A Comparative Evaluation of Pain Experience and Time of Onset of 2% Lignocaine and 4% Articaine in Inferior Alveolar Nerve Block among Pediatric Population: A Clinical Study.

Aim: The objective of this research was to conduct a comparison and evaluate the pain perception and time of onset of 2% lignocaine 1:80,000 epinephrine with 4% articaine 1:100,000 epinephrine in the pediatric population. Materials and methods: A split-mouth randomized control trial was conducted on 50 children aged 9-14 years who required inferior alveolar nerve block (IANB) anesthesia for bilateral dental treatment in the mandibular arch. The time of onset was recorded when no sensation was reported even when maximum electrical stimulus was applied in an electric pulp testing (EPT). The pain perception was assessed using a visual analog scale (VAS) rated by the patient for subjective symptoms and face, legs, activity, cry, and consolability (FLACC) scale for objective pain rated by the operator. Results: The mean onset of time, pain-VAS, and FLACC score decreased by 1.31, 12.07, and 18.39%, respectively in 4% articaine as compared to 2% lignocaine but the difference did not reach statistical significance (p > 0.05), that is, found to be statistically the same.In conclusion, it can be inferred that the utilization of 4% articaine is as potent as 2% lignocaine solution but showed slightly better onset of anesthesia and pain experience among the children although the findings were not statistically significant. Clinical significance: Local anesthesia (LA) is one of the main methods of pain management in pediatric practice which makes it essential to choose an LA agent with a shorter time of onset and less pain on administration. How to cite this article: Singh SS, Koul M. A Comparative Evaluation of Pain Experience and Time of Onset of 2% Lignocaine and 4% Articaine in Inferior Alveolar Nerve Block among Pediatric Population: A Clinical Study. Int J Clin Pediatr Dent 2024;17(1):67-71.

Evaluation of Mother's Complementary Feeding Knowledge and Occlusion.

Aim: Mothers' understanding of feeding methods and how they affect deciduous dentition were the focus of this study. Materials and Methods: This study looked at people from different parts of the population. In total, 230 moms of children aged 6 months to 5 years who completed an oral health questionnaire were included in the study. Mothers' awareness of feeding patterns and their impact on deciduous dentition were examined in the study. Results: Illiterate moms' children showed a significant difference in the quality of their occlusion compared to similarly raised children of literate mothers. Children who began supplementary feeding before the age of 6 months were more likely to have occlusion changes. Conclusion: Malocclusion prevalence was shown to be unrelated to meal behaviors. However, further research is required as there are just a few studies currently available.

A non-canonical promoter element drives spurious transcription of horizontally acquired bacterial genes.

RNA polymerases initiate transcription at DNA sequences called promoters. In bacteria, the best conserved promoter feature is the AT-rich -10 element; a sequence essential for DNA unwinding. Further elements, and gene regulatory proteins, are needed to recruit RNA polymerase to the -10 sequence. Hence, -10 elements cannot function in isolation. Many horizontally acquired genes also have a high AT-content. Consequently, sequences that resemble the -10 element occur frequently. As a result, foreign genes are predisposed to spurious transcription. However, it is not clear how RNA polymerase initially recognizes such sequences. Here, we identify a non-canonical promoter element that plays a key role. The sequence, itself a short AT-tract, resides 5 base pairs upstream of otherwise cryptic -10 elements. The AT-tract alters DNA conformation and enhances contacts between the DNA backbone and RNA polymerase.

Horizontally acquired AT-rich genes in Escherichia coli cause toxicity by sequestering RNA polymerase.

Horizontal gene transfer permits rapid dissemination of genetic elements between individuals in bacterial populations. Transmitted DNA sequences may encode favourable traits. However, if the acquired DNA has an atypical base composition, it can reduce host fitness. Consequently, bacteria have evolved strategies to minimize the harmful effects of foreign genes. Most notably, xenogeneic silencing proteins bind incoming DNA that has a higher AT content than the host genome. An enduring question has been why such sequences are deleterious. Here, we showed that the toxicity of AT-rich DNA in Escherichia coli frequently results from constitutive transcription initiation within the coding regions of genes. Left unchecked, this causes titration of RNA polymerase and a global downshift in host gene expression. Accordingly, a mutation in RNA polymerase that diminished the impact of AT-rich DNA on host fitness reduced transcription from constitutive, but not activator-dependent, promoters.

DNA recognition by Escherichia coli CbpA protein requires a conserved arginine-minor-groove interaction.

Curved DNA binding protein A (CbpA) is a co-chaperone and nucleoid associated DNA binding protein conserved in most γ-proteobacteria. Best studied in Escherichia coli, CbpA accumulates to >2500 copies per cell during periods of starvation and forms aggregates with DNA. However, the molecular basis for DNA binding is unknown; CbpA lacks motifs found in other bacterial DNA binding proteins. Here, we have used a combination of genetics and biochemistry to elucidate the mechanism of DNA recognition by CbpA. We show that CbpA interacts with the DNA minor groove. This interaction requires a highly conserved arginine side chain. Substitution of this residue, R116, with alanine, specifically disrupts DNA binding by CbpA, and its homologues from other bacteria, whilst not affecting other CbpA activities. The intracellular distribution of CbpA alters dramatically when DNA binding is negated. Hence, we provide a direct link between DNA binding and the behaviour of CbpA in cells.

Widespread suppression of intragenic transcription initiation by H-NS.

Widespread intragenic transcription initiation has been observed in many species. Here we show that the Escherichia coli ehxCABD operon contains numerous intragenic promoters in both sense and antisense orientations. Transcription from these promoters is silenced by the histone-like nucleoid structuring (H-NS) protein. On a genome-wide scale, we show that 46% of H-NS-suppressed transcripts in E. coli are intragenic in origin. Furthermore, many intergenic promoters repressed by H-NS are for noncoding RNAs (ncRNAs). Thus, a major overlooked function of H-NS is to prevent transcription of spurious RNA. Our data provide a molecular description for the toxicity of horizontally acquired DNA and explain how this is counteracted by H-NS.

H-NS can facilitate specific DNA-binding by RNA polymerase in AT-rich gene regulatory regions.

Extremely AT-rich DNA sequences present a challenging template for specific recognition by RNA polymerase. In bacteria, this is because the promoter -10 hexamer, the major DNA element recognised by RNA polymerase, is itself AT-rich. We show that Histone-like Nucleoid Structuring (H-NS) protein can facilitate correct recognition of a promoter by RNA polymerase in AT-rich gene regulatory regions. Thus, at the Escherichia coli ehxCABD operon, RNA polymerase is unable to distinguish between the promoter -10 element and similar overlapping sequences. This problem is resolved in native nucleoprotein because the overlapping sequences are masked by H-NS. Our work provides mechanistic insight into nucleoprotein structure and its effect on protein-DNA interactions in prokaryotic cells.

E. coli Fis protein insulates the cbpA gene from uncontrolled transcription.

The Escherichia coli curved DNA binding protein A (CbpA) is a poorly characterised nucleoid associated factor and co-chaperone. It is expressed at high levels as cells enter stationary phase. Using genetics, biochemistry, and genomics, we have examined regulation of, and DNA binding by, CbpA. We show that Fis, the dominant growth-phase nucleoid protein, prevents CbpA expression in growing cells. Regulation by Fis involves an unusual "insulation" mechanism. Thus, Fis protects cbpA from the effects of a distal promoter, located in an adjacent gene. In stationary phase, when Fis levels are low, CbpA binds the E. coli chromosome with a preference for the intrinsically curved Ter macrodomain. Disruption of the cbpA gene prompts dramatic changes in DNA topology. Thus, our work identifies a novel role for Fis and incorporates CbpA into the growing network of factors that mediate bacterial chromosome structure.

Escherichia coli σ7° senses sequence and conformation of the promoter spacer region.

In bacteria, promoter identification by RNA polymerase is mediated by a dissociable σ factor. The housekeeping σ(70) factor of Escherichia coli recognizes two well characterized DNA sequence elements, known as the '-10' and '-35' hexamers. These elements are separated by 'spacer' DNA, the sequence of which is generally considered unimportant. Here, we use a combination of bioinformatics, genetics and biochemistry to show that σ(70) can sense the sequence and conformation of the promoter spacer region. Our data illustrate how alterations in spacer region sequence can increase promoter activity. This stimulatory effect requires σ(70) side chain R451, which is located in close proximity to the non-template strand at promoter position -18. Conversely, R451 is not required to mediate transcriptional stimulation by improvement of the -10 element. Mutation of σ(70) residue R451, which is highly conserved, results in reduced growth rate, consistent with a central role in promoter recognition.