PfHDAC1 is an essential regulator of P. falciparum asexual proliferation and host cell invasion genes with a dynamic genomic occupancy responsive to artemisinin stress.

Plasmodium falciparum, the deadly protozoan parasite responsible for malaria, has a tightly regulated gene expression profile closely linked to its intraerythrocytic development cycle. Epigenetic modifiers of the histone acetylation code have been identified as key regulators of the parasite's transcriptome but require further investigation. In this study, we map the genomic distribution of Plasmodium falciparum histone deacetylase 1 (PfHDAC1) across the erythrocytic asexual development cycle and find it has a dynamic occupancy over a wide array of developmentally relevant genes. Overexpression of PfHDAC1 results in a progressive increment in parasite load over consecutive rounds of the asexual infection cycle and is associated with enhanced gene expression of multiple families of host cell invasion factors (merozoite surface proteins, rhoptry proteins, etc.) and with increased merozoite invasion efficiency. With the use of class-specific inhibitors, we demonstrate that PfHDAC1 activity in parasites is crucial for timely intraerythrocytic development. Interestingly, overexpression of PfHDAC1 results in decreased sensitivity to frontline-drug dihydroartemisinin in parasites. Furthermore, we identify that artemisinin exposure can interfere with PfHDAC1 abundance and chromatin occupancy, resulting in enrichment over genes implicated in response/resistance to artemisinin. Finally, we identify that dihydroartemisinin exposure can interrupt the in vitro catalytic deacetylase activity and post-translational phosphorylation of PfHDAC1, aspects that are crucial for its genomic function. Collectively, our results demonstrate PfHDAC1 to be a regulator of critical functions in asexual parasite development and host invasion, which is responsive to artemisinin exposure stress and deterministic of resistance to it. IMPORTANCE: Malaria is a major public health problem, with the parasite Plasmodium falciparum causing most of the malaria-associated mortality. It is spread by the bite of infected mosquitoes and results in symptoms such as cyclic fever, chills, and headache. However, if left untreated, it can quickly progress to a more severe and life-threatening form. The World Health Organization currently recommends the use of artemisinin combination therapy, and it has worked as a gold standard for many years. Unfortunately, certain countries in southeast Asia and Africa, burdened with a high prevalence of malaria, have reported cases of drug-resistant infections. One of the major problems in controlling malaria is the emergence of artemisinin resistance. Population genomic studies have identified mutations in the Kelch13 gene as a molecular marker for artemisinin resistance. However, several reports thereafter indicated that Kelch13 is not the main mediator but rather hinted at transcriptional deregulation as a major determinant of drug resistance. Earlier, we identified PfGCN5 as a global regulator of stress-responsive genes, which are known to play a central role in artemisinin resistance generation. In this study, we have identified PfHDAC1, a histone deacetylase as a cell cycle regulator, playing an important role in artemisinin resistance generation. Taken together, our study identified key transcriptional regulators that play an important role in artemisinin resistance generation.

Genomic analysis of Indian isolates of Plasmodium falciparum: Implications for drug resistance and virulence factors.

The emergence of drug resistance to frontline treatments such as Artemisinin-based combination therapy (ACT) is a major obstacle to the control and eradication of malaria. This problem is compounded by the inherent genetic variability of the parasites, as many established markers of resistance do not accurately predict the drug-resistant status. There have been reports of declining effectiveness of ACT in the West Bengal and Northeast regions of India, which have traditionally been areas of drug resistance emergence in the country. Monitoring the genetic makeup of a population can help to identify the potential for drug resistance markers associated with it and evaluate the effectiveness of interventions aimed at reducing the spread of malaria. In this study, we performed whole genome sequencing of 53 isolates of Plasmodium falciparum from West Bengal and compared their genetic makeup to isolates from Southeast Asia (SEA) and Africa. We found that the Indian isolates had a distinct genetic makeup compared to those from SEA and Africa, and were more similar to African isolates, with a high prevalence of mutations associated with antigenic variation genes. The Indian isolates also showed a high prevalence of markers of chloroquine resistance (mutations in Pfcrt) and multidrug resistance (mutations in Pfmdr1), but no known mutations associated with artemisinin resistance in the PfKelch13 gene. Interestingly, we observed a novel L152V mutation in PfKelch13 gene and other novel mutations in genes involved in ubiquitination and vesicular transport that have been reported to support artemisinin resistance in the early stages of ACT resistance in the absence of PfKelch13 polymorphisms. Thus, our study highlights the importance of region-specific genomic surveillance for artemisinin resistance and the need for continued monitoring of resistance to artemisinin and its partner drugs.

Histidinal-Based Potent Antimalarial Agents.

Herein we report the synthesis and evaluation of peptide-histidinal conjugated drug scaffolds, which have the potential to target the hemoglobin-degrading proteases falcipain-2/3 from the human malaria parasite. Scaffolds with various substitutions were tested for antimalarial activity, and compounds 8 g, 8 h, and 15 exhibited EC50 values of ∼0.018 µM, ∼0.069 µM, and ∼0.02 µM, respectively. Structure-based docking studies on falcipain-2/3 proteases (PDB:2GHU and PDB:3BWK) revealed that compounds 8 g, 8 h, and 15 interact strongly with binding sites of falcipain-2/3 in a substrate-like manner. In silico ADME studies revealed that the molecules of interest showed no or minimal violations of drug-likeness parameters. Further, phenotypic assays revealed that compound 8 g and its biotinylated version inhibit hemoglobin degradation in the parasite food vacuole. The identification of falcipain-2/3 targeting potent inhibitors of the malaria parasite can serve as a starting point for the development of lead compounds as future antimalarial drug candidates.

Identification of Co-Existing Mutations and Gene Expression Trends Associated With K13-Mediated Artemisinin Resistance in Plasmodium falciparum.

Plasmodium falciparum infects millions and kills thousands of people annually the world over. With the emergence of artemisinin and/or multidrug resistant strains of the pathogen, it has become even more challenging to control and eliminate the disease. Multiomics studies of the parasite have started to provide a glimpse into the confounding genetics and mechanisms of artemisinin resistance and identified mutations in Kelch13 (K13) as a molecular marker of resistance. Over the years, thousands of genomes and transcriptomes of artemisinin-resistant/sensitive isolates have been documented, supplementing the search for new genes/pathways to target artemisinin-resistant isolates. This meta-analysis seeks to recap the genetic landscape and the transcriptional deregulation that demarcate artemisinin resistance in the field. To explore the genetic territory of artemisinin resistance, we use genomic single-nucleotide polymorphism (SNP) datasets from 2,517 isolates from 15 countries from the MalariaGEN Network (The Pf3K project, pilot data release 4, 2015) to dissect the prevalence, geographical distribution, and co-existing patterns of genetic markers associated with/enabling artemisinin resistance. We have identified several mutations which co-exist with the established markers of artemisinin resistance. Interestingly, K13-resistant parasites harbor α-ß hydrolase and putative HECT domain-containing protein genes with the maximum number of SNPs. We have also explored the multiple, publicly available transcriptomic datasets to identify genes from key biological pathways whose consistent deregulation may be contributing to the biology of resistant parasites. Surprisingly, glycolytic and pentose phosphate pathways were consistently downregulated in artemisinin-resistant parasites. Thus, this meta-analysis highlights the genetic and transcriptomic features of resistant parasites to propel further exploratory studies in the community to tackle artemisinin resistance.

Oral Health Assessment of Children with Autism Spectrum Disorder in Special Schools.

BACKGROUND: Sensory over-responsivity is an important factor influencing the ability of children with an autism spectrum disorder to receive proper oral care. Dental care remains the most prevalent, unmet health care need for children with special health care needs. AIM AND OBJECTIVE: To assess the oral health of children with autism in special schools. MATERIALS AND METHODS: A cross-sectional study was conducted to record the oral health problems of 142 autistic children attending special schools across the suburbs of Mumbai city in India. Clinical examination was carried out for the presence of dental plaque, gingivitis, caries, restorations, traumatic injuries, and self-injurious habits. The participants were divided into three groups based on their age. RESULTS: Children with primary and mixed dentition had a higher incidence of dental caries when compared with the permanent dentition group. Good oral hygiene was observed in the study population with a mean OHI-S score of 0.88 ± 0.79. Traumatic dental injuries, bruxism, drooling of saliva from the corner of the mouth, and self-injurious habits were also recorded. CONCLUSION: Due to the nature of their neurological deficit and difficulty in providing dental treatment, it is recommended that preventive dental care be enforced on these children. HOW TO CITE THIS ARTICLE: Santosh A, Kakade A, Mali S, et al. Oral Health Assessment of Children with Autism Spectrum Disorder in Special Schools. Int J Clin Pediatr Dent 2021;14(4):548-553.

Ultrasonography as a diagnostic aid for a neonate with gingival swelling in a COVID-19 neonatal intensive care unit.

COVID-19 pandemic has impacted all the aspects of life and has emerged as the biggest challenge to the health-care sector. Dental fraternity has also taken its significant impact since the transmission of disease is primarily through aerosol droplets. Management of infants with orofacial anomalies such as natal and neonatal teeth born to COVID-19-positive mothers is another challenge due to unavailability of dental facilities in the isolation wards. In such unforeseen circumstances, out-of-routine approaches such as extraoral mandibular ultrasonography were performed for the management of a congenital intraoral swelling in an infant and are being described in this case report.

Scanning electron microscopic observation of primary tooth dentin following final irrigation with 95% ethanol: An in vitro study.

BACKGROUND: The beneficial effects of irrigants during endodontic treatment are well known; however, it may have some deleterious effects on the internal root canal wall, thereby altering its physical properties. AIM: The purpose of the study was to assess the effect of 95% ethanol on morphological characteristics of primary root dentin. MATERIALS AND METHODS: Biomechanical preparation was done in twenty extracted single-rooted primary anterior teeth using Rotary ProTaper Universal System. Samples were divided into two groups based on the final irrigation protocol: nonalcohol group (NAG) and alcohol group (AG). 3% sodium hypochlorite and 17% ethylenediaminetetraacetic acid were used for irrigation in both the groups, whereas 95% ethanol was used as a final irrigant in AG. After the treatment, these teeth were longitudinally sectioned and studied under the scanning electron microscope (SEM). RESULTS: SEM observation of NAG showed scattered debris with unaffected morphology of dentinal tubules (DT). In AG, DT showed severe erosion with the loss of peritubular and intertubular dentin. CONCLUSION: A final rinse with 95% ethanol can change the morphology of the internal root surface and aid in smear layer removal in primary teeth.

Tamponade effect of resorbable biological barrier in quality of obturation in primary molar.

AIM: Physical properties of obturating materials have a direct effect on the quality of obturation; less viscous material will tend to extrude beyond the apex. We hypothesize that the use of absorbable gelatin sponge (AGS) can prevent the extrusion of these materials. This study aimed to evaluate the quality of obturation in root canals filled with iodoform-calcium hydroxide (Metapex) premixed paste and Metapex with AGS (MAGS) in primary molars. METHODS: This in vivo study comprised 60 primary mandibular molars which after instrumentation were divided into 2 groups according to the obturation material used, Metapex and MAGS, followed by radiographic evaluation to assess the quality of the obturation. The χ2 -test was applied for statistical analysis. RESULTS: There was a statistically significant difference between Metapex and MAGS groups in achieving optimum obturation (P < .001). Metapex and MAGS exhibited 86.65% and 38.88% optimum obturation respectively. The overfilling of root canals effectively reduced from 38.88% to 4.44%. CONCLUSION: The addition of AGS to Metapex causes a "tamponade effect", which reduces the tendency of Metapex to extrude beyond the root apex. Root canal obturation using a modified filling paste like MAGS is effective in obtaining optimum obturation in primary teeth.