Your browser does not fully support modern features. Please upgrade for a smoother experience.
Subject:
All Disciplines Arts & Humanities Biology & Life Sciences Business & Economics Chemistry & Materials Science Computer Science & Mathematics Engineering Environmental & Earth Sciences Medicine & Pharmacology Physical Sciences Public Health & Healthcare Social Sciences
Sort by:
Most Viewed Latest Alphabetical (A-Z) Alphabetical (Z-A)
Filter:
All Topic Review Biography Peer Reviewed Entry Video Entry
Topic Review
Corynebacterium Pseudotuberculosis
Corynebacterium pseudotuberculosis is a Gram-positive bacterium known globally to infect ruminants, horses, and rarely people. This bacterium is a facultative anaerobic organism that is catalase positive and capable of beta-hemolysis. In small ruminants, C. pseudotuberculosis causes a disease called caseous lymphadenitis characterized by pyogranulomatous abscess formation. In general, this bacterium causes lesions of the skin, lymph nodes, and internal organs. A disease known as ulcerative lymphagenitis can also result from infection with C. pseudotuberculosis in the distal limbs of horses. This bacterium uses the virulence factors phospholipase D and mycolic acid to damage eukaryotic cell walls and resist phagocytic lysosomal degradation, respectively. Infection with this bacterium is often confirmed by bacterial culture of the purulent exudate. Once the diagnosis has been made, treatment of the infection can begin, but this is difficult due to the nature of the organism and the lesions it forms. Specifically, C. pseudotuberculosis is intrinsically resistant to streptomycin, with varying resistance to penicillin and neomycin depending on the strain. It has been shown to be susceptible to ampicillin, gentamicin, tetracycline, lincomycin, and chloramphenicol. Vaccines have also been produced to develop acquired immunity to this infection.
  • 1.5K
  • 19 Oct 2022
Topic Review
Gut Microbiome and Lipid Metabolism
Lipids are the major structural constituents of cell membranes.
  • 1.5K
  • 18 Mar 2021
Topic Review
Hepatitis B Virus Infection Understanding
Chronic hepatitis B virus (HBV) infection affects 292 million people worldwide and is associated with a broad range of clinical manifestations including cirrhosis, liver failure, and hepatocellular carcinoma (HCC). Despite the availability of an effective vaccine HBV still causes nearly 900,000 deaths every year. Current treatment options keep HBV under control, but they do not offer a cure as they cannot completely clear HBV from infected hepatocytes. The recent development of reliable cell culture systems allowed for a better understanding of the host and viral mechanisms affecting HBV replication and persistence. Recent advances into the understanding of HBV biology, new potential diagnostic markers of hepatitis B infection, as well as novel antivirals targeting different steps in the HBV replication cycle are summarized in this review article.
  • 1.5K
  • 29 Sep 2020
Topic Review
Heavy Metals Bioremediation
Cadmium (Cd), chromium (Cr) and lead (Pb) are heavy metals that have been classified as priority pollutants in aqueous environment while methane-oxidizing bacteria as a biofilter arguably consume up to 90% of the produced methane in the same aqueous environment before it escapes into the atmosphere. However, the underlying kinetics and active methane oxidizers are poorly understood for the hotspot of epipelon that provides a unique micro-ecosystem containing diversified guild of microorganisms including methane oxidizers for potential bioremediation of heavy metals. In the present study, the Pb2+, Cd2+and Cr6+ bioremediation potential of epipelon biofilm was assessed under both high (120,000 ppm) and near-atmospheric (6 ppm) methane concentrations. Epipelon biofilm demonstrated a high methane oxidation activity following microcosm incubation amended with a high concentration of methane, accompanied by the complete removal of 50 mg L−1 Pb2+ and 50 mg L−1 Cd2+ (14 days) and partial (20%) removal of 50 mg L−1 Cr6+ after 20 days. High methane dose stimulated a faster (144 h earlier) heavy metal removal rate compared to near-atmospheric methane concentrations. DNA-based stable isotope probing (DNA-SIP) following 13CH4 microcosm incubation revealed the growth and activity of different phylotypes of methanotrophs during the methane oxidation and heavy metal removal process. High throughput sequencing of 13C-labelled particulate methane monooxygenase gene pmoA and 16S rRNA genes revealed that the prevalent active methane oxidizers were type I affiliated methanotrophs, i.e., Methylobacter. Type II methanotrophs including Methylosinus and Methylocystis were also labeled only under high methane concentrations. These results suggest that epipelon biofilm can serve as an important micro-environment to alleviate both methane emission and the heavy metal contamination in aqueous ecosystems with constant high methane fluxes.
  • 1.5K
  • 27 Oct 2020
Topic Review
Fungal Melanins in Healthcare
Melanin is a complex multifunctional pigment found in all kingdoms of life, including fungi. The complex chemical structure of fungal melanins, yet to be fully elucidated, lends them multiple unique functions ranging from radioprotection and antioxidant activity to heavy metal chelation and organic compound absorption. Given their many biological functions, fungal melanins present many possibilities as natural compounds that could be exploited for human use. 
  • 1.5K
  • 25 Jun 2021
Topic Review
Cyclospora Cayetanensis
Cyclospora cayetanensis is a coccidian protozoan that causes cyclosporiasis, a severe gastroenteric disease, especially for immunocompromised patients, children, and the elderly. The parasite is considered as an emerging organism and a major contributor of gastroenteritis worldwide. Although the global prevalence of cyclosporiasis morbidity and mortality has not been assessed, global concern has arisen since diarrheal illness and gastroenteritis significantly affect both developing and industrialized countries. In the last two decades, an increasing number of foodborne outbreaks have been associated with the consumption of fresh produce that is difficult to clean thoroughly and is consumed without processing. Investigations of these outbreaks have revealed the necessity to increase the awareness in clinicians of this infection, since this protozoan is often ignored by surveillance systems, and to establish control measures to reduce contamination of fresh produce.
  • 1.5K
  • 01 Dec 2020
Topic Review
Bacterial Phospholipase ExoU
The opportunistic pathogen Pseudomonas aeruginosa employs the type III secretion system (T3SS) and four effector proteins, ExoS, ExoT, ExoU, and ExoY, to disrupt cellular physiology and subvert the host's innate immune response. Of the effector proteins delivered by the T3SS, ExoU is the most toxic. In P. aeruginosa infections, where the ExoU gene is expressed, disease severity is increased with poorer prognoses. This is considered to be due to the rapid and irreversible damage exerted by the phospholipase activity of ExoU, which cannot be halted before conventional antibiotics can successfully eliminate the pathogen. Here we explore what is currently known about ExoU and its potential as a therapeutic target, highlighting some of the small molecule ExoU inhibitors that have been discovered from screening approaches.
  • 1.5K
  • 23 Oct 2020
Topic Review
Gut Microbiome in the Populations
The gut microbiota is emerging as a promising target for the management or prevention of inflammatory and metabolic disorders in humans. Many of the current research efforts are focused on the identification of specific microbial signatures, more particularly for those associated with obesity, type 2 diabetes, and cardiovascular diseases. The Firmicutes/Bacteroidetes ratio is frequently cited in the scientific literature as a healthy hallmark. The aim of the present review was to discuss the validity of this potential marker, based on the great amount of contradictory results reported in the literature. We re-analyzed the 16S rRNA gene sequence data from nine published studies to allow direct comparisons among their Firmicutes/Bacteroidetes ratio. We observed that the relative abundance of the Firmicutes and Bacteroidetes phyla is highly variable between subjects from a same population. This is probably due to many lifestyle-associated factors including diet, physical activity, food additives and contaminants, antibiotic consumption, physical activity, among others that influence the composition of the microbiota in the gastrointestinal tract. This could explain the contradictory results observed when comparing the microbiota between normal-weight and obese subjects, making it difficult to associate the Firmicutes/Bacteroidetes ratio with a determined health status.
  • 1.5K
  • 02 Nov 2020
Topic Review
Outer Membrane Porins in Gram-Negative Bacteria
Gram-negative bacteria depend on their cell membranes for survival and environmental adaptation. They contain two membranes, one of which is the outer membrane (OM), which is home to several different outer membrane proteins (Omps). One class of important Omps is porins, which mediate the inflow of nutrients and several antimicrobial drugs. The microorganism’s sensitivity to antibiotics, which are predominantly targeted at internal sites, is greatly influenced by the permeability characteristics of porins.
  • 1.5K
  • 14 Jul 2023
Topic Review
Cryptococcosis
Cryptococcosis is an important opportunistic infection and a leading cause of meningitis in patients with HIV infection. The current antifungal pharmacological treatment is limited; in addition, the high toxicity, increased resistance rate, and difficulty of the currently available antifungal molecules to cross the blood-brain barrier hamper the treatment. Thus, the search for new alternatives for the treatment of cryptococcosis is extremely necessary. Here we describe the therapeutic strategies currently available and discuss new molecules with antifungal potential in different phases of clinical trials and in the advanced pre-clinical phase.
  • 1.5K
  • 29 Oct 2020
Topic Review
Fungal Infections in COVID-19 Patients
Patients with severe COVID-19, such as individuals in intensive care units (ICU), are exceptionally susceptible to bacterial and fungal infections. The most prevalent fungal infections are aspergillosis and candidemia. Nonetheless, other fungal species (for instance, Histoplasma spp., Rhizopus spp., Mucor spp., Cryptococcus spp.) have recently been increasingly linked to opportunistic fungal diseases in COVID-19 patients. These fungal co-infections are described with rising incidence, severe illness, and death that is associated with host immune response. Awareness of the high risks of the occurrence of fungal co-infections is crucial to downgrade any arrear in diagnosis and treatment to support the prevention of severe illness and death directly related to these infections. 
  • 1.5K
  • 08 Sep 2021
Topic Review
Staphylococcus schweitzeri
The Staphylococcus aureus-related complex is formed by the Staphylococcus aureus, Staphylococcus schweitzeri, Staphylococcus argenteus, Staphylococcus roterodami and Staphylococcus singaporensis. Within this complex, S. schweitzeri is the only species mainly found in African wildlife, but it is rarely detected as a colonizer in humans or as a contaminant of fomites. The few detections in humans are most likely spillover events after contact with wildlife. However, since S. schweitzeri can be misidentified as S. aureus using culture-based routine techniques, it is likely that S. schweitzeri is under-reported in humans. The low number of isolates in humans, though, is consistent with the fact that the pathogen has typical animal adaptation characteristics (e.g., growth kinetics, lack of immune evasion cluster and antimicrobial resistance); however, evidence from selected in vitro assays (e.g., host cell invasion, cell activation, cytotoxicity) indicate that S. schweitzeri might be as virulent as S. aureus. In this case, contact with animals colonized with S. schweitzeri could constitute a risk for zoonotic infections. 
  • 1.5K
  • 24 May 2022
Topic Review
Reactive Oxygen and Nitrogen Species
Oxidative stress is the result of an imbalance between the presence of reactive oxygen species (ROS) and the ability of a biological system to detoxify them and their side products. Similarly, nitrosative stress is an imbalance of reactive nitrogen species (RNS). Some of these molecules can play an important role in signalization in both eukaryotes and prokaryotes.
  • 1.5K
  • 16 May 2022
Topic Review
Nanocellulose Functional Material
Nanocellulose is generally defined as cellulose particles or fibers with dimensions in the nanometer range. It can be derived from different cellulose sources, such as wood pulp, agricultural residues, or bacterial cultures, using various methods including mechanical treatment, enzymatic hydrolysis, or chemical processes.
  • 1.5K
  • 28 Jul 2023
Topic Review
Source and Structure of Exopolysaccharides
Marine microorganisms, as important members of marine organisms, can produce numerous specific active substances in an extreme environment in low temperature, high salt, high pressure, and oligotrophic conditions. They have gained scientific interest due to their potential applications in the pharmaceutical, cosmetic and food industries, for environmental remediation, and astrobiology. The monosaccharide composition, high molecular weight, hydrophobicity and polycharged characteristics of marine Exopolysaccharides (EPS) are involved in their cryoprotective effect, water-holding capacity, and good thermostability. The source and structure  of exopolysaccharides are summarized. 
  • 1.5K
  • 23 Aug 2022
Topic Review
Na+-ATPase in Protozoan Parasites
The ENA ATPases (from exitus natru: the exit of sodium), also known as Na+-ATPases, are responsible for exchanges Na+ for H+; it belongs to the P-type ATPases are structurally very similar to the sarco/endoplasmic reticulum Ca2+-ATPase (SERCA). ENA ATPases are essential for salt tolerance and in alkaline conditions, where other transporters cannot mediate an uphill Na+ efflux. P-type ATPases are classified in subclasses like types IIA, IIB, IIC, IID, and recently, was identified the type ATP4-type ATPases, related to Na+-ATPases found in Plasmodium falciparum and Toxoplasma gondii. In malaria, some drugs, like spiroindolones, targets PfATP4 and destroy Na+ homeostasis; these drugs are now in clinical trials. The ENA P-type (IID P-type ATPase) and ATP4-type ATPases have no structural homolog in mammalian cells, appearing only in fungi, plants, and protozoan parasites, e.g., Trypanosoma cruzi, Leishmania sp., Toxoplasma gondii, and Plasmodium falciparum. This exclusivity turns the Na+-ATPase a potential candidate for the biologically-based design of new therapeutic interventions; for this reason, Na+-ATPases deserves more attention.
  • 1.5K
  • 06 Nov 2020
Topic Review
Zetaproteobacteria
The class Zetaproteobacteria is the sixth and most recently described class of the Proteobacteria. Zetaproteobacteria can also refer to the group of organisms assigned to this class. The Zetaproteobacteria were originally represented by a single described species, Mariprofundus ferrooxydans, which is an iron-oxidizing neutrophilic chemolithoautotroph originally isolated from Loihi Seamount in 1996 (post-eruption). Molecular cloning techniques focusing on the small subunit ribosomal RNA gene have also been used to identify a more diverse majority of the Zetaproteobacteria that have as yet been unculturable. Regardless of culturing status, the Zetaproteobacteria show up worldwide in estuarine and marine habitats associated with opposing steep redox gradients of reduced (ferrous) iron and oxygen, either as a minor detectable component or as the dominant member of the microbial community. Zetaproteobacteria have been most commonly found at deep-sea hydrothermal vents, though recent discovery of members of this class in near-shore environments has led to the reevaluation of Zetaproteobacteria distribution and significance.
  • 1.5K
  • 18 Nov 2022
Topic Review
Antimicrobial Peptides with Antiendotoxin
A strategy was described to design antimicrobial peptides (AMPs) with enhanced salt resistance and antiendotoxin activities by linking two helical AMPs with the Ala-Gly-Pro (AGP) hinge. Among the designed peptides, KR12AGPWR6 demonstrated the best antimicrobial activities even in high salt conditions (NaCl ~300 mM) and possessed the strongest antiendotoxin activities. These activities may be related to hydrophobicity, membrane-permeability, and α-helical content of the peptide. Amino acids of the C-terminal helices were found to affect the peptide-induced permeabilization of LUVs, the α-helicity of the designed peptides under various LUVs, and the LPS aggregation and size alternation. A possible model was proposed to explain the mechanism of LPS neutralization by the designed peptides. These findings could provide a new approach for designing AMPs with enhanced salt resistance and antiendotoxin activities for potential therapeutic applications.
  • 1.5K
  • 26 Oct 2020
Topic Review
Microbial Colonization of Stone
Colonization and deterioration of stone heritage buildings by microorganisms, especially cyanobacteria. Aesthetic, chemical and physical types of deterioration are covered. Future changes in climate will affect these processes. Seven figures illustrate various aspects and organisms involved.
  • 1.4K
  • 16 Dec 2020
Topic Review
Lactic Acid Bacteria from Vagina
During the selection process of probiotics for vaginal applications, twenty-five lactic acid bacteria (LAB) isolates from human vagina belonging to six different species were tested for antimicrobial resistance by a microdilution method. Gene-specific PCR amplifications proved the strains carry no acquired antibiotic resistance genes, except for a tet(W) gene present in two tetracycline-susceptible Bifidobacterium bifidum strains. Genome analysis of a selected set of strains showed no other acquired resistance determinants. The tet(W) of B. bifidum was inactive by the insertion of two guanine residues in the middle of the gene. Surprisingly, the inactive gene became active and functional very easily, providing resistance to tetracycline and remaining stable afterward. LAB intended to be used in health applications must be free of acquired antimicrobial resistance genes; these could be spread and transferred to human pathogens.
  • 1.4K
  • 29 Oct 2020
  • Page
  • of
  • 51
Featured Entry Collections
>>

Featured Reprints

>>
Encyclopedia of Digital Society, Industry 5.0 and Smart City
Encyclopedia of Engineering
Encyclopedia of Social Sciences
Encyclopedia of Medieval Royal Iconography
Academic Video Service
Feedback