Topic Review
Blood-Brain Barrier: Functionalised Chitosan
The major impediment to the delivery of therapeutics to the brain is the presence of the blood-brain barrier (BBB). The BBB allows for the entrance of essential nutrients while excluding harmful substances, including most therapeutic agents; hence, brain disorders, especially tumors, are very difficult to treat. Chitosan is a well-researched polymer that offers advantageous biological and chemical properties, such as mucoadhesion and ease of functionalization. Chitosan-based nanocarriers (CsNCs) establish ionic interactions with the endothelial cells, facilitating the crossing of drugs through the BBB by adsorptive mediated transcytosis. This process is further enhanced by modifications of the structure of chitosan, owing to the presence of reactive amino and hydroxyl groups. Finally, by permanently binding ligands or molecules, such as antibodies or lipids, CsNCs have shown a boosted passage through the BBB, in both in vivo and in vitro studies which will be discussed in this review.
  • 439
  • 21 Nov 2020
Topic Review
Bisphenols
Bisphenols (BPs), and especially bisphenol A (BPA), are known endocrine disruptors (EDCs), capable of interfering with estrogen and androgen activities, as well as being suspected of other health outcomes.
  • 416
  • 28 Oct 2020
Topic Review
Congenital Malformations in Sea Turtles
Congenital malformations can lead to embryonic mortality in many species, and sea turtles are no exception. Genetic and/or environmental alterations occur during early development in the embryo, and may produce aberrant phenotypes, many of which are incompatible with life. Causes of malformations are multifactorial; genetic factors may include mutations, chromosomal aberrations, and inbreeding effects, whereas non-genetic factors may include nutrition, hyperthermia, low moisture, radiation, and contamination. It is possible to monitor and control some of these factors (such as temperature and humidity) in nesting beaches, and toxic compounds in feeding areas, which can be transferred to the embryo through their lipophilic properties.
  • 407
  • 22 Feb 2021
Topic Review
Bradoriids and the Cambrian Diversification
Bradoriids, among the earliest arthropods to appear in the fossil record, are extinct, ostracod-like bivalved forms that ranged from the early Cambrian to the Middle Ordovician. Bradoriids are notable for having appeared in the Cambrian fossil record before the earliest trilobites, and considering their rapid ascent to high genus-level diversity, provide key data for our understanding of the evolutionary dynamics of the Cambrian Explosion. This paper presents a broad review of bradoriid paleobiology. 
  • 378
  • 29 Oct 2020
Topic Review
Surfactant and the Glycocalyx
Gas exchange in the lung takes place via the air-blood barrier in the septal walls of alveoli. The tissue elements that oxygen molecules have to cross are the alveolar epithelium, the interstitium and the capillary endothelium. The epithelium that lines the alveolar surface is covered by a thin and continuous liquid lining layer. Pulmonary surfactant acts at this air-liquid interface. By virtue of its biophysical and immunomodulatory functions, surfactant keeps alveoli open, dry and clean. What needs to be added to this picture is the glycocalyx of the alveolar epithelium. Here, we briefly review what is known about this glycocalyx and how it can be visualized using electron microscopy. The application of colloidal thorium dioxide as a staining agent reveals differences in the staining pattern between type I and type II alveolar epithelial cells and shows close associations of the glycocalyx with intraalveolar surfactant subtypes such as tubular myelin. These morphological findings indicate that specific spatial interactions between components of the surfactant system and those of the alveolar epithelial glycocalyx exist which may contribute to the maintenance of alveolar homeostasis, in particular to alveolar micromechanics, to the functional integrity of the air-blood barrier, to the regulation of the thickness and viscosity of the alveolar lining layer, and to the defence against inhaled pathogens. Exploring the alveolar epithelial glycocalyx in conjunction with the surfactant system opens novel physiological perspectives of potential clinical relevance for future research.
  • 359
  • 03 May 2021
Topic Review
Spinal-Deformities and Advancement in Corrective-Orthoses
Spinal deformity is an abnormality in the spinal curves and can seriously affect the activities of daily life. The conventional way to treat spinal deformities, such as scoliosis, kyphosis, and spondylolisthesis, is to use spinal orthoses (braces). Braces have been used for centuries to apply corrective forces to the spine to treat spinal deformities or to stabilize the spine during postoperative rehabilitation. Braces have not modernized with advancements in technology, and very few braces are equipped with smart sensory design and active actuation. There is a need to enable the orthotists, ergonomics practitioners, and developers to incorporate new technologies into the passive field of bracing. 
  • 354
  • 30 Jan 2021
Topic Review
Adhesion Protein Sialylation
The importance of adhesion protein sialylation was recognized by studying the changes of adhesion behavior of human tissue cells exposed in vitro to microgravity. Proteins involved in cell-cell or cell-extracellular matrix adhesion were investigated by retrieving and evaluation of information about sialylation of cell adhesion molecules detected by omics studies on cells, which change their adhesion behavior when exposed to microgravity. Using a knowledge graph created from experimental omics data and semantic searches across several reference databases, sialylation of adhesion proteins glycosylated at their extracellular domains and their impact in cellular processes were studied. This way, experimental omics data networked with the current knowledge about binding of sialic acids to cell adhesion proteins, its regulation and interactions in-between those proteins provided insights in the mechanisms behind experimental findings suggesting that balancing sialylation against de-sialylation of the terminal ends of the adhesion proteins’ glycans influences the binding activity of adhesion proteins, the interaction of cells and their aggregation. This shed light on the transition from the cells’ growth in a monolayer to spheroid formation observed in microgravity mirroring cell migration and cancer metastasis in vivo.
  • 351
  • 30 Oct 2020
Topic Review
Bamboo Node’s Vascular Bundle
The vascular bundle is an important structural unit that determines the growth and properties of bamboo. A high-resolution X-ray microtomography (μCT) was used to observe and reconstruct a three-dimensional (3D) morphometry model of the vascular bundle of the Qiongzhuea tumidinoda node due to its advantages of quick, nondestructive, and accurate testing of plant internal structure.
  • 281
  • 23 Dec 2021
Topic Review
T-Cell Receptor Signalosome
Human immunodeficiency virus type-1 (HIV-1) can undergo either a lytic pathway to cause productive systemic infection or enter a latent state in which the integrated provirus remains transcriptionally silent for decades. The ability to latently infected T-cells enables HIV-1 to establish persistent infections in resting memory CD4+ T-lymphocytes which become reactivated following disruption or cessation of intensive drug therapy. Maintenance of viral latency occurs through epigenetic and non-epigenetic mechanisms. Epigenetic mechanisms of HIV latency regulation involve deacetylation and methylation of histone proteins within Nucleosome 1 (nuc -1) at the viral long terminal repeats (LTR) such that inhibition of histone deacetyltransferase and histone lysine methyltransferase activities, respectively, reactivates HIV from latency. Non-epigenetic mechanisms involve nuclear restriction of critical cellular transcription factors such as Nuclear factor-kappa Beta (NF-kB) or Nuclear factor of activated T-cells (NFAT) which activate transcription from the viral LTR, limiting nuclear levels of viral transcription transactivator protein Tat and its cellular co-factor; positive transcription elongation factor b (P-TEFb) which together regulate HIV transcriptional elongation. The T-cell receptor (TCR) activation efficiently induces NF-kB, NFAT, and activator protein 1 (AP-1) transcription factors through multiple signal pathways and how these factors efficiently regulate HIV LTR transcription through the non-epigenetic mechanism. Elongation factor P-TEFb induced through an extracellular signal-regulated kinase (ERK) dependent mechanism regulates HIV transcriptional elongation before Tat is synthesized and the role of AP-1 in the modulation of HIV transcriptional elongation through functional synergy with NF-kB. The TCR signaling induces critical posttranslational modifications of the Cyclin-dependent kinase 9 (CDK9) subunit of P-TEFb which enhances interactions between P-TEFb and viral Tat protein and the resultant enhancement of HIV transcriptional elongation.
  • 248
  • 13 Aug 2020
Topic Review
Gastrointestinal and Intestinal Signals
Signals mediating satiety and satiation arise from various locations within the luminal gastrointestinal tract including the stomach, duodenum, jejunum, ileum and colon. Ingestion of food results in mechanical stimulation by distension of the stomach and small intestine and in chemical stimulation via activation of nutrient receptors on enteroendocrine cells (EECs). These EECs play a pivotal role in the gastrointestinal and central regulation of not only of gastrointestinal (GI) motility and secretion but also of food intake.
  • 229
  • 18 Jun 2021
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