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Finite element analysis and clinical complications in mandibular implant-overdentures opposing maxillary dentures

Khuder T, Yunus N, Sulaiman E, Dabbagh A

J Mech Behav Biomed Mater, 2017 11;75:97-104.
PMID: 28709037 DOI: 10.1016/j.jmbbm.2017.06.039

Denture fracture is a common clinical complication caused by improper material selection, design, or fabrication technique. This study aimed to investigate the effect of two attachment systems on fracture risk of the implant-overdentures (IOD) via finite element analysis (FEA), using the force distributions obtained from patients' occlusal analyses and to compare the obtained results with the clinical complications associated with these attachments. A three-dimensional jaw model comprised of the edentulous bones was constructed. Three types of mandibular prostheses including complete denture (CD) (model LCD), IOD with Locator attachment (model LID-L), and IOD with telescopic attachment (model LID-T), as well as a maxillary CD (model UCD) were assembled. The vertical occlusal forces at anterior and posterior quadrants were obtained from the patients wearing mandibular CDs or IODs. The FEA results were further compared with the mechanical failures of different prostheses observed at patient recalls. In overall, the fracture risk of mandibular prostheses was lower than the maxillary compartments. The UCD opposing LCD underwent higher strains than that opposing LID-L and LID-T, which was mostly concentrated at the anterior mid-palatal polished surface. On the other hand, LID-L showed the lowest strain, followed by LID-T, and LCD. The obtained results were consistent with the clinical complications observed in the patient recalls.
Fulltext Investigation of Embedded Si/C System Exposed to a Hybrid Reaction of Centrifugal-Assisted Thermite Method

Mahmoodian R, Yahya R, Dabbagh A, Hamdi M, Hassan MA

PLoS One, 2015;10(12):e0144632.
PMID: 26641651 DOI: 10.1371/journal.pone.0144632

A novel method is proposed to study the behavior and phase formation of a Si+C compacted pellet under centrifugal acceleration in a hybrid reaction. Si+C as elemental mixture in the form of a pellet is embedded in a centrifugal tube. The pellet assembly and tube are exposed to the sudden thermal energy of a thermite reaction resulted in a hybrid reaction. The hybrid reaction of thermite and Si+C produced unique phases. X-ray diffraction pattern (XRD) as well as microstructural and elemental analyses are then investigated. XRD pattern showed formation of materials with possible electronic and magnetic properties. The cooling rate and the molten particle viscosity mathematical model of the process are meant to assist in understanding the physical and chemical phenomena took place during and after reaction. The results analysis revealed that up to 85% of materials converted into secondary products as ceramics-matrix composite.
Tissue-mimicking gel phantoms for thermal therapy studies

Dabbagh A, Abdullah BJ, Ramasindarum C, Abu Kasim NH

Ultrason Imaging, 2014 Oct;36(4):291-316.
PMID: 24626566 DOI: 10.1177/0161734614526372

Tissue-mimicking phantoms that are currently available for routine biomedical applications may not be suitable for high-temperature experiments or calibration of thermal modalities. Therefore, design and fabrication of customized thermal phantoms with tailored properties are necessary for thermal therapy studies. A multitude of thermal phantoms have been developed in liquid, solid, and gel forms to simulate biological tissues in thermal therapy experiments. This article is an attempt to outline the various materials and techniques used to prepare thermal phantoms in the gel state. The relevant thermal, electrical, acoustic, and optical properties of these phantoms are presented in detail and the benefits and shortcomings of each type are discussed. This review could assist the researchers in the selection of appropriate phantom recipes for their in vitro study of thermal modalities and highlight the limitations of current phantom recipes that remain to be addressed in further studies.
Reusable heat-sensitive phantom for precise estimation of thermal profile in hyperthermia application

Dabbagh A, Abdullah BJ, Abu Kasim NH, Ramasindarum C

Int J Hyperthermia, 2014 Feb;30(1):66-74.
PMID: 24286257 DOI: 10.3109/02656736.2013.854930

The emergence of thermal modalities has promoted the use of heat-sensitive phantoms for calibration, measurement, and verification purposes. However, development of durable phantoms with high precision ability to represent the temperature distribution remains a challenge. This study aims to introduce a reusable phantom that provides an accurate assessment of the heated region in various thermal modalities.
Fulltext Lifestyle and reproductive health: the aetiology of ovarian cancer in Pakistan

Alvi Q, Baloch GM, Chinna K, Dabbagh A

F1000Res, 2020;9:901.
PMID: 32802322 DOI: 10.12688/f1000research.24866.1

Ovarian cancer is a fatal gynaecological cancer and eighth most common cancer in women globally. Lifestyle, reproductive and sociodemographic factors are among the influential parameters that may significantly affect the risk of ovarian cancer and its mortality rate. However, the epidemiological investigations have shown that the risk of ovarian cancers associated with these factors is different in varied geographical distributions. Lifestyle and reproductive factors have not been investigated thoroughly across a wide cultural diversity. The objective of this study is to investigate the association of these factors with ovarian cancer in Pakistan. This investigation will focus on the lifestyle effects of fat intake, intake of tea, habitual exercise, use of talc, personal hygiene, habit of holding urine for long time, obesity on ovarian cancer among Pakistani women. Reproductive variables will include age at menarche, natural menopausal age, parity, nulliparity (miscarriages, abortion, stillbirths), infertility, fertility treatment, tubal ligation, oral contraceptive use, and family history of breast or ovarian cancer. Sociodemographic variables will include effect of age, income, education, and geographical location. A case-control study will be conducted in the major cancer hospitals of Pakistan and the patients will also be interviewed. The controls will be recruited outside the hospital. For controls the same age limit and residency requirements will be applied. The information gained from this research will be an important contribution to develop programs for health promotion, with a focus on ovarian cancer prevention and women's health. The findings could be used for health policies and planning to prevent ovarian cancer. The research will pave the way for a public policy and interventions to reduce the burden of ovarian cancer in Pakistan.
Fulltext Controlled temperature-mediated curcumin release from magneto-thermal nanocarriers to kill bone tumors

Khodaei A, Jahanmard F, Madaah Hosseini HR, Bagheri R, Dabbagh A, Weinans H, et al.

Bioact Mater, 2022 May;11:107-117.
PMID: 34938916 DOI: 10.1016/j.bioactmat.2021.09.028

Systemic chemotherapy has lost its position to treat cancer over the past years mainly due to drug resistance, side effects, and limited survival ratio. Among a plethora of local drug delivery systems to solve this issue, the combinatorial strategy of chemo-hyperthermia has recently received attention. Herein we developed a magneto-thermal nanocarrier consisted of superparamagnetic iron oxide nanoparticles (SPIONs) coated by a blend formulation of a three-block copolymer Pluronic F127 and F68 on the oleic acid (OA) in which Curcumin as a natural and chemical anti-cancer agent was loaded. The subsequent nanocarrier SPION@OA-F127/F68-Cur was designed with a controlled gelation temperature of the shell, which could consequently control the release of curcumin. The release was systematically studied as a function of temperature and pH, via response surface methodology (RSM). The bone tumor killing efficacy of the released curcumin from the carrier in combination with the hyperthermia was studied on MG-63 osteosarcoma cells through Alamar blue assay, live-dead staining and apoptosis caspase 3/7 activation kit. It was found that the shrinkage of the F127/F68 layer stimulated by elevated temperature in an alternative magnetic field caused the curcumin release. Although the maximum release concentration and cell death took place at 45 °C, treatment at 41 °C was chosen as the optimum condition due to considerable cell apoptosis and lower side effects of mild hyperthermia. The cell metabolic activity results confirmed the synergistic effects of curcumin and hyperthermia in killing MG-63 osteosarcoma cells.
Low-melting-point polymeric nanoshells for thermal-triggered drug release under hyperthermia condition

Dabbagh A, Mahmoodian R, Abdullah BJ, Abdullah H, Hamdi M, Abu Kasim NH

Int J Hyperthermia, 2015;31(8):920-9.
PMID: 26670340 DOI: 10.3109/02656736.2015.1094147

The aim of this paper was to synthesise core-shell nanostructures comprised of mesoporous silica core and a low melting-point polyethylene glycol (PEG) nanoshell with a sharp gel-liquid phase transition for rapid drug release at hyperthermia temperature range.
A new mechanism of thermal sensitivity for rapid drug release and low systemic toxicity in hyperthermia and thermal ablation temperature ranges

Dabbagh A, Abdullah BJ, Abu Kasim NH, Abdullah H, Hamdi M

Int J Hyperthermia, 2015 Jun;31(4):375-85.
PMID: 25716769 DOI: 10.3109/02656736.2015.1006268

The aim of this paper was to introduce a new mechanism of thermal sensitivity in nanocarriers that results in a relatively low drug release at physiological temperature and rapid release of the encapsulated drug at hyperthermia and thermal ablation temperature range (40-60 °C).
Triggering Mechanisms of Thermosensitive Nanoparticles Under Hyperthermia Condition

Dabbagh A, Abdullah BJ, Abdullah H, Hamdi M, Kasim NH

J Pharm Sci, 2015 Aug;104(8):2414-28.
PMID: 26073304 DOI: 10.1002/jps.24536

Nanoparticle-based hyperthermia is an effective therapeutic approach that allows time- and site-specific treatment with minimized off-site effects. The recent advances in materials science have led to design a diversity of thermosensitive nanostructures that exhibit different mechanisms of thermal response to the external stimuli. This article aims to provide an extensive review of the various triggering mechanisms in the nanostructures used as adjuvants to hyperthermia modalities. Understanding the differences between various mechanisms of thermal response in these nanostructures could help researchers in the selection of appropriate materials for each experimental and clinical condition as well as to address the current shortcomings of these mechanisms with improved material design.
Critical Parameters for Particle-Based Pulmonary Delivery of Chemotherapeutics

Dabbagh A, Abu Kasim NH, Yeong CH, Wong TW, Abdul Rahman N

J Aerosol Med Pulm Drug Deliv, 2018 06;31(3):139-154.
PMID: 29022837 DOI: 10.1089/jamp.2017.1382

Targeted delivery of chemotherapeutics through the respiratory system is a potential approach to improve drug accumulation in the lung tumor, while decreasing their negative side effects. However, elimination by the pulmonary clearance mechanisms, including the mucociliary transport system, and ingestion by the alveolar macrophages, rapid absorption into the blood, enzymatic degradation, and low control over the deposition rate and location remain the main complications for achieving an effective pulmonary drug delivery. Therefore, particle-based delivery systems have emerged to minimize pulmonary clearance mechanisms, enhance drug therapeutic efficacy, and control the release behavior. A successful implementation of a particle-based delivery system requires understanding the influential parameters in terms of drug carrier, inhalation technology, and health status of the patient's respiratory system. This review aims at investigating the parameters that significantly drive the clinical outcomes of various particle-based pulmonary delivery systems. This should aid clinicians in appropriate selection of a delivery system according to their clinical setting. It will also guide researchers in addressing the remaining challenges that need to be overcome to enhance the efficiency of current pulmonary delivery systems for aerosols.
Nanomechanical properties, wear resistance and in-vitro characterization of Ta2O5nanotubes coating on biomedical grade Ti-6Al-4V

Sarraf M, Razak BA, Nasiri-Tabrizi B, Dabbagh A, Kasim NHA, Basirun WJ, et al.

J Mech Behav Biomed Mater, 2017 02;66:159-171.
PMID: 27886563 DOI: 10.1016/j.jmbbm.2016.11.012

Tantalum pentoxide nanotubes (Ta2O5NTs) can dramatically raise the biological functions of different kinds of cells, thus have promising applications in biomedical fields. In this study, Ta2O5NTs were prepared on biomedical grade Ti-6Al-4V alloy (Ti64) via physical vapor deposition (PVD) and a successive two-step anodization in H2SO4: HF (99:1)+5% EG electrolyte at a constant potential of 15V. To improve the adhesion of nanotubular array coating on Ti64, heat treatment was carried out at 450°C for 1h under atmospheric pressure with a heating/cooling rate of 1°Cmin-1. The surface topography and composition of the nanostructured coatings were examined by atomic force microscopy (AFM) and X-ray electron spectroscopy (XPS), to gather information about the corrosion behavior, wear resistance and bioactivity in simulated body fluids (SBF). From the nanoindentation experiments, the Young's modulus and hardness of the 5min anodized sample were ~ 135 and 6GPa, but increased to ~ 160 and 7.5GPa, respectively, after annealing at 450°C. It was shown that the corrosion resistance of Ti64 plates with nanotubular surface modification was higher than that of the bare substrate, where the 450°C annealed specimen revealed the highest corrosion protection efficiency (99%). Results from the SBF tests showed that a bone-like apatite layer was formed on nanotubular array coating, as early as the first day of immersion in simulated body fluid (SBF), indicating the importance of nanotubular configuration on the in-vitro bioactivity.
Fulltext A review on chitosan and its development as pulmonary particulate anti-infective and anti-cancer drug carriers

Rasul RM, Tamilarasi Muniandy M, Zakaria Z, Shah K, Chee CF, Dabbagh A, et al.

Carbohydr Polym, 2020 Dec 15;250:116800.
PMID: 33049807 DOI: 10.1016/j.carbpol.2020.116800

Chitosan, as a biodegradable and biocompatible polymer, is characterized by anti-microbial and anti-cancer properties. It lately has received a widespread interest for use as the pulmonary particulate backbone materials of drug carrier for the treatment of infectious disease and cancer. The success of chitosan as pulmonary particulate drug carrier is a critical interplay of their mucoadhesive, permeation enhancement and site/cell-specific attributes. In the case of nanocarriers, various microencapsulation and micro-nano blending systems have been devised to equip them with an appropriate aerodynamic character to enable efficient pulmonary aerosolization and inhalation. The late COVID-19 infection is met with acute respiratory distress syndrome and cancer. Chitosan and its derivatives are found useful in combating HCoV and cancer as a function of their molecular weight, substituent type and its degree of substitution. The interest in chitosan is expected to rise in the next decade from the perspectives of drug delivery in combination with its therapeutic performance.
Polyethylene glycol-coated porous magnetic nanoparticles for targeted delivery of chemotherapeutics under magnetic hyperthermia condition

Dabbagh A, Hedayatnasab Z, Karimian H, Sarraf M, Yeong CH, Madaah Hosseini HR, et al.

Int J Hyperthermia, 2019;36(1):104-114.
PMID: 30428737 DOI: 10.1080/02656736.2018.1536809

PURPOSE: Although magnetite nanoparticles (MNPs) are promising agents for hyperthermia therapy, insufficient drug encapsulation efficacies inhibit their application as nanocarriers in the targeted drug delivery systems. In this study, porous magnetite nanoparticles (PMNPs) were synthesized and coated with a thermosensitive polymeric shell to obtain a synergistic effect of hyperthermia and chemotherapy.
MATERIALS AND METHODS: PMNPs were produced using cetyltrimethyl ammonium bromide template and then coated by a polyethylene glycol layer with molecular weight of 1500 Da (PEG1500) and phase transition temperature of 48 ± 2 °C to endow a thermosensitive behavior. The profile of drug release from the nanostructure was studied at various hyperthermia conditions generated by waterbath, magnetic resonance-guided focused ultrasound (MRgFUS), and alternating magnetic field (AMF). The in vitro cytotoxicity and hyperthermia efficacy of the doxorubicin-loaded nanoparticles (DOX-PEG1500-PMNPs) were assessed using human lung adenocarcinoma (A549) cells.
RESULTS: Heat treatment of DOX-PEG1500-PMNPs containing 235 ± 26 mg·g-1 DOX at 48 °C by waterbath, MRgFUS, and AMF, respectively led to 71 ± 4%, 48 ± 3%, and 74 ± 5% drug release. Hyperthermia treatment of the A549 cells using DOX-PEG1500-PMNPs led to 77% decrease in the cell viability due to the synergistic effects of magnetic hyperthermia and chemotherapy.
CONCLUSION: The large pores generated in the PMNPs structure could provide a sufficient space for encapsulation of the chemotherapeutics as well as fast drug encapsulation and release kinetics, which together with thermosensitive characteristics of the PEG1500 shell, make DOX-PEG1500-PMNPs promising adjuvants to the magnetic hyperthermia modality.
Neuro-fuzzy method for predicting the viability of stem cells treated at different time-concentration conditions

Bindal P, Bindal U, Lin CW, Kasim NHA, Ramasamy TSAP, Dabbagh A, et al.

Technol Health Care, 2017 Dec 04;25(6):1041-1051.
PMID: 28800347 DOI: 10.3233/THC-170922

Dental stem cells isolated for human dental pulp are an excellent source for regenerative medicine and dentistry. Simulation of clinical scenario is one of the crucial challenges for evaluation of the efficacy of DPSCs in various regenerative therapies. In this study we evaluated the viability of DPSCs after treatment with artificial bacterial lipopolysaccharides (LPS) as the main component responsible for inducing inflammatory response in majority of the inflammatory conditions in clinical scenario. Although a number of studies have previously treated stem cells with LPS from bacteria, however the accuracy level of the outcome was not established. Here we have analyzed the outcome using adaptive neuro-fuzzy inferences system (ANFIS) to predict the viability of human DPSCs after treatment with bacterial LPS.

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