Theranostic nanoplatforms of emodin-chitosan with blue laser light on enhancing the anti-biofilm activity of photodynamic therapy against Streptococcus mutans biofilms on the enamel surface.

BACKGROUND: Combining photosensitizer and light irradiation, named antimicrobial photodynamic therapy (aPDT) is an adjuvant therapy for eliminating microbial biofilms. This ex vivo study evaluates the effect of anti-biofilm activity of aPDT based on emodin-chitosan nanoparticles (Emo-CS-NPs) plus blue laser light against Streptococcus mutans biofilm on the enamel surface. MATERIALS: After determination of the fractional inhibitory concentration index of Emo and CS by checkerboard array assay, Emo-CS-NPs were synthesized and characterized. Following treatment of pre-formed S. mutans biofilms on the enamel slabs, cellular uptake of Emo-CS-NPs and intracellular reactive oxygen species (ROS) production were determined. The anti-biofilm and anti-metabolic activities of aPDT were investigated. Eventually, lactic acid production capacity, concentrations of S. mutans extracellular DNA (eDNA) levels, and expression of the gene involved in the biofilm formation (gtfB) were evaluated. RESULTS: The maximum uptake of Emo-CS-NPs occurs in an incubation time of 5 min. When irradiated, Emo-CS-NPs were photoactivated, generating ROS, and led to a decrease in the cell viability and metabolic activity of S. mutans significantly (P < 0.05). S. mutans eDNA and lactic acid production outcomes indicated that Emo-CS-NPs-mediated aPDT led to a significant reduction of eDNA levels (48%) and lactic acid production (72.4%) compared to the control group (P < 0.05). In addition, gtfB mRNA expression in S. mutans was downregulated (7.8-fold) after aPDT in comparison with the control group (P < 0.05). CONCLUSIONS: Our data support that, aPDT using Emo-CS-NPs revealed the highest cellular uptake and ROS generation. Emo-CS-NPs based aPDT could inhibit significantly biofilm formation and reduce effectively virulence potency of S. mutans; thus, it could be an adjuvant therapy against dental caries.

Evaluation of human coronavirus OC43 and SARS-COV-2 in children with respiratory tract infection during the COVID-19 pandemic.

The coronavirus disease 2019 (COVID-19) pandemic is an overwhelming crisis across the world. Human Coronavirus OC43 (HCoV-OC43) is a Betacoronavirus responsible mostly for mild respiratory symptoms. Since the presentations of HCoV-OC43 and severe acute respiratory syndrome coronavirus 2 (SARS-COV-2) are believed to resemble a lot, the aim of this study was to evaluate the frequency and characteristics of HCoV-OC43 in the current pandemic and the rate of coinfection for the two viruses. One hundred and seventeen patients referred to Children's Medical Center, Tehran, Iran with respiratory symptoms were included. Real-time reverse transcription-polymerase chain reaction (RT-PCR) methods were performed for the detection of HCoV-OC43 and SARS-COV-2. Totally, 23 (20%) had a positive RT-PCR for HCoV-OC43 and 25 (21%) were positive for SARS-COV-2. Two patients (2%) had a positive PCR for both HCoV-OC43 and SARS-COV-2. The two groups showed significant differences in having contact with family members with suspected or confirmed COVID-19 (p = 0.017), fever (p = 0.02), edema (p = 0.036), vomiting (p < 0.001), abdominal complaints (p = 0.005), and myalgia (p = 0.02). The median level of lymphocyte count in patients with HCoV-OC43 was significantly lower than patients with SARS-COV-2 infection (p = 0.039). The same frequency of SARS-COV-2 and HCoV-OC43 was found in children with respiratory symptoms during the COVID-19 pandemic. The rate of coinfection of SARS-COV-2 with HCoV-OC43 in our study was 0.08. Further research into the cocirculation of endemic coronaviruses, such as HCoV-OC43 and SARS-CoV2, in different regions, is highly recommended. Attempts to determine the geographic distribution and recruit more flexible test panel designs are also highly recommended.

Patterns of stress and strain in complete-arch prostheses supported by four or six implants: A literature review of finite element analyses.

Background: Tilted implants have been recommended as an alternative to the bone graft procedures in implant sites although with possibly higher stress concentrations. This study reviews finite element studies to evaluate patterns of stress and strain in complete-arch prostheses supported by 4‒6 implants. Methods: A literature search was performed using the online databases. Articles published in English from 2003 to 2015 were reviewed. A total of 100 articles were found related to the subject and after evaluating the titles and abstracts, 18 studies were selected. Results: By increasing the number of implants, a reduction was detected in the amount of stress in the bone and implants, while in others, the stress level did not change with the increase in the number of implants. Conclusion: According to finite element analyses, placing a distal implant in an angular position results in better distribution of forces and stresses. Using less cantilever lengths would reduce the stress.

Epidemiology of children with acquired immune deficiency syndrome (stage 3): A referral hospital-based study in Iran.

Lack of recognition of human immunodeficiency virus (HIV) infection especially in children and delayed implementation of effective control programs makes HIV infection as a major cause for concern. Information on HIV epidemiology in Iran as well as other Islamic countries is limited. The aim of our study was to describe the clinical manifestation and laboratory finding of HIV infected children who were admitted to a referral Children Medical Center (CMC) in Tehran, Iran, during 11 years from January 2002 to January 2013. This was a retrospective study carried out over a period of 11 years. The records of all patients attending to the CMC with confirmed acquired immunodeficiency syndrome (AIDS) were screened. The patients were evaluated for social circumstance, family history, age, gender, clinical, and laboratory features. Clinical data including fever, respiratory distress, diarrhea, rash, etc. as well as laboratory tests including complete blood count, serum glucose level, electrolytes, liver function test, cultures, CD4 lymphocyte count were evaluated. During the study period, 32 HIV positive children were enrolled. The majority of patients were presented with weight loss, prolonged fever, respiratory infection and chronic diarrhea. In this study, salmonella infections as well as streptococcal pneumonia and candida infections followed by, tuberculosis and Pseudomonas aeruginosa infections were the predominant opportunistic infections. Since the number of HIV-positive children has been alarmingly increasing in recent years and perinatal transmission is the most common route of HIV infection in children, essential recommendations for prenatal HIV testing as well as appropriate antiretroviral therapy by HIV infected mothers are needed.

Comparison of Antimicrobial Effects of Three Different Mouthwashes.

BACKGROUND: This study investigated the in vitro and in vivo antibacterial effects of three mouthwashes on supragingival plaque microbiota. The three mouthwashes under study were 0.2% chlorhexidine (CHX), Listerine®, and Persica (PM). Water was used as negative control. METHODS: Supragingival plaque samples were collected from 32 patients with gingivitis in the Dental School of Shahid Beheshti University of Medical Sciences in March 2014. Plaque samples were swabbed on agar plates and discs (previously immersed in the three mouthwashes) were placed on the agar. The zone of bacterial inhibition (ZOI) was measured after incubation for 24 hours. For the in vivo testing, the same plaque samples were inoculated on agar and the colony forming units (CFU) were counted. The patients were then instructed to use the mouthwashes (cases) and water (controls) for two weeks, after which plaque samples were again collected, inoculated and the CFUs were counted. RESULTS: For the ZOI test, 0.2% CHX inhibited the growth of bacteria to an average diameter of 18.38 mm, while Listerine®, PM and water caused no inhibition of bacterial growth around the discs after 24 hours. The mean bacterial count after using 0.2% CHX for two weeks decreased by 23.13 CFU. This was followed by Listerine®, with a mean reduction of 19.75 CFU. PM resulted in 13.5 CFU decrease in the mean bacterial count, while water reduced the bacterial count by only 1 CFU. CONCLUSION: 0.2% CHX inhibits bacterial growth considerably. All three mouthwashes can reduce total bacterial count after 2 weeks although with different mean bacterial count reduction.