Filtering property of myelinated internode can change neural information representability and might trigger a compensatory action during demyelination.

In this paper, for the first time, we showed that an Internode Segment (INS) of a myelinated axon acts as a lowpass filter, and its filter characteristics depend on the number of myelin turns. Consequently, we showed how the representability of a neural signal could be altered with myelin loss in pathological conditions involving demyelinating diseases. Contrary to the traditionally held viewpoint that myelin geometry of an INS is optimised for maximising Conduction Velocity (CV) of Action Potential (AP), our theory provides an alternative viewpoint that myelin geometry of an INS is optimised for maximizing representability of the stimuli a fibre is meant to carry. Subsequently, we show that this new viewpoint could explain hitherto unexplained experimentally observed phenomena such as, shortening of INS length during demyelination and remyelination, and non-uniform distribution of INS in the central nervous system fibres and associated changes in diameter of nodes of ranvier along an axon. Finally, our theory indicates that a compensatory action could take place during demyelination up to a certain number of loss of myelin turns to preserve the neural signal representability by simultaneous linear scaling of the length of an INS and the inner radius of the fibre.

An automated toolchain for quantitative characterisation of structural connectome from MRI based on non-anatomical cortical parcellation.

Brain connectivity analysis is a new multidisciplinary approach in neuroscience for determining neurological disorders from brain imaging data. But, there is no end-to-end toolchain that processes raw MRI data and extracts brain connectivity network metrics. Again, the existing method of cortical parcellation from MRI data is mainly based on fixed Brodmann atlas; which does not support neonate's brain or adult's brain with neuroplasticity anomalies. In this work, we design an end-to-end toolchain that processes raw MRI data and generates network metrics for brain connectivity analysis using non-anatomical equal-area parcellation. We process the structural and diffusion MRI data to generate the parcellated and segmented image, extract white matter tracks and build structural connectome and then interface it with Brain Connectivity Toolbox to extract graph theory measures.Clinical relevance An automated tool for end-to-end processing of MRI data to brain connectivity pattern extraction and its quantitative characterisation for diagnosing brain disorder.

Use of denaturing gradient gel electrophoresis for analysis of the stool microbiota of hospitalized patients.

Denaturing gradient gel electrophoresis (DGGE) of PCR-amplified ribosomal RNA gene amplicons was used to study the stool microbiota of hospitalized patients and to examine the effect of antibiotic therapy. For one patient, 16 anaerobic species identified by random cloning and sequencing of PCR-amplified rRNA genes from stool were represented by bands on the DGGE gel. DGGE analysis and similarity index comparisons demonstrated that the anaerobic microbiota of this individual remained stable in the absence of antibiotic therapy, was minimally affected by ciprofloxacin but markedly reduced by clindamycin therapy, and recovery of some organisms was evident within days after discontinuation of clindamycin. DGGE analysis of additional patients demonstrated similar disruptions of the intestinal microbiota associated with antibiotic therapy. The DGGE banding patterns of nine patients showed considerable variability, but several bands were shared among patients. Thus, our findings are consistent with previous studies that utilized culture techniques, and suggest that DGGE is a useful technique for analysis of the stool microbiota of hospitalized patients.

Recurrence of vancomycin-resistant Enterococcus stool colonization during antibiotic therapy.

OBJECTIVE: To test the hypothesis that antibiotic therapy may promote recurrence of vancomycin-resistant Enterococcus (VRE) stool colonization in patients who have previously had three consecutive negative stool cultures obtained at least 1 week apart. DESIGN: One-year prospective cohort study examining the effect of antibiotic therapy on recurrence and density of VRE stool colonization in patients who have cleared colonization. Pulsed-field gel electrophoresis (PFGE) was performed to determine whether recurrent VRE strains were the same clone as the previous colonizing strain. SETTING: A Department of Veterans Affairs medical center including an acute care hospital and nursing home. PATIENTS: All patients with at least one stool culture positive for VRE who subsequently had three consecutive negative stool cultures obtained at least 1 week apart. RESULTS: Of the 16 patients who cleared VRE colonization, 13 received antibiotic therapy during the study period. Eight (62%) of the 13 patients who received antibiotics developed recurrent high-density VRE stool colonization (range, 4.9 to 9.1 log10 colony-forming units per gram) during a course of therapy. Five patients had VRE strains available for PFGE analysis; recurrent strains were unrelated to the prior strain in 3 patients, closely related in 1 patient, and indistinguishable in 1 patient. CONCLUSIONS: Antibiotic therapy may be associated with recurrent high-density VRE stool colonization in many patients who have previously had three consecutive negative stool cultures. These patients should be screened for recurrent stool colonization when antibiotic therapy is administered.

Undetected vancomycin-resistant Enterococcus stool colonization in a Veterans Affairs Hospital using a Clostridium difficile-focused surveillance strategy.

We examined the point prevalence of undetected vancomycin-resistant Enterococcus (VRE) stool colonization in an institution that screens stool samples submitted for Clostridium difficile testing. Of 112 patients not known to be colonized, 10 (9%) had rectal VRE colonization. A prospective algorithm was effective for identification of colonized patients.