Nafia Al-Mutawaly

Bio: Nafia Al-Mutawaly is an academic researcher from McMaster University. The author has contributed to research in topics: Harmonics & Electromagnetic coil. The author has an hindex of 6, co-authored 28 publications receiving 212 citations. Previous affiliations of Nafia Al-Mutawaly include University of Michigan & Mohawk College.

Visceral pain perception is determined by the duration of colitis and associated neuropeptide expression in the mouse

Abstract: Background: Even though inflammation is a traditional tool for the induction of hyperalgesia in many tissues, recent observations suggest that not all inflammatory processes produce this change. Tolerance to colorectal distension (CRD) is reduced in patients with acute ulcerative colitis but is increased in patients with chronic inflammatory bowel disease. This suggests that the nature of the inflammatory infiltrate influences visceral perception. Aim: To test this hypothesis by assessing responses to CRD in mice with mild, acute or chronic colitis. Methods: CRD responses were measured in mice with mild non-specific colitis, and dextran sodium sulphate (DSS)-induced acute and chronic colitis. Responses were compared with tissue infiltrate and damage, interleukin (IL)1β and myeloperoxidase (MPO) activity and substance P, β-endorphin and μ opioid receptor (MOR) expression. Results: Mild and acute colitis were associated with increased responsiveness to CRD. In contrast, CRD responses were not increased in mice with chronic colitis and this difference was not due to altered colonic wall compliance. MPO and IL1β levels were greater in acute than in chronic colitis. Larger increases in tissue substance P were seen in acute than in chronic DSS, whereas CD4 T cells, β-endorphin and MOR expression were evident only in chronic colitis. An inverse correlation was seen between substance P and MOR in these tissues. Conclusions: Acute colitis increased responsiveness to CRD and is accompanied by an acute inflammatory infiltrate and increased tissue substance P. Chronic DSS is accompanied by an increase in β-endorphin and MOR expression, and CD4 T cells, but no change in compliance or CRD responses. We conclude that acute inflammation generates hyperalgesia, whereas chronic inflammation involves infiltration by lymphocytes accompanied by MOR and β-endorphin up regulation, and this provides an antinociceptive input that restores normal visceral perception.

The role of luminal factors in the recovery of gastric function and behavioral changes after chronic Helicobacter pylori infection.

Abstract: The role of chronic infections, such as Helicobacter pylori (Hp), to produce sustained changes in host physiology remains controversial. In this study, we investigate whether the antigenic or bacte...

The effects of pulse configuration on magnetic stimulation

Abstract: A study is presented in which the authors have examined the effects of pulse configuration, stimulation intensity, and coil current direction during magnetic stimulation. Using figure-8 and circular coils, the median nerve was stimulated at the cubital fossa and at the wrist of 10 healthy volunteers, and the response amplitude and site of stimulation were determined. The key findings of this study are in agreement with other researchers' findings and confirm that biphasic stimulating pulses produce significantly higher M-wave amplitudes than monophasic stimulating pulses for the same stimulus intensity. Mean response amplitudes for biphasic stimuli applied by both coils at the elbow and wrist are consistently higher for the normal current direction. Mean response amplitudes for monophasic pulses are almost always higher for reversed currents. The site for effective stimulation (the position of the virtual cathode) cannot be defined within a fixed distance from the center of the coil (3 to 4 cm), as has been suggested by other researchers, but was found to vary depending on the coil current amplitude and direction as well as the degree of inhomogeneity of the tissues surrounding the nerve. There is a statistically significant relationship between virtual cathode shift and stimulus intensity for biphasic and monophasic pulses. Reversing the coil current direction has no statistically significant effect on the virtual cathode position. Virtual cathode shifts can be measured for biphasic and monophasic stimulations using a figure-8 coil at the wrist and the elbow. However, such a shift is difficult to determine with a circular coil.

Impacts of modern residential loads on power grids

Abstract: Modern residential loads use variable frequency drive motors and solid state electronics to improve operational efficiency and reduce energy consumption. The drawback of such energy efficient loads is the introduction of harmonics onto the local distribution grid. Elevated harmonic content due to the increased use of such devices can potentially impact residential distribution networks and adjacent customers. This paper quantifies the current harmonics generated by modern appliances, subsequently fed back to distribution grids. Multiple tests were performed using typical, commercially available appliances and results were analyzed against the IEEE-519-1992 power quality Standard. Research findings will be used to estimate harmonic content on the power grid, model future residential distribution networks and clarify the need to update the IEEE-519-1992 Standard.

Minute by Minute Differences in Co-activation during Treadmill Walking in Cerebral Palsy

Abstract: The primary purpose of this study was to determine, in children and adolescents with mild spastic cerebra palsy (CP); 1) minute-by-minute differences in lower limb antagonist muscle co-activation and stride length (SL) during treadmill walking following 12-15 minutes of treadmill walking practice, and 2) if the minute-by-minute pattern of co-activation is affected by site (thigh or lower leg) and lower limb dominance. A secondary purpose was to determine if overall there is a difference in co-activation between the dominant and non-dominant lower limbs. Eight independently ambulatory children and adolescents with mild spastic CP (9.2-15.7 yr) participated in the study. Minute-by-minute lower limb antagonist muscle co-activation and SL were measured during a 3-minute treadmill walk at 90% of individually determined fastest treadmill walking speed. Non-dominant thigh (quadriceps, hamstring muscles) co-activation decreased between minute 1 and a) minute 2 (6%), b) minute 3 (7.2%). Co-activation for the dominant lower leg (tibialis anterior, triceps surae muscles) decreased between minute 1 and minute 3 (11.3%). Non-dominant thigh co-activation was on average 27.3% higher than for the dominant thigh. Thigh co-activation was on average 27.7% higher than for the lower leg, independent of dominance or time. SL increased between minute 1 and minute 3 by 2.1%. Twelve to 15 minutes of treadmill walking practice may be sufficient time to obtain stable co-activation and SL values by minute 2 of a fast treadmill walk. Dominance and site affect the magnitude of co-activation.

The Microbiota-Gut-Brain Axis

Abstract: The importance of the gut-brain axis in maintaining homeostasis has long been appreciated. However, the past 15 yr have seen the emergence of the microbiota (the trillions of microorganisms within ...

Gut feelings: the emerging biology of gut–brain communication

Abstract: The concept that the gut and the brain are closely connected, and that this interaction plays an important part not only in gastrointestinal function but also in certain feeling states and in intuitive decision making, is deeply rooted in our language. Recent neurobiological insights into this gut-brain crosstalk have revealed a complex, bidirectional communication system that not only ensures the proper maintenance of gastrointestinal homeostasis and digestion but is likely to have multiple effects on affect, motivation and higher cognitive functions, including intuitive decision making. Moreover, disturbances of this system have been implicated in a wide range of disorders, including functional and inflammatory gastrointestinal disorders, obesity and eating disorders.

The anxiolytic effect of Bifidobacterium longum NCC3001 involves vagal pathways for gut–brain communication

Abstract: Background The probiotic Bifidobacterium longum NCC3001 normalizes anxiety-like behavior and hippocampal brain derived neurotrophic factor (BDNF) in mice with infectious colitis. Using a model of chemical colitis we test whether the anxiolytic effect of B. longum involves vagal integrity, and changes in neural cell function.

Intestinal microbiota in functional bowel disorders: a Rome foundation report

Abstract: It is increasingly perceived that gut host–microbial interactions are important elements in the pathogenesis of functional gastrointestinal disorders (FGID) The most convincing evidence to date is the finding that functional dyspepsia and irritable bowel syndrome (IBS) may develop in predisposed individuals following a bout of infectious gastroenteritis There has been a great deal of interest in the potential clinical and therapeutic implications of small intestinal bacterial overgrowth in IBS However, this theory has generated much debate because the evidence is largely based on breath tests which have not been validated The introduction of culture-independent molecular techniques provides a major advancement in our understanding of the microbial community in FGID Results from 16S rRNA-based microbiota profiling approaches demonstrate both quantitative and qualitative changes of mucosal and faecal gut microbiota, particularly in IBS Investigators are also starting to measure host–microbial interactions in IBS The current working hypothesis is that abnormal microbiota activate mucosal innate immune responses which increase epithelial permeability, activate nociceptive sensory pathways and dysregulate the enteric nervous system While we await important insights in this field, the microbiota is already a therapeutic target Existing controlled trials of dietary manipulation, prebiotics, probiotics, synbiotics and non-absorbable antibiotics are promising, although most are limited by suboptimal design and small sample size In this article, the authors provide a critical review of current hypotheses regarding the pathogenetic involvement of microbiota in FGID and evaluate the results of microbiota-directed interventions The authors also provide clinical guidance on modulation of gut microbiota in IBS

Electric field depth-focality tradeoff in transcranial magnetic stimulation: simulation comparison of 50 coil designs.

Abstract: Background Various transcranial magnetic stimulation (TMS) coil designs are available or have been proposed. However, key coil characteristics such as electric field focality and attenuation in depth have not been adequately compared. Knowledge of the coil focality and depth characteristics can help TMS researchers and clinicians with coil selection and interpretation of TMS studies.