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دينو الديناصور
يعرض الكتاب قصة\" دينو\" وهو ديناصور صغير، له رقبة طويلة فتسخر منه الديناصورات الأخرى. ورغم ذلك يساعدها بذكائه، في مواقف صعبة عديدة، مما ينمى داخل الطفل الإحساس بالآخر المختلف وقبوله وأهمية التعامل معه. وذلك بأسلوب جديد مبتكر حيث تتخذ الرسوم رموزا لكلمات وعلى القارئ أن يخمنها لكي ينسج القصة ويكملها ويساعد على ذلك طبيعة تكوين الجملة العربية البسيط إلى جانب قائمة مفردات بآخر الرواية. مما يثير خيال الطفل وحب المعرفة لديه والقدرة على الحدس.
Book
Ruminococcus torques is a keystone degrader of intestinal mucin glycoprotein, releasing oligosaccharides used by Bacteroides thetaiotaomicron
ABSTRACT Symbiotic interactions between humans and our communities of resident gut microbes (microbiota) play many roles in health and disease. Some gut bacteria utilize mucus as a nutrient source and can under certain conditions damage the protective barrier it forms, increasing disease susceptibility. We investigated how Ruminococcus torques— a known mucin degrader that has been implicated in inflammatory bowel diseases (IBDs)—degrades mucin glycoproteins or their component O -linked glycans to understand its effects on the availability of mucin-derived nutrients for other bacteria. We found that R. torques utilizes both mucin glycoproteins and released oligosaccharides from gastric and colonic mucins, degrading these substrates with a panoply of mostly constitutively expressed, secreted enzymes. Investigation of mucin oligosaccharide degradation by R. torques revealed strong α-L-fucosidase, sialidase and β1,4-galactosidase activities. There was a lack of detectable sulfatase and weak β1,3-galactosidase degradation, resulting in accumulation of glycans containing these structures on mucin polypeptides. While the Gram-negative symbiont, Bacteroides thetaiotaomicron grows poorly on mucin glycoproteins, we demonstrate a clear ability of R. torques to liberate products from mucins, making them accessible to B. thetaiotaomicron . This work underscores the diversity of mucin-degrading mechanisms in different bacterial species and the probability that some species are contingent on others for the ability to more fully access mucin-derived nutrients. The ability of R. torques to directly degrade a variety of mucin and mucin glycan structures and unlock released glycans for other species suggests that it is a keystone mucin degrader, which might contribute to its association with IBD. IMPORTANCE An important facet of maintaining healthy symbiosis between host and intestinal microbes is the mucus layer, the first defense protecting the epithelium from lumenal bacteria. Some gut bacteria degrade the various components of intestinal mucins, but detailed mechanisms used by different species are still emerging. It is imperative to understand these mechanisms as they likely dictate interspecies interactions and may illuminate species associated with bacterial mucus damage and subsequent disease susceptibility. Ruminococcus torques is positively associated with IBD in multiple studies. We identified mucin glycan-degrading enzymes in R. torques and found that it shares mucin degradation products with another species of gut bacteria, Bacteroides thetaiotaomicron . Our findings underscore the importance of understanding mucin degradation mechanisms in different gut bacteria and their consequences on interspecies interactions, which may identify keystone bacteria that disproportionately affect mucus damage and could therefore be key players in effects that result from reductions in mucus integrity.
Journal Article
A single sulfatase is required to access colonic mucin by a gut bacterium
Humans have co-evolved with a dense community of microbial symbionts that inhabit the lower intestine. In the colon, secreted mucus creates a barrier that separates these microorganisms from the intestinal epithelium
1
. Some gut bacteria are able to utilize mucin glycoproteins, the main mucus component, as a nutrient source. However, it remains unclear which bacterial enzymes initiate degradation of the complex
O
-glycans found in mucins. In the distal colon, these glycans are heavily sulfated, but specific sulfatases that are active on colonic mucins have not been identified. Here we show that sulfatases are essential to the utilization of distal colonic mucin
O
-glycans by the human gut symbiont
Bacteroides thetaiotaomicron
. We characterized the activity of 12 different sulfatases produced by this species, showing that they are collectively active on all known sulfate linkages in
O
-glycans. Crystal structures of three enzymes provide mechanistic insight into the molecular basis of substrate specificity. Unexpectedly, we found that a single sulfatase is essential for utilization of sulfated
O
-glycans in vitro and also has a major role in vivo. Our results provide insight into the mechanisms of mucin degradation by a prominent group of gut bacteria, an important process for both normal microbial gut colonization
2
and diseases such as inflammatory bowel disease
3
.
A single sulfatase produced by a bacterium found in the human colon is essential for degradation of sulfated
O
-glycans in secreted mucus.
Journal Article
Kinetic modelling for concentration and toxicity changes during the oxidation of 4-chlorophenol by UV/H2O2
This work develops a kinetic model that allow to predict the water toxicity and the main degradation products concentration of aqueous solutions containing 4-chlorophenol oxidised by UV/H
2
O
2
. The kinetic model was developed grouping degradation products of similar toxicological nature: aromatics (hydroquinone, benzoquinone, 4-chlorocatechol and catechol), aliphatics (succinic, fumaric, maleic and malonic acids) and mineralised compounds (oxalic, acetic and formic acids). The degradation of each group versus time was described as a mathematical function of the rate constant of a second-order reaction involving the hydroxyl radical, the quantum yield of lump, the concentration of the hydroxyl radicals and the intensity of the emitted UV radiation. The photolytic and kinetic parameters characterising each lump were adjusted by experimental assays. The kinetic, mass balance and toxicity equations were solved using the Berkeley Madonna numerical calculation tool. Results showed that 4-chlorophenol would be completely removed during the first hour of the reaction, operating with oxidant molar ratios higher than
R
= 200 at pH 6.0 and UV = 24 W. Under these conditions, a decrease in the rate of total organic carbon (TOC) removal close to 50% from the initial value was observed. The solution colour, attributed to the presence of oxidation products as
p
-benzoquinone and hydroquinone, were oxidised to colourless species, that resulted in a decrease in the toxicity of the solutions (9.95 TU) and the aromaticity lost.
Journal Article
Sulfated glycan recognition by carbohydrate sulfatases of the human gut microbiota
Sulfated glycans are ubiquitous nutrient sources for microbial communities that have coevolved with eukaryotic hosts. Bacteria metabolize sulfated glycans by deploying carbohydrate sulfatases that remove sulfate esters. Despite the biological importance of sulfatases, the mechanisms underlying their ability to recognize their glycan substrate remain poorly understood. Here, we use structural biology to determine how sulfatases from the human gut microbiota recognize sulfated glycans. We reveal seven new carbohydrate sulfatase structures spanning four S1 sulfatase subfamilies. Structures of S1_16 and S1_46 represent novel structures of these subfamilies. Structures of S1_11 and S1_15 demonstrate how non-conserved regions of the protein drive specificity toward related but distinct glycan targets. Collectively, these data reveal that carbohydrate sulfatases are highly selective for the glycan component of their substrate. These data provide new approaches for probing sulfated glycan metabolism while revealing the roles carbohydrate sulfatases play in host glycan catabolism.Comprehensive structural biology analysis of seven members of the S1 carbohydrate sulfatase family derived from human gut microbiome Bacteroides reveals mechanisms of glycan recognition and sulfate hydrolysis.
Journal Article
Impact of Hydrogen Peroxide Concentration on Diclofenac Degradation by UV/H2O2: Kinetic Modeling for Water Treatment Applications
This study researches the impact of diclofenac (DCF) oxidation via UV/H2O2 on water quality, focusing on aromaticity and color changes. The process effectively degrades DCF and its intermediates through hydroxyl radical attack on the aromatic structure, leading to the formation of oxidized by-products. Initially, chromophoric compounds such as quinones and conjugated intermediates cause a yellow coloration, which diminishes as mineralization progresses. Turbidity remains below 1 NTU, aligning with European water quality standards. Aromaticity initially increases due to the stable intermediates (e.g., catechols and hydroquinones) but decreases as advanced oxidation cleaves aromatic rings. Kinetic modeling shows that DCF degradation follows first-order kinetics, while aromatic intermediates degrade via fractional-order kinetics (~0.3), indicating a non-linear relationship with concentration. The formation of chromophore compounds follows first-order kinetics, whereas their degradation transitions to zero-order kinetics when hydroxyl radicals are abundant. The study highlights the environmental relevance of these transformations, as aromatic intermediates like anilines and phenols, which contribute to water toxicity, are ultimately converted into less hazardous compounds (e.g., carboxylic acids and inorganic ions). Experimental validation confirms that degradation kinetics depend on hydrogen peroxide concentration, underscoring the potential of UV/H2O2 for water purification and pollutant removal.
Journal Article
In vitro and in silico evaluations of resin-based dental restorative material toxicity
ObjectivesThis study aims to evaluate the cytocompatibility of three provisional restoration materials and predict neurotoxic potential of their monomers. These materials are Tab 2000® (methyl methacrylate based), ProTemp 4™ (bis-acrylic based) and Structur 3® (urethane dimethacrylate based).Materials and methodsResin samples were incubated in a cell culture medium and the cytotoxic effects of these extracts were studied in 3T3 fibroblast cells through MTT and crystal violet assays as well as ROS assessment. The presence of relevant leached monomers was determined by HPLC. Additionally, the blood-brain barrier (BBB) permeability to these resin-based monomers was predicted using ACD/Labs algorithms model.ResultsCell survival rates were compared with the resin extracts, and Structur 3® was statistically significant different from the others (p < 0.001) at all-time incubation periods. All materials induced a dose-dependent loss of cell viability; however, only Structur 3 extracts were cytotoxic against 3T3 fibroblasts. The highest cytotoxic effect (77%, p < 0.001) was observed at 24 h incubation period, which may be associated with the presence of urethane dimethacrylate (UDMA) leached monomers. Furthermore, the computational model showed that most monomers under study are expectedly capable of crossing the BBB.ConclusionsOur results showed that Structur 3® is not cytocompatible with our cell model and UDMA is a potential neurotoxic compound.Clinical relevanceThese results indicate that only ProTemp 4™ and Tab 2000® are safe for provisional restorations.
Journal Article
Peripheral Nerve Injury Treatments and Advances: One Health Perspective
Peripheral nerve injuries (PNI) can have several etiologies, such as trauma and iatrogenic interventions, that can lead to the loss of structure and/or function impairment. These changes can cause partial or complete loss of motor and sensory functions, physical disability, and neuropathic pain, which in turn can affect the quality of life. This review aims to revisit the concepts associated with the PNI and the anatomy of the peripheral nerve is detailed to explain the different types of injury. Then, some of the available therapeutic strategies are explained, including surgical methods, pharmacological therapies, and the use of cell-based therapies alone or in combination with biomaterials in the form of tube guides. Nevertheless, even with the various available treatments, it is difficult to achieve a perfect outcome with complete functional recovery. This review aims to enhance the importance of new therapies, especially in severe lesions, to overcome limitations and achieve better outcomes. The urge for new approaches and the understanding of the different methods to evaluate nerve regeneration is fundamental from a One Health perspective. In vitro models followed by in vivo models are very important to be able to translate the achievements to human medicine.
Journal Article
Kinetic Modelling of Aromaticity and Colour Changes during the Degradation of Sulfamethoxazole Using Photo-Fenton Technology
Sulfamethoxazole (SMX) is an antibiotic that is extensively used in veterinary medicine, and its occurrence in wastewater and surface water can reach up to 20 μg/L. SMX is categorized as a pollutant of emerging concern by the US EPA due to its persistence and effects on humans and the environment. In this study, photo-Fenton technology is proposed for the removal of SMX. Aqueous solutions of SMX (50.0 mg/L) are treated in a 150 W UV photoreactor, using [Fe2+]0 = 0.5 mg/L and varying [H2O2]0 = 0–3.0 mM. During the reaction, colour (AU) was assessed along with SMX (mg/L), turbidity (NTU), and TC (mg/L). SMX degrades to aromatic intermediates with chromophoric groups, exhibiting colour (yellow to brown) and turbidity. As these intermediates are mineralized into CO2 and H2O, the colour and turbidity of the water lose intensity. Using a molar ratio of 1 mol SMX:10 mol H2O2, the maximum degradation of aromatic species takes place (71% elimination), and colourless water with turbidity < 1 NTU is obtained. A kinetic modelling for aromaticity loss and colour formation as a function of the oxidant concentration has been proposed. The application of this model allows the estimation of oxidant amounts for an efficient removal of SMX under environmentally friendly conditions.
Journal Article