Low-dose zinc oxide nanoparticles trigger the growth and biofilm formation of Pseudomonas aeruginosa: a hormetic response.

INTRODUCTION: Hormesis describes an inverse dose-response relationship, whereby a high dose of a toxic compound is inhibitory, and a low dose is stimulatory. This study explores the hormetic response of low concentrations of zinc oxide nanoparticles (ZnO NPs) toward Pseudomonas aeruginosa. METHOD: Samples of P. aeruginosa, i.e. the reference strain, ATCC 27,853, together with six strains recovered from patients with cystic fibrosis, were exposed to ten decreasing ZnO NPs doses (0.78-400 µg/mL). The ZnO NPs were manufactured from Peganum harmala using a chemical green synthesis approach, and their properties were verified utilizing X-ray diffraction and scanning electron microscopy. A microtiter plate technique was employed to investigate the impact of ZnO NPs on the growth, biofilm formation and metabolic activity of P. aeruginosa. Real-time polymerase chain reactions were performed to determine the effect of ZnO NPs on the expression of seven biofilm-encoding genes. RESULT: The ZnO NPs demonstrated concentration-dependent bactericidal and antibiofilm efficiency at concentrations of 100-400 µg/mL. However, growth was significantly stimulated at ZnO NPs concentration of 25 µg/mL (ATCC 27853, Pa 3 and Pa 4) and at 12.5 µg/mL and 6.25 µg/mL (ATCC 27853, Pa 2, Pa 4 and Pa 5). No significant positive growth was detected at dilutions < 6.25 µg/mL. similarly, biofilm formation was stimulated at concentration of 12.5 µg/mL (ATCC 27853 and Pa 1) and at 6.25 µg/mL (Pa 4). At concentration of 12.5 µg/mL, ZnO NPs upregulated the expression of LasB ( ATCC 27853, Pa 1 and Pa 4) and LasR and LasI (ATCC 27853 and Pa 1) as well as RhII expression (ATCC 27853, Pa 2 and Pa 4). CONCLUSION: When exposed to low ZnO NPs concentrations, P. aeruginosa behaves in a hormetic manner, undergoing positive growth and biofilm formation. These results highlight the importance of understanding the response of P. aeruginosa following exposure to low ZnO NPs concentrations.

Gastroesophageal reflux in lockdown.

Aim: This study examines the changes in gastroesophageal reflux disease (GERD) symptom frequency among patients with GERD throughout the COVID-19 pandemic. Methods: A structured questionnaire was distributed among 198 GERD patients. The questionnaire consisted of a demographic characteristic assessment, the GerdQ questionnaire, and a reflux symptom index (RSI) questionnaire. Result & conclusion: A statistically significant increase in GerdQ score was identified among participants during the COVID-19 pandemic (t = 7.055, df = 209, p < 0.001), who had experienced an increase in the frequency of positive predictors of GERD and a decrease in the frequency of negative predictors of GERD. The COVID-19 pandemic and its related lockdown countermeasures may have led to exacerbating and worsening GERD symptoms.

There is a lack of decisive research into the impacts of the COVID-19 pandemic and its lockdown countermeasures on patients with GERD. We investigated the changes in symptomatic frequency among GERD patients in Jordan during the COVID-19 pandemic in a cross-sectional study involving 198 GERD patients. A statistically significant number of participants experienced an increase in the frequency of positive predictors of GERD, and a decrease in the frequency of negative predictors of GERD. In addition, the impacts of GERD itself were also found to have increased during the pandemic, with patients struggling to sleep or attain additional medication to treat their condition.

The impact of biosynthesized ZnO nanoparticles from Olea europaea (Common Olive) on Pseudomonas aeruginosa growth and biofilm formation.

There is a limitation in the range of effectual antibiotics due to the Pseudomonas aeruginosa (PA) infection due to its innate antimicrobial resistance. Researchers have therefore been concentrating their efforts to discover advanced and cost effective antibacterial agents among the ever-increasing PA bacterial resistance strains. It has been discovered that various nanoparticles can be employed as antimicrobial agents. Here, we evaluated the antibacterial properties of the Zinc Oxide nanoparticles (ZnO NPs), which was biosynthesized, being examined on six hospital strains of PA alongside a reference strain (ATCC 27853). A chemical approach was applied to biosynthesize the ZnO NPs from Olea europaea was performed, and confirmed by using X-ray diffraction and Scanning Electron Microscopes. The nanoparticles then applied their antibacterial properties to examine them against six clinically isolated PA strains alongside the reference strain. This process tested for the results of the minimum inhibitory concentration (MIC) and the minimum bactericidal concentration (MBC). The Growth, biofilm formation and eradication were analyzed. The influence of the differentiating degrees ZnO NPs in regard to Quorom sensing gene expression were further examined. The ZnO NPs exhibited a crystalline size and diameter (Dc) of 40-60 nm and both the MIC and MBC tests revealed positive outcomes of concentrations of 3 and 6 mg/ml for each PA strain, respectively. At sub inhibitory concentration, The ZnO NPs were found to significantly inhibit the growth and biofilm formation of all PA strains and decreases in the biomass and metabolic behavior of PA established biofilms; these decreases varied depending on the dosage. At ZnO NPs concentrations of 900 µg/ml, the expression of majority of quorum sensing genes of all strains were significantly reduced, at ZnO NPs concentrations of 300 µg/ml, few genes were significantly impacted. In conclusion, the treatment of PA and could be other antibiotic resistant bacteria can therefore be approached by using ZnO NPs as it has been uncovered that they withhold advanced antibacterial properties.

Prevalence and psychological stress in recurrent aphthous stomatitis among female dental students in Saudi Arabia.

INTRODUCTION: Recurrent Aphthous Stomatitis (RAS) is a common oral mucosal disorder which is characterized by recurrent ulcerations mainly confined to non-keratinized oral mucosa. Though the exact etiology is imprecise, stress and anxiety were found to be linked with the onset of RAS. The present study was directed to know the prevalence of RAS among female dental students in King Khalid University, to find out the association between RAS and psychological stress and the effectiveness of Hospital Anxiety and Depression scale (HADS) in finding out the psychological profile of RAS patients. METHOD: 122 female dental students of age group 17 to 25 years were selected for the study. Subjects with relevant medical problems and deleterious habits were excluded. A questionnaire comprising general stress related questions and HAD scale were used to assess stress. Those who were giving history of ulcer were diagnosed as RAS based on the clinical features. The questionnaire results were used for statistical analysis and processed. RESULT: 14% of the total students were having RAS. 70% could correlate the onset of ulcer with certain specific factors; stress being the major causative agent (91%). In HAD scale, 88% of students were having anxiety and 65% had depression; all patients with depression had anxiety. CONCLUSION: The prevalence of RAS in female dental students in KKU was around 14%. There is a strong relationship between psychological stress and RAS, as in most of the other studies. HAD scale alone can be used for detecting the psychological factor in RAS.