis (CoMFA), and comparative molecular similarity analysis (CoMSIA) studies were conducted on 35 aurone derivatives having antimalarial activity. 2D-QSAR models were developed on the training sets by Y-based ranking method. This model was validated on 50 pairs of the test and the training sets by k-Means cluster analysis method. HQSAR, CoMFA, and CoMSIA models were validated by standard techniques and each method validates the DFT-based 2D-QSAR study and in turn validates the earlier observed structural activity relationship data as well as each other. DFT-based 2D-QSAR model suggests that the increase of Mulliken charge at C₁₄ and HOMO density located on C₁₁ may be conducive to antimalarial activity. Ethyl group attached to C₁₄ and the increase of the value of chemical potential may be beneficial for antimalarial activity. Methoxy fragment is important for better antimalarial activity by HQSAR study. CoMFA analysis shows a favorable steric green region is located near C₁₄ whereas the unfavorable yellow region is far away from C₁₄. A large blue region located near C₁₄ indicates the positively charged groups are favorable at this position. CoMSIA steric features correlates well with the CoMFA steric features. CoMSIA study suggests the bulky hydrophobic substitution at C₁₄ is necessary for antimalarial activity. These results may be utilized to obtain potential antimalarial molecules.     

Psychological predictors of SMR-BCI performance

Background

After about 30 years of research on Brain-Computer Interfaces (BCIs) there is little knowledge about the phenomenon, that some people - healthy as well as individuals with disease - are not able to learn BCI-control. To elucidate this “BCI-inefficiency” phenomenon, the current study investigated whether psychological parameters, such as attention span, personality or motivation, could predict performance in a single session with a BCI controlled by modulation of sensorimotor rhythms (SMR) with motor imagery.

Methods

A total of N = 83 healthy BCI novices took part in the session. Psychological parameters were measured with an electronic test-battery including clinical, personality and performance tests. Predictors were determined by binary logistic regression analyses.

Results

The output variable of the Two-Hand Coordination Test (2HAND) “overall mean error duration” which is a measure for the accuracy of fine motor skills accounted for 11% of the variance in BCI-inefficiency. The Attitudes Towards Work (AHA) test variable “performance level” which can be interpreted as a degree of concentration and a neurophysiological SMR predictor were also identified as significant predictors of SMR BCI performance.

Conclusion

Psychological parameters as measured in this study play a moderate role for one-session performance in a BCI controlled by modulation of SMR.     

A new (semantic) reflexive brain-computer interface: in search for a suitable classifier

The goal of the current study is to find a suitable classifier for electroencephalogram (EEG) data derived from a new learning paradigm which aims at communication in paralysis. A reflexive semantic classical (Pavlovian) conditioning paradigm is explored as an alternative to the operant learning paradigms, currently used in most brain-computer interfaces (BCIs). Comparable with a lie-detection experiment, subjects are presented with true and false statements. The EEG activity following true and false statements was classified with the aim to separate covert ‘yes’ from covert ‘no’ responses.Four classification algorithms are compared for classifying off-line data collected from a group of 14 healthy participants: (i) stepwise linear discriminant analysis (SWLDA), (ii) shrinkage linear discriminant analysis (SLDA), (iii) linear support vector machine (LIN-SVM) and (iv) radial basis function kernel support vector machine (RBF-SVM).The results indicate that all classifiers perform at chance level when separating conditioned ‘yes’ from conditioned ‘no’ responses. However, single conditioned reactions could be successfully classified on a single-trial basis (single conditioned reaction against a baseline interval). All of the four investigated classification methods achieve comparable performance, however results with RBF-SVM show the highest single-trial classification accuracy of 68.8%. The results suggest that the proposed paradigm may allow affirmative and negative (disapproving negative) communication in a BCI experiment.