Toward a brain-computer interface for Alzheimer's disease patients by combining classical conditioning and brain state classification

Brain-computer interfaces (BCIs) provide alternative methods for communicating and acting on the world, since messages or commands are conveyed from the brain to an external device without using the normal output pathways of peripheral nerves and muscles. Alzheimer's disease (AD) patients in the most advanced stages, who have lost the ability to communicate verbally, could benefit from a BCI that may allow them to convey basic thoughts (e.g., "yes" and "no") and emotions. There is currently no report of such research, mostly because the cognitive deficits in AD patients pose serious limitations to the use of traditional BCIs, which are normally based on instrumental learning and require users to self-regulate their brain activation. Recent studies suggest that not only self-regulated brain signals, but also involuntary signals, for instance related to emotional states, may provide useful information about the user, opening up the path for so-called "affective BCIs". These interfaces do not necessarily require users to actively perform a cognitive task, and may therefore be used with patients who are cognitively challenged. In the present hypothesis paper, we propose a paradigm shift from instrumental learning to classical conditioning, with the aim of discriminating "yes" and "no" thoughts after associating them to positive and negative emotional stimuli respectively. This would represent a first step in the development of a BCI that could be used by AD patients, lending a new direction not only for communication, but also for rehabilitation and diagnosis.     

Cytomorphological Analyses of Abnormal Blood Cells of Acute Leukemic Patients

The current study was undertaken to measure and compare the size of different atypical cells according to different age groups (like 0–10, 10–20, 20–30, 30–40, 40–50, 50–60 and 60 years and above) between male and female acute leukemic patients. Blood is collected from the bone marrow of 36 acute leukemic patients (19 males, 17 females), smeared, stained with Giemsa’s stain and measured under light microscope. Three types of atypical (abnormal) cells such as tadpole shaped cell, tear drop shaped cell and rod shaped cell were observed in this study. Both male and female acute leukemic patients of different age groups reflected highly significant difference (p < 0.01) regarding cell length and breadth of tadpole and tear drop shaped cell. Significant difference (p < 0.05) was found among the age groups of male acute leukemic patients with respect to cell length and breadth of rod shaped cell. Percentage of abnormal cells found in bone marrow of both male and female acute leukemic patients according to different age groups are enlisted. Significant difference (p < 0.05) is found only in the rod shaped cells of female between 10–20 and 60 and above, 10–20 and 30–40 age groups.     

The impact of visual impairment on functional vision of children in rural South India: the Kariapatti Pediatric Eye Evaluation Project

PURPOSE: To determine the impact of visual impairment on functional vision of children in a rural population of south India. METHODS: A visual function questionnaire (LVP-VFQ) was administered to 1194 children aged 7 to 15 years identified through a systematic random sampling technique from 144 hamlets of Kariapatti in rural south India as part of a larger population-based project. Visual acuity estimations and clinical examinations for morbidity were performed in these 1194 children. A Rasch analysis was performed to validate the use of the instrument in this population. Bootstrap estimates (95% confidence intervals) of the regression coefficients were used to compare visual function scores between children with normal sight and children with uncorrected monocular and binocular visual impairment. RESULTS: The mean age of children was 10.3 +/- 2.1 years. The reliability estimates were 0.82 for person ability and 0.88 for item difficulty parameters, according to the Rasch analysis. A separation index of 2.15 was obtained for person measures and 2.74 for item measures, and the mean square infit and outfit statistics were 1.03 (Z(STD) 0.1) and 0.99 (Z(STD) -0.1), respectively. Children with monocular visual impairment (bootstrap estimate [95%CI] -0.05 [-0.08 to -0.01]) and binocular visual impairment (bootstrap estimate [95%CI] -0.09 [-0.11 to -0.07]) were more likely to have functional visual deficits than were normally sighted peers. CONCLUSIONS: Monocular or binocular visual impairment impacts on the functional vision of children in this rural population. Further studies are needed to determine the impact of treatment of visual impairment on functional vision in children of this population.     

Psychometric properties of visual functioning index using Rasch analysis

Acta Ophthalmol. 2010: 88: 797–803

Abstract.

Purpose: The visual functioning index (VFI) was one of the first questionnaires developed using classical test theory to assess outcomes of cataract surgery. However, it was not Rasch‐validated. The objective of this study was to examine the psychometric properties of the VFI using Rasch analysis in patients with cataract. Methods: The 11‐item VFI was self‐administered to 243 patients (mean age 73.9 years) drawn from a cataract surgery waiting list. We examined the response category thresholds, item fit statistics, differential item functioning and unidimensionality for the VFI and its three subscales. Results: Category thresholds were ordered. The person separation and reliability were low, indicating the poor discriminatory ability of the VFI. No items misfit but there was suboptimal targeting of item difficulty to patient ability. On the whole the items in the VFI were too easy for the sample. Only one item showed moderate differential item functioning. Conclusion: The VFI does not meet the stringent requirements of the Rasch model. However adding more items to suit the more able patients with cataract as well as those awaiting second‐eye cataract surgery could optimize the VFI.     

Addition and omission analogs of the 13-residue antibacterial and hemolytic peptide PKLLKTFLSKWIG: structural preferences,model membrane binding and biological activities

The consequences of selective addition or deletion of polar amino acids in a 13-residue antibacterial peptide PKLLKTFLSKWIG on structure, membrane binding and biological activities have been investigated. The variants generated are (a) S and T residues replaced by K, (b) S and T residues deleted individually and together, (c) introduction of two additional K and (d) deletion of L and L with T. In the aqueous environment all the peptides were unordered. In trifluoroethanol, the spectra of peptides belonging to groups (a-c) suggest distorted helical conformation. Peptides in group (d) appear to adopt β-sheet conformation. The peptides bind to zwitterionic and negatively charged lipid vesicles, although to different extents. With the exception of peptides in group (d), all the other peptides exhibited comparable antibacterial activity against Escherichia coli and Staphylococcus aureus. However, the changes made in the peptides in groups (a-c) resulted in reduction of hemolytic activity compared to the parent peptide. Extent of binding to lipid vesicles composed of phosphatidylcholine and cholesterol appears to correlate with hemolytic activity. It appears that polar and charged residues play a major role in modulating the biological activities of the 13-residue peptide PKLLKTFLSKWIG. The 11-residue peptide-like PKLLKFLKWIG has selective antibacterial activity. Thus, by judicious engineering it should be possible to generate short peptides with selective antibacterial activity.