Effect of mindfulness meditation on brain-computer interface: fMRI perspective

@#This study observed the functional changes in brain activity while performing real and imagery movement using functional MRI (fMRI); and to compare the fMRI changes of motor imagery before and after mindfulness meditation (MM) training for correlation with actual brain computer interface (BCI) performance. Thirty-eight participants completed a randomized control trial consisting of 2 groups (MM and non-intervention control groups) to study the effect of MM on BCI performance. The MM group participated in a 4-week MM intervention programme. Out of the 38 cohorts, five participants from the MM group and five from the control group were fMRI scanned for real and imagery movement of right hand, left hand and both feet, before and after intervention. Statistical parametric mapping was used for post processing and analysis of fMRI data. The MM group showed a significant improvement in BCI performance compared to the control group. The fMRI results showed activation of right hand, left hand and both feet motor imagery at fronto-parietal regions before MM training (p <0.05, family wise error). After MM training, the fMRI results revealed a focused activation in 3 out of 4 of the trained subjects during right hand motor imagery, 2 out of 4 of the trained subjects during both feet motor imagery and 1 out of 4 of the trained subjects during left hand motor imagery, compared to the control group. This is also correlated with the improvement of BCI accuracy of the intervention group after MM training. Mindfulness meditation improves BCI performance and is correlated with focused activation of the fronto-parietal region in fMRI during motor imagery.

Hemodynamic effects resulting from a common carotid to middle cerebral bypass with varying degrees of proximal internal carotid stenosis

Objective: To investigate the degree of stenosis of the internal carotid artery required for continuous blood flow in an interposition vein bypass to the middle cerebral artery. Methods: Computational fluid dynamics techniques were used to investigate a case of common carotid to middle cerebral artery brain bypass with varying degrees of internal carotid artery stenosis. Blood flow patterns across the patient-specific brain bypass were evaluated. Results: Simulation found that for cross section stenosis of less than 60%, no flow occurred in the bypass graft. Further narrowing of the internal carotid artery increased flow linearly within the bypass graft. There was significant energy loss and pressure gradient difference between the proximal and distal anastomosis sites of the bypass. Conclusion: Computational fluid dynamics helps us to quantify the flow distribution, wall shear stress and pressure gradient in brain bypass surgery. The angle of the distal anastomosis had no effect on hemodynamic indices, allowing this consideration to be ignored in modeling. This modeling technique is useful to estimate the required degree of stenosis in the artery that is to be occluded to ensure sustained flow in the bypass. This will be of importance where there is staged surgery with a time interval between the bypass and the definitive internal carotid artery occlusion.

Bacteriological study of diabetic foot infections

Introduction: Foot infections are one of the major complications of diabetes mellitus and a significant risk factor for lower extremity amputation. Providing effective antimicrobial therapy is an important component in treating these infections. This study assesses the microbial isolates of patients with diabetic foot infections and their antibiotic susceptibility pattern. Materials and Methods: A retrospective study of 75 patients with diabetic foot infections admitted to RIPAS hospital between June 2008 and June 2010 was undertaken. Bacteriological specimens were obtained and processed using standard hospital procedure for microbiological culture and sensitivity testing. Results: Overall, 40 (54%) patients had subcutaneous infections, 22 (29%) had infected superficial ulcers, seven (9%) had infected deep ulcers involving muscle tissues and six (8%) had osteomyelitis. A total of 98 pathogens were isolated. Forty percent of the patients had polymicrobial infection, 39 (52%) had single organism and 6(8%) had no growth. Gram-negative bacteria (67%) were more commonly isolated than gram-positive bacteria (30%). The three most frequently found gram-negative organisms were Pseudomonas aeruginosa (19.4%), Klebsiella pneumoniae (15.3%), and Acinetobacter spp. (10.2%) and gram-positive organisms were Staphylococcus aureus (10.2%), Streptococcus pyogenes (7.1%) and Methicillin resistant Staphylococcus aureus [MRSA] (7.1%). Vancomycin was found to be the most effective against gram-positive bacteria while amikacin was the most effective against gram-negative bacteria based on antibiotic testing. Conclusion: In 40% of diabetic feet infection was polymicrobial. Staphylococcus aureus and Pseudomonas aeruginosa were the most common gram-positive and gram-negative organisms respectively. This study helps us to choose the empirical antibiotics for cases of diabetic foot infections.