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Topic Review
Epigenetic Regulation of the β-Globin Genes
Beta-like globin gene expression is developmentally regulated during life by transcription factors, chromatin looping and epigenome modifications of the β-globin locus. Epigenome modifications, such as histone methylation/demethylation and acetylation/deacetylation and DNA methylation, are associated with up- or down-regulation of gene expression. The understanding of these mechanisms and their outcome in gene expression has paved the way to the development of new therapeutic strategies for treating various diseases, such as β-hemoglobinopathies.
  • 1.9K
  • 06 Mar 2023
Topic Review
Pluripotent Stem Cell
Pluripotent stem cells (PSC) such as embryonic stem cells (ESC) and induced PSCs (iPSC) are originated from embryos and induced from adult tissue cells, respectively. PSCs are capable of proliferating almost indefinitely, and differentiating into all somatic cells, through processes that mimic early embryogenesis. The resulting cells tend to carry embryonic characteristics.
  • 1.8K
  • 11 Oct 2021
Topic Review
Structural Neuroimaging Findings in Developmental Language Disorder
Developmental language disorder (DLD) is a heterogenous neurodevelopmental disorder that affects a child’s ability to comprehend and/or produce spoken and/or written language, yet it cannot be attributed to hearing loss or overt neurological damage. The link between brain development and language outcomes in children with DLD is unclear, and this lack of connection is apparent when reviewing the DLD neuroimaging literature. Over the past 50 years, there have been fewer than 60 neuroimaging studies (excluding EEG studies) with children diagnosed with DLD. The majority of these studies have focused on structural brain differences when compared to language-unimpaired (neurotypical) children or children with other neurodevelopmental language disorders, such as children diagnosed with ASD and concomitant language impairment. Though there are some consistencies differences in participant selection and inclusion, diagnostic criteria, methodology, and analyses used underlie the disparate findings to date. As such, comparing the results across studies and evaluating how structural brain abnormalities contribute to language impairment in children with DLD is challenging. Nonetheless, the researchers provide a general overview of structural neuroimaging findings in DLD and highlight consistent patterns of results.
  • 1.8K
  • 14 Dec 2023
Topic Review
Spleen Reparative Regeneration
The spleen is the largest lymphoid unpaired parenchymal organ of the abdominal cavity found in all vertebrates. Spleen is able to regenerate, though not necessarily to the initial volume. The recovery lasts one month and preserves the architecture, albeit with an increase in the relative volume of lymphoid follicles. The renovated tissues, however, exhibit skewed functional profiles; notably, the decreased production of antibodies and the low cytotoxic activity of T cells, consistent with the decline of T-dependent zones and prolonged reduction in T cell numbers. Autotransplantations of splenic material are of particular clinical interest, as the procedure can possibly mitigate the development of post-splenectomy syndrome. Under these conditions, regeneration lasts 1-2 months, depending on the species. The transplants effectively destroy senescent erythrocytes, assist in microbial clearance, and produce antibodies, thus averting sepsis and bacterial pneumonia. Meanwhile, cellular sources of splenic recovery in such models remain obscure, as well as the time required for T and B cell number re-constitution.
  • 1.6K
  • 21 Jun 2022
Topic Review
Branchiomeric Muscle Development
Branchiomeric skeletal muscles are a subset of head muscles originating from skeletal muscle progenitor cells in the mesodermal core of pharyngeal arches. These muscles are involved in facial expression, mastication, and function of the larynx and pharynx. Branchiomeric muscles have been the focus of many studies over the years due to their distinct developmental programs and common origin with the heart muscle.
  • 1.6K
  • 06 Sep 2022
Topic Review
Alveologenesis
Alveologenesis is the final stage of lung maturation, when an alveolar region is divided into smaller units called alveoli via the process known as secondary septation. Each of the formed septa serves as a new gas exchange surface, and all together, they dramatically increase the respiratory surface area. Alveologenesis is divided into 2 phases: classical and continued. During the classical alveologenesis, the secondary septa are formed and the number of alveoli increases. During the continued alveologenesis, the maturation and thinning of the septa occur and the size of alveoli increases. The disruption of alveologenesis leads to the simplification of the alveoli, as seen in preterm infants diagnosed with bronchopulmonary dysplasia (BPD), a widespread pulmonary disease that is often connected with lifelong respiratory failure.
  • 1.6K
  • 23 Nov 2021
Topic Review
Cell Cycle Regulation in Pluripotent Stem Cells
Pluripotent stem cells (PSCs) hold great promise in cell-based therapy because of their pluripotent property and the ability to proliferate indefinitely. Embryonic stem cells (ESCs) derived from inner cell mass (ICM) possess unique cell cycle control with shortened G1 phase. In addition, ESCs have high expression of homologous recombination (HR)-related proteins, which repair double-strand breaks (DSBs) through HR or the non-homologous end joining (NHEJ) pathway.
  • 1.6K
  • 17 Nov 2021
Topic Review
Organ Abnormalities Caused by Turner Syndrome
Turner syndrome (TS), a genetic disorder due to incomplete dosage compensation of X-linked genes, affects multiple organ systems, leading to hypogonadotropic hypogonadism, short stature, cardiovascular and vascular abnormalities, liver disease, renal abnormalities, brain abnormalities, and skeletal problems. Patients with TS experience premature ovarian failure with a rapid decline in ovarian function caused by germ cell depletion, and pregnancies carry a high risk of adverse maternal and fetal outcomes. Aortic abnormalities, heart defects, obesity, hypertension, and liver abnormalities, such as steatosis, steatohepatitis, biliary involvement, liver cirrhosis, and nodular regenerative hyperplasia, are commonly observed in patients with TS.
  • 1.6K
  • 23 May 2023
Topic Review
Stem Cell Therapy for Infertility
Stem cells are a subtype of cells that remain in undifferentiated form in embryos and in adult tissues and can self-renew and differentiate as and when required. Stem cells in differentiated organs contribute to the restoration of function through organ damage repair. According to their origin, stem cells are classified as embryonic stem cells (ESC), adult stem cells (includes mesenchymal stem cells MSC), induced pluripotent stem cells (iPSC), spermatogonial stem cells (SSCs), and ovarian stem cells. Stem Cells can be applicable for several disorders including infertility both in male and female.
  • 1.6K
  • 22 Jul 2021
Topic Review
Congenital Lung Malformations
Congenital lung malformations arise during development and include numerous anatomical anomalies of the lung and respiratory tree. They are usually detected prenatally by ultrasonography and comprise congenital pulmonary airway malformation (CPAM), bronchopulmonary sequestration (BPS), bronchogenic cysts (BC), and more rarely bronchial atresia, congenital lobar emphysema (CLE), and congenital tracheal obstruction. This entry focuses on the molecular and genetic determinants of the most frequent anomalies: CPAM, BPS, and BC. Congenital diaphragmatic hernia (CDH) is not usually included in this group; however, since the lung is also highly affected in this condition, we have also incorporated evidence related to lung hypoplasia.
  • 1.5K
  • 30 Nov 2021
Topic Review
Ubiquitination of ETS Transcription Factors
Genome expansion, whole genome and gene duplication events during metazoan evolution produced an extensive family of ETS genes whose members express transcription factors with a conserved winged helix-turn-helix DNA-binding domain. Key determinants of the cellular repertoire of ETS proteins are their stability and turnover, controlled largely by the actions of selective E3 ubiquitin ligases and deubiquitinases. Here we discuss the known relationships between ETS proteins and enzymes that determine their ubiquitin status, their integration with other developmental signal transduction pathways and how suppression of ETS protein ubiquitination contributes to the malignant cell phenotype in multiple cancers.
  • 1.5K
  • 21 Jul 2021
Topic Review
Ovarian Organogenesis along the Cortical–Medullary Axis in Mammals
In most mammals, the sex of the gonads is based on the fate of the supporting cell lineages, which arises from the proliferation of coelomic epithelium (CE) that surfaces on the bipotential genital ridge in both XY and XX embryos. Genetic studies and single-cell transcriptome analyses in mice have revealed the cellular and molecular events in the two-wave proliferation of the CE that produce the supporting cells. This proliferation contributes to the formation of the primary sex cords in the medullary region of both the testis and the ovary at the early phase of gonadal sex differentiation, as well as to that of the secondary sex cords in the cortical region of the ovary at the perinatal stage. To support gametogenesis, the testis forms seminiferous tubules in the medullary region, whereas the ovary forms follicles mainly in the cortical region. The medullary region in the ovary exhibits morphological and functional diversity among mammalian species that ranges from ovary-like to testis-like characteristics. 
  • 1.5K
  • 31 Jan 2023
Topic Review
Development of SARS-CoV-2 Variants
A novel coronavirus (SARS-CoV-2) emerged towards the end of 2019 that caused a severe respiratory disease in humans called COVID-19. It led to a pandemic with a high rate of morbidity and mortality that is ongoing and threatening humankind. Most of the mutations occurring in SARS-CoV-2 are synonymous or deleterious, but a few of them produce improved viral functions. The first known mutation associated with higher transmissibility, D614G, was detected in early 2020. Since then, the virus has evolved; new mutations have occurred, and many variants have been described. Depending on the genes affected and the location of the mutations, they could provide altered infectivity, transmissibility, or immune escape. To date, mutations that cause variations in the SARS-CoV-2 spike protein have been among the most studied because of the protein’s role in the initial virus–cell contact and because it is the most variable region in the virus genome. Some concerning mutations associated with an impact on viral fitness have been described in the Spike protein, such as D614G, N501Y, E484K, K417N/T, L452R, and P681R, among others. To understand the impact of the infectivity and antigenicity of the virus, the mutation landscape of SARS-CoV-2 has been under constant global scrutiny. The virus variants are defined according to their origin, their genetic profile (some characteristic mutations prevalent in the lineage), and the severity of the disease they produce, which determines the level of concern. If they increase fitness, new variants can outcompete others in the population. The Alpha variant was more transmissible than previous versions and quickly spread globally. The Beta and Gamma variants accumulated mutations that partially escape the immune defenses and affect the effectiveness of vaccines. Nowadays, the Delta variant, identified around March 2021, has spread and displaced the other variants, becoming the most concerning of all lineages that have emerged. The Delta variant has a particular genetic profile, bearing unique mutations, such as T478K in the spike protein and M203R in the nucleocapsid. This entry summarizes the current knowledge of the different mutations that have appeared in SARS-CoV-2, mainly on the spike protein. It analyzes their impact on the protein function and, subsequently, on the level of concern of different variants and their importance in the ongoing pandemic. 
  • 1.5K
  • 28 Dec 2021
Topic Review
Aperture Formation in Angiosperms
Apertures are the areas where the exine is thinner or even lacking. A great diversity in pollen grain morphology is observed in angiosperms.
  • 1.4K
  • 18 Feb 2022
Topic Review
Autosomal Dominant Lateral Temporal Epilepsy
Autosomal dominant lateral temporal epilepsy (ADLTE) is a genetic focal epilepsy associated with mutations in the LGI1, RELN, and MICAL1 genes. A previous study linking ADLTE with two MICAL1 mutations that resulted in the substitution of a highly conserved glycine residue for serine (G150S) or a frameshift mutation that swapped the last three C-terminal amino acids for 59 extra residues (A1065fs) concluded that the mutations increased enzymatic activity and promoted cell contraction.
  • 1.4K
  • 11 May 2022
Topic Review
Development of Schwann Cells
Schwann cells are glial cells of the peripheral nervous system. They exist in several subtypes and perform a variety of functions in nerves. Their derivation and culture in vitro are interesting for applications ranging from disease modeling to tissue engineering. Since primary human Schwann cells are challenging to obtain in large quantities, in vitro differentiation from other cell types presents an alternative. To achieve differentiation of Schwann cells from stem cell sources in vitro, cultures are manipulated using molecular factors to emulate developmental signaling events which lead to development of Schwann cells in vivo. Therefore, knowledge of molecular determinants in embryonal development of the Schwann cell fate is key to develop and refine in vitro differentiation protocols.
  • 1.4K
  • 05 Dec 2022
Topic Review
Isthmin Protein Family
Isthmin (ISM) is a secreted protein family with two members, namely ISM1 and ISM2, both containing a TSR1 domain followed by an AMOP domain. Its broad expression pattern suggests diverse functions in developmental and physiological processes. Multiple studies have focused on the functional analysis of the ISM protein family in several events, including angiogenesis, metabolism, organ homeostasis, immunity, craniofacial development, and cancer.
  • 1.4K
  • 06 Jan 2023
Topic Review
Chromatoid Bodies in the Regulation of Spermatogenesis
The CB is a membrane-less perinuclear organelle present in male germ cells which serve as storehouse for mRNAs transported by RNA binding and transport proteins like GRTH/DDX25. It also serves as a processing center of mRNAs awaiting translation during later stages of spermatogenesis. These CBs are involved in diverse pathways like RNA transport, decay, surveillance and regulate the stability of mRNAs to secure the correct timing of protein expression at different stages of spermiogenesis.
  • 1.4K
  • 11 Mar 2022
Topic Review
Human Heart Organoid Development
The emergence of human-induced Pluripotent Stem Cells (hiPSCs) has dramatically improved the understanding of human developmental processes under normal and diseased conditions. The hiPSCs have been differentiated into various tissue-specific cells in vitro, and the advancement in three-dimensional (3D) culture has provided a possibility to generate those cells in an in vivo-like environment. Tissues with 3D structures can be generated using different approaches such as self-assembled organoids and tissue-engineering methods, such as bioprinting. Researchers are interested in studying the self-assembled organoids differentiated from hiPSCs, as they have the potential to recapitulate the in vivo developmental process and be used to model human development and congenital defects. Organoids of tissues such as those of the intestine and brain were developed many years ago, but heart organoids were not reported until recently.
  • 1.4K
  • 10 May 2022
Topic Review
In Vitro Embryogenesis and Gastrulation Using Stem Cells
During early mammalian embryonic development, fertilized one-cell embryos develop into pre-implantation blastocysts and subsequently establish three germ layers through gastrulation during post-implantation development. Stem cells have emerged as a powerful tool to study embryogenesis and gastrulation without the need for eggs, allowing for the generation of embryo-like structures known as synthetic embryos or embryoids. These in vitro models closely resemble early embryos in terms of morphology and gene expression and provide a faithful recapitulation of early pre- and post-implantation embryonic development. Synthetic embryos can be generated through a combinatorial culture of three blastocyst-derived stem cell types, such as embryonic stem cells, trophoblast stem cells, and extraembryonic endoderm cells, or totipotent-like stem cells alone. 
  • 1.4K
  • 26 Sep 2023
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