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  1. Arashi M, Roozbeh M, Hamzah NA, Gasparini M
    PLoS One, 2021;16(4):e0245376.
    PMID: 33831027 DOI: 10.1371/journal.pone.0245376
    With the advancement of technology, analysis of large-scale data of gene expression is feasible and has become very popular in the era of machine learning. This paper develops an improved ridge approach for the genome regression modeling. When multicollinearity exists in the data set with outliers, we consider a robust ridge estimator, namely the rank ridge regression estimator, for parameter estimation and prediction. On the other hand, the efficiency of the rank ridge regression estimator is highly dependent on the ridge parameter. In general, it is difficult to provide a satisfactory answer about the selection for the ridge parameter. Because of the good properties of generalized cross validation (GCV) and its simplicity, we use it to choose the optimum value of the ridge parameter. The GCV function creates a balance between the precision of the estimators and the bias caused by the ridge estimation. It behaves like an improved estimator of risk and can be used when the number of explanatory variables is larger than the sample size in high-dimensional problems. Finally, some numerical illustrations are given to support our findings.
  2. Hamzah NA, Tengku MA
    MyJurnal
    Background : Safety and health is one of major concerns in public health issues. There are lots of injuries or accidents reported in the news which include school accidents and injuries.
    Methodology : This survey was conducted among head of primary schools in Kota Bharu from May to June 2004. The objective of this study was to investigate the awareness about safety and health status among school’s head using a questionnaire.
    Result : The study showed that knowledge on safety and health among the school’s heads were relatively low (7.7%). Forty-two percent of the schools did not implement any safety and health programme while more than 50 % did not have safety policies in their school.
    Conclusions : It is necessary to have specific safety programmes in school in order to improve the safety and health awareness among teachers, staff, students and community.
  3. Mohd-Aspar MA, Edros R, Hamzah NA
    Trop Biomed, 2021 Sep 01;38(3):226-238.
    PMID: 34362865 DOI: 10.47665/tb.38.3.062
    The study aims to formulate and optimise topical antibacterial preparation by using Malaysian kelulut honey as the active ingredient and xanthan gum as the polymeric agent. Response surface methodology was used to optimise the preparation. The acidity, honey concentration and xanthan gum concentration were the independent variables. The zone of inhibitions on S. aureus ATCC6538 and E. coli ATCC8739 were the response variables. The optimal preparation was evaluated on its physicochemical properties, viscosity, antibacterial efficacy and stability. The antibacterial efficacy of the optimal preparation was compared to the commercially antibacterial gel (MediHoney™, Comvita). The optimal preparation was formulated at pH of 3.5, honey concentration of 90% (w/v) and xanthan gum concentration of 1.5% (w/v) with the inhibition zones measured on S. aureus ATCC6538 was 16.2 mm and E. coli ATCC8739 was 15.8 mm respectively. The factors of acidity and honey concentration have significantly influenced the inhibition zone on S. aureus ATCC6538 and E. coli ATCC8739. The utilisation of xanthan gum as the polymeric agent was fit for the preparation which showed by adequate physicochemical properties and retained of the antibacterial effects. This was supported by constant viscosity and efficacy of the preparation within the six months of stability study indicating stable and reliable preparation. Xanthan gum is a potential polymeric agent due to its effective use in preparing stable preparation with effective antibacterial properties.
  4. Hamzah NA, Yong CSY, Nallappan M
    Data Brief, 2022 Dec;45:108613.
    PMID: 36164310 DOI: 10.1016/j.dib.2022.108613
    Roselle (Hibiscus sabdariffa L.) is recognized for its phytochemical compounds such as anthocyanins, which possess pharmacological potentials in the treatments of hypertension, diabetes, cancer, hyperlipidaemia and hyperglycaemia. The calyx is the most commercially valuable part of the roselle and usually harvested at maturation. However, genetic study to understand the transcriptome changes in the calyx during maturation has yet to be explored. In this study, we sequenced the transcriptomes of roselle calyces at maturation stages III and IV using Illumina NextSeq 500 platform. These are the two most critical maturation stages in roselle, as these stages are often associated with the quality of the calyx. Over 200 million good quality paired-end reads were generated and de novo assembled into a reference transcriptome consisting of 221,334 transcripts with N50 score of 491bp. Among these transcripts, 92,974 transcripts (42%) were successfully annotated. The total number of significantly differentially expressed genes (DEGs) and the top five most significantly regulated genes in each of the maturation stage were presented. Twenty-one genes implicated in the biosynthesis of anthocyanins and their relative expressions in the calyx tissues at the two maturation stages were reported. Two secondary metabolites biosynthesis pathways that attained a relatively higher number of DEG mappings compared to other pathways were also reported. The findings from this work provide novel insights to better understand the transcriptional changes in roselle during calyx maturation, and the data made available here is intended for continued genetic study on roselle. The work is registered under NCBI Bioproject PRJNA664826. The raw sequencing reads are available in Short Read Archive with the accession numbers SRX9171161, SRX9171162, SRX9171163, SRX9171164, SRX9171165 and SRX9171166.
  5. Ahmad F, Che Hamzah NA, Mustaffa N, Hua GS
    Hepatogastroenterology, 2011 07 15;58(110-111):1725-9.
    PMID: 21940338 DOI: 10.5754/hge11107
    BACKGROUND/AIMS: CYP3A4 is the major cytochrome in humans which shows reduced activity in chronic liver disease as well as in hepatic cirrhosis. The detection of this polymorphism may give an indication on the prognosis of patients having chronic viral hepatitis with superimposed hepatitis A infection. The aim of this study is to correlate the seroprevalence of anti-HAV antibodies in chronic liver disease patients having CYP3A4*18 polymorphisms.

    METHODOLOGY: This is a prospective study where patients (n=119) blood was tested for anti-HAVIgG and CYP3A4*18 polymorphism.

    RESULTS: The overall anti-HAV seroprevalence was 88.2%. The etiology of CLD was hepatitis B in 96 patients (80.7%) and hepatitis C in 23 patients (19.3%). There was a significant increase in the age of the prevalence of this disease after 30 years of age (p=0.008). CYP3A4*18 polymorphism was detected in 3 (2.5%) of the patients with chronic liver disease. However, there was no significant association between CP3A4*18 mutation and anti-HAV serology.

    CONCLUSIONS: Age was the most important factor in determining anti-HAV positivity. It is concluded that CYP3A4*18 genetic polymorphism does not play a main role in influencing the seroprevalence of anti-hepatitis A among chronic viral hepatitis B and C liver disease patients.

  6. Ahmad F, Hamzah NA, Mustaffa N, Gan SH
    World J Gastroenterol, 2011 Sep 28;17(36):4130-4.
    PMID: 22039329 DOI: 10.3748/wjg.v17.i36.4130
    To determine the seroprevalence of anti-hepatitis A virus (HAV) antibodies in patients with chronic liver disease (CLD) and to justify the need for hepatitis A vaccination.
  7. Hamzah NA, Razak NAA, Karim MSA, Salleh SZ
    Sci Rep, 2022 Feb 16;12(1):2636.
    PMID: 35173198 DOI: 10.1038/s41598-022-05173-3
    The Biosculptor's CNC milling machine, the Biomill, offered four different surfaces machined on positive models. This study aims to adopt the surface topography method in characterizing the four different surface roughness of polyethylene Pe-Lite liner as a product of the Biomill. Three surface parameters chosen were the arithmetic average (Ra), root mean square roughness (Rq), and ten-point height (Rz). The surface parameters were used to define the four different surfaces (STANDARD, FINE, COARSE, and FAST) and then compared with the same liner material from a conventionally fabricated socket. The Ra values of the conventional liner, 8.43 μm, were determined to be in-between the Ra values of STANDARD and FAST surfaces which were 8.33 μm and 8.58 μm respectively. STANDARD surface required 43.2 min to be carved while FAST surface took almost only a third of the time compared to STANDARD surface (conventional socket takes 2-3 days). The results of this study would be one of the guidelines to the prosthetists using the Biosculptor in socket fabrication to produce sockets according to the suitable surface to cater to different requirements and levels of activity of each amputee.
  8. Hamzah NA, Mohd Tamrin SB, Ismail NH
    Int J Occup Environ Health, 2016 07;22(3):224-232.
    PMID: 27392157 DOI: 10.1080/10773525.2016.1207040
    BACKGROUND: Metallic dust is a heterogeneous substance with respiratory sensitizing properties. Its long term exposure adversely affected lung function, thus may cause acute or chronic respiratory diseases.

    METHODS: A cross-sectional study was conducted in a steel factory in Terengganu, Malaysia to assess the metal dust exposure and its relationship to lung function values among 184 workers. Metal dust concentrations values (Co, Cr, and Ni) for each worker were collected using air personal sampling. Lung function values (FEV1, FVC, and %FEV1/FVC) were determined using spirometer.

    RESULTS: Exposure to cobalt and chromium were 1-3 times higher than permissible exposure limit (PEL) while nickel was not exceeding the PEL. Cumulative of chromium was the predictor to all lung function values (FEV1, FVC, and %FEV1/FVC). Frequency of using mask was positively associated with FVC (Adj b = 0.263, P = 0.011) while past respiratory illnesses were negatively associated with %FEV1/FVC (Adj b = -1.452, P = 0.026). Only few workers (36.4%) were found to wear their masks all times during the working hours.

    CONCLUSIONS: There was an exposure-response relationship of cumulative metal dust exposure with the deterioration of lung function values. Improvement of control measures as well as proper and efficient use or personal protection equipment while at work could help to protect the respiratory health of workers.

  9. Hamzah NA, Razak NAA, Karim MSA, Salleh SZ
    Acta Bioeng Biomech, 2021;23(4):173-182.
    PMID: 37341100
    PURPOSE: This study aimed to examine the accuracy and validity of the Biosculptor's Bioscanner shape capturing system as a portable measuring device by analysing the changes in transtibial residual limb circumference parameters while walking. Assessment on an amputee could also allow for the clinical usability of the digital scanner to be studied.

    METHODS: To verify the accuracy of the system, the Bioscanner method was compared to the widely used standard anthropometric manual measurement technique (i.e., tape measure). One transtibial prosthetic user was recruited to conduct a walking activity at a normal walking pace for 5 to 15 minutes. Circumferential profiles of the participant were obtained digitally and manually during 2-5 minutes of resting walking intervals. The mean differences between the two methods were compared and percentage differences were calculated. The means were used to calculate the standard error measurement (SEM) and the 95% confidence intervals. Study of the limit of agreement between the two method was also used to validate the accuracy of Bioscanner.

    RESULTS: The findings showed that both measurements gave a general comparable linear pattern. The averaged results from both methods resulted in only small distinctive differences especially at circumference near the mid-patella tendon. Similarly, the pressure-sensitive areas of the limb resulted in only an average of 2.28% differences between the two measurement techniques. The system showed high reliability and SEM with <1 of 95% CI values and repeatability study gave ICC >0.9.

    CONCLUSIONS: Bioscanner appeared to be comparable with the standard manual method. The Biosculptor system provides the portability, fast, reliable, and high accuracy measurements of the transtibial residual limb circumference, thus, it can be considered as a valuable tool for daily measurement of amputee's residual limb and pre-prosthetic training.

  10. Jamaludin S, Mustaffa N, Che Hamzah NA, Syed Abdul Aziz SH, Lee YY
    BMC Gastroenterol, 2015;15:101.
    PMID: 26264957 DOI: 10.1186/s12876-015-0332-0
    Unchanged substrate in a negative rapid urease test may be reused to detect Helicobacter pylori (H. pylori). This could potentially reduce costs and wastage in low prevalence and resource-poor settings. We thus aimed to investigate the diagnostic accuracy of reused Pronto Dry and CLOtest kits, comparing this to the use of new Pronto Dry test kits and histopathological evaluation of gastric mucosal biopsies.
  11. Ibrahim MF, Kuan G, Hashim HA, Hamzah NA, Kueh YC
    PMID: 33450935 DOI: 10.3390/ijerph18020622
    The objective of this study was to validate the translated Malay version of the Quality of Life Enjoyment and Satisfaction Questionnaire (Q-LES-Q-M) scale among Malaysian primary school children using the confirmatory factor analysis (CFA). The Q-LES-Q-M measures the level of enjoyment and satisfaction experienced with relation to physical health, feelings, homework, and leisure. The participants were 607 Malay students, 240 (39.5%) boys and 367 (60.5%) girls, with an age range from 10 to 11 years old. The original version of the Q-LES-Q was translated into the Malay language by forward to backward translation procedures with consideration for the local culture and suitable vocabulary for primary school students. The participants then completed the Q-LES-Q-M. CFA was performed using Mplus 8 software. Using CFA, the initial model did not result in a good data fit. Further analysis of the CFA suggested some changes to the model to improve the fit indices. Model modification included the deletion of three problematic items and co-varying some error items. This resulted in improved fit indices and 40 items remained in the final model. The final model showed good reliability based on two indicators of composite reliability (CR) and Cronbach's alpha (CA). The factors with their CR and CA were physical activity (CR = 0.857, CA = 0.854), feelings (CR = 0.808, CA = 0.813), homework (CR = 0.837, CA = 0.837) and leisure (CR = 0.742, CA = 0.737). The final measurement consists of 40 items. The retained items were deemed suitable for Malay primary school children. The revised Q-LES-Q-M with 40 items is suitable for measuring the levels of children's involvement in determining the enjoyment and satisfaction of learning and physical activity.
  12. Othman AK, Udin N, Shab MS, Hamzah NA, Mat Azmi IS, Naing NN
    Med J Malaysia, 2020 11;75(6):705-709.
    PMID: 33219181
    INTRODUCTION: Brain tumour (BT) is a tremendous burden on patients, families as well as the surrounding communities, especially the healthcare services. It can be classified into either a benign slow growing tumour (non-cancerous) and malignant tumour (cancerous). The purpose of this study was to determine the incidence and pattern of brain tumour admitted to the Neurosurgery Department in Hospital Sultanah Nurzahirah (HSNZ), Terengganu, Malaysia.

    METHODS: This is a retrospective study of incidence and pattern of BT admitted to the Neurosurgery Department in HSNZ. Data was collected from the yearly census of BT registered from 2013 to 2018.

    RESULTS: A total number of 386 new cases of primary BT were registered. The number of cases of BT was found to be lowest among children (0 to 10 years old) with only 4.4% but at peak among elderly aged between 51 to 60 years old (26.2%). As for gender, males constituted about 44.5% (n=172) whereas females accounted for 55.5% (n= 214) of the cases. In total, meningioma was found to have the highest incidence (27.2%) followed by metastases brain tumour (18.1%) and glioma (17.4%).

    CONCLUSIONS: This study has shown that the incidence of BT was led by meningioma which had a high prevalence among the elderly population, followed by metastasis BT and gliomas.

  13. Ibrahim MF, Kuan G, Hashim HA, Hamzah NA, Kueh YC
    BMC Public Health, 2021 10 07;21(1):1798.
    PMID: 34620133 DOI: 10.1186/s12889-021-11869-4
    BACKGROUND: This study aimed to verify a translated Malay version of the Achievement Emotions Questionnaire for Physical Education (AEQ-PE) by assessing the level of achievement emotions in six constructs among the Malaysian primary school pupils using the Confirmatory Factor Analysis (CFA).

    METHODS: A total of 607 Malay pupils, comprising 240 (39.5%) boys and 367 (60.5%) girls aged between 10 and 11, were recruited from 10 schools to answer the questionnaire, which measured their views on 24 items through a five-point Likert scale. The AEQ-PE was translated into Malay language (AEQ-PE-M) using forwarding to backward translation techniques. Certain phrases were adopted in accordance with the local culture and vocabulary appropriate for primary school pupils. CFA was performed using the Mplus 8.0 software, and the final model demonstrated high reliability in terms of the composite reliability and Cronbach's alpha.

    RESULTS: Analysis of the CFA showed an acceptable fit indices in CFI (0.936), TLI (0.926), RMSEA = 0.039 (90% CI, 0.034, 0.045) and SRMR (0.049) of the AEQ-PE measurement model. All of the items in the original AEQ-PE version were retained and deemed suitable for Malay primary school pupils.

    CONCLUSION: The AEQ-PE-M with 24 items was a suitable tool for measuring the level of school children's involvement in determining achievement emotions and their motivation towards physical education.

  14. Law KB, Chang KM, Hamzah NA, Ng KH, Ong TC
    Indian J Hematol Blood Transfus, 2017 Dec;33(4):483-491.
    PMID: 29075058 DOI: 10.1007/s12288-017-0790-3
    The study aimed to investigate the effect of consolidation treatment with fludarabine, high-dose cytarabine and granulocyte colony-stimulating factor or FLAG in older AML patients. The study included 41 eligible patients above 54 years old, who received both induction and consolidation chemotherapy for AML from 2008 to 2013. The study cohort had a minimum 24 months follow-up period. Survival analysis was carried out to assess patients' overall survival and disease free survival based on types of consolidation regimens. The consolidation treatment with FLAG exerted a protective effect to both overall survival and disease free survival in older patients. Patients who were consolidated with FLAG regimen had a significant longer overall survival (log-rank, p = 0.0025) and disease free survival (log-rank, p = 0.0026). The median overall survival was longer (18.70 months) with the use of FLAG when compared to non-FLAG group (8.09 months). The median disease free survival was also longer (13.84 months) with use of FLAG when compared to the non-FLAG group (4.44 months). Regression analysis with Cox model yielded hazard ratio of 0.245 (p = 0.0094) in overall survival and 0.217 (p = 0.0068) in disease free survival. The use of FLAG as consolidation treatment was associated with approximately 60-80% reduction in hazard rates. The result was adjusted for age, race and gender in regression analysis. Older AML patients had longer remission and survival when consolidated with FLAG regimen after the induction chemotherapy.
  15. Aziz MHN, Safaruddin ADA, Hamzah NA, Supadi SS, Yuhao Z, Aziz MA
    Acta Biotheor, 2022 Nov 17;71(1):2.
    PMID: 36394646 DOI: 10.1007/s10441-022-09453-3
    A modified version of the SEIR model with the effects of vaccination and inter-state movement is proposed to simulate the spread of COVID-19 in Malaysia. A mathematical analysis of the proposed model was performed to derive the basic reproduction number. To enhance the model's forecasting capabilities, the model parameters were estimated using the Nelder-Mead simplex method by fitting the model outputs to the observed data. Our results showed a good fit between the model outputs and available data, where the model was then able to perform short-term predictions. In line with the rapid vaccination program, our model predicted that the COVID-19 cases in the country would decrease by the end of August. Furthermore, our findings indicated that relaxing travel restrictions from a highly vaccinated region to a low vaccinated region would result in an epidemic outbreak.
  16. Tavafzadeh SS, Chen CK, Ooi FK, Hamzah NA, Sulaiman SA, Osman JM
    Malays J Med Sci, 2023 Jun;30(3):151-166.
    PMID: 37425377 DOI: 10.21315/mjms2023.30.3.14
    BACKGROUND: Regular physical activity and proper nutritional intake are crucial for bone health. However, it is unclear if this health benefit is maintained after the removal of these stimuli. This study investigated the combined effects of aerobic dance exercise and honey supplementation, followed by their subsequent cessation on bone metabolism markers and antioxidant status in females.

    METHODS: Forty-eight young female college students were assigned into four groups: i) 16S (16 weeks of sedentary activity); ii) 8E×8S (8 weeks of exercise followed by 8 weeks of sedentary activity); iii) 8H8S (8 weeks of honey supplementation followed by 8 weeks of sedentary activity) and iv) 8E×H8S (8 weeks of combined exercise and honey supplementation followed by 8 weeks of sedentary activity). Blood samples were collected from the participants prior to the intervention, at week 8 and at week 16 for the analysis of bone metabolism markers and antioxidant status.

    RESULTS: At the mid test, bone speed of sound (SOS) (P < 0.01), serum alkaline phosphatase (ALP) (P < 0.001) and serum osteocalcin (P < 0.01) were significantly higher in the 8E×H8S group as compared to 16S group. After 8 weeks of cessation of exercise and honey supplementation, bone SOS was also significantly higher (P < 0.001) in the 8E×H8S group as compared to 16S group. In addition, the serum total calcium (P < 0.001), serum ALP (P < 0.01), total antioxidant status (TAS) (P < 0.01) and glutathione (GSH) (P < 0.01) in the 8E×H8S group were significantly higher at the post-test as compared to their respective pre-test values.

    CONCLUSION: These findings demonstrate that there was improved maintenance of the beneficial effects induced by 8 weeks of combined exercise and honey supplementation on bone properties and the antioxidant status after 8 weeks of cessation of exercise and honey supplementation as compared to exercise and honey supplementation alone.

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