Volume 8, Issue 4 (fall 2022)
Abstract
Backgrounds: SARS-COV-2 infection is not always correlated with protection. Antibody seroprevalence in unvaccinated individuals, which is usually measured by N-specific antibodies, is not necessarily correlated with protection, while antibodies against S protein show a better correlation with protection due to its neutralizing epitopes. In this study, we tried to improve our conception of the hidden perspective of SARS-COV-2 in epidemiological reports and investigate anti-S antibody prevalence among anti-N antibody-positive asymptomatic and mildly symptomatic patients.
Materials & Methods: Blood samples were collected from asymptomatic or mildly symptomatic volunteer participants and symptomatic hospitalized patients with negative PCR results from May 30 to June 17, 2020. Detection of SARS-COV-2 antibodies was done using an ELISA kit targeting N or S protein.
Findings: Totally, 716 samples from volunteer participants and 81 samples from symptomatic hospitalized patients with negative PCR results were evaluated. The test performance-adjusted seroprevalence (95% CI) of SARS-COV-2 antibody was 17.3% (8.8-25.8%) for anti-N IgG in volunteers and 25.5% (12.8-39.7%) for anti-N and anti-S IgM in hospitalized patients. Among anti-N IgG positive infected individuals, 49.2% (21.4 and 78.8%) were anti-S antibody positive.
Conclusion: The results showed that SARS-COV-2 infection sometimes occurs in individuals without symptoms or with mild symptoms, but in more than half of them, the produced antibody is not protective. The findings of hospitalized patients showed that the combination of IgM assay with real-time PCR improved the disease diagnosis by more than 25% in cases with negative molecular test results.
Narges Rakhshan, Mohammadreza Mansournia, Fereshteh Jookar Kashi,
Volume 15, Issue 3 (6-2024)
Abstract
The aim of present research is development of a simple green approach to produce Ag/AgCl nanocomposites using bacterial strains Bacillus haynesii and Bacillus halotorans, nominated at PN14F and B3, respectively, via an extracellular process. The bacterial strains PN14F and B3 were isolated from the soil and wastewater samples, using dilution and direct cultivation method. The Ag/AgCl nanocomposites were synthesized from the reaction of silver(I) nitrate solution and supernatant under completely sterile conditions in the presence of light. Moreover, a series of controlled experiments were provided to optimize some reaction conditions such as substrate concentration, PH, substrate volume, bacterial volume, the presence of glucose as an electron donor and silver(I) nitrate as inducer. The products were characterized using various techniques such as UV-Vis, XRD, FT-IR, FE-SEM and EDX. The resulting bionanocomposites (Ag1 and Ag2), with an average particle size of 30 and 22.3 nm, were efficient heterogeneous catalysts for reducing para-nitrophenol to para-aminophenl. Further, it was demonstrated their activity as the antibacterial properties against gram positive and negative bacteria. The results showed that the Ag2 sample with reducing time of 15 min is a more efficient catalyst than the Ag1 nanocomposite, which can be attributed to the smaller size of the Ag2 nanoparticles.
Volume 21, Issue 154 (December 2024)
Abstract
Ascorbyl palmitate is a fat-soluble ester of vitamin C and palmitic acid, which is used to increase the oxidative stability of oils. In this study, in order to increase its stability to the environmental conditions of heat, humidity, oxidation and light, encapsulation technologies (nanoliposome) were used in refined soybean oil without antioxidants. In this regard, in this study, 5 concentrations of nanoliposomes containing ascorbyl palmitate (0, 50, 100, 200 and 500 ppm) were used to increase the oxidative stability of soybean oil stored at 63°C (electric oven) for a period of 16 days. Tests such as acidity, peroxide, conjugated dienes, anisidine and oxidative stability were performed on those oils. The results showed that acidity, conjugated dienes and anisidine increased with increasing storage time, but with increasing concentration of nanoliposome containing ascorbyl palmitate, the increase in these characteristics was less intense. By increasing the storage time until the 12th day, the amount of peroxide in the samples increased and then decreased, and with the increase in the antioxidant concentration, the amount of peroxide in the samples decreased. On the other hand, it was shown that increasing the concentration of nanoliposome from zero to 500 ppm in soybean oil increases the oxidative stability by about 96%. Finally, it was found that increasing the concentration of nanoliposomes containing ascorbyl palmitate in soybean oil reduces oil oxidation.
