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"Hamad, Ibrahim"
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Polymeric additions effect on mechanical properties of heat-polymerized denture base resin: an in vitro study
Background
Heat-polymerized acrylic resin is one of the most widely used polymeric materials in denture fabrication. Therefore, improving these resin materials is crucial to ensuring optimal denture properties and performance.
Purpose
This in vitro study aimed to evaluate the influence of polyurethane incorporation on the mechanical properties of heat-polymerized PMMA denture base resin.
Materials and methods
Polymethyl methacrylate (PMMA) is used to produce dentures due to its aesthetics and ease of manufacture. However, it has low impact and flexural strength. Tough and flexible polyurethane was employed to overcome these difficulties. A control group with unmodified PMMA (30 samples) and an experimental group (90 samples) with 1%, 3%, and 5% polyurethane received 120 heat-polymerized acrylic resin samples (10 samples per test). Experimental samples were compared to the control group for flexural strength, impact strength, and hardness to see how polyurethane addition influenced resin mechanical properties.
Results
Based on composition, polyurethane polymers boosted PMMA’s flexural, impact, and surface hardness. Control samples were unmodified PMMA and 1%, 3%, and 5% polyurethane volume fractions. Statistical analysis used one-way ANOVA and Tukey’s post-hoc test to assess group differences, with a significance threshold of p < 0.05.
Conclusions
The interpenetrating polymer network composite significantly influences and improves the mechanical properties of the heat-polymerized denture base resin, making it more challenging, stronger, and resistant to flexural and hardness stresses.
Journal Article
Impact of denture cleansers on the color stability, surface roughness, microhardness, and antibacterial activity of PMMA denture base materials reinforced with titanium dioxide nanoparticles
ObjectiveThis study aimed to assess the effects of various denture cleansers on the color stability, surface roughness, microhardness, and antibacterial activity of polymethyl methacrylate (PMMA) denture base materials modified with titanium dioxide TiO2 nanoparticles.Materials and methodsNinety disc-shaped PMMA specimens (10 × 10 × 2 mm) were fabricated and divided into three groups based on TiO2 concentration: 0% (control), 3%, and 5%. Each group was further subdivided based on the cleanser used: distilled water, Corega oxygenating tablets, or 0.5% sodium hypochlorite (n = 10). Measurements of color change (ΔE, using the CIE Lab* system), surface roughness (Ra), microhardness (Vickers hardness test), and antibacterial activity (zone of inhibition against Streptococcus mutans and Candida albicans) were conducted at 90 and 180 days. Statistical analysis included one-way ANOVA and Tukey’s post hoc test (α = 0.05).ResultsSodium hypochlorite induced the most significant color changes and surface roughness, particularly in the unreinforced group. TiO2-reinforced samples demonstrated improved resistance to surface degradation and maintained higher microhardness values, especially with 5% nanoparticle concentration. Chemical cleansers reduced antibacterial activity slightly, but TiO2-containing samples still exhibited superior efficacy compared to controls.ConclusionThe incorporation of TiO2 nanoparticles enhances the durability, aesthetic stability, and antimicrobial properties of PMMA denture base materials. However, cleanser selection plays a critical role in preserving these properties. Sodium hypochlorite, while effective, may compromise surface integrity. Enzymatic and non-abrasive cleansers are more suitable for long-term use with nanoparticle-reinforced denture bases.
Journal Article
Prevalence of physical and mental health problems among internally displaced persons in White Nile state, Sudan 2023: a cross sectional study
Background
Following the latest war in 2023, over nine million people have been internally displaced, of which White Nile State received over 50,000. They lived in different camps and moved to big cities. This study assessed the scope of mental and physical concerns among the IDPs to identify important healthcare needs.
Methods
This is a cross-sectional survey of four localities of internally displaced persons in White Nile state, Sudan. Between December 4th and December 14th, 2023, 800 directly interviewed participants were randomly selected using a face-to-face semi-structured interview. Potential participants were determined using a stratified simple random method.
Results
The findings revealed that 45% of IDPs experienced poor physical health, with prevalent ailments among adults including minor colds (67%), respiratory infections (43%), prolonged flu episodes (36%), insomnia (38%), headaches (42%), gastric upset (44%), nausea (35%), and gastrointestinal issues (40%). Depression, PTSD, and anxiety were prevalent among adults at rates of 18%, 20%, and 14% respectively. Moreover, a staggering 72% of children under five suffered from malnutrition, with males accounting for 44% and females 56%.
Conclusion
Alarming numbers of IDPs in White Nile State face significant physical and mental health problems, warranting urgent interventions from local and international relief agencies.
Journal Article
A four-factor model of consumption values in a multicultural society: Measurement invariance and the duality of materialism and frugality in Qatar
Societies undergoing rapid economic modernization face a tension between materialist consumption and sustainability, yet few psychometrically sound tools exist to measure these values in non-Western contexts. This study aimed to develop and validate a scale of consumption values in the multicultural, high-income setting of Qatar. We conducted a large-scale survey (N = 2,026) of Qatari nationals and expatriates using a comprehensive questionnaire. Exploratory factor analysis revealed four distinct and interpretable dimensions of consumption values: (1) Materialism/Social Status, an orientation valuing luxury and wealth as markers of success; (2) Extravagance, a tendency toward impulsive and unnecessary spending; (3) Frugality, a disposition toward thrift and careful budgeting; and (4) Environmental Consciousness, a concern for the ecological impact of consumption. A four-factor model was confirmed using confirmatory factor analysis, demonstrating good model fit. Multi-group analyses established measurement invariance (configural, metric, and scalar) across nationality, gender, and income groups, ensuring that comparisons between these groups are meaningful. Latent mean comparisons revealed that Qatari nationals scored significantly higher on Materialism and Extravagance but lower on Frugality than expatriates. Critically, materialism and extravagance were associated with poorer self-reported financial well-being, whereas frugality was linked to better financial standing. This research provides a robust, multi-dimensional instrument for assessing consumption values in diverse societies and offers insights into the psychological factors shaping financial and environmental outcomes in modernizing economies.
Journal Article
The Impact of Dietary Components on Regulatory T Cells and Disease
The rise in the prevalence of autoimmune diseases in developed societies has been associated with a change in lifestyle patterns. Among other factors, increased consumption of certain dietary components, such as table salt and fatty acids and excessive caloric intake has been associated with defective immunological tolerance. Dietary nutrients have shown to modulate the immune response by a direct effect on the function of immune cells or, indirectly, by acting on the microbiome of the gastrointestinal tract. FOXP3
regulatory T cells (Tregs) suppress immune responses and are critical for maintaining peripheral tolerance and immune homeostasis, modulating chronic tissue inflammation and autoimmune disease. It is now well-recognized that Tregs show certain degree of plasticity and can gain effector functions to adapt their regulatory function to different physiological situations during an immune response. However, plasticity of Tregs might also result in conversion into effector T cells that may contribute to autoimmune pathogenesis. Yet, which environmental cues regulate Treg plasticity and function is currently poorly understood, but it is of significant importance for therapeutic purposes. Here we review the current understanding on the effect of certain dietary nutrients that characterize Western diets in Treg metabolism, stability, and function. Moreover, we will discuss the role of Tregs linking diet and autoimmunity and the potential of dietary-based interventions to modulate Treg function in disease.
Journal Article
High-Salt Diet Induces Depletion of Lactic Acid-Producing Bacteria in Murine Gut
Dietary habits are amongst the main factors that influence the gut microbiome. Accumulating evidence points to the impact of a high-salt diet (HSD) on the composition and function of the intestinal microbiota, immune system and disease. In the present study, we thus investigated the effects of different NaCl content in the food (0.03%/sodium deficient, 0.5%/control, 4% and 10% NaCl) on the gut microbiome composition in mice. The bacterial composition was profiled using the 16S ribosomal RNA (rRNA) gene amplicon sequencing. Our results revealed that HSD led to distinct gut microbiome compositions compared to sodium-deficient or control diets. We also observed significant reduction in relative abundances of bacteria associated with immuno-competent short-chain fatty acid (SCFA) production (Bifidobacterium, Faecalibaculum, Blautia and Lactobacillus) in HSD-fed mice along with significant enrichment of Clostridia, Alistipes and Akkermansia depending on the sodium content in food. Furthermore, the predictive functional profiling of microbial communities indicated that the gut microbiota found in each category presents differences in metabolic pathways related to carbohydrate, lipid and amino acid metabolism. The presented data show that HSD cause disturbances in the ecological balance of the gastrointestinal microflora primarily through depletion of lactic acid-producing bacteria in a dose-dependent manner. These findings may have important implications for salt-sensitive inflammatory diseases.
Journal Article
Cortactin is in a complex with VE-cadherin and is required for endothelial adherens junction stability through Rap1/Rac1 activation
Vascular permeability is mediated by Cortactin (Cttn) and regulated by several molecules including cyclic-adenosine-monophosphate, small Rho family GTPases and the actin cytoskeleton. However, it is unclear whether Cttn directly interacts with any of the junctional components or if Cttn intervenes with signaling pathways affecting the intercellular contacts and the cytoskeleton. To address these questions, we employed immortalized microvascular myocardial endothelial cells derived from wild-type and Cttn-knock-out mice. We found that lack of Cttn compromised barrier integrity due to fragmented membrane distribution of different junctional proteins. Moreover, immunoprecipitations revealed that Cttn is within the VE-cadherin-based adherens junction complex. In addition, lack of Cttn slowed-down barrier recovery after Ca
2+
repletion. The role of Cttn for cAMP-mediated endothelial barrier regulation was analyzed using Forskolin/Rolipram. In contrast to Cttn-KO, WT cells reacted with increased transendothelial electrical resistance. Absence of Cttn disturbed Rap1 and Rac1 activation in Cttn-depleted cells. Surprisingly, despite the absence of Cttn, direct activation of Rac1/Cdc42/RhoA by CN04 increased barrier resistance and induced well-defined cortical actin and intracellular actin bundles. In summary, our data show that Cttn is required for basal barrier integrity by allowing proper membrane distribution of junctional proteins and for cAMP–mediated activation of the Rap1/Rac1 signaling pathway.
Journal Article
Plakoglobin does not participate in endothelial barrier stabilization mediated by cAMP
Critical for maintenance of endothelial barrier is the remodeling of the actin cytoskeleton and the precise control of junctional integrity. Plakoglobin (PG) is a structural and signaling protein involved in vascular permeability regulation together with key signaling molecules such as cAMP, Rho GTPases and actin-binding proteins. Here, we investigated the role of PG in cAMP-mediated endothelial barrier stabilization by establishing myocardial endothelial cells derived from wild type (WT) and PG knock-out (PG-KO) mice. Under basal conditions, TEER measurements showed increased barrier function of PG-KO, an effect associated with enhanced protein levels and junctional VE-cadherin and β-catenin accumulation. PG-KO cells also displayed more PECAM-1 and VE-PTP-phosphatase and less phosphorylated VE-cadherin, typically linked with modulation of junctional integrity. PG ablation neither changed the composition of VE-cadherin/β-catenin complex nor activities of Rac1 and RhoA but decreased the basal intracellular cAMP concentration. Remarkably, cAMP augmentation led to enhanced Rac1 activity and TEER in both cell lines, but the effect was less prominent in PG-KO. The tighter barrier in WT was paralleled with more VE-cadherin, β-catenin and cortactin, an actin-binding protein, towards junctions. Surprisingly, PG phosphorylation at Ser665 was not required for cAMP-mediated endothelial barrier integrity, which is different to cardiomyocyte and keratinocyte cell adhesion.
Journal Article
Lack of adducin impairs the stability of endothelial adherens and tight junctions and may be required for cAMP-Rac1-mediated endothelial barrier stabilization
Adducin (Add) is an actin binding protein participating in the stabilization of actin/spectrin networks, epithelial junctional turnover and cardiovascular disorders such as hypertension. Recently, we demonstrated that Add is required for adherens junctions (AJ) integrity. Here we hypothesized that Add regulates tight junctions (TJ) as well and may play a role in cAMP-mediated barrier enhancement. We evaluated the role of Add in MyEnd cells isolated from WT and Add-Knock-Out (KO) mice. Our results indicate that the lack of Add drastically alters the junctional localization and protein levels of major AJ and TJ components, including VE-Cadherin and claudin-5. We also showed that cAMP signaling induced by treatment with forskolin and rolipram (F/R) enhances the barrier integrity of WT but not Add-KO cells. The latter showed no junctional reorganization upon cAMP increase. The absence of Add also led to higher protein levels of the small GTPases Rac1 and RhoA. In vehicle-treated cells the activation level of Rac1 did not differ significantly when WT and Add-KO cells were compared. However, the lack of Add led to increased activity of RhoA. Moreover, F/R treatment triggered Rac1 activation only in WT cells. The function of Rac1 and RhoA per se was unaffected by the total ablation of Add, since direct activation with CN04 was still possible in both cell lines and led to improved endothelial barrier function. In the current study, we demonstrate that Add is required for the maintenance of endothelial barrier by regulating both AJ and TJ. Our data show that Add may act upstream of Rac1 as it is necessary for its activation via cAMP.
Journal Article