1.Effective connectivity between superior temporal gyrus and Heschl’s gyrus during white noise listening: linear versus non-linear models
Hamid KA ; Yusoff AN ; Rahman MZA ; Mohamad M ; Hamid AIA
Biomedical Imaging and Intervention Journal 2012;8(2):1-13
Purpose: This fMRI study is about modelling the effective connectivity between Heschl’s gyrus (HG) and the
superior temporal gyrus (STG) in human primary auditory cortices.
Materials & methods: Ten healthy male participants were required to listen to white noise stimuli during
functional magnetic resonance imaging (fMRI) scans. Statistical parametric mapping (SPM) was used to generate
individual and group brain activation maps. For input region determination, two intrinsic connectivity models
comprising bilateral HG and STG were constructed using dynamic causal modelling (DCM). The models were estimated
and inferred using DCM while Bayesian Model Selection (BMS) for group studies was used for model comparison and
selection. Based on the winning model, six linear and six non-linear causal models were derived and were again
estimated, inferred, and compared to obtain a model that best represents the effective connectivity between HG and the STG, balancing accuracy and complexity.
Results: Group results indicated significant asymmetrical activation (puncorr < 0.001) in bilateral HG and STG.
Model comparison results showed strong evidence of STG as the input centre. The winning model is preferred by 6 out
of 10 participants. The results were supported by BMS results for group studies with the expected posterior probability,r = 0.7830 and exceedance probability, φ = 0.9823. One-sample t-tests performed on connection values obtained from the winning model indicated that the valid connections for the winning model are the unidirectional parallel connections from STG to bilateral HG (p < 0.05). Subsequent model comparison between linear and non-linear models using BMS prefers non-linear connection (r = 0.9160, φ = 1.000) from which the connectivity between STG and the ipsi- and contralateral HG is gated by the activity in STG itself.
Conclusion: We are able to demonstrate that the effective connectivity between HG and STG while listening to
white noise for the respective participants can be explained by a non-linear dynamic causal model with the activity in STG influencing the STG-HG connectivity non-linearly.
2.Prevalence of Needle Stick Injuries and Compliance to Infection Control Guidelines Among Health Care Workers in a Teaching Hospital, Malaysia
MZA Hamid ; NA Aziz ; WB Lim ; SLM Salleh ; SNS Rahman ; R Anita ; O Norlijah
Malaysian Journal of Medicine and Health Sciences 2011;7(1):3-8
Introduction: Health care workers (HCW) are constantly exposed to blood-borne illnesses through
needle stick injuries (NSI). Despite the increasing trend of NSI, evidence regarding the actual practice
of universal precautions among these HCWs is lacking. This study assessed the practice of universal
precautions towards prevention of NSI among HCWs in a teaching hospital setting. Methods: This
cross-sectional survey involved a newly-designed self-completed questionnaire assessing demographic
data, exposure to NSI and practice of universal precautions. Questionnaires were distributed to every
ward and completed questionnaires were collected after a period of 7 days. Results: A total of 215
HCWs responded to the survey. 35.8% were exposed to bodily fluid, with 22.3% had NSI in the last
12 months. Blood taking was the commonest procedure associated with NSI. Of practices of universal
precautions, recapping needle and removing needle from syringe were still wrongly practiced by the
HCWs assessed. Conclusion: NSI among HCW are still common despite the introduction of universal
precautions in our hospital. Incorrect practices in handling sharps should be looked into in order to
reduce the incidence of blood-borne illnesses through NSI in the hospital.
3.Risk Determinants of Peripheral Neuropathy in Patients with Type II Diabetes Mellitus Attending Follow-Up Clinics at Universiti Kebangsaan Malaysia Medical Center (UKMMC): A Cross-Sectional Study
Fatimah AB ; Aziz NA ; Amaramalar SN ; Aznida FAA ; Hamid MZA ; Norlaila M
Medicine and Health 2010;5(1):34-40
Peripheral neuropathy is highly associated with foot complications among diabetics. This study aimed to identify risk factors associated with the development of peripheral neuropathy in diabetic patients and their association with degree of severity of peripheral neuropathy. A cross-sectional study was conducted in follow-up clinics at the Universiti Kebangsaan
Malaysia Medical Centre (UKMMC), Malaysia involving 72 diabetic patients and 19 controls. Exclusion criteria were those with amputated limbs, gross foot deformity
and existing peripheral neuropathy. Controls were non diabetics who walked normally, had no history of foot problem and attended the clinic as subjects’ companion. Quantitative assessment of neuropathy was done using Semmes-Weinstein monofilament. Neuropathy
Disability Score (NDS) were used to quantify severity of diabetic neuropathy. Spearman’s Rank test and Mann-Whitney test were used to determine correlation between
variables and their differences. Logistic regression analysis was used to determine risk factors associated with peripheral neuropathy. The mean HbA1c among diabetics
was 8.6% + 4.1, and mean NDS was 7.0 + 6.0. A total of 79.1% demonstrated various level of neuropathy with presence of callus was associated with higher NDS
scores. Older age (P=0.02), body weight (P=0.03), HbA1c (P=0.005) and duration of diabetes (P <0.005) showed positive correlation with NDS. Proper foot care program for
diabetics should include recognition of the callus, with special emphasis given to those with heavier weight and increasing age.