Dysregulation of Ion Homeostasis by Antifungal Agents

Ion-signaling and transduction networks are central to fungal development and virulence because they regulate gene expression, filamentation, host association, and invasion, pathogen stress response and survival. Dysregulation of ion homeostasis rapidly mediates cell death, forming the mechanistic basis by which a growing number of amphipathic but structurally unrelated compounds elicit antifungal activity. Included in this group is carvacrol, a terpenoid phenol that is a prominent component of oregano and other plant essential oils. Carvacrol triggers an early dose-dependent Ca2+ burst and long lasting pH changes in the model yeast Saccharomyces cerevisiae. The distinct phases of ionic transients and a robust transcriptional response that overlaps with Ca2+ stress and nutrient starvation point to specific signaling events elicited by plant terpenoid phenols, rather than a non-specific lesion of the membrane, as was previously considered. We discuss the potential use of plant essential oils and other agents that disrupt ion-signaling pathways as chemosensitizers to augment conventional antifungal therapy, and to convert fungistatic drugs with strong safety profiles into fungicides

Cod1p/Spf1p is a P-type ATPase involved in ER function and Ca2+ homeostasis

The internal environment of the ER is regulated to accommodate essential cellular processes, yet our understanding of this regulation remains incomplete. Cod1p/Spf1p belongs to the widely conserved, uncharacterized type V branch of P-type ATPases, a large family of ion pumps. Our previous work suggested Cod1p may function in the ER. Consistent with this hypothesis, we localized Cod1p to the ER membrane. The cod1Δ mutant disrupted cellular calcium homeostasis, causing increased transcription of calcium-regulated genes and a synergistic increase in cellular calcium when paired with disruption of the Golgi apparatus–localized Ca2+ pump Pmr1p. Deletion of COD1 also impaired ER function, causing constitutive activation of the unfolded protein response, hypersensitivity to the glycosylation inhibitor tunicamycin, and synthetic lethality with deletion of the unfolded protein response regulator HAC1. Expression of the Drosophila melanogaster homologue of Cod1p complemented the cod1Δ mutant. Finally, we demonstrated the ATPase activity of the purified protein. This study provides the first biochemical characterization of a type V P-type ATPase, implicates Cod1p in ER function and ion homeostasis, and indicates that these functions are conserved among Cod1p's metazoan homologues

Critical success factor bagi program keusahawanan di jabatan perdagangan politeknik

Konsep Critical Success Factor berkait rapat mengenai pengurusan dalam mencapai misi dan matlamat perniagaan dalam sesebuah organisasi. Oleh itu, kajian ini adalah bertujuan untuk mengkaji empat elemen Critical Success Factor di Jabatan Perdagangan Politeknik seterusnya melihat kecenderungan pelajar untuk melibatkan diri dalam bidang keusahawanan. Kajian jenis kuantitatif ini telah dibuat ke atas pensyarah di Jabatan Perdagangan Politeknik bagi zon Utara. Seramai 190 sampel kajian yang terlibat dalam penyelidikan ini melalui pengedaran borang kaji selidik. Antara enam buah politeknik di zon Utara yang terlibat dalam penyelidikkan ini adalah Politeknik Politeknik Tunku Syed Sirajuddin, Perlis, Politeknik Sultan Abdul Halim Muazzam Shah, Kedah, Politeknik Tunku Sultanah Bahiyah, Kedah, Politeknik Seberang Perai, Pulau Pinang, Politeknik Ungku Omar, Perak dan Politeknik Sultan Azlan Shah, Perak. Data yang diperolehi dianalisis mendapati nilai skor min bagi ketiga-tiga persoalan kajian iaitu, mengenalpasti elemen Critical Success Factor yang digunakan, cabaran dalam usaha melaksanakan elemen Critical Success Factor dan mengenalpasti tahap kecenderungan pelajar untuk melibatkan diri dalam bidang keusahawanan adalah tinggi. Manakala bagi persoalan kajian keempat iaitu mencari hubungan korelasi Pearson antara elemen Critical Suceess Factor dengan kecenderungan pelajar untuk melibatkan diri dalam bidang keusahawanan adalah berada pada tahap lemah, sekaligus menunjukkan Ho tidak diterima. Kesimpulannya, elemen Critical Success Factor ini memainkan peranan dalam pembentukkan organisasi yang berkesan supaya pembentukan matlamat dan objektif tercapa

Effects of maternal immune activation on gene expression patterns in the fetal brain

We are exploring the mechanisms underlying how maternal infection increases the risk for schizophrenia and autism in the offspring. Several mouse models of maternal immune activation (MIA) were used to examine the immediate effects of MIA induced by influenza virus, poly(I:C) and interleukin IL-6 on the fetal brain transcriptome. Our results indicate that all three MIA treatments lead to strong and common gene expression changes in the embryonic brain. Most notably, there is an acute and transient upregulation of the α, β and γ crystallin gene family. Furthermore, levels of crystallin gene expression are correlated with the severity of MIA as assessed by placental weight. The overall gene expression changes suggest that the response to MIA is a neuroprotective attempt by the developing brain to counteract environmental stress, but at a cost of disrupting typical neuronal differentiation and axonal growth. We propose that this cascade of events might parallel the mechanisms by which environmental insults contribute to the risk of neurodevelopmental disorders such as schizophrenia and autism

Requirement for Ergosterol in V-ATPase Function Underlies Antifungal Activity of Azole Drugs

Ergosterol is an important constituent of fungal membranes. Azoles inhibit ergosterol biosynthesis, although the cellular basis for their antifungal activity is not understood. We used multiple approaches to demonstrate a critical requirement for ergosterol in vacuolar H+-ATPase function, which is known to be essential for fungal virulence. Ergosterol biosynthesis mutants of S. cerevisiae failed to acidify the vacuole and exhibited multiple vma− phenotypes. Extraction of ergosterol from vacuolar membranes also inactivated V-ATPase without disrupting membrane association of its subdomains. In both S. cerevisiae and the fungal pathogen C. albicans, fluconazole impaired vacuolar acidification, whereas concomitant ergosterol feeding restored V-ATPase function and cell growth. Furthermore, fluconazole exacerbated cytosolic Ca2+ and H+ surges triggered by the antimicrobial agent amiodarone, and impaired Ca2+ sequestration in purified vacuolar vesicles. These findings provide a mechanistic basis for the synergy between azoles and amiodarone observed in vitro. Moreover, we show the clinical potential of this synergy in treatment of systemic fungal infections using a murine model of Candidiasis. In summary, we demonstrate a new regulatory component in fungal V-ATPase function, a novel role for ergosterol in vacuolar ion homeostasis, a plausible cellular mechanism for azole toxicity in fungi, and preliminary in vivo evidence for synergism between two antifungal agents. New insights into the cellular basis of azole toxicity in fungi may broaden therapeutic regimens for patient populations afflicted with systemic fungal infections

An overview of burst, buckling, durability and corrosion analysis of lightweight FRP composite pipes and their applicability

© 2019 Elsevier Ltd. All rights reserved.The main aim of this review article was to address the performance of filament wound fibre reinforced polymer (FRP) composite pipes and their critical properties, such as burst, buckling, durability and corrosion. The importance of process parameters concerning merits and demerits of the manufacturing methods was discussed for the better-quality performance. Burst analysis revealed that the winding angle of ±55° was observed to be optimum with minimum failure mechanisms, such as matrix cracking, whitening, leakage and fracture. The reduction of buckling effect was reported in case of lower hoop stress value in the hoop to axial stress ratio against axial, compression and torsion. A significant improvement in energy absorption was observed in the hybrid composite pipes with the effect of thermal treatment. However, the varying winding angle in FRP pipe fabrication was reported as an influencing factor affecting all the aforementioned properties. Almost 90% of the reviewed studies was done using E-glass/epoxy materials for the composite pipe production. By overcoming associated limitations, such as replacing synthetic materials, designing new material combinations and cost-benefit analysis, the production cost of the lightweight FRP composite pipes can be decreased for the real-time applications.Peer reviewe

Mechanism of Antifungal Activity of Terpenoid Phenols Resembles Calcium Stress and Inhibition of the TOR Pathway ▿

Terpenoid phenols, including carvacrol, are components of oregano and other plant essential oils that exhibit potent antifungal activity against a wide range of pathogens, including Candida albicans, Staphylococcus aureus, and Pseudomonas aeruginosa. To gain a mechanistic view of the cellular response to terpenoid phenols, we used Saccharomyces cerevisiae as a model organism and monitored temporal changes in metabolic activity, cytosolic and vacuolar pH, and Ca2+ transients. Using a panel of related compounds, we observed dose-dependent Ca2+ bursts that correlated with antifungal efficacy. Changes in pH were long lasting and followed the Ca2+ transients. A vma mutant lacking functional vacuolar H+-ATPase (V-ATPase) and defective in ion homeostasis was hypersensitive to carvacrol toxicity, consistent with a role for ionic disruptions in mediating cell death. Genomic profiling within 15 min of exposure revealed a robust transcriptional response to carvacrol, closely resembling that of calcium stress. Genes involved in alternate metabolic and energy pathways, stress response, autophagy, and drug efflux were prominently upregulated, whereas repressed genes mediated ribosome biogenesis and RNA metabolism. These responses were strongly reminiscent of the effects of rapamycin, the inhibitor of the TOR pathway of nutrient sensing. The results point to the activation of specific signaling pathways downstream of cellular interaction with carvacrol rather than a nonspecific lesion of membranes, as has been previously proposed

Effect of combination polymers of natural and semi synthetic origin on the drug release of Flavoxate. HCl: Design and Characterization of gastro retentive floating tablets for Flavoxate.HCl.

The objective of current work is to study the effect of combination of macromolecules (polymers) of natural (Lannea coromandelica gum) and semi synthetic (HPMCK100M) origin on the drug release of Flavoxate.HCl from the Gastro retentive floating formulation.  Flavoxate.HCl, an antispasmodic agent. Mainly used for treating urinary incontinence, urgency of urination. Floating tablets of Flavoxate.HCl were prepared using variable composition of HPMCK100M, Lannea coromandelica gum (LCG) with effervescent mixtures by direct compression technique. 9 formulations were made and evaluated for quality control parameters. From the obtained results clears that all formulations passes the compendial limits.  Data obtained from the dissolution study fitted well to kinetic modeling, kinetic parameters were determined. GRFX5 composed of 40 mg of HPMCK100M & 40 mg of LCG, is the best formulation showing similarity f2=84.66, f1= 4.29 with the marketed product (URISPAS). Formulation GRFX5 follow first order, whereas release mechanism found to be nonfickian type (n= 0.77)