Injury patterns associated with cognitive motor dissociation.

In unconscious appearing patients with acute brain injury, wilful brain activation to motor commands without behavioural signs of command following, known as cognitive motor dissociation (CMD), is associated with functional recovery. CMD can be detected by applying machine learning to EEG recorded during motor command presentation in behaviourally unresponsive patients. Identifying patients with CMD carries clinical implications for patient interactions, communication with families, and guidance of therapeutic decisions but underlying mechanisms of CMD remain unknown. By analysing structural lesion patterns and network level dysfunction we tested the hypothesis that, in cases with preserved arousal and command comprehension, a failure to integrate comprehended motor commands with motor outputs underlies CMD. Manual segmentation of T2-fluid attenuated inversion recovery and diffusion weighted imaging sequences quantifying structural injury was performed in consecutive unresponsive patients with acute brain injury (n = 107) who underwent EEG-based CMD assessments and MRI. Lesion pattern analysis was applied to identify lesion patterns common among patients with (n = 21) and without CMD (n = 86). Thalamocortical and cortico-cortical network connectivity were assessed applying ABCD classification of power spectral density plots and weighted pairwise phase consistency (WPPC) to resting EEG, respectively. Two distinct structural lesion patterns were identified on MRI for CMD and three for non-CMD patients. In non-CMD patients, injury to brainstem arousal pathways including the midbrain were seen, while no CMD patients had midbrain lesions. A group of non-CMD patients was identified with injury to the left thalamus, implicating possible language comprehension difficulties. Shared lesion patterns of globus pallidus and putamen were seen for a group of CMD patients, which have been implicated as part of the anterior forebrain mesocircuit in patients with reversible disorders of consciousness. Thalamocortical network dysfunction was less common in CMD patients [ABCD-index 2.3 (interquartile range, IQR 2.1-3.0) versus 1.4 (IQR 1.0-2.0), P < 0.0001; presence of D 36% versus 3%, P = 0.0006], but WPPC was not different. Bilateral cortical lesions were seen in patients with and without CMD. Thalamocortical disruption did not differ for those with CMD, but long-range WPPC was decreased in 1-4 Hz [odds ratio (OR) 0.8; 95% confidence interval (CI) 0.7-0.9] and increased in 14-30 Hz frequency ranges (OR 1.2; 95% CI 1.0-1.5). These structural and functional data implicate a failure of motor command integration at the anterior forebrain mesocircuit level with preserved thalamocortical network function for CMD patients with subcortical lesions. Amongst patients with bilateral cortical lesions preserved cortico-cortical network function is associated with CMD detection. These data may allow screening for CMD based on widely available structural MRI and resting EEG.

Recurrent Lactobacillus Bacteremia in a Patient With Leukemia.

Lactobacillus species are a commensal flora of the human gastrointestinal and the female genitourinary tract. Lactobacilli especially the rhamnosus species, are common components of commercial probiotics. They are rarely associated with pathology in immunocompetent people, but they have been known to cause dental caries, bacteremia, and endocarditis in patients with suppressed immune function. Cases of Lactobacillus bacteremia have been reported in patients with acute myeloid leukemia, large granular lymphocytic leukemia, and in transplant recipients. In this article, we report a strange case of recurrent Lactobacillus bacteremia causing multiple episodes of fever of unknown origin in a patient with leukemia. This report is unique as Lactobacillus is not recognized as a common source of bacteremia. Moreover, the source of the bacillus continued to elude us even after extensive investigation.

Nitrogen deposition, plant carbon allocation, and soil microbes: changing interactions due to enrichment.

PREMISE OF THE STUDY: Nitrogen (N) inputs to the terrestrial environment have doubled worldwide during the past century. N negatively impacts plant diversity, but it is unknown why some species are more susceptible than others. While it is often assumed that competition drives species decline, N enrichment also strongly affects soil microbial communities. Can these changes affect plant-microbe interactions in ways that differentially influence success of plant species? Furthermore, can altered plant-microbe interactions lead to carbon (C) limitation in plants? METHODS: We focused on a species that increases (Deschampsia cespitosa) and one that decreases (Geum rossii) in abundance in N-fertilized plots in alpine tundra. We measured soil microbes using phospholipid fatty acids, and C limitation and transfer using a (13)C tracer experiment, C:N ratios, nonstructural carbohydrates, and leaf preformation. KEY RESULTS: While N profoundly influenced microbial communities, this change occurred similarly in association with both plant species. N addition did not alter total C allocation to microbes in either species, but it changed patterns of microbial C acquisition more in Geum, specifically in gram-negative bacteria. Geum showed evidence of C limitation: it allocated less C to storage organs, had lower C:N and carbohydrate stores, and fewer preformed leaves in N plots. CONCLUSIONS: Carbon limitation may explain why some species decline with N enrichment, and the decline may be due to physiological responses of plants to N rather than to altered plant-microbe interactions. Global change will alter many processes important in structuring plant communities; noncompetitive mechanisms of species decline may be more widespread than previously thought.