Numerical investigation of transcranial direct current stimulation on cortical modulation

Transcranial direct current stimulation (tDCS) is a non-invasive and sub-convulsive functional stimulation technique with applications in both clinical therapy and neuro-science research. The technique provides researchers and clinicians with a unique tool capable of modulating the neural excitability in both the central and peripheral nervous system. On a clinical level, the procedure has been used quite extensively for its potential therapeutic applications in a number of neurological disorders. Despite the advantages of being safe, low cost and easy to administer, our limited under-standing on interaction mechanisms between the stimulation parameters and biologi-cal materials has impeded the development and optimisation of tDCS based therapies. The focus of this thesis is to develop a realistic finite element based human head model to address the problems involved in the forward modelling of transcranial direct current stimulation. The study explores the effects of model complexities and anisotropic material properties on field estimations. The sensitivity of electric field and current density on accurate modelling of cortical and non-cortical structures, and the influence of heterogeneously defined anisotropic electric conductivity on field parameters were analysed in an incremental manner. Using the averaged and the subject specific Magnetic Resonance Imaging (MRI) and Diffusion Tensor Imaging (DTI) data, the head models with detailed anatomical features and realistic tissue conductive properties, were developed and employed to specifically address the role of stimulation parameters, such as: morphological variations, structural details, tissue behaviour, inter-subject variations, electrode montages and neural fibre pathways for defining the site and strength of modulation/stimulation. This thesis demonstrates the importance of human head modelling in elucidating the complex electric field and current density profiles instigated by the non-invasive electric stimulation. The results of this study strongly support the initial hypothesis that model complexity and accurate conductivity estimation play a crucial role in determining the accurate predictions of field variables. The study also highlighted the inadequacy of scalar field maps to decipher the complex brain current flow patterns and axonal/neural polarization. With the proposed refinements, model based strategies can be employed to optimally select the required stimulation strength and electrode montage specific to individual dose requirements. Therefore, the work con-ducted in this study will bridge the gap between the current clinical practices and the subject specific treatments by providing accurate physiologically representative simulation

Metastatic signet ring gastric adenocarcinoma presenting with microangiopathic hemolytic anemia.

Metastatic adenocarcinoma presenting as microangiopathic hemolytic anemia (MAHA) and leukoerythroblastic blood picture is rare. We report three patients who presented with MAHA as the initial symptom of metastatic signet ring cell gastric adenocarcinoma. One patient had past history of gastric ulcer. In all these patients the initial diagnosis was based on peripheral blood smear followed by bone marrow biopsy; upper GI endoscopy showed presence of gastric ulcers with focally scattered neo-plastic signet ring cells on histopathology. All patients died within a week of diagnosis

Anemia in a middle aged female with aortitis: a case report.

Abstract BACKGROUND: Idiopathic aortitis is among the most common causes of non-infectious aortitis, which rarely presents with anemia. CASE PRESENTATION: Here we report a case of a 49-year-old muhajir female who presented with shortness of breath and easy fatigability for the past 6 months. Physical examination revealed pallor and a diastolic murmur in the aortic region. Echocardiography showed thickened and calcified aortic and mitral valves, severe aortic regurgitation and dilatation of ascending aorta. She was advised aortic valve replacement and was referred to a haematologist due to concomitant anemia. Complete blood counts revealed haemoglobin: 7.7 gm/dl, mean corpuscular volume (MCV): 78 fl, mean corpuscular haemoglobin (MCH):23 pg, total white cell count: 9.0 × 10(9)/L and platelet count: 227 × 10(9)/L. Erythrocyte sedimentation rate (ESR) was 100 mm/hr. There was suspicion of myelodysplastic syndrome, but could not be confirmed as the patient refused bone marrow and cytogenetic studies. She was given erythropoietin, folic acid and ferrous sulphate. Following relatively prolonged therapy, her haemoglobin level increased to approximately 9.0 gm/dL. She was transfused with packed red cells and underwent aortic valve and ascending aorta replacement. The ascending aorta was dilated and aortic wall markedly thick and irregular. Histopathology of the resected aorta revealed granulomatous aortitis. She was prescribed prednisolone, which resulted in further incremental rise of haemoglobin to 13.1 gm/dL. One month later, she developed complaints of blurred vision in the right eye and was diagnosed with central retinal vein occlusion. She was treated with antiplatelet agents and her vision improved. After 3 months, she was asymptomatic and her haemoglobin level rose to 11.2 gm/dL without hematinic therapy or blood transfusion. She was begun on anticoagulant therapy and remains clinically stable. CONCLUSION: We report a case of idiopathic aortitis with presumed diagnosis of anemia of chronic disease exhibiting a transient response towards steroid therapy post-valvuloplasty

Utilization of RSM for optimization of physical variables to improve bacteriocin production from Lactobacillus plantarum strain MS

The utilization of natural antimicrobial substances has been increased in the pharmaceutical sector due to their stability and inhibition activity against pathogenic microorganisms. In the current study, the bacteriocin synthesis by locally isolated Lactobacillus plantarum MS from yogurt, has been optimized by using response surface methodology. Statistical optimization of physical variables by using Box-Behnken design, 3200 AU/mL bacteriocin activity was detected at 30 °C temperature, 18h incubation time and pH 6 against Staphylococcus aureus. The resulting bacteriocin was found to be stable a broad range of pH (2-12) and temperature (37-100 °C) but the activity of bacteriocin was slightly disturbed at 121 °C. Besides, bacteriocin showed stability after treatment with various enzymes (catalase, amylase, and lipase), salt (NaCl), and surfactants (triton X-100, EDTA, and SDS) but found sensitive by treating with proteolytic enzymes (proteinase K and trypsin) in comparison with untreated bacteriocin. Because of such biochemical characteristics, these antibacterial peptides could be possibly incorporated in the field of pharmacy to fulfil consumer’s demand for natural remedies

Performance Enhancement of Wearable Antenna Using High Impedance Surfaces

This paper presents a novel textile wearable antenna that has been designed to operate at Wi-Fi bands of 2.4GHz & 5.8GHz. Antenna performance in free space environment showed Gain of 1.8dBi at 2.4GHz and 4.5dBi at 5.8GHz. However, performance deteriorated when antenna was operated near human body which is lossy and complex in nature. For mitigating the human body effect on antenna performance, high impedance surface (HIS) was designed and integrated with this textile antenna. Due to shielding effect of HIS, antenna Gain increased to 8dBi at 2.4GHz and 9dBi at 5.8GHz. The SAR values were also reduced to 0.682W/Kg at 2.4GHz and 0.0692W/Kg at 5.8GHz for 10g tissue. The proposed antenna was also tested under bending and crumpling conditions. It was observed that antenna performance was not significantly deteriorated. The proposed textile antenna can have exciting applications in emerging wearable technologies

The frequency of heparin induced thrombocytopenia in patients undergoing elective cardiac bypass surgeries

OBJECTIVE: To determine the frequency of Heparin Induced Thrombocytopenia (HIT) in patients undergoing elective cardiac bypass surgeries and to observe the platelets evolution post surgically in these patients. METHOD: A prospective study was designed and 100 unselected consecutive patients undergoing elective cardiac bypass surgery were enrolled and evaluated. The clinical and laboratory details were noted before and after surgery. Their platelet counts were observed from day 0 (prior to surgery) to day 5 post operatively. Particle gel immunoassay was used to demonstrate the presence of antibodies against heparin-platelet factor 4 complexes. RESULTS: There were 86 males and 14 females with median age of 59 and 53.5 years respectively. Marked platelet count variation was detected during post operative period in all patients (n=100) ranging from 23 +/- SD 186.73 to 389 +/- 84.12 X 109/L. However, 20 patients showed \u3e50% drop on day 5 and seven of these also showed seroconversion. The clinical scoring for HIT was found to have a good negative predictive value. Thromboembolic complications were not observed in any of our patients. CONCLUSIONS: HIT is prevalent to a significant extent in patients after cardiac surgery in our clinical setting though it mostly remains undetected and is an under-diagnosed entity

Simplified in-situ tailoring of cross-linked self-doped sulfonated polyaniline (S-PANI) membranes for nanofiltration applications

Sulfonated polyaniline (S-PANI) membranes could have wide-ranging applications due to their electrical tunability, antifouling behaviour and chlorine resistance. However, S-PANI membranes below the ultrafiltration (UF) separation range have not been successfully established. This study presents a scalable approach to produce the first in-situ cross-linked S-PANI membranes at nanofiltration (NF) range. S-PANI membranes were produced by non-solvent induced phase separation (NIPS). The presence of sulfonic groups as polymer cross-linking anchors and controlling the coagulation bath's acidic strength resulted in instant stabilisation of the selective layer, which hindered the solvent/non-solvent exchange rate. This enabled the production of a tailored membrane morphology with a dense skin layer, suppressed macro-voids, reduced porosity, enhanced tensile strength, increased hydrophilicity and solvent stability. S-PANI membranes cast in 3 M HCl(aq) with MWCO≈680 g mol−1 (sucrose octa-acetate) showed a rejection of 99 % for PEG 1000 g mol−1 and 91–100 % for dye solution (MW range of 320–1017 g mol−1) compared to 34 % and 74–85 % rejection for a commercial fluoropolymer membrane (nominal MWCO 1000 g mol−1), respectively. The reported approach is simple and can be applied to design new classes of cross-linked solvent stable S-PANI NF membranes

Elucidating the complex organization of neural micro-domains in the locust Schistocerca gregaria using dMRI.

To understand brain function it is necessary to characterize both the underlying structural connectivity between neurons and the physiological integrity of these connections. Previous research exploring insect brain connectivity has typically used electron microscopy techniques, but this methodology cannot be applied to living animals and so cannot be used to understand dynamic physiological processes. The relatively large brain of the desert locust, Schistercera gregaria (Forksȧl) is ideal for exploring a novel methodology; micro diffusion magnetic resonance imaging (micro-dMRI) for the characterization of neuronal connectivity in an insect brain. The diffusion-weighted imaging (DWI) data were acquired on a preclinical system using a customised multi-shell diffusion MRI scheme optimized to image the locust brain. Endogenous imaging contrasts from the averaged DWIs and Diffusion Kurtosis Imaging (DKI) scheme were applied to classify various anatomical features and diffusion patterns in neuropils, respectively. The application of micro-dMRI modelling to the locust brain provides a novel means of identifying anatomical regions and inferring connectivity of large tracts in an insect brain. Furthermore, quantitative imaging indices derived from the kurtosis model that include fractional anisotropy (FA), mean diffusivity (MD) and kurtosis anisotropy (KA) can be extracted. These metrics could, in future, be used to quantify longitudinal structural changes in the nervous system of the locust brain that occur due to environmental stressors or ageing

Frequency of Noise Induced Hearing Loss Among Traffic Wardens of Lahore

Background: Noise-induced hearing loss (NIHL) is a major cause of disability throughout the world. It is the most common irreversible job-related hazard in the world with a higher burden in the developing regions of the world. Certain occupations are at high risk for NIHL. Traffic wardens could be considered highly vulnerable group as they are exposed to long hours of traffic noise. The objective of this study was to determine the frequency of noise induced hearing loss among traffic wardens of Lahore city.Material and Methods: It was a cross-sectional, descriptive study, carried out from 1st December 2018 to 31st May 2019, in which 329 traffic wardens appointed in 34 beats/sectors of Lahore city were included. Data was collected through a structured questionnaire, followed by Pure Tone Audiometry (PTA) of all the subjects.Results: A total of 329 traffic wardens were selected for this study. Mean age of the traffic wardens was 35.35 ± 1.21 years. NIHL was present in 174 (52.9%) traffic wardens, out of which, 138 (79.3%) had mild, 32 (18.4%) moderate, and 4 (2.3%) had moderately severe degree of hearing loss. Among the 329 traffic wardens, 165 (50.2%) had exposure to noise between 7am to 3pm (morning shift) and 42 (12.8%) had some problem with their hearing. Only 12 (3.6%) had ringing in the ears or tinnitus, 140 (42.6%) wore any hearing protection during duty hours and 42 (12.8%) said they had difficulty in hearing and frequently asked people to repeat themselves.Conclusion: In this study a high frequency of noise induced hearing loss was reported among traffic wardens of Lahore city with most of them having mild to moderate degree of hearing loss

A wide range and high resolution one-filtration molecular weight cut-off method for aqueous based nanofiltration and ultrafiltration membranes

A new and superior one-filtration method for the determination of the molecular weight cut-off (MWCO) of aqueous based nanofiltration and ultrafiltration membranes has been developed using the widest range of polyethylene glycol oligomers as MWCO probes of any MWCO method so far. This method was enabled by a new, high resolution oligomer separation and detection using high performance liquid chromatography (HPLC) coupled with an evaporative light scattering detector (ELSD). The refined method can determine the MWCO of membranes over a MW range from 678 to 4594 g mol−1 with a molecular weight difference of just 44 g mol−1 and a bonus further one point extension to 6000 g mol−1 – giving the widest range and most precise difference of MWs that can be resolved of any single filtration MWCO method that exists. MWCO determination of five commercial membranes from GE Osmonics™ and Millipore showed good agreement with manufacturer and literature values, confirming the accuracy of the method. As this new method has significant advantages over all other existing aqueous MWCO determinations (i.e. single filtration, higher resolution over a wider MW range, low cost MWCO molecular probes), it is suggested that it could be adopted as the new standard for determining aqueous MWCO over a MW range from 678 to 6000 g mol−1