Displaying all 12 publications

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  1. Hossain MZ, Munawar KM, Rahim ZH, Bakri MM
    Arch Oral Biol, 2016 Apr;64:85-91.
    PMID: 26803673 DOI: 10.1016/j.archoralbio.2016.01.001
    Stature estimation is an important step during medico-legal and forensic examination. Difficulty arises when highly decomposed and mutilated dead bodies with fragmentary remains are brought for forensic identification like in mass disaster or airplane crash. The body remains could be just a jaw with some teeth. The objective of this study was to explore if the stature of an individual can be determined from the tooth crown dimensions.
  2. Hossain MZ, Selvaraj JA, Rahim NA
    PLoS One, 2018;13(11):e0206691.
    PMID: 30500857 DOI: 10.1371/journal.pone.0206691
    Over the past few years, high step-up dc-dc converters have been drawn substantial attention because of their wide-ranging application not only in the renewable energy sector but also in many other applications. To acquire a high voltage gain in photovoltaic (PV) and other renewable energy applications, a high step-up dc-dc converter is proposed in this paper. The proposed converter structure consists of a full-bridge (FB) module along with an input boost inductor and a voltage multiplier based on the Cockcroft-Walton (CW) principle with a parallel inductor. The key features of the proposed converter are: 1) high voltage gain with lower voltage stress on the switches, diodes and other passive elements without affecting the number of cascaded stages, 2) a minimum size of boost inductance and cascaded stage capacitance that ensures its compactness and low cost, and 3) a minimal number of major components. Circuit operation, steady-state analysis and various design parameters of the proposed converter are explained in details. In order to prove the performance of the theoretical analysis, a laboratory prototype is also implemented. The peak voltage gain and the maximum efficiency obtained are 11.9 and 94.6% respectively with very low input current ripple and output voltage ripple generated.
  3. Hossain MZ, Selvaraj JA, Rahim NA
    PLoS One, 2024;19(8):e0306906.
    PMID: 39146264 DOI: 10.1371/journal.pone.0306906
    High conversion ratio dc-dc converters have received significant attention in renewable energy systems, primarily due to their necessary high-gain characteristics. This research proposes a high step-up ratio full-bridge resonant cascaded (FBRC) dc-dc converter designed for use in photovoltaics (PV), fuel cells (FC), electric vehicles (EV), and other low-voltage output energy sectors to achieve high voltage gain. This converter contains a full-bridge cell with a boost input inductor, a diode-capacitor cascaded stage that replaces the transformer as a voltage multiplier and an inductor-capacitor (LC) parallel-series resonant network across the FB terminal. One of the strategic features of the converter is its high voltage step-up characteristic combined with lower duty cycle operation that limits the maximum current through the active devices, making it particularly suitable for systems that generate low output voltage. In addition, zero-voltage switching (ZVS) is achieved during the turn-off and turn-on operation of the FB switches from 25% to full load, thereby lessening the switching losses. Moreover, the diminished necessity for passive components and the decreased voltage stress on both active and passive devices lead to the use of smaller and more cost-effective components. The theoretical analysis of the proposed converter is validated using a 500 W laboratory-scale prototype wherein high-performance SiC-based MOSFETs have been utilized as switching devices. It offers reduced ripples, with input current ripple at 5% and output voltage ripple at 0.76%. When the load is 400 W and 60 V as the input voltage, the maximum efficiency is found 95.8% at 400 V output voltage. The proposed dc-dc converter, with its high voltage gain and reduced component stress, shows significant promise for application in renewable energy systems.
  4. Daud S, Nambiar P, Hossain MZ, Rahman MR, Bakri MM
    Gerodontology, 2016 Sep;33(3):315-21.
    PMID: 25266855 DOI: 10.1111/ger.12154
    OBJECTIVES: The aim of this study was to determine the changes in cell density and morphology of selected cells of the ageing human dental pulp.

    BACKGROUND: Changes in cell density and morphology of dental pulp cells over time may affect their capability to respond to tooth injury.

    MATERIALS AND METHODS: One hundred thirty-one extracted teeth were obtained from individuals between the ages of 6 and 80 years. The apical 1/3 of the root region was removed from all teeth prior to routine processing for producing histological slides. The histology slides were used to study the changes in cell density and morphology of selected pulp cells; odontoblasts, subodontoblasts and fibroblasts in the crown and root regions of the dental pulp. Student's t-test and one-way anova were used for statistical analyses.

    RESULTS: In all age groups, the cell density for all types of cells was found to be higher in the crown than in the root (p 

  5. Hossain MZ, Daud S, Nambiar P, Razak FA, Ab-Murat N, Saub R, et al.
    Arch Oral Biol, 2017 Aug;80:51-55.
    PMID: 28371626 DOI: 10.1016/j.archoralbio.2017.03.018
    OBJECTIVE: The aim of this study was to investigate correlations between dental pulp cell count of odontoblasts, subodontoblasts and fibroblasts and age, within different age groups. Formulation of regression equations using the dental pulp cell count for predicting age was attempted.

    DESIGN: Eighty-one extracted teeth were grouped into two age groups (6-25 years, 26-80 years). The teeth were demineralized and histological sections were prepared for cell count. Regression equations were generated from regression analysis of cell count and tested for age estimation.

    RESULTS: The number of dental pulp cells were found to increase until around the third decade of life and following this, the odontoblasts and subodontoblasts cell numbers began to decline while the fibroblasts seemed to remain almost stationary. The Pearson correlation test revealed a significant positive correlation between the cell number for all type of cells and age in the 6-25 years group (r=+0.791 for odontoblasts, r=+0.600 for subodontoblasts and r=+0.680 for fibroblasts). In the 26-80 years age group, a significant negative correlation of the odontoblasts (r=-0.777) and subodontoblasts (r=-0.715) with age was observed but for fibroblasts, the correlation value was negligible (r=-0.165). Regression equations generated using odontoblasts and subodontoblasts cell number were applicable for age estimation. The standard error of estimates (SEEs) were around±5years for 6-25 years and±8years for 26-80 years age groups. The mean values of the estimated and chronological ages were not significantly different.

    CONCLUSIONS: A significant correlation between the cell count of odontoblasts and subodontoblasts with age was demonstrated. Regression equations using odontoblasts and subodontoblasts cell number can be used to predict age with some limitations.

  6. Bakri MM, Hossain MZ, Razak FA, Saqina ZH, Misroni AA, Ab-Murat N, et al.
    Aust Dent J, 2017 Jun;62(2):186-191.
    PMID: 27813093 DOI: 10.1111/adj.12484
    BACKGROUND: Dentine hypersensitivity is a common problem attributed by patent dentinal tubules. Ingredients incorporated in toothpastes aim to occlude patent dentinal tubules to minimize the dentine hypersensitivity. However, frequent consumption of acidic soft drinks may reverse the dentinal tubules' occlusion. In this in vitro study, the efficacy of dentinal tubules occluded by commercially available toothpastes to withstand different durations of an acidic soft drink challenge was investigated.

    METHODS: One hundred and twenty dentine discs were divided into three groups. The discs from each group were brushed with toothpaste containing bioactive glass, arginine and control toothpaste. Each group was then divided into four subgroups and exposed to acidic soft drink over four different time durations.

    RESULTS: The scoring and the percentage of occluded dentinal tubules by Novamin-containing toothpaste was significantly better compared with arginine or the control toothpaste. Acidic soft drink challenge reduced the extent of dentinal tubules occlusion along with time. Dentinal tubules occluded by Novamin-containing toothpaste withstand the acidic challenge comparatively for a longer period.

    CONCLUSIONS: The findings demonstrated that occlusion of dentinal tubules is more efficient by the bioactive glass-containing toothpaste and thus may contribute to its better resistance to acidic soft drink challenge.

  7. Hossain MZ, Bakri MM, Yahya F, Ando H, Unno S, Kitagawa J
    Int J Mol Sci, 2019 Jan 27;20(3).
    PMID: 30691193 DOI: 10.3390/ijms20030526
    Dental pain is a common health problem that negatively impacts the activities of daily living. Dentine hypersensitivity and pulpitis-associated pain are among the most common types of dental pain. Patients with these conditions feel pain upon exposure of the affected tooth to various external stimuli. However, the molecular mechanisms underlying dental pain, especially the transduction of external stimuli to electrical signals in the nerve, remain unclear. Numerous ion channels and receptors localized in the dental primary afferent neurons (DPAs) and odontoblasts have been implicated in the transduction of dental pain, and functional expression of various polymodal transient receptor potential (TRP) channels has been detected in DPAs and odontoblasts. External stimuli-induced dentinal tubular fluid movement can activate TRP channels on DPAs and odontoblasts. The odontoblasts can in turn activate the DPAs by paracrine signaling through ATP and glutamate release. In pulpitis, inflammatory mediators may sensitize the DPAs. They could also induce post-translational modifications of TRP channels, increase trafficking of these channels to nerve terminals, and increase the sensitivity of these channels to stimuli. Additionally, in caries-induced pulpitis, bacterial products can directly activate TRP channels on DPAs. In this review, we provide an overview of the TRP channels expressed in the various tooth structures, and we discuss their involvement in the development of dental pain.
  8. Bakri MM, Yahya F, Munawar KMM, Kitagawa J, Hossain MZ
    Arch Oral Biol, 2018 May;89:94-98.
    PMID: 29499561 DOI: 10.1016/j.archoralbio.2018.02.011
    OBJECTIVE: Transient receptor potential vanilloid 4 (TRPV4) has been considered as a mechano-, thermo- and osmo-receptor. Under inflammatory conditions in dental pulp, teeth can become sensitive upon exposure to a variety of innocuous stimuli. The objective of the present study was to investigate the expression of the TRPV4 channel on nerve fibers in human dental pulp of non-symptomatic and symptomatic teeth associated with inflammatory conditions.

    DESIGN: Dental pulp from extracted human permanent teeth was processed for fluorescence immunohistochemistry. Ten asymptomatic (normal) and 10 symptomatic (symptoms associated with pulpitis) teeth were used in this study. Nerve fibers were identified by immunostaining for a marker, protein gene product 9.5, and the cells were counterstained with 4',6-diamidino-2-phenylindole. An anti-TRPV4 antibody was used to trace TRPV4 expression.

    RESULTS: TRPV4 expression was co-localized with the nerve fiber marker. Immunoreactivity for TRPV4 was more intense (p 

  9. Yahya F, Mohd Bakri M, Hossain MZ, Syed Abdul Rahman SN, Mohammed Alabsi A, Ramanathan A
    Medicina (Kaunas), 2022 Sep 06;58(9).
    PMID: 36143906 DOI: 10.3390/medicina58091229
    Background and Objectives: Oral squamous cell carcinoma (OSCC) is the sixth most common malignancy in the world. Transient receptor potential vanilloid 4 (TRPV4) channel has been shown to be involved in angiogenesis in multiple types of tumors. However, not much is known about TRPV4′s involvement in OSCC. Thus, in this study, we investigate the effect of administering a TRPV4 agonist on angiogenesis in OSCC. Materials and Methods: Thirty-six Sprague Dawley (SD) rats were used in this study. 4-nitroquinoline 1-oxide (4NQO) was used to induce OSCC. Cisplatin (an anticancer drug), and GSK1016790A (an agonist for TRPV4) was used in this study. Immunohistochemistry was employed to examine the TRPV4 expression. An RT2 Profiler PCR Array was performed for gene expression analysis of TRPV4, vascular growth factors that correspond directly with angiogenesis, such as angiopoietin (Ang-1 and Ang-2), and tyrosine kinase (Tie-1 and Tie-2) receptors. Tumor vessel maturity was assessed by microvessel density and microvessel-pericyte-coverage index. Results: RT2 profiler PCR array showed significant elevated levels of Ang-1 (2.1-fold change; p < 0.05) and Tie-2 (4.5-fold change; p < 0.05) in OSCC following the administration of a combination of GSK1016790A and cisplatin. Additionally, the combination treatment significantly reduced the microvessel density (p < 0.01) and significantly increased the percentage of microvessels covered with pericytes (p < 0.01) in OSCC. Furthermore, tumor size was significantly reduced (p < 0.05) in rats that received cisplatin alone. The combination treatment also greatly reduced the tumor size; however, the data were not statistically significant. Conclusions: The findings suggest that combining a TRPV4 agonist with cisplatin for treatment of OSCC promote vessels normalization via modulation of Ang-1/Tie-2 pathway.
  10. Hossain MT, Islam MA, Jahan N, Nahar MT, Sarker MJA, Rahman MM, et al.
    Front Psychiatry, 2022;13:938230.
    PMID: 35958639 DOI: 10.3389/fpsyt.2022.938230
    BACKGROUND: Following the outbreak of the COVID-19 pandemic, the government of Bangladesh implemented strict non-therapeutic measures, i.e., "social distancing," "lockdown," "work from home," in the first quarter of 2020. Like other professionals, teachers at schools, colleges and universities were confined within households. However, the introduction of online education imposed an additional burden on teachers along with growing household responsibilities, thus, affecting their psychological state.

    AIMS: This study was aimed to explore the prevalence of mental health problems among teachers in Bangladesh and to identify the associated risk factors.

    METHODS: This web-based cross-sectional study was conducted during the second wave of COVID-19 pandemic in Bangladesh. Data were collected from 381 teachers working at schools, colleges, and universities between 01 August and 29 August 2021 by administering a self-reported e-questionnaire using Google Form, where the mental health of teachers was assessed by depression, anxiety, and stress scale. Data were analyzed using IBM SPSS Statistics (Version 26) and STATA Version 16, and multiple linear regression was executed to predict mental health problems among teachers.

    RESULTS: The findings indicate that the overall prevalence of depression, anxiety, and stress among teachers was 35.4%, 43.7%, and 6.6%, respectively. The prevalence was higher among male and older teachers than among their female and younger colleagues. The findings further showed that place of residence, institution, self-reported health, usage of social and electronic media, and fear of COVID-19 significantly influenced the mental health status of teachers.

    CONCLUSION: It is strongly recommended that the government and policymakers provide proper mental health services to teachers in order to reduce mental health problems and thus sustain the quality of education during and after the pandemic.

  11. Kabir MF, Yin KN, Jeffree MS, Ahmedy FB, Zainudin MF, Htwe O, et al.
    BMC Infect Dis, 2024 Apr 04;24(1):375.
    PMID: 38575878 DOI: 10.1186/s12879-024-09267-3
    BACKGROUND: Pain is one of the prevalent Long COVID Symptoms (LCS). Pain interferes with the quality of life (QoL) and induces disease burden.

    PURPOSE: The study aimed to elicit the clinical presentation of pain and determine the relationships between QoL and pain in LCS.

    METHODS: This household cross-sectional study of 12,925 SARS-CoV-2 cases between July and December 2021 was carried out in eight administrative divisions of Bangladesh. Stratified random sampling from the cases retrieved from the Ministry of Health was employed. Symptom screening was performed through COVID-19 Yorkshire Rehabilitation Scale, and long COVID was diagnosed according to World Health Organization (WHO) criteria. The analyses were conducted using IBM SPSS (Version 20.00).

    RESULTS: The prevalence of pain in long COVID was between 01 and 3.1% in the studied population. The study also found five categories of pain symptoms as LCS in Bangladesh: muscle pain 3.1% (95% CI; 2.4-3.8), chest pain 2.4% (95% CI; 1.8-3.1), joint pain 2.8% (95% CI; 2.2-2.3), headache 3.1% (95% CI; 2.4-3.8), and abdominal pain 0.3% (95% CI; 0.01-0.5). People with LCS as pain, multiple LCS, and longer duration of LCS had significantly lower quality of life across all domains of the WHOQOL-BREF (P 

  12. Kabir MF, Nyein Yin K, Htwe O, Saffree Jeffree M, Binti Ahmedy F, Faizal Zainudin M, et al.
    PLoS One, 2024;19(6):e0304824.
    PMID: 38941308 DOI: 10.1371/journal.pone.0304824
    BACKGROUND: Spinal cord injury (SCI) is a consequence of significant disability and health issues globally, and long COVID represents the symptoms of neuro-musculoskeletal, cardiovascular and respiratory complications.

    PURPOSE: This study aimed to identify the symptom responses and disease burden of long COVID in individuals with spinal cord injury.

    METHODS: This case-control study was conducted on patients with SCI residing at a specialised rehabilitation centre in Bangladesh. Forty patients with SCI with and without long COVID symptoms (LCS) were enrolled in this study at a 1:1 ratio according to WHO criteria.

    RESULT: Twelve LCS were observed in patients with SCI, including fatigue, musculoskeletal pain, memory loss, headache, respiratory problems, anxiety, depression, insomnia, problem in ADL problem in work, palpitation, and weakness. The predictors of developing long COVID include increasing age (p<0.002), increasing BMI (p<0.03), and longer duration of spinal cord injury (p<0.004). A significant difference (p<0.01) in overall years of healthy life lost due to disability (YLD) for non-long COVID cases was 2.04±0.596 compared to long COVID (LC) cases 1.22±2.09 was observed.

    CONCLUSION: Bangladeshi patients of SCI presented 12 long COVID symptoms and have a significant disease burden compared to non long COVID cases.

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