3D Printed SiO2-Tricalcium Phosphate Scaffolds Loaded with Carvacrol Nanoparticles for Bone Tissue Engineering Application

Bone damage resulting from trauma or aging poses challenges in clinical settings that need to be addressed using bone tissue engineering (BTE). Carvacrol (CA) possesses anti-inflammatory, anticancer, and antibacterial properties. Limited solubility and physicochemical stability restrict its biological activity, requiring a stable carrier system for delivery. Here, we investigate the utilization of a three-dimensional printed (3DP) SiO2-doped tricalcium phosphate (TCP) scaffold functionalized with carvacrol-loaded lipid nanoparticles (CA-LNPs) to improve bone health. It exhibits a negative surface charge with an entrapment efficiency of ∼97% and size ∼129 nm with polydispersity index (PDI) and zeta potential values of 0.18 and -16 mV, respectively. CA-LNPs exhibit higher and long-term release over 35 days. The CA-LNP loaded SiO2-doped TCP scaffold demonstrates improved antibacterial properties against Staphylococcus aureus and Pseudomonas aeruginosa by >90% reduction in bacterial growth. Functionalized scaffolds result in 3-fold decrease and 2-fold increase in osteosarcoma and osteoblast cell viability, respectively. These findings highlight the therapeutic potential of the CA-LNP loaded SiO2-doped TCP scaffold for bone defect treatment.

Mental nerve shielding from possible injury during mandibular surgical procedures: technical note

Injuries to the mental nerve are not an uncommon complication in maxillofacial surgeries. Manipulation close to the mental nerve poses a great risk of nerve injury from drills, bone cutting and trimming burs, and oscillating/reciprocating saws. Nerve injuries can be painful and affect the patient's quality of life. The accompanying complication of the nerve injury depends on the severity of the damage inflicted and can range from transient hypoesthesia to neuropathic pain or trigeminal neuralgia. It is considered that direct injury to the nerve may lead to permanent damage and more severe postoperative clinical symptoms than indirect injuries caused by nerve stretching or during endosteal implant fixation. This technical note describes a technique for shielding the mental nerve and protecting it from rotary drill injury during mandibular inferior border recontouring, orthognathic surgeries, and mandibular body fracture fixation.

Utility of advanced echocardiographic deformation measures to delineate cause of pathological left ventricular hypertrophy: value of a multiparametric approach

Background

Early diagnosis of cardiac amyloidosis (CA) is warranted to initiate specific treatment and improve outcomes. Conventional echocardiography is unable to reliably differentiate CA from other causes of increased left ventricular (LV) wall thickness.

Purpose

To demonstrate the value of a multiparametric approach utilising both standard and advanced echocardiographic measures to distinguish CA from other pathological causes of increased LV wall thickness.

Results

Patients with HCM had the highest septal thickness, maximum LV wall thickness, septum/posterior wall (Sep/PW) thickness ratio and left ventricular outflow tract (LVOT) gradient and lowest PW thickness (p<0.0001) among all groups. Patients with CA had the lowest global longitudinal strain (GLS), tissue Doppler-derived myocardial systolic and diastolic velocities and LV ejection fraction (EF) (p<0.0001). EF strain ratio (EFSR=LVEF/GLS) and LV longitudinal strain (apex/base) ratio were highest (largest number) in CA patients (p<0.0001). Multivariate linear regression identified 5 independent predictors (PW thickness, Sep/PW thickness ratio, LVOT gradient, LV longitudinal strain (apex/base) ratio and GLS) that discriminated CA from other causes of increased LV wall thickness. A regression equation (using multivariate linear regression) {CA prediction value = (0.230*LS apex/base) − (0.002*LVOT gradient) − [0.068*(Sep/PW ratio)] + (0.007*PW thickness) + (0.022*GLS) + 0.189; r=0.667)} was derived which allowed reliable distinction of CA with a sensitivity of 92.3% and specificity of 91.2% at the optimal cut-off.

Conclusion

PW thickness, Sep/PW thickness ratio, LVOT gradient, LV longitudinal strain (apex/base) ratio and GLS are independent predictors of CA. We developed a multiparametric regression equation which allowed discrimination of CA from other causes of increased LV wall thickness. Future studies involving larger cohorts are required to validate these findings.

Funding Acknowledgement

Type of funding sources: None.

The way to a man's heart is through his stomach? A unique case report of transient constrictive pericarditis secondary to infarction of herniated omentum following bariatric surgery

Background

Intrapericardial diaphragmatic hernias are a rare form of diaphragmatic hernia. The presentation is usually acute due to trauma or from iatrogenic causes. In some instances however, these patients can present years later. We describe an unusual case of transient constrictive pericarditis associated with herniation of omentum through a diaphgragmatic hernia extending into the pericardial space, which infarcted following recent bariatric surgery. A multi-disciplinary approach was required with surgical correction of the diaphragmatic defect and removal of omentum from the pericardial space.

Case summary

A 38-year-old gentleman with a history of a remote abdominal stab wound and recent laparoscopic gastric sleeve procedure presented with sharp central chest pain radiating to the shoulder. Chest imaging [echocardiography, computed tomography (CT), and cardiac magnetic resonance imaging (MRI)] revealed the presence of an intrapericardial diaphragmatic hernia and herniation of devascularized omentum into the pericardial space. Surgery was undertaken to remove the pericardial omentum. Echocardiography and cardiac MRI revealed changes of pericardial constriction which resolved with anti-inflammatories.

Discussion

A multi-disciplinary approach was required in this case with surgical correction of the diaphragmatic defect and removal of omentum from the pericardial space. Multi-modal imaging proved essential in the diagnosis of this rare condition, aiding in timely diagnosis, ongoing management decisions, and for assessing therapeutic response.

Considerations for Pregnant Dental and Health Care Workers amid COVID-19

INTRODUCTION

Coronavirus disease 2019 (COVID-19) is a highly contagious disease that quickly reached pandemic levels. Over 5 million COVID-19 cases and approximately 330,000 deaths have been recorded worldwide. Transmission is primarily spread through direct, indirect (through contaminated objects or surfaces), or close contact with infected people via respiratory droplets, the mouth, and/or nose secretions. Health care professionals (HCPs), including dental HCPs, are recognized to be at considerably high risk for infection due to the close proximity to patients and aerosol-generating procedures. During pregnancy, HCPs may be at even higher risk since pregnancy substantially increases the susceptibility to infectious diseases.

OBJECTIVES

Here, we present the posed risks and potential effects of COVID-19 on maternal and fetal health. Current prevention and management strategies for COVID-19 on pregnant dental and HCPs are also discussed.

RESULTS

Significant progress is being made in understanding the pathogenesis and clinical consequences of COVID-19. Pregnant women are affected more adversely with viral illnesses, although evidence of vertical transmission of COVID-19 is controversial. Based on the presence of atypical symptoms, the significant numbers of asymptomatic individuals who are COVID-19 positive, and the high susceptibility to viral diseases observed in pregnant women, recommendations have been put forth to limit the exposure of COVID-19-positive or even suspected cases to pregnant HCPs, and these are likely to evolve as new information becomes available.

CONCLUSION

Pregnant HCPs require extra caution: not only are they considered a high-risk population, but their work at the frontline in a pandemic may expose them to additional risks. Complete awareness of the effects of COVID-19 on maternal and fetal/infant health, as well as prevention and management guidelines for pregnant HCPs, will allow for a safer work environment. Health care institutional policies aimed at protecting pregnant HCPs should consider avoiding their assignment as first responders, especially if equally trained staff are available.

KNOWLEDGE TRANSFER STATEMENT

Dental and health care professionals can use the information in this review to improve their awareness of COVID-19 risks, signs, and symptoms and the associated effects on the health of pregnant health care professionals and their unborn/newborn children.

21: DETERMINANTS OF VASCULAR INFLAMMATION BY 18-FLUORODEOXYGLUCOSE PET/MRI: FINDINGS FROM THE PSORIASIS, ATHEROSCLEROSIS AND CARDIOMETABOLIC DISEASE INITIATIVE

Purpose of Study

Psoriasis (PSO), a chronic inflammatory disease associated with increased CV risk, provides a clinical human model to study inflammatory atherogenesis. We aimed to assess the major determinants of vascular inflammation (VI) measured by 18FDG PET-MRI in a well-phenotyped PSO cohort.

Methods Used

124 consecutive patients with PSO underwent 18FDG PET-MRI scans. We used target-to-background ratio to quantify VI 120 minutes post FDG injection. Homeostatic model assessment of insulin resistance (HOMA-IR) was measured, along with cholesterol efflux capacity (CEC) and HDL particle concentration by NMR (Liposcience) fasting.

Summary of Results

Our cohort was middle aged (mean 49±13.3 years) with mild to moderate PSO, and low CV risk (median Framingham Risk Score (FRS) 2, IQR 2–6). PSO was associated with increased VI (β=0.27, p<0.005), compared to healthy controls. VI was associated with HOMA-IR (β=0.26, p<0.001), CEC (β=−0.12, p=0.04) and HDL particle concentration (β=−0.19, p=0.003) beyond traditional CV risk factors (age, gender, FRS and BMI). Among these, HOMA-IR provided maximum incremental value in predicting VI beyond traditional risk factors (χ2=39.36, p<0.001).

Conclusions

VI by FDG PET MRI is associated with traditional CV risk factors and cardiometabolic parameters. Insulin resistance and CEC were most strongly associated with VI by 18FDG PET-MRI beyond traditional CV risk factors and BMI in PSO suggesting that cardiometabolic disease increases CV risk in PSO.

Abstract 21 Figure 1

Linking the Rb and polycomb pathways

Polycomb group (PcG) proteins associate to form complexes that repress Hox genes, thereby imposing the patterning of Hox expression required for development. However, these proteins have a second Hox-independent role in regulating cell proliferation. Our results suggest that association between Rb and PcG proteins forms a repressor complex that blocks entry of cells into mitosis. Also, we provide evidence that Rb colocalizes with nuclear PcG complexes and is important for association of PcG complexes with nuclear targets. The Rb-PcG complex may provide a means to link cell cycle arrest to differentiation events leading to embryonic pattern formation.

Role of the LXCXE binding site in Rb function

Oncoproteins from DNA tumor viruses such as adenovirus E1a, simian virus 40 T antigen, and human papillomavirus E7 contain an LXCXE sequence, which they use to bind the retinoblastoma protein (Rb) and inhibit its function. Cellular proteins such as histone deacetylases 1 and 2 (HDAC1 and -2) also contain an LXCXE-like sequence, which they use to interact with Rb. The LXCXE binding site in Rb was mutated to assess its role in Rb function. These mutations inhibited binding to HDAC1 and -2, which each contain an LXCXE-like sequence, but had no effect on binding to HDAC3, which lacks an LXCXE-like sequence. Mutation of the LXCXE binding site inhibited active transcriptional repression by Rb and prevented it from effectively repressing the cyclin E and A gene promoters. In contrast, mutations in the LXCXE binding site did not prevent Rb from binding and inactivating E2F. Thus, the LXCXE mutations appear to separate Rb's ability to bind and inactivate E2F from its ability to efficiently recruit HDAC1 and -2 and actively repress transcription. In transient assays, several of the LXCXE binding site mutants caused an increase in the percentage of cells in G(1) by flow cytometry, suggesting that they can arrest cells. However, this effect was transient, as none of the mutants affected cell proliferation in longer-term assays examining bromodeoxyuridine incorporation or colony formation. Our results then suggest that the LXCXE binding site is important for full Rb function. Mutation of the LXCXE binding site does not inhibit binding of the BRG1 ATPase component of the SWI/SNF nucleosome remodeling complex, which has been shown previously to be important for Rb function. Indeed, overexpression of BRG1 and Rb in cells deficient for the proteins led to stable growth inhibition, suggesting a cooperative role for SWI/SNF and the LXCXE binding site in efficient Rb function.

Exit from G1 and S phase of the cell cycle is regulated by repressor complexes containing HDAC-Rb-hSWI/SNF and Rb-hSWI/SNF

We present evidence that Rb forms a repressor containing histone deacetylase (HDAC) and the hSWI/SNF nucleosome remodeling complex, which inhibits transcription of genes for cyclins E and A and arrests cells in the G1 phase of the cell cycle. Phosphorylation of Rb by cyclin D/cdk4 disrupts association with HDAC, relieving repression of the cyclin E gene and G1 arrest. However, the Rb-hSWI/SNF complex persists and is sufficient to maintain repression of the cyclin A and cdc2 genes, inhibiting exit from S phase. HDAC-Rb-hSWI/SNF and Rb-hSWI/SNF then appear to maintain the order of cyclin E and A expression during the cell cycle, which in turn regulates exit from G1 and from S phase, respectively.

Maxillary expansion--an interceptive modality in mixed dentition

Maxillary expansion is a very useful procedure for arch length augmentation, posterior crossbite treatment and removing cross arch interferences. Removable appliances are in the realm of a pedodontist and general dentist. However, one should be aware of the problems arising at an early age of the child, should be able to properly diagnose the condition and if required, a timely referral to a specialist is also expected.