COVID-19 vaccines breakthrough infection and adverse reactions in medical students: a nationwide survey in Iran.

Introduction: There are different types of COVID-19 vaccines approved worldwide. Since no national studies focus on vaccine-related adverse reactions and breakthrough cases, this study aimed to investigate the rate of adverse events and COVID-19 infection in medical students in Iran. Methods: This retrospective cohort study included Iranian medical students who received two doses of COVID-19 vaccines. The medical team gathered the demographic characteristics, comorbidities, type of vaccine, adverse events following vaccination, and history of COVID-19 infection data through a phone interview. The frequency of adverse events and breakthrough infection was stratified by vaccine type (ChAdOx1-S, Gam-COVID-Vac, and BIBP-CorV). Results: A total of 3,591 medical students enrolled in this study, of which 57.02% were females, with a mean age of 23.31 + 4.87. A PCR-confirmed and suspicious-for-COVID-19 breakthrough infection rate of 4.51 and 7.02% was detected, respectively. There was no significant relation between breakthrough infection and gender, BMI, blood groups, and comorbidities. However, there was a significant difference in breakthrough infection rate among different types of vaccines (p = 0.001) and history of COVID-19 infection (p = 0.001). A total of 16 participants were hospitalized due to COVID-19 infection after vaccination for reasons such as dyspnea, abnormal imaging, or decreased oxygen saturation. No severe infection or death was observed in the studied population. Conclusion: Vaccination prevented severe COVID-19 infection, although a high breakthrough infection rate was evident among Iranian medical students during the Delta variant's peak. Vaccine effectiveness may be fragile during emerging new variants and in high-exposure settings. Moreover, adverse events are rare, and the benefits of vaccination outweigh the side effects. However, many limitations challenged this study, and the results should be cautious.

A (GCC) repeat in SBF1 reveals a novel biological phenomenon in human and links to late onset neurocognitive disorder.

The human SBF1 (SET binding factor 1) gene, alternatively known as MTMR5, is predominantly expressed in the brain, and its epigenetic dysregulation is linked to late-onset neurocognitive disorders (NCDs), such as Alzheimer's disease. This gene contains a (GCC)-repeat at the interval between + 1 and + 60 of the transcription start site (SBF1-202 ENST00000380817.8). We sequenced the SBF1 (GCC)-repeat in a sample of 542 Iranian individuals, consisting of late-onset NCDs (N = 260) and controls (N = 282). While multiple alleles were detected at this locus, the 8 and 9 repeats were predominantly abundant, forming > 95% of the allele pool across the two groups. Among a number of anomalies, the allele distribution was significantly different in the NCD group versus controls (Fisher's exact p = 0.006), primarily as a result of enrichment of the 8-repeat in the former. The genotype distribution departed from the Hardy-Weinberg principle in both groups (p < 0.001), and was significantly different between the two groups (Fisher's exact p = 0.001). We detected significantly low frequency of the 8/9 genotype in both groups, higher frequency of this genotype in the NCD group, and reverse order of 8/8 versus 9/9 genotypes in the NCD group versus controls. Biased heterozygous/heterozygous ratios were also detected for the 6/8 versus 6/9 genotypes (in favor of 6/8) across the human samples studied (Fisher's exact p = 0.0001). Bioinformatics studies revealed that the number of (GCC)-repeats may change the RNA secondary structure and interaction sites at least across human exon 1. This STR was specifically expanded beyond 2-repeats in primates. In conclusion, we report indication of a novel biological phenomenon, in which there is selection against certain heterozygous genotypes at a STR locus in human. We also report different allele and genotype distribution at this STR locus in late-onset NCD versus controls. In view of the location of this STR in the 5' untranslated region, RNA/RNA or RNA/DNA heterodimer formation of the involved genotypes and alternative RNA processing and/or translation should be considered.

Novel implications of a strictly monomorphic (GCC) repeat in the human PRKACB gene.

PRKACB (Protein Kinase CAMP-Activated Catalytic Subunit Beta) is predominantly expressed in the brain, and regulation of this gene links to neuroprotective effects against tau and Aß-induced toxicity. Here we studied a (GCC)-repeat spanning the core promoter and 5' UTR of this gene in 300 human subjects, consisting of late-onset neurocognitive disorder (NCD) (N = 150) and controls (N = 150). We also implemented several models to study the impact of this repeat on the three-dimensional (3D) structure of DNA. While the PRKACB (GCC)-repeat was strictly monomorphic at 7-repeats, we detected two 7/8 genotypes only in the NCD group. In all examined models, the (GCC)7 and its periodicals had the least range of divergence variation on the 3D structure of DNA in comparison to the 8-repeat periodicals and several hypothetical repeat lengths. A similar inert effect on the 3D structure was not detected in other classes of short tandem repeats (STRs) such as GA and CA repeats. In conclusion, we report monomorphism of a long (GCC)-repeat in the PRKACB gene in human, its inert effect on DNA structure, and enriched divergence in late-onset NCD. This is the first indication of natural selection for a monomorphic (GCC)-repeat, which probably evolved to function as an "epigenetic knob", without changing the regional DNA structure.

Natural Selection at the NHLH2 Core Promoter Exceptionally Long CA-Repeat in Human and Disease-Only Genotypes in Late-Onset Neurocognitive Disorder.

BACKGROUND: Approximately 2% of the human core promoter short tandem repeats (STRs) reach lengths of ≥6 repeats, which may in part be a result of adaptive evolutionary processes and natural selection. A single-exon transcript of the human nescient helix loop helix 2 (NHLH2) gene is flanked by the longest CA-repeat detected in a human protein-coding gene core promoter (Ensembl transcript ID: ENST00000369506.1). NHLH2 is involved in several biological and pathological pathways, such as motivated exercise, obesity, and diabetes. METHODS: The allele and genotype distribution of the NHLH2 CA-repeat were investigated by sequencing in 655 Iranian subjects, consisting of late-onset neurocognitive disorder (NCD) as a clinical entity (n = 290) and matched controls (n = 365). The evolutionary trend of the CA-repeat was also studied across vertebrates. RESULTS: The allele range was between 9 and 25 repeats in the NCD cases, and 12 and 24 repeats in the controls. At the frequency of 0.56, the 21-repeat allele was the predominant allele in the controls. While the 21-repeat was also the predominant allele in the NCD patients, we detected significant decline of the frequency (p < 0.0001) and homozygosity (p < 0.006) of this allele in this group. Furthermore, 12 genotypes were detected across 16 patients (5.5% of the entire NCD sample) and not in the controls (disease-only genotypes; p < 0.0003), consisting of at least one extreme allele. The extreme alleles were at 9, 12, 13, 18, and 19 repeats (extreme short end), and 23, 24, and 25 repeats (extreme long end), and their frequencies ranged between 0.001 and 0.04. The frequency of the 21-repeat allele significantly dropped to 0.09 in the disease-only genotype compartment (p < 0.0001). Evolutionarily, while the maximum length of the NHLH2 CA-repeat was 11 repeats in non-primates, this CA-repeat was ≥14 repeats in primates and reached maximum length in human. CONCLUSION: We propose a novel locus for late-onset NCD at the NHLH2 core promoter exceptionally long CA-STR and natural selection at this locus. Furthermore, there was indication of genotypes at this locus that unambiguously linked to late-onset NCD. This is the first instance of natural selection in favor of a predominantly abundant STR allele in human and its differential distribution in late-onset NCD.

The Impact of Addictive Behaviors on Adolescents Psychological Well-Being: The Mediating Effect of Perceived Peer Support.

Studies exploring excessive Internet use and gambling are rapidly expanding concerns regarding its impact on mental health, especially in young people due to the increased prevalence of Internet and gambling addictions. Research suggests that perceived peer support plays a significant role in adolescents' psychological well-being. However, no empirical study has dealt with the mediating effect of perceived peer support on the relationship between Internet and gambling addictions and psychological well-being. Thus, the present study aimed to examine whether perceived peer support mediates the relation between Internet and gambling addictions and psychological well-being of adolescents. A sample of 347 Iranian adolescents aged 14 to 18 (Mean age 16.14, 50.4% male) who were studying in Kuala Lumpur, Malaysia participated in this study. Subjective Vitality Scale (SVS), Compulsive Internet Use Scale (CIUS), Six-item Social Support Questionnaire (SSQ6), and The South Oaks Gambling Screen (SOGS) were used to collect data. Mediation analyses showed a significant indirect effect of compulsive Internet use and problem gambling on psychological well-being through perceived peer support. The total effects of compulsive Internet use and problem gambling on psychological well-being were negative. This study implies the significance of strengthening the knowledge about the impact of peer relationships among adolescents.

Effect of Layering Technique on Push-Out Bond Strength of Composite Resin to Intracanal Dentin of Primary Anterior Teeth.

OBJECTIVES: This in-vitro study aimed to compare the push-out bond strength of composite resin posts packed into the root canal of primary anterior teeth using two different layering techniques. MATERIALS AND METHODS: Thirty-two primary anterior teeth were randomly divided into two groups. In group 1, after the preparation of post spaces, a posterior composite resin (Filtek P60) was packed in three horizontal layers by a composite condenser instrument with a cylindrical tip using the horizontal layering technique (HLT). In group 2, this was done using a condenser with a conical tip in three funnel-shaped layers according to the funnel-shaped layering technique (FSLT). Next, the specimens were subjected to push-out bond strength testing. Data were analyzed using t-test and the Kaplan-Meier curves. RESULTS: The mean±standard deviation (SD) bond strengths of composite resin posts were 8.46±3.45 MPa and 7.7±2.24 MPa for the HLT and FSLT, respectively; the difference was not statistically significant (P=0.46). CONCLUSIONS: The layering technique by which composite resin was packed into the root canal of primary anterior teeth (HLT versus FSLT) had no significant effect on the push-out bond strength of composite resin posts.

Role of Anatomic and Salivary Factors in Dental Calculus Formation in Primary and Mixed Dentition Stages.

PURPOSE: Clinical experience shows that formation of calculus is a very rare phenomenon in primary teeth, but it increases as the permanent teeth erupt. The purpose of this study was to assess the relationship between dental calculus, dental anatomy, and salivary factors in primary and mixed dentition stages. METHODS: A cross-sectional study was carried out to determine the buccolingual dimensions of the most concave and the most convex surfaces of the lingual aspect of mandibular central incisor crowns in a sample group of 120 three- to five-old children and 120 eight- to 10-year old children. Saliva samples were collected from 20 in each group. Data were analyzed using t tests. RESULTS: Significant differences were found between the ratio of the buccolingual dimensions of the most convex to the most concave areas of the lingual surfaces in primary and permanent incisors (P=0.028). Saliva analysis revealed significant differences in total protein (P=0.002), sodium (P=0.037), bicarbonate (P=0.003), and ammonia (P=0.025) between the two age groups. CONCLUSIONS: Anatomic and salivary factors may be important reasons for the differences in calculus formation.

Effect of Etching Time and Preparation on Push-Out Bond Strength of Composite to Intracanal Dentin of Primary Anterior Teeth.

OBJECTIVES: This in-vitro study aimed to compare the push-out bond strength of composite to prepared and unprepared intracanal dentin using a 5th generation bonding agent in primary anterior teeth after etching for seven and 15 seconds. MATERIALS AND METHODS: Sixty primary anterior teeth were randomly divided into four groups. In groups one and two, intracanal dentin remained intact while in groups three and four it was prepared using a #5 round bur and low-speed handpiece. Single Bond 2 was used in groups one and three after 15 seconds and in groups two and four after seven seconds of etching with phosphoric acid. After restoring with composite resin and incubation, the specimens were subjected to push-out bond strength test. Data were analyzed using two-way ANOVA and Kaplan Meier curves. RESULTS: The mean bond strength was not significantly different between seven and 15 seconds etching times (P=0.198). Dentin preparation had no significant effect on the mean bond strength (P=0.838). The interaction effect of etching time and dentin preparation was not significant either (P=0.680). CONCLUSIONS: Decreasing the etching time from 15 to seven seconds and preparation of intracanal dentin had no significant effect on push-out bond strength of composite to intracanal dentin of primary anterior teeth.

Comparison of Primary Molar Crown Dimensions with Stainless Steel Crowns in a Sample of Iranian Children.

Background and aims. Due to anatomic variation in tooth anatomy between populations, this study compared the buccolingual (BL) and mesiodistal (MD) dimensions of primary molars with those of stainless steel crowns (SSCs) in anIranian population. Materials and methods. Impressions were taken from both dental arches of children, and casts were poured. Teeth with caries, restoration, hypoplasia or other dental anomalies were excluded. 216 primary molars were selected and divided into 4 groups of 54 each (maxillary and mandibular first and second primary molars). MD/BL dimensions were measured using a digital caliper with 0.01 mm precision on casts and SCCs (3M brand). Data were assessed using paired t-test, post hoc test and ANOVA. P < 0.05 was considered statistically significant. Results. The MD dimension of the lower first molar SSC and the BL dimension of the lower second molar SSC had the least difference with the corresponding values of the respective teeth. The MD dimension of the upper second molar SSC and the BL dimension of the upper first molar SSC had the greatest difference with the corresponding values in the respective teeth. Comparison of the two different brands of SSCs for the upper first molar revealed that both types had significant differences with the teeth in terms of both MD (P = 0.0) and BL (P = 0.0) dimensions. Conclusion. In the studied population, best adaptation was seen in second lower molars and the least adaptationswere seen in first and second upper molars.

Bond Strength of 5(th), 6(th) and 7(th) Generation Bonding Agents to Intracanal Dentin of Primary Teeth.

OBJECTIVES: This in-vitro study sought to assess the push-out bond strength of a total etch and 2 self-etch bonding systems to intracanal dentin of primary anterior teeth (PAT). MATERIALS AND METHODS: Thirty-six primary anterior teeth were randomly divided into 3 groups of 5(th) generation (Single Bond 2), 6(th) generation (Clearfil SE) and 7(th) generation (Single Bond Universal) bonding agents. The canal orifice was restored with composite resin and the push-out test was carried out to assess the bond strength. After applying the push-out load, specimens were evaluated under a light microscope at 40X magnification. One-way ANOVA and log-rank test on Kaplan-Meier curves were applied for the comparison of bond strength among the 3 groups. RESULTS: The mean± standard deviation (SD) bond strength was 13.6±5.33 MPa for Single Bond 2, 13.85±5.86 MPa for Clearfil SE and 12.28±5.24 MPa for Single Bond Universal. The differences in bond strength among the 3 groups were not statistically significant (P>0.05). CONCLUSION: All three bonding agents are recommended for use with composite posts in PAT. However, due to high technical sensitivity of the Total Etch system, single or two-step self etch systems may be preferred for uncooperative children.

Comparison of Marginal Circumference of Two Different Pre-Crimped Stainless Steel Crowns for Primary Molars After Re-Crimping.

OBJECTIVES: It is not clear what type of pre-crimped crown is more successful in achieving greater marginal adaptation following re-crimping. This study aimed to assess the changes in the circumference of 3M ESPE and MIB pre-crimped stainless steel crowns (SSCs) for the primary maxillary and mandibular first and second molars following re-crimping. MATERIALS AND METHODS: This was an in-vitro, experimental study. Initial photographs were obtained from the margins of 3M and MIB SSCs for the upper and lower primary molars using a digital camera. Crown margins were crimped by applying 0.2N force using 114 and 137 pliers. Post-crimping photographs were also obtained and the changes in crown circumference after crimping were calculated using AutoCad software. The percentage of reduction in the circumference of crowns for each tooth was statistically analyzed based on the type of crown using student t-test. The effect of crown design and the associated teeth on the decreased circumference percentage was statistically analyzed by two-sided ANOVA. RESULTS: The percentage of reduction in lower E SSC circumference was 3.71±0.39% in MIB and 6.29±0.62% in 3M crowns. These values were 3.55±0.55% and 7.15±1.13% for the lower Ds, and 3.95±0.43 and 6.24±0.85% for the upper Ds, respectively. For the upper Es, these values were found to be 3.12±0.65% and 5.14±0.94%, respectively. For each tooth, a significant difference was found between MIB and 3M SSCs in terms of the percentage of reduction in crown circumference following crimping. The magnitude of this reduction was smaller in MIB compared to 3M SSCs (P<0.001). CONCLUSION: Considering the significant reduction in the marginal circumference of precrimped SSCs following re-crimping, it appears that this manipulation must be necessarily performed for MIB and 3M pre-crimped SSCs. By using 3M SSCs, higher marginal adaptation can be achieved following crimping.

Informing Parents about the Pharmacological and Invasive Behavior Management Techniques Used in Pediatric Dentistry.

Background and aims. Parental acceptance and consent are important parameters in selecting the required behavior management technique during pediatric dental treatment. The present study sought to assess the effect of three different informing methods on the parental acceptance, consent and concern regarding the pharmacological and invasive behavior management techniques used in pediatric dentistry. Materials and methods. Ninety mothers of 3-6-year-old uncooperative children were selected and randomly assigned to three study groups. The parents in each group were initially asked to answer three questions related to their levels of 'acceptance','consent', and 'concern' toward the five behavior management techniques. Then, the information about the techniques was presented through a piece of writing in group I, verbal presentation in group II and showing a film in group III. At last, the parents answered the same three questions again. Score changes were analyzed by using ANOVA, correlations, Mann-Whitney U and Kruskal-Wallis methods. Results. There were no statistically significant differences in score changes of parental acceptance, consent and concern between the three groups, overall and in relation to each behaviour management technique (P > 0.05). Mothers with aca-demic education revealed more statistically significant concern following presentation of information by film (P < 0.05). Conclusion. None of the presentation methods had a significant preference over the others; in selecting the behavioral management techniques, it is advisable to observe individual factors, such as the level of education of the mothers.

The effect of using different rinsing angles on the micro-tensile bond strength of the sealant to the etched enamel.

BACKGROUND: Attempts to enhance bond strength of the sealant have been among the most important sides of dental research. AIM: The purpose of the present study was to evaluate the effect of using different rinsing angles on the micro-tensile bond strength of the sealant to the etched enamel. SETTINGS AND DESIGN: Experimental study. MATERIALS AND METHODS: Sixty first-premolars were randomly assigned to six groups based on the rinsing angle applied (15°, 30°, 45°, 60°, 75°, and 90°). Following etching and rinsing, a 4-mm height build up of sealant material was created. Bonded specimens were sectioned into sticks (1 × 1 mm), which were subjected to micro-tensile bond strength, testing at a cross-head speed of 0.5 mm/min. STATISTICAL ANALYSIS USED: The data were analyzed by Kolmogorov-Smirnov and post-hoc Tukey test. RESULTS: The tensile bond strength in specimens rinsed at 90° were statistically higher compared to those rinsed at 15° and 30° (P < 0.05), and increasing the angle from 15° to 90° was correlated with a reduction in the number of specimens with adhesive failures. CONCLUSIONS: Rinsing the conditioned enamel surface at 90° may improve the bond strength and retention of the sealant.

The effect of using different rinsing angles on the micro-tensile bond strength of the sealant to the etched enamel.

BACKGROUND AND OBJECTIVES: Attempts to enhance bond strength of the sealant have been among the most important sides of dental research. The purpose of the present study was to evaluate the effect of using different rinsing angles on the micro-tensile bond strength of the sealant to the etched enamel. MATERIALS AND METHODS: Sixty first-premolars were randomly assigned to six groups based on the rinsing angle applied (15°, 30°, 45°, 60°, 75° and 90°). Following etching and rinsing, a 4-mm height build-up of sealant material was created. Bonded specimens were sectioned into sticks (1 mm × 1 mm), which were subjected to micro-tensile bond strength, testing at a cross head speed of 0.5 mm/min. STATISTICAL ANALYSIS USED: The data were analyzed by Kolmogorov-Smirnov and post-hoc Tukey test. RESULTS: The tensile bond strength in specimens rinsed at 90° were statistically higher compared to those rinsed at 15° and 30° (P < 0.05) and increasing the angle from 15° to 90° was correlated with a reduction in the number of specimens with adhesive failures. CONCLUSIONS: Rinsing the conditioned enamel surface at 90° may improve the bond strength and retention of the sealant.

Neuroprotective effects of the immunomodulatory drug Setarud on cerebral ischemia in male rats.

Anti-inflammatory and anti-oxidant agents can alleviate ischemic cerebral injury. The immunomodulary drug Setarud, which is composed of herbal extracts including Rosa canina, Urtica dioica and Tanacetum vulgare, supplemented with selenium exhibits anti-inflammatory and anti-oxidant properties. Therefore, we hypothesized that Setarud will have a neuroprotective effect against ischemic cerebral injury. To validate this hypothesis, rats were intraperitoneally administered with 0.66 mL/kg Setarud for 30 minutes after middle cerebral artery occlusion. Triphenyltetrazolium chloride staining showed that Setarud could reduce cerebral infarct volume of rats subjected to cerebral ischemia. Transmission electron microscopy and hematoxylin-eosin staining results showed that Setarud could alleviate the degenerative changes in cortical neurons of rats with cerebral ischemia. The inclined plate test and prehensile test showed that Setarud could significantly improve the motor function of rats with cerebral ischemia. These findings suggest that Setarud shows neuroprotective effects against ischemic brain injury.

The Effect of Parental Presence on the 5 year-Old Children's Anxiety and Cooperative Behavior in the First and Second Dental Visit.

OBJECTIVE: One of the most significant problems in pediatric dentistry is behavioral resistance of preschool children in the first visit. There is a debate on parental presence in operation room. The purpose of this study was to evaluate the Iranian 5-year-old children's behavior including anxiety and cooperation relative to parental presence in the first and second dental appointments. METHODS: The study was conducted on sixty seven 5-year-old children selected according to inclusion criteria and randomly divided into two subgroups. Children in group I were visited in parent's presence and in group II in parent's absence. Before the child's first dental visit, parents were interviewed. Forty eight of the children receiving the initial examination were recalled for a second visit. The children's responses during the Holst procedure of the first visit and restorative second visit were assessed using a combination of two measures including heart rate and clinical behavior. The dentist-patient interactions were regulated by standardized scripts and recorded on videotape. Then, the behavior of the child on the recording during each visit was quantified by two pediatric dentists independently according to Venham 6-point rating scale and Frankle 4-point rating scale. FINDINGS: There were no significant differences between the heart rate measures of children in group I and II in the first and second visit (0.67, 0.8 respectively). There were also no significant differences between the clinical anxiety scores of children in the two groups in the first and second visit (0.98, 0.42 respectively). Moreover, there were no significant differences between the clinical cooperation scores of children in group I and group II in the first and second visit (0.88, 0.40 respectively), neither were there any significant differences between response measures of each child between two visits (P>0.05). In addition, there were no significant differences related to sex, parental education and dental experiences (P>0.05). CONCLUSION: Parental presence or absence doesn't affect an Iranian 5-year-old child's anxiety on the first and second dental visit, as well as an Iranian 5-year-old child's cooperation on the first and second dental visit.