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Topic Review
Emerging SARS-CoV-2 Variants of Concern (VOC)
The worldwide battle against the SARS-CoV-2 virus rages on, with millions infected and many innocent lives lost. The causative organism, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), is a beta coronavirus that belongs to the Coronaviridae family. Many clinically significant variants have emerged, as the virus’s genome is prone to various mutations, leading to antigenic drift and resulting in evasion of host immune recognition. The current variants of concern (VOCs) include B.1.1.7 (Alpha), B.1.351 (Beta), B.1.617/B.1.617.2 (Delta), and P.1 (Gamma). The emerging variants contain various important mutations on the spike protein, leading to deleterious consequences, such as immune invasion and vaccine escape. These adverse effects result in increased transmissibility, morbidity, and mortality and the evasion of detection by existing or currently available diagnostic tests, potentially delaying diagnosis and treatment. This review discusses the key mutations present in the VOC strains and provides insights into how these mutations allow for greater transmissibility and immune evasion than the progenitor strain. Continuous monitoring and surveillance of VOC strains play a vital role in preventing and controlling the virus’s spread.
  • 1.5K
  • 08 Oct 2021
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
Essential Oil from Cistus ladanifer L.
In Oulmes (Middle Atlas, Morocco), the local population uses C. ladanifer traditionally to treat various diseases and health issues due to its antioxidant, gastric, anti-inflammatory, antitumor, antimicrobial, and antiviral properties. This plant is usually harvested in May in this area (flowering time). The leaves of all Cistus species secrete essential oils. Essential oils from different species of medicinal plants have been documented to possess antimicrobial propriety with strong activity against Gram-negative and Gram-positive bacteria and also fungi.
  • 1.5K
  • 25 Oct 2021
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
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
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
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.
  • 1.4K
  • 29 Oct 2020
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.
  • 1.4K
  • 26 Oct 2020
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. 
  • 1.4K
  • 24 May 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.
  • 1.4K
  • 06 Nov 2020
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. 
  • 1.4K
  • 23 Aug 2022
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
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. 
  • 1.4K
  • 08 Sep 2021
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.
  • 1.4K
  • 16 May 2022
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.
  • 1.4K
  • 18 Nov 2022
Topic Review
Campylobacteriosis
Campylobacteriosis is an infection by the Campylobacter bacterium, most commonly C. jejuni. It is among the most common bacterial infections of humans, often a foodborne illness. It produces an inflammatory, sometimes bloody, diarrhea or dysentery syndrome, mostly including cramps, fever and pain.
  • 1.4K
  • 30 Oct 2022
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
Probiotics and Photobiomodulation
Multiple interconditioning between photobiomodulation (PBM), probiotics, and the human microbiota, their effects on the human body, and their implications for the management of viral infectious diseases is essential. Coupled complex PBM and probiotic interventions can control the microbiome, improve the activity of the immune system, and save the lives of people with immune imbalances. 
  • 1.4K
  • 20 May 2021
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