Correlation between Radiomorphometric Indices and Edentulous Mandibular Arches to Diagnose Osteoporosis Using Orthopantomogram in West Bengal State in India.

AIM: To assess the influence of gender and age on different parameters of alveolar bone loss using orthopantomogram. MATERIALS AND METHODS: Eighty subjects were enrolled in the study (20 dentulous and 60 completely edentulous), fulfilling the inclusion and exclusion criteria. Completely edentulous subjects were divided into four groups (15 males and 15 females above 60 years) and (15 males and 15 females below 60 years). Dentulous group comprised 20 subjects (10 males and 10 females) between 41 and 75 years. After taking panoramic radiographs, vertical as well as horizontal reference lines were drawn. The parameters used for evaluation included mandibular cortical index (MCI), inferior mandibular cortical width (MCW), panoramic mandibular index (PMI), alveolar bone loss (ABL), and height of bone at first premolar (Hp) and first molar (Hm) of the mandible. RESULTS: There was significant association between MCI and age for females with C2 and C3 categories being more common with advancing age. MCW was stable in all groups, except in females above 60 years of age. PMI and ABL were nonsignificant for age and gender. Although the average values of bone height (Hm and Hp) for males were higher than those of females, the results were statistically insignificant. CONCLUSION: Panoramic radiographic measurements could provide much valuable information and could help in evaluating patients with a low bone mineral density (BMD) with a few limitations. CLINICAL SIGNIFICANCE: Dental professionals could screen the patients through panoramic radiographs taken during routine clinical examination, which could help in identifying patients with a low BMD so that further treatment could be initiated early and thus to prevent a pathologic fracture.

Partial ligand-receptor engagement yields functional bias at the human complement receptor, C5aR1.

The human complement component, C5a, binds two different seven-transmembrane receptors termed C5aR1 and C5aR2. C5aR1 is a prototypical G-protein-coupled receptor that couples to the Gαi subfamily of heterotrimeric G-proteins and ß-arrestins (ßarrs) following C5a stimulation. Peptide fragments derived from the C terminus of C5a can still interact with the receptor, albeit with lower affinity, and can act as agonists or antagonists. However, whether such fragments might display ligand bias at C5aR1 remains unexplored. Here, we compare C5a and a modified C-terminal fragment of C5a, C5apep, in terms of G-protein coupling, ßarr recruitment, endocytosis, and extracellular signal-regulated kinase 1/2 mitogen-activated protein kinase activation at the human C5aR1. We discover that C5apep acts as a full agonist for Gαi coupling as measured by cAMP response and extracellular signal-regulated kinase 1/2 phosphorylation, but it displays partial agonism for ßarr recruitment and receptor endocytosis. Interestingly, C5apep exhibits full-agonist efficacy with respect to inhibiting lipopolysaccharide-induced interleukin-6 secretion in human macrophages, but its ability to induce human neutrophil migration is substantially lower compared with C5a, although both these responses are sensitive to pertussis toxin treatment. Taken together, our data reveal that compared with C5a, C5apep exerts partial efficacy for ßarr recruitment, receptor trafficking, and neutrophil migration. Our findings therefore uncover functional bias at C5aR1 and also provide a framework that can potentially be extended to chemokine receptors, which also typically interact with chemokines through a biphasic mechanism.

Potential role of arteether on N-methyl-D-aspartate (NMDA) receptor expression in experimental cerebral malaria mice and extension of their survival.

Cerebral malaria (CM) is the severe neurological complication causing acute non-traumatic encephalopathy in tropical countries. The mechanisms underlying the fatal cerebral complications are still not fully understood. Glutamate, a major excitatory neurotransmitter in the central nervous system of the mammalian brain, plays a key role in the development of neuronal cells, motor function, synaptic plasticity, learning and memory processes under normal physiological conditions. The subtypes of ionotropic glutamate receptor are N-methyl-D-aspartate receptors (NMDARs) which are involved in cellular mechanisms of learning and memory, synaptic plasticity and also mediate excitotoxic neuronal injury. In the present study, we found that glutamate level in synaptosomes, as well as expression of NMDAR, was elevated during the extreme condition of CM in C57BL6 mice. Arteether at 50 mg kg-1 × 1, 25 mg kg-1 × 2, days decreased the NMDAR expression and increased the overall survival of the experimental CM mice.

Mefloquine induces ROS mediated programmed cell death in malaria parasite: Plasmodium.

Recent studies pioneer the existence of a novel programmed cell death pathway in malaria parasite plasmodium and suggest that it could be helpful in developing new targeted anti-malarial therapies. Considering this fact, we evaluated the underlying action mechanism of this pathway in mefloquine (MQ) treated parasite. Since cysteine proteases play a key role in apoptosis hence we performed preliminary computational simulations to determine binding affinity of MQ with metacaspase protein model. Binding pocket identified using computational studies, was docked with MQ to identify it's potential to bind with the predicted protein model. We further determined apoptotic markers such as mitochondrial dysregulation, activation of cysteine proteases and in situ DNA fragmentation in MQ treated/untreated parasites by cell based assay. Our results showed low mitochondrial membrane potential, enhanced activity of cysteine protease and increased number of fragmented DNA in treated parasites compared to untreated ones. We next tested the involvement of oxidative stress in MQ mediated cell death and found significant increase in reactive oxygen species generation after 24 h of treatment. Therefore we conclude that apart from hemozoin inhibition, MQ is competent to induce apoptosis in plasmodium by activating metacaspase and ROS production.

Potential cerebral malaria therapy: intramuscular arteether and vitamin D co-administration.

Cerebral malaria (CM) shows lethality rate of 15-25% despite effective antimalarial chemotherapy. The effective adjunct treatment to counteract the CM pathogenesis is urgently required. In murine CM model, most interventions studied till date are administered before the onset of CM symptoms, which belittle its translational value to human. We studied intramuscular arteether-vitamin D (ART-VD) combination treatment for CM outcome improvement after the onset of neurological symptoms. The intramuscular dose of 50 µg kg-1 VD for 3 days combined with a loading dose of 25 mg kg-1 α/ß arteether followed by 12·5 mg kg-1 dose for two consecutive days led to significant improvement in survival (73% in combination group vs 29 and 0% in arteether and VD monotherapy, respectively) and clinical recovery. The treatment in all the groups partially restored the blood-brain barrier integrity and reduced the level of serum proinflammatory cytokines tumour necrosis factor-α and interferon-γ. The brain transcripts of inflammatory chemokines viz. CXCL10, CXCL9, CCL4 and CCL5 and T cell migration in the brain microvasculature were significantly diminished in all the treatment groups. ART-VD treatment significantly reduced intercellular cell adhesion molecule-1 expression. Taken together, our findings show that coordinated actions of ART-VD improve the outcome of experimental CM.

Analysis of the Microstructural and Mechanical Properties of 3D-Printed Removable Partial Denture Base Materials.

Background: Recent advancements in three-dimensional (3D) printing have introduced novel materials for removable partial dentures (RPD) base fabrication, promising improved mechanical properties, and biocompatibility. Materials and Methods: In this study, three different RPD base materials were evaluated: conventional heat-cured acrylic resin (Control), biocompatible 3D-printed resin (Test Group A), and a novel nanocomposite 3D-printed resin (Test Group B). A total of 30 standardized RPD base specimens (n = 10 per group) were fabricated according to established protocols. Microstructural analysis was performed using scanning electron microscopy (SEM), and the mechanical properties, including flexural strength and modulus, were determined using a universal testing machine. Results: Microstructural analysis revealed distinct differences among the materials. SEM images showed a well-defined and homogeneous microstructure in Test Group B, while Test Group A exhibited fewer voids compared to the Control group. Mechanical testing results indicated that Test Group B had the highest flexural strength (120 ± 5 MPa), followed by Test Group A (90 ± 4 MPa), and the Control group (75 ± 3 MPa). Similarly, Test Group B demonstrated the highest flexural modulus (3.5 ± 0.2 GPa), followed by Test Group A (2.8 ± 0.1 GPa), and the Control group (2.1 ± 0.1 GPa). Conclusion: These findings suggest that 3D-printed RPD base materials, particularly nanocomposite resins, hold promise for improving the overall quality and durability of removable partial dentures.

Antimalarial interaction of quinine and quinidine with clarithromycin.

Quinine (QN) and quinidine (QND) have been commonly used as effective and affordable antimalarials for over many years. Quinine primarily is used for severe malaria treatment. However, plasmodia resistance to these drugs and poor patient compliance limits their administration to the patients. The declining sensitivity of the parasite to the drugs can thus be dealt with by combining with a suitable partner drug. In the present study QN/QND was assessed in combination with clarithromycin (CLTR), an antibiotic of the macrolide family. In vitro interactions of these drugs with CLTR against Plasmodium falciparum (P. falciparum) have shown a synergistic response with mean sum fractional inhibitory concentrations (ΣFICs) of ≤1 (0.85 ± 0.11 for QN + CLTR and 0.64 ± 0.09 for QND + CLTR) for all the tested combination ratios. Analysis of this combination of QN/QND with CLTR in mouse model against Plasmodium yoelii nigeriensis multi-drug resistant (P. yoelii nigeriensis MDR) showed that a dose of 200 mg/kg/day for 4 days of QN or QND produces 100% curative effect with 200 mg/kg/day for 7 days and 150 mg/kg/day for 7 days CLTR respectively, while the same dose of individual drugs could produce only up to a maximum 20% cure. It is postulated that CLTR, a CYP3A4 inhibitor, might have caused reduced CYP3A4 activity leading to increased plasma level of the QN/QND to produce enhanced antimalarial activity. Further, parasite apicoplast disruption by CLTR synergies the antimalarial action of QN and QND.

A Systematic Review on Prosthodontic Rehabilitation of Hemimandibulectomy Defects.

Restoration of hemimandibulectomy defects following tumour extirpation to restore oral function is a herculean task for practitioners. Prosthetic treatment alternatives available for rehabilitation of acquired hemimandibulectomy defects according to mandibular reconstruction type and extent (Cantor-Curtis classification) are unclear. This systematic review aims to assess the spectrum of prosthodontic rehabilitation approaches with regard to reconstruction type and extent of mandibular surgical defects. The databases incorporated for literature search were Google Scholar and Medline (PubMed). Relevant search terms for hemimandibulectomy and reconstruction with prosthetic rehabilitation were used. Two reviewers independently assessed the articles using eligibility criteria; published case reports and case series in the English language and depicting prosthodontic treatment modality of patients greater than 15 years were included. A total of 202 records were identified from the database search of which 19 duplicates were removed. The remaining articles were assessed for eligibility, and 55 articles (comprising 58 cases) were finally included in the study. This review revealed various prosthetic alternatives ranging from guide flange, twin occlusion, palatal ramp, conventional to hybrid partial and complete dentures to implant-supported prosthesis including a few innovative prosthetic approaches. This systematic review provides a plethora of prosthodontic rehabilitation approaches according to the extent of hemimandibular surgical defect and type of reconstruction. This will facilitate practitioners and prosthodontists in sequential treatment planning and management of hemimandibulectomy cases in their routine practice.

Denture hygiene awareness, attitude and practice among complete denture wearers during COVID-19 lockdown Pandemic: A questionnaire based survey.

OBJECTIVE: To determine the denture hygiene habits in complete denture wearers during Covid-19 lockdown in Assam state. MATERIALS AND METHODS: In this study, a self-administered structured questionnaire was developed to know the attitude of the patients regarding denture hygiene. The study sample consisted of 150 subjects, which included 63 (42%) males and 87 (58%) females. RESULTS: 50.7% of individuals said that they have knowledge about denture cleansing methods, while only 40% individuals clean their dentures once daily. After education through an online survey, most individuals started practicing three times or at least two times. After educating two members in the same family, all subjects were cleaning either twice or thrice. All subjects were either using brushing or combination methods. CONCLUSION: Poor condition of complete dentures seen in the population is mainly due to lack of knowledge and irregular cleansing habits. Dentists must give proper instructions and do regular follow-up regarding maintenance of denture hygiene.

Measuring agonist-induced ERK MAP kinase phosphorylation for G-protein-coupled receptors.

Agonist stimulation of G-protein-coupled receptors (GPCRs) typically results in phosphorylation and activation of ERK (Extracellular-signal Regulated Kinase) which is a member of MAP kinase (Mitogen-Activated Protein kinase) family. Detection of phosphorylated ERK1/2 MAP kinase has been widely used as readout of GPCR signaling in heterologous cells, primary cells, tissues and even in animal studies. ERK1/2 phosphorylation downstream of GPCRs is now well established to arise from the activation of both, the heterotrimeric G-proteins and ß-arrestins (ßarrs) with distinct spatio-temporal components. Here, we present a step-by-step protocol for measuring agonist-induced ERK1/2 MAP kinase activation downstream of GPCRs using standard Western blotting assay. Note: ERK1/2 is also referred to as p44/42 MAP kinase. ERK1 and ERK2 are same as Mitogen-Activated Protein Kinase 3 (MAP3) and Mitogen-Activated Protein Kinase 1 (MAP1), respectively.

Conformational Sensors and Domain Swapping Reveal Structural and Functional Differences between ß-Arrestin Isoforms.

Desensitization, signaling, and trafficking of G-protein-coupled receptors (GPCRs) are critically regulated by multifunctional adaptor proteins, ß-arrestins (ßarrs). The two isoforms of ßarrs (ßarr1 and 2) share a high degree of sequence and structural similarity; still, however, they often mediate distinct functional outcomes in the context of GPCR signaling and regulation. A mechanistic basis for such a functional divergence of ßarr isoforms is still lacking. By using a set of complementary approaches, including antibody-fragment-based conformational sensors, we discover structural differences between ßarr1 and 2 upon their interaction with activated and phosphorylated receptors. Interestingly, domain-swapped chimeras of ßarrs display robust complementation in functional assays, thereby linking the structural differences between receptor-bound ßarr1 and 2 with their divergent functional outcomes. Our findings reveal important insights into the ability of ßarr isoforms to drive distinct functional outcomes and underscore the importance of integrating this aspect in the current framework of biased agonism.

GPCR Signaling: The Interplay of Gαi and ß-arrestin.

Biased agonism at G-protein-coupled receptors is generally conceptualized as the ability of certain stimuli to trigger downstream signaling exclusively through one of two effectors. Recent studies reveal that signaling downstream of the ß1 adrenergic receptor and the angiotensin II type 1 receptor induced by biased stimuli actually involves both effectors.

Novel Structural Insights into GPCR-ß-Arrestin Interaction and Signaling.

G protein-coupled receptors (GPCRs) are major signal recognition and transmission units in the plasma membrane. The interaction of activated and phosphorylated GPCRs with the multifunctional adaptor proteins ß-arrestins (ßarrs) is crucial for regulation of their signaling and functional outcomes. Over the past few years, a range of structural, biochemical, and cellular studies have revealed novel insights into GPCR-ßarr interaction and signaling. Some of these findings have come as a surprise and therefore have the potential to significantly refine the conceptual framework of the GPCR-ßarr system. Here we discuss these recent advances with particular emphasis on biphasic GPCR-ßarr interaction, the formation of GPCR-G-protein-ßarr supercomplexes, and receptor-specific conformational signatures in ßarrs. We also underline the emerging research areas that are likely to be at the center stage of investigations in the coming years.

A synthetic intrabody-based selective and generic inhibitor of GPCR endocytosis.

Beta-arrestins (ßarrs) critically mediate desensitization, endocytosis and signalling of G protein-coupled receptors (GPCRs), and they scaffold a large number of interaction partners. However, allosteric modulation of their scaffolding abilities and direct targeting of their interaction interfaces to modulate GPCR functions selectively have not been fully explored yet. Here we identified a series of synthetic antibody fragments (Fabs) against different conformations of ßarrs from phage display libraries. Several of these Fabs allosterically and selectively modulated the interaction of ßarrs with clathrin and ERK MAP kinase. Interestingly, one of these Fabs selectively disrupted ßarr-clathrin interaction, and when expressed as an intrabody, it robustly inhibited agonist-induced endocytosis of a broad set of GPCRs without affecting ERK MAP kinase activation. Our data therefore demonstrate the feasibility of selectively targeting ßarr interactions using intrabodies and provide a novel framework for fine-tuning GPCR functions with potential therapeutic implications.

Integrated machine learning, molecular docking and 3D-QSAR based approach for identification of potential inhibitors of trypanosomal N-myristoyltransferase.

N-Myristoyltransferase (NMT) catalyzes the transfer of myristate to the amino-terminal glycine of a subset of proteins, a co-translational modification involved in trafficking substrate proteins to membrane locations, stabilization and protein-protein interactions. It is a studied and validated pre-clinical drug target for fungal and parasitic infections. In the present study, a machine learning approach, docking studies and CoMFA analysis have been integrated with the objective of translation of knowledge into a pipelined workflow towards the identification of putative hits through the screening of large compound libraries. In the proposed pipeline, the reported parasitic NMT inhibitors have been used to develop predictive machine learning classification models. Simultaneously, a TbNMT complex model was generated to establish the relationship between the binding mode of the inhibitors for LmNMT and TbNMT through molecular dynamics simulation studies. A 3D-QSAR model was developed and used to predict the activity of the proposed hits in the subsequent step. The hits classified as active based on the machine learning model were assessed as the potential anti-trypanosomal NMT inhibitors through molecular docking studies, predicted activity using a QSAR model and visual inspection. In the final step, the proposed pipeline was validated through in vitro experiments. A total of seven hits have been proposed and tested in vitro for evaluation of dual inhibitory activity against Leishmania donovani and Trypanosoma brucei. Out of these five compounds showed significant inhibition against both of the organisms. The common topmost active compound SEW04173 belongs to a pyrazole carboxylate scaffold and is anticipated to enrich the chemical space with enhanced potency through optimization.

Arteether nanoemulsion for enhanced efficacy against Plasmodium yoelii nigeriensis malaria: an approach by enhanced bioavailability.

The present work is focused on the preparation of nanoemulsions (NEs) loaded with arteether (ART) for its enhanced efficacy against malaria parasites. ART-NEs have been prepared using high pressure homogenization (HPH) technique with the aim of improving its solubility and thus its bioavailability. ART-NEs were optimized in terms of pressure and number of cycles. Globule size and size distributions were chosen as quality parameters. The maximum drug loading was achieved up to 93 ± 7.4% with globule size 156 ± 10.2 nm and zeta potential of -23.3 ± 3.4 mV. The developed ART-NEs were found to be stable in terms of globule size and size distribution at different pH. The in vitro release profile of the ART-NEs showed 62% drug release within 12h. The percentage cell viability of blank NEs were within acceptable limits. A sensitive assay method for the determination of ART in rat plasma by liquid chromatography-mass spectrometry (LC-MS) was employed after oral administration of ART-NEs. The pharmacokinetic study showed significantly enhanced bioavailability of ART in ART-NE-V. The area under curve (AUC) of ART-NE-V was AUC0-t 1988.411 ± 119.66 h ng/ml which was significantly higher (p<0.05) than ART in ground nut oil (GNO) AUC0-t 671.852 ± 187.05 h ng/ml. The Cmax of ART-NE-V (1506 ± 161.22 ng/ml) was also significantly higher (p<0.05) than ART in GNO (175.2 ± 16.54 ng/ml) and ART given intramuscularly (IM) (278.05 ± 38.59 ng/ml). The ART-NE-V was having significantly high antimalarial efficacy and survival rate of mice giving 80% cure rate at 12.5 mg/kg for 5 days in comparison to 30% cure rate of ART in GNO at the same daily dose and it was also comparable to the 100% cure rate at 12.5 mg/kg for 5 days for ART given intramuscularly. In conclusion ART-NE can be a promising oral delivery system for ART.

Ketoconazole, a cytochrome P(450) inhibitor can potentiate the antimalarial action of α/ß arteether against MDR Plasmodium yoelii nigeriensis.

The emergence of multidrug resistant (MDR) strains of Plasmodium falciparum in South East Asia and other tropical countries, is posing serious challenge for the international efforts to eradicate malaria. New drug target/ACT/non-ACT combinations need to be discovered to control the spread of MDR malaria. The present communication deals with antimalarial potential of a new combination comprising of ketoconazole (KTZ) (an antifungal/inhibitor of CYP3A4) and artemisinin derivative α/ß arteether (ART). In vitro interactions of these drugs against chloroquine sensitive/resistant P. falciparum (Pf3D7/K1) have shown an overall additive interaction with mean sum fractional inhibitory concentrations (∑FICs) of 1.1±0.33 against 3D7 and 1.51±0.42 against K1 strains. Sub-curative doses of KTZ (150mg/kg×7 days) combined with ART (6.25-12.5mg/kg×5 days) both administered orally have shown 100% curative action against MDR P. yoelii nigeriensis in Swiss mice. Besides lower dose of KTZ (75mg/kg) which is non-curative itself, in combination with 12.5mg/kg×5 days of ART treatment, was also 100% curative. Further studies on mechanism of action of KTZ (150mg/kg single dose) have shown that significant inhibitory action of the antifungal drug is through very high level of suppression of CYP (nearly 90%) compared to that of healthy mice liver. The companion drug therapy comprising of KTZ together with ART (25mg/kg×1 dose) also produced more than 50% inhibitory effect on the CYP enzyme level. Since the ART is known to be rapidly metabolized by the liver cytochrome P450 (CYP) 3A4 to Dihydroquinghasu, the combined therapy with KTZ (a strong CYP 3A4 inhibitor) may influence the pharmacokinetics of ART and consequently slow down the drug metabolism and prolong the plasma life of the active drug, which would contribute to enhanced antimalarial action of ART against MDR P. yoelii nigeriensis.