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Reviews of Environmental Contamination... 2016Caenorhabditis elegans is a nematode of microscopic size which, due to its biological characteristics, has been used since the 1970s as a model for research in molecular... (Review)
Review
Caenorhabditis elegans is a nematode of microscopic size which, due to its biological characteristics, has been used since the 1970s as a model for research in molecular biology, medicine, pharmacology, and toxicology. It was the first animal whose genome was completely sequenced and has played a key role in the understanding of apoptosis and RNA interference. The transparency of its body, short lifespan, ability to self-fertilize and ease of culture are advantages that make it ideal as a model in toxicology. Due to the fact that some of its biochemical pathways are similar to those of humans, it has been employed in research in several fields. C. elegans' use as a biological model in environmental toxicological assessments allows the determination of multiple endpoints. Some of these utilize the effects on the biological functions of the nematode and others use molecular markers. Endpoints such as lethality, growth, reproduction, and locomotion are the most studied, and usually employ the wild type Bristol N2 strain. Other endpoints use reporter genes, such as green fluorescence protein, driven by regulatory sequences from other genes related to different mechanisms of toxicity, such as heat shock, oxidative stress, CYP system, and metallothioneins among others, allowing the study of gene expression in a manner both rapid and easy. These transgenic strains of C. elegans represent a powerful tool to assess toxicity pathways for mixtures and environmental samples, and their numbers are growing in diversity and selectivity. However, other molecular biology techniques, including DNA microarrays and MicroRNAs have been explored to assess the effects of different toxicants and samples. C. elegans has allowed the assessment of neurotoxic effects for heavy metals and pesticides, among those more frequently studied, as the nematode has a very well defined nervous system. More recently, nanoparticles are emergent pollutants whose toxicity can be explored using this nematode. Overall, almost every type of known toxicant has been tested with this animal model. In the near future, the available knowledge on the life cycle of C. elegans should allow more studies on reproduction and transgenerational toxicity for newly developed chemicals and materials, facilitating their introduction in the market. The great diversity of endpoints and possibilities of this animal makes it an easy first-choice for rapid toxicity screening or to detail signaling pathways involved in mechanisms of toxicity.
Topics: Animals; Caenorhabditis elegans; Models, Biological; Toxicology
PubMed: 26613986
DOI: 10.1007/978-3-319-23573-8_1 -
IARC Scientific Publications 2004The biological model of gastric carcinogenesis can be described as a series of sequential phases. The first consists of a chronic active inflammatory response to... (Review)
Review
The biological model of gastric carcinogenesis can be described as a series of sequential phases. The first consists of a chronic active inflammatory response to Helicobacter pylori infection. Infiltration of the gastric mucosa by mucosa-associated lymphoid tissue and polymorphonuclear neutrophils, as well as damage to the epithelial cells, characterize this phase. The second phase is dominated by alterations of the epithelial cell cycle, especially increased rates of apoptosis and cell proliferation. These changes may be responsible for the multifocal atrophy that characterizes the type of gastritis associated with an increased risk of cancer. The third, more advanced phase of the model displays nuclear and architectural abnormalities, which may represent progressive mutational events as expected in classical molecular models of carcinogenesis. The importance of a comprehensive view of the biological model is stressed.
Topics: Cell Differentiation; Cell Division; Disease Susceptibility; Gastric Mucosa; Gastritis; Helicobacter Infections; Humans; Models, Biological; Oxidation-Reduction; Stomach Neoplasms
PubMed: 15055303
DOI: No ID Found -
Stem Cells (Dayton, Ohio) Dec 2021Schizophrenia (SCZ) is a severe brain disorder, characterized by psychotic, negative, and cognitive symptoms, affecting 1% of the population worldwide. The precise... (Review)
Review
Schizophrenia (SCZ) is a severe brain disorder, characterized by psychotic, negative, and cognitive symptoms, affecting 1% of the population worldwide. The precise etiology of SCZ is still unknown; however, SCZ has a high heritability and is associated with genetic, environmental, and social risk factors. Even though the genetic contribution is indisputable, the discrepancies between transcriptomics and proteomics in brain tissues are consistently challenging the field to decipher the disease pathology. Here we provide an overview of the state of the art of neuronal two-dimensional and three-dimensional model systems that can be combined with proteomics analyses to decipher specific brain pathology and detection of alternative entry points for drug development.
Topics: Humans; Models, Biological; Neurons; Proteomics; Schizophrenia; Transcriptome
PubMed: 34431581
DOI: 10.1002/stem.3447 -
Biological Cybernetics Aug 2021Model reduction is a central problem in mathematical biology. Reduced order models enable modeling of a biological system at different levels of complexity and the...
Model reduction is a central problem in mathematical biology. Reduced order models enable modeling of a biological system at different levels of complexity and the quantitative analysis of its properties, like sensitivity to parameter variations and resilience to exogenous perturbations. However, available model reduction methods often fail to capture a diverse range of nonlinear behaviors observed in biology, such as multistability and limit cycle oscillations. The paper addresses this need using differential analysis. This approach leads to a nonlinear enhancement of classical balanced truncation for biological systems whose behavior is not restricted to the stability of a single equilibrium. Numerical results suggest that the proposed framework may be relevant to the approximation of classical models of biological systems.
Topics: Biological Clocks; Models, Biological
PubMed: 34382116
DOI: 10.1007/s00422-021-00888-4 -
Bio Systems Mar 2022The hippocampus is an essential brain region for spatial memory and learning. Recently, a theoretical model of the hippocampus based on temporal difference (TD) learning...
The hippocampus is an essential brain region for spatial memory and learning. Recently, a theoretical model of the hippocampus based on temporal difference (TD) learning has been published. Inspired by the successor representation (SR) learning algorithms, which decompose value function of TD learning into reward and state transition, they argued that the rate of firing of CA1 place cells in the hippocampus represents the probability of state transition. This theory, called predictive map theory, claims that the hippocampus representing space learns the probability of transition from the current state to the future state. The neural correlates of expecting the future state are the firing rates of the CA1 place cells. This explanation is plausible for the results recorded in behavioral experiments, but it is lacking the neurobiological implications. Modifying the SR learning algorithm added biological implications to the predictive map theory. Similar with the simultaneous needs of information of the current and future state in the SR learning algorithm, the CA1 place cells receive two inputs from CA3 and entorhinal cortex. Mathematical transformation showed that the SR learning algorithm is equivalent to the heterosynaptic plasticity rule. The heterosynaptic plasticity phenomena in CA1 were discussed and compared with the modified SR update rule. This study attempted to interpret the TD algorithm as the neurobiological mechanism occurring in place learning, and to integrate the neuroscience and artificial intelligence approaches in the field.
Topics: Artificial Intelligence; Brain; Hippocampus; Models, Biological; Reward
PubMed: 35093444
DOI: 10.1016/j.biosystems.2022.104612 -
Simulation in Healthcare : Journal of... Oct 2021Simulation training is an increasingly used method to train medical students in the use of ultrasound guidance for vascular access positioning. Although very efficient...
INTRODUCTION
Simulation training is an increasingly used method to train medical students in the use of ultrasound guidance for vascular access positioning. Although very efficient for basic training, commercial simulators for vascular access do not reproduce real-life conditions. We developed a biological training model, using porcine liver, and compared it with an existing commercial model.
METHODS
Whole porcine livers were used by perfusing the portal vein system after inferior vena cava clamping. Thirty-three practitioners accustomed to ultrasound-guided procedure were enrolled to perform an ultrasound-guided vascular procedure on both biological and commercial models. Procedure duration was recorded and 10-point scales were used to compare the 2 models regarding image quality, procedure feeling, and similarity with the real-life procedure.
RESULTS
Participants reported a better image quality with the biological model (8.8 ± 1 vs. 7.7 ± 2, P = 0.007) as well as a significant difference in the procedure feeling (8.0 ± 1 vs. 6.9 ± 1.9, P = 0.002). Real-life likeness was significantly better for the biological model (8.4 ± 1.1 vs. 4.5 ± 6, P < 0.0001). Procedure duration was almost 3 times longer using the biological model than the commercial model (209.6 ± 189.0 vs. 59.8 ± 50.1, P < 0.0001).
CONCLUSIONS
This study validates our biological model of porcine's liver as an interesting training model, allowing closer real-life perception than its commercial counterpart. This model could complement and enhance simulation learning.
Topics: Animals; Humans; Models, Biological; Simulation Training; Students, Medical; Swine; Ultrasonography; Ultrasonography, Interventional
PubMed: 33196608
DOI: 10.1097/SIH.0000000000000520 -
Extremophiles : Life Under Extreme... Mar 2009Thermus spp is one of the most wide spread genuses of thermophilic bacteria, with isolates found in natural as well as in man-made thermal environments. The high growth... (Review)
Review
Thermus spp is one of the most wide spread genuses of thermophilic bacteria, with isolates found in natural as well as in man-made thermal environments. The high growth rates, cell yields of the cultures, and the constitutive expression of an impressively efficient natural competence apparatus, amongst other properties, make some strains of the genus excellent laboratory models to study the molecular basis of thermophilia. These properties, together with the fact that enzymes and protein complexes from extremophiles are easier to crystallize have led to the development of an ongoing structural biology program dedicated to T. thermophilus HB8, making this organism probably the best so far known from a protein structure point view. Furthermore, the availability of plasmids and up to four thermostable antibiotic selection markers allows its use in physiological studies as a model for ancient bacteria. Regarding biotechnological applications this genus continues to be a source of thermophilic enzymes of great biotechnological interest and, more recently, a tool for the over-expression of thermophilic enzymes or for the selection of thermostable mutants from mesophilic proteins by directed evolution. In this article, we review the properties of this organism as biological model and its biotechnological applications.
Topics: Biotechnology; Genes, Reporter; Models, Biological; Models, Genetic; Nitrogen; Oxygen Consumption; Plasmids; Temperature; Thermus thermophilus
PubMed: 19156357
DOI: 10.1007/s00792-009-0226-6 -
International Journal of Molecular... Dec 2022Spermatogenesis is a genetically driven differentiation process that occurs in the testis and leads to the formation of spermatozoa. This process is extensively studied... (Review)
Review
Spermatogenesis is a genetically driven differentiation process that occurs in the testis and leads to the formation of spermatozoa. This process is extensively studied in several experimental models, particularly in vertebrates that share the morphological structure and functionality of the mammalian testis. Although reptiles are not generally considered biological models, the lizard has represented a suitable organism for the study of spermatogenesis over the years. In this lizard, the process of spermatogenesis is regulated by the interaction between systemic factors such as gonadotropins and local factors, i.e., molecules produced by the somatic and germinal cells of the testis. Many exogenous substances are able to alter the production of these regulative factors, thus altering the course of spermatogenesis, and has proven to be an excellent model for studying the effects of various endogenous or exogenous substances on mechanisms underlying spermatogenesis. This review summarizes the available data on the effects of different substances on the control of spermatogenesis, highlighting the induced morphological and molecular alterations. Overall, the data show that sex hormone levels as well as the final stages of spermatogenesis are most affected by an imbalance of endogenous compounds or contamination by environmental pollutants. This is helpful for the male individual, since the damage, not affecting the spermatogonial stem cells, can be considered transient and not irreversible.
Topics: Animals; Male; Spermatogenesis; Testis; Lizards; Reproduction; Models, Biological; Mammals
PubMed: 36499547
DOI: 10.3390/ijms232315220 -
Environmental Science and Pollution... Mar 2023Over time, a growing increase in human pollutants in the aquatic environment has been observed. The global presence of residues in water bodies reinforces the need to... (Review)
Review
Over time, a growing increase in human pollutants in the aquatic environment has been observed. The global presence of residues in water bodies reinforces the need to develop improved methods to detect them and evaluate their ecotoxicological effects in aquatic environments. Thus, this study aimed to present the main assays using Biomphalaria glabrata as a biological model for ecotoxicological studies. We performed a systematic literature review with data published up to June 2022 on the Web of Science, SCOPUS, Science Direct, PubMed, and SciELO databases. Thirty studies were selected for this review after screening. Biomphalaria glabrata has been studied as an ecotoxicological model for different substances through toxicity, embryotoxicity, cytotoxicity, genotoxicity, and bioaccumulation assays. Studies evaluating the impact of B. glabrata exposure to several substances have reported effects on their offspring, as well as toxicity and behavioral and reproductive effects. This review presents various assays using B. glabrata as a biological model for ecotoxicological studies. The use of a representative species of ecosystems from tropical regions is a necessary tool for tropical environmental monitoring. It was observed that the freshwater snail B. glabrata was effective for the evaluation of the ecotoxicity of several types of chemical substances, but further studies are needed to standardize the model.
Topics: Animals; Humans; Biomphalaria; Ecotoxicology; Ecosystem; Fresh Water; Models, Biological
PubMed: 36701061
DOI: 10.1007/s11356-023-25455-1 -
Medecine Sciences : M/S Dec 2017The ability to remember past events in all of their dimensions (what? where? when? i.e. autobiographic/episodic memory) is highly adaptive. Conversely, individuals who... (Review)
Review
The ability to remember past events in all of their dimensions (what? where? when? i.e. autobiographic/episodic memory) is highly adaptive. Conversely, individuals who do not have such ability are less likely to benefit from recognizing situations similar to previous ones, e.g. to avoid being defeated several times. We will present the different types of memory and their ontogeny, focusing on those that are found in dogs. We will then describe more precisely the episodic memory, i.e. remembering events or actions from others, and their location and the time of the events and will present to which degree such a skill is found in dogs. We will show that, even if dogs are a social species whose specificities should reveal the existence of an episodic-like memory, dogs remember who and what happened but no study evidenced yet that they remember the precise time it was done. Further studies are thus needed, especially as dogs represent a relevant biological model for comparative cognition to study the ontogeny or senescence of non verbal episodic memory.
Topics: Animals; Behavior, Animal; Cognition; Dogs; Humans; Memory, Episodic; Mental Recall; Models, Animal; Models, Biological
PubMed: 29261497
DOI: 10.1051/medsci/20173312016