Presence of viral RNA of SARS-CoV-2 in conjunctival swab specimens of COVID-19 patients

Purpose:

To detect the presence of viral RNA of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) in conjunctival swab specimens of coronavirus disease-19 (COVID-19) patients.

Methods:

Forty-five COVID-19 patients positive for real-time reverse transcription-polymerase chain reaction (RT-PCR) for SARS-CoV-2 in nasopharyngeal swab with or without ocular manifestations were included in the study. The conjunctival swab of each patient was collected by an ophthalmologist posted for COVID duty.

Results:

Out of 45 patients, 35 (77.77%) were males and the rest were females. The mean age was 31.26 ± 12.81 years. None of the patients had any ocular manifestations. One (2.23%) out of 45 patients was positive for RT-PCR SARS-CoV-2 in the conjunctival swab.

Conclusion:

This study shows that SARS-CoV-2 can be detected in conjunctival swabs of confirmed cases of COVID-19 patients. Though the positivity rate of detecting SARS-CoV-2 in conjunctival swabs is very less, care should be exercised during the ocular examination of patients of COVID-19.

Insulin treatment promotes tyrosine phosphorylation of PKR and inhibits polyIC induced PKR threonine phosphorylation

Tyrosine phosphorylation of insulin receptor beta (IRβ) in insulin treated HepG2 cells is inversely correlated to ser(51) phosphorylation in the alpha-subunit of eukaryotic initiation factor 2 (eIF2α) that regulates protein synthesis. Insulin stimulates interaction between IRβ and PKR, double stranded RNA-dependent protein kinase, also known as EIF2AK2, and phosphorylation of tyrosine residues in PKR, as analyzed by immunoprecipitation and pull down assays using anti-IRβ and anti-phosphotyrosine antibodies, recombinant IRβ and immunopurified PKR. Further polyIC or synthetic double stranded RNA-induced threonine phosphorylation or activation of immunopurified and cellular PKR is suppressed in the presence of insulin treated purified IRβ and cell extracts. Acute, but not chronic, insulin treatment enhances tyrosine phosphorylation of IRβ, its interaction with PKR and tyrosine phosphorylation of PKR. In contrast, lipopolysaccharide that stimulates threonine phosphorylation of PKR and eIF2α phosphorylation and AG 1024, an inhibitor of the tyrosine kinase activity of IRβ, reduces PKR association with the receptor, IRβ in HepG2 cells. These findings therefore may suggest that tyrosine phosphorylated PKR plays a role in the regulation of insulin induced protein synthesis and in maintaining insulin sensitivity, whereas, suppression of polyIC-mediated threonine phosphorylation of PKR by insulin compromises its ability to fight against virus infection in host cells.

Synthesis, characterization, and antimicrobial activity of nano-hydroxyapatite-zinc for bone tissue engineering applications

The bone implants used in tissue repair are susceptible to infections caused by staphylococci, specifically Staphylococcus aureus. Hence, the development of better biological materials that provide antimicrobial activity in bone tissue engineering is required. The nanoparticles of hydroxyapatite (nHAp) and nHAp dopped with Zn (nHAp-Zn) were prepared by the wet chemical method and the ion exchange method, respectively. They were characterized using SEM, AFM, FTIR and XRD. The antibacterial activity of nHAp and nHAp-Zn was determined with Gram-negative and Gram-positive bacterial strains. The results indicated that nHAp alone was acting as an inert matrix and when substituted with Zn, it showed better antibacterial activity. The nHAp-Zn was found to be non-toxic to osteoprogenitor cells. Thus, due to the antimicrobial property of nHAp-Zn nanoparticles, we suggest that they would have potential applications towards bone tissue engineering.

Indirect versus direct bonding--a shear bond strength comparison: an in vitro study

AIM

The process of bonding orthodontic appliances to the enamel surface of the teeth has come to the forefront as a major improvement in bonding techniques. The purpose of this study is to compare the shear bond strength of stainless steel orthodontic brackets bonded using conventional direct bonding and indirect bonding as described by Thomas.

MATERIALS AND METHODS

Forty sound human premolars were divided into two groups of 20 each. Group I samples were bonded directly on the tooth surface using concise two paste adhesive system after etching and drying. Group II samples were bonded indirectly on the tooth surface according to Thomas indirect bonding technique using concise two paste adhesive system. The stored specimen was tested for shear bond strength in an Instron universal testing machine at a crosshead speed of 0.5 mm/minute. Data obtained were subjected to statistical analysis.

RESULTS

The results showed that there was no statistically significant difference in the shear bond strength between direct and indirect bonding techniques. Chi-square test showed that there were significant differences among the adhesive remnant index scores between direct and indirect bonding groups.

CONCLUSION

In vitro shear bond strength comparison between direct and indirect-bonded attachments showed no significant difference between the two groups. Bond strength obtained with Thomas indirect bonding technique was comparable with direct bonding technique.

CLINICAL SIGNIFICANCE

Thomas indirect bonding technique can be used for bonding of the posterior teeth, where the risk of moisture contamination is high during bonding.