Evaluating the Effect of Different Intra-Orifice Barriers and Various Bleaching Agents on the Fracture Resistance of Teeth After the Walking Bleach Procedure: An In Vitro Study.

Objective This study aimed to evaluate the effect of three different commercially available intra-orifice barriers and bleaching agents on root canal-treated teeth. Materials and methods Forty-five freshly extracted single-rooted incisors, canine, and premolars were collected and stored in 10% formalin. Root canal procedures were performed on the extracted teeth and these were classified into three groups and three subgroups (n=5). Group 1: resin-modified glass ionomer cement (RMGIC); placed at the level of cemento-enamel junction (CEJ) and cured for 20 seconds. Group 2: BiodentinTM (Septodont Ltd., Saint Maur des Fausse´s, France); powder and liquid were mixed according to the manufacturer's instructions and placed at the level of CEJ, and waited for 15 minutes to set. Group 3: bulk-fill composite; placed at the level of CEJ. Group A was treated with 35% carbamide peroxide (Ultradent Opalescence 35% PF regular). Group B was bleached with 35% hydrogen peroxide (Pola Office). Group C, which was the control group, was treated with distilled water. The bleaching procedure was repeated once every seven days for a period of three weeks. After bleaching, every sample was sectioned 2 mm above the level of CEJ to remove the crown. Auniversal testing machine (UTM) was used for the evaluation of the fracture resistance of teeth. Data were analyzed for significance by using analysis of variance (ANOVA) and further pair-wise comparison was performed by pos-hoc analysis. The level of significance was set at p<0.05 Results There was a significant difference between the fracture resistance of the three materials when bleached using distilled water (p<0.05). The fracture resistance of Group 3 was significantly greater than that of Group 2 and Group 1 (p<0.05). The difference in the fracture resistance between Group 1 and Group 2 was nonsignificant (p>0.05). Conclusion Walking bleach performed via bleaching agents 35% carbamide peroxide and 35% hydrogen peroxide leads to a reduction in the fracture resistance of endodontically treated teeth; 35% hydrogen peroxide causes more fracture resistance reduction than carbamide peroxide of the same concentration. The presence of intra-orifice barriers leads to greater fracture resistance and reinforcement of endodontically treated teeth that undergo the walking bleach procedure. Bulk-fill composite can be used as an intra-orifice barrier with good fracture resistance.

Endogenous fungal endophthalmitis following intensive corticosteroid therapy in severe COVID-19 disease.

Purpose: To report endogenous fungal endophthalmitis, postrecovery from severe COVID-19 infection in otherwise immunocompetent individuals, treated with prolonged systemic steroids. Methods: Retrospective chart review of cases with confirmed and presumed fungal endogenous endophthalmitis, following severe COVID-19 disease, treated at two tertiary care referral eye institutes in North India. Results: Seven eyes of five cases of endogenous fungal endophthalmitis were studied. All cases had been hospitalized for severe COVID-19 pneumonia and had received systemic steroid therapy for an average duration of 42 ± 25.1 days (range 18-80 days). All the cases initially complained of floaters with blurred vision after an average of 6 days (range 1-14 days) following discharge from hospital. They had all been misdiagnosed as noninfectious uveitis by their primary ophthalmologists. All eyes underwent pars plana vitrectomy (PPV) with intravitreal antifungal therapy. Five of the seven eyes grew fungus as the causative organism (Candida sp. in four eyes, Aspergillus sp. in one eye). Postoperatively, all eyes showed control of the infection with a marked reduction in vitreous exudates and improvement in vision. Conclusion: Floaters and blurred vision developed in patients after they recovered from severe COVID-19 infection. They had received prolonged corticosteroid treatment for COVID-19 as well as for suspected noninfectious uveitis. We diagnosed and treated them for endogenous fungal endophthalmitis. All eyes showed anatomical and functional improvement after PPV with antifungal therapy. It is important for ophthalmologists and physicians to be aware of this as prompt treatment could control the infection and salvage vision.

Pyrrolnitrin from Rhizospheric Serratia marcescens NCIM 5696: Optimization of Process Parameters Using Statistical Tools and Seed-Applied Bioprotectants for Vigna radiata (L.) Against Fusarium oxysporum MTCC 9913.

The extensive use of chemical fungicide in the health and agriculture sectors has increased environmental concerns and promoted an extensive search for alternative bioactives from the microbial system. In the present study, two rhizospheric strains of Serratia spp. (TO-2 and TW-3) have been shown to secrete pyrrolnitrin (PRN) in the range of 11.35 to 35.97 µg ml-1 using MSG and MSD medium after 72 h under static and shake conditions, respectively, but thereafter marginally declined in 96 to 240 h. Alternative one variable assortment at a time (OVAT) for PRN secretion by TW-3 yielded 59.27 µg ml-1 using (gl-1) glycerol (20), monosodium glutamate (14), KH2PO4 (14), NH4Cl (3), Na2HPO4 (4), and MgSO4 (0.3) at pH 7, 120 rpm within 72 h. Further, the Placket-Burman Design (PBD) identified KH2PO4, glycerol, pH, and monosodium glutamate as significant variables and optimized by centered composite design. Accordingly, 3% glycerol, 1.72% KH2PO4, 1.1% monosodium glutamate, 0.4% Na2HPO4, 0.03% MgSO4, 0.05% FeSO4, and 0.01% ZnSO4 were found to enhance the yield of PRN to 96.54 µg ml-1 by TW-3 in 72 h, 120 rpm. Thus, the statistical tool employed in the present study showed a threefold hike in PRN secretion over the OVAT approach, thereby indicating the scope for more PRN production from rhizobacteria. Further, seed application of low PRN (30 µg ml-1) concentration in treatments I and II showed > 90% germination in the initial seed germination and pot assay with the Fusarium oxysporum challenge compared to the control. Also, various growth parameters calculated during 11 days of experiment were significantly increased compared to the negative control (seed + fungus) in both treatments. Thus, the application of PRN at a low concentration to seeds of Vigna radiata (L.) offered protection against the phytopathogenic F. oxysporum MTCC 9913 challenge, suggesting biocontrol activity potential for use in agriculture soils particularly salt-affected soil.

Microbial Pyrrolnitrin: Natural Metabolite with Immense Practical Utility.

Pyrrolnitrin (PRN) is a microbial pyrrole halometabolite of immense antimicrobial significance for agricultural, pharmaceutical and industrial implications. The compound and its derivatives have been isolated from rhizospheric fluorescent or non-fluorescent pseudomonads, Serratia and Burkholderia. They are known to confer biological control against a wide range of phytopathogenic fungi, and thus offer strong plant protection prospects against soil and seed-borne phytopathogenic diseases. Although chemical synthesis of PRN has been obtained using different steps, microbial production is still the most useful option for producing this metabolite. In many of the plant-associated isolates of Serratia and Burkholderia, production of PRN is dependent on the quorum-sensing regulation that usually involves N-acylhomoserine lactone (AHL) autoinducer signals. When applied on the organisms as antimicrobial agent, the molecule impedes synthesis of key biomolecules (DNA, RNA and protein), uncouples with oxidative phosphorylation, inhibits mitotic division and hampers several biological mechanisms. With its potential broad-spectrum activities, low phototoxicity, non-toxic nature and specificity for impacts on non-target organisms, the metabolite has emerged as a lead molecule of industrial importance, which has led to developing cost-effective methods for the biosynthesis of PRN using microbial fermentation. Quantum of work narrating focused research efforts in the emergence of this potential microbial metabolite is summarized here to present a consolidated, sequential and updated insight into the chemistry, biology and applicability of this natural molecule.

Isolation, selection and biodegradation profile of phenol degrading bacteria from oil contaminated soil.

In the present study, an aerobic bacterial strains OCS-A and OCS- B were isolated from an oil contaminated soil. The strains were identified to be Citrobacter freundi and Proteus mirabilis according to morphological, physiological and biochemical characteristics. The strains were able to degrade about 90% of 100 mg/L phenol within 80 h as sole carbon and energy source. The lag phase increased with increase in phenol concentration. Determination of metabolic intermediate 2-HMS, was done which indicate meta-cleavage pathway of phenol metabolism. Hence these isolates can be effectively used for bioremediation of phenol contaminated sites.