An extensive review on antifungal approaches in the treatment of mucormycosis

During the period of COVID-19, the occurrences of mucormycosis in immunocompromised patients have increased significantly. Mucormycosis (black fungus) is a rare and rapidly progressing fungal infection associated with high mortality and morbidity in India as well as globally. The causative agents for this infection are collectively called mucoromycetes which are the members of the order Mucorales. The diagnosis of the infection needs to be performed as soon as the occurrence of clinical symptoms which differs with types of Mucorales infection. Imaging techniques magnetic resonance imaging or computed tomography scan, culture testing, and microscopy are the approaches for the diagnosis. After the diagnosis of the infection is confirmed, rapid action is needed for the treatment in the form of antifungal therapy or surgery depending upon the severity of the infection. Delaying in treatment declines the chances of survival. In antifungal therapy, there are two approaches first-line therapy (monotherapy) and combination therapy. Amphotericin B ( 1 ) and isavuconazole ( 2 ) are the drugs of choice for first-line therapy in the treatment of mucormycosis. Salvage therapy with posaconazole ( 3 ) and deferasirox ( 4 ) is another approach for patients who are not responsible for any other therapy. Adjunctive therapy is also used in the treatment of mucormycosis along with first-line therapy, which involves hyperbaric oxygen and cytokine therapy. There are some drugs like VT-1161 ( 5 ) and APX001A ( 6 ), Colistin, SCH 42427, and PC1244 that are under clinical trials. Despite all these approaches, none can be 100% successful in giving results. Therefore, new medications with favorable or little side effects are required for the treatment of mucormycosis.     

Increasing picocyanobacteria success in shelf waters contributes to long‐term food web degradation

Continental margins are disproportionally important for global primary production, fisheries and CO₂ uptake. However, across the Northeast Atlantic shelves, there has been an ongoing summertime decline of key biota—large diatoms, dinoflagellates and copepods—that traditionally fuel higher tropic levels such as fish, sea birds and marine mammals. Here, we combine multiple time series with in situ process studies to link these declines to summer nutrient stress and increasing proportions of picophytoplankton that can comprise up to 90% of the combined pico‐ and nanophytoplankton biomass in coastal areas. Among the pico‐fraction, it is the cyanobacterium Synechococcus that flourishes when iron and nitrogen resupply to surface waters are diminished. Our field data show how traits beyond small size give Synechococcus a competitive edge over pico‐ and nanoeukaryotes. Key is their ability to grow at low irradiances near the nutricline, which is aided by their superior light‐harvesting system and high affinity to iron. However, minute size and lack of essential biomolecules (e.g. omega‐3 polyunsaturated fatty acids and sterols) render Synechococcus poor primary producers to sustain shelf sea food webs efficiently. The combination of earlier spring blooms and lower summer food quantity and quality creates an increasing period of suboptimal feeding conditions for zooplankton at a time of year when their metabolic demand is highest. We suggest that this nutrition‐related mismatch has contributed to the widespread, ~50% decline in summer copepod abundance we observe over the last 60 years. With Synechococcus clades being prominent from the tropics to the Arctic and their abundances increasing worldwide, our study informs projections of future food web dynamics in coastal and shelf areas where droughts and stratification lead to increasing nutrient starvation of surface waters.     

Saikosaponin-d,a novel SERCA inhibitor,induces autophagic cell death in apoptosis-defective cells

Autophagy is an important cellular process that controls cells in a normal homeostatic state by recycling nutrients to maintain cellular energy levels for cell survival via the turnover of proteins and damaged organelles. However, persistent activation of autophagy can lead to excessive depletion of cellular organelles and essential proteins, leading to caspase-independent autophagic cell death. As such, inducing cell death through this autophagic mechanism could be an alternative approach to the treatment of cancers. Recently, we have identified a novel autophagic inducer, saikosaponin-d (Ssd), from a medicinal plant that induces autophagy in various types of cancer cells through the formation of autophagosomes as measured by GFP-LC3 puncta formation. By computational virtual docking analysis, biochemical assays and advanced live-cell imaging techniques, Ssd was shown to increase cytosolic calcium level via direct inhibition of sarcoplasmic/endoplasmic reticulum Ca²⁺ ATPase pump, leading to autophagy induction through the activation of the Ca²⁺/calmodulin-dependent kinase kinase–AMP-activated protein kinase–mammalian target of rapamycin pathway. In addition, Ssd treatment causes the disruption of calcium homeostasis, which induces endoplasmic reticulum stress as well as the unfolded protein responses pathway. Ssd also proved to be a potent cytotoxic agent in apoptosis-defective or apoptosis-resistant mouse embryonic fibroblast cells, which either lack caspases 3, 7 or 8 or had the Bax-Bak double knockout. These results provide a detailed understanding of the mechanism of action of Ssd, as a novel autophagic inducer, which has the potential of being developed into an anti-cancer agent for targeting apoptosis-resistant cancer cells.     

Monoclonal antibodies to rabbit liver cytochrome P-448

Cytochrome P-448 (mol wt 55,000 Daltons) from rabbit liver was purified to a specific content of 16.6 nmol/mg. Mice were immunised with this preparation, their spleens removed and dissociated lymphocytes hybridised with myeloma cells. Four monoclonal antibodies against cytochrome P-448 were raised and partially characterised. All four antibodies interacted with cytochrome P-448 in intact microsomal fractions and selectively immunoadsorbed cytochrome P-448 from solubilised microsomal preparations. One of the antibodies inhibited benzo[a] pyrene hydroxylase activity in a reconstituted system, one had no effect on activity and two increased activity. The possible applications of such antibodies are discussed.     

Comparative effects of trichothecene mycotoxins on bovine platelet function: Acetyl T-2 toxin,a more potent inhibitor than T-2 toxin

The effects of the trichothecene mycotoxins (acetyl T-2 toxin, T-2 toxin, HT-2 toxin, palmityl T-2 toxin, diacetoxyscirpenol (DAS), deoxynivalenol (DON), and T-2 tetraol) on bovine platelet function were examined in homologous plasma stimulated with platelet activating factor (PAF). The mycotoxins inhibited platelet function with the following order of potency: acetyl T-2 toxin > palmityl T-2 toxin = DAS > HT-2 toxin = T-2 toxin. While T-2 tetraol was completely ineffective as an inhibitor, DON exhibited minimal inhibitory activity at concentrations above 10×10^?4M. The stability of the platelet aggregates formed was significantly reduced in all mycotoxin treated platelets compared to that of the untreated PAF controls. It is suggested that the increased sensitivity of PAF stimulated bovine platelets to the more lipophilic mycotoxins may be related to their more efficient partitioning into the platelet membrane compared to the more hydrophilic compounds.     

Comparative analysis of Dp427-deficient mdx tissues shows that the milder dystrophic phenotype of extraocular and toe muscle fibres is associated with a persistent expression of beta-dystroglycan

The cell biological hypothesis of Duchenne muscular dystrophy assumes that deficiency in the membrane cytoskeletal element dystrophin triggers a loss in surface glycoproteins, such as beta-dystroglycan, thereby rendering the sarcolemmal membrane more susceptible to micro-rupturing. Secondary changes in ion homeostasis, such as increased cytosolic Ca2+ levels and impaired luminal Ca2+ buffering, eventually lead to Ca2+-induced myonecrosis. However, individual muscle groups exhibit a graded pathological response during the natural time course of x-linked muscular dystrophy. The absence of the dystrophin isofom Dp427 does not necessarily result in a severe dystrophic phenotype in all muscle groups. In the dystrophic mdx animal model, extraocular and toe muscles are not as severely affected as limb muscles. Here, we show that the relative expression and sarcolemmal localization of the central trans-sarcolemmal linker of the dystrophin-glycoprotein complex, beta-dystroglycan, is preserved in mdx extraocular and toe fibres by means of two-dimensional immunoblotting and immunofluorescence microscopy. Thus, with respect to improving myology diagnostics, the relative expression levels of beta-dystroglycan appear to represent reliable markers for the severity of secondary changes in dystrophin-deficient fibres. Immunoblotting and enzyme assays revealed that mdx toe muscle fibres exhibit an increased expression and activity of the sarcoplasmic reticulum Ca2+-ATPase. Chemical crosslinking studies demonstrated impaired calsequestrin oligomerization in mdx gastrocnemius muscle indicating that abnormal calsequestrin clustering is involved in reduced Ca2+ buffering of the dystrophic sarcoplasmic reticulum. Previous studies have mostly attributed the sparing of certain mdx fibres to the special protective properties of small-diameter fibres. Our study suggests that the rescue of dystrophin-associated glycoproteins, and possibly the increased removal of cytosolic Ca2+ ions, might also play an important role in protecting muscle cells from necrotic changes.     

Studies on Enhancement of Anti-microbial Activity of Pristine MWCNTs Against Pathogens

Carbon nanotubes (CNTs), owing to their inherently unique properties in the domain of biomedical sciences including drug delivery, offer an exciting platform to the researchers. Of late, their applications have also been successfully established. Recently, single-walled CNTs (SWCNTs) have been explored for antibacterial efficacy, but naïve multi-walled CNTs (MWCNTs) still remained unearthed. The present studies endeavor the investigation of the potential of various non-ionic surfactants in solubility enhancement of MWCNTs and their subsequent antibacterial efficacy against Escherichia coli and Staphylococcus aureus. Polysorbates offer more solubility to MWCNTs vis-à-vis the phospholipids. However, the antibacterial effect was found to be less influenced by solubility but significantly determined by the type of surfactant. Transmission electron photomicrographs confirmed significant adhesion of MWCNTs to the bacterial walls only in the presence of unsaturated phospholipids and this was expressed in the form of lowest minimum inhibitory concentration (MIC) values of MWCNTs dispersed with the same. The findings are unique as MWCNTs were found to be active against both Gram-negative and Gram-positive bacteria to a similar extent, though somewhat milder than SWCNTs. However, when dispersed with unsaturated phospholipids, the former offer almost comparable antibacterial effects to that of the latter. The study opens a new research domain to further explore the antibacterial effects of non-functionalized and relatively safer MWCNTs, accentuating the importance of biocomponents like unsaturated phospholipids in this purview.