Median effective dose of intranasal dexmedetomidine for satisfactory mask induction in children undergoing examination under anaesthesia for retinoblastoma - A prospective up and down sequential allocation study.

Background and Aims: Inhalational technique is used to induce anaesthesia in children without intravenous access. We aimed to determine the median effective dose (ED50) of intranasal dexmedetomidine to ensure satisfactory mask acceptance during inhalation induction in children with retinoblastoma undergoing examination under anaesthesia. Methods: A prospective sequential allocation study was conducted in children aged 1-60 months divided into Group A (1-18 months) and Group B (18-60 months). Children were administered dexmedetomidine intranasally as premedication. Sedation was assessed using the modified Observer Assessment of Alertness and Sedation Scale until induction. Successful mask acceptance was defined as a cooperative or asleep child during inhalational induction. The starting dose of dexmedetomidine was 1 µg/kg. The next dose varied by 0.2 µg/kg depending on the outcome of this case. According to the Dixon up-and-down method, the mean of midpoints of the failure-success sequence was calculated to obtain the ED50 values. Results: The ED50 of intranasal dexmedetomidine for satisfactory mask acceptance was 0.7 µg/kg (95% confidence interval [CI]: 0.54-0.86) in Group A (n = 23) and 0.96 µg/kg (95% CI: 0.83-1.08) in Group B (n = 25) (P = 0.020). The mean (standard deviation) duration of anaesthesia was 33.5 (14.9) minutes in group A versus 23.5 (8.48) minutes in Group B (P = 0.007). Conclusion: ED50 was lower in children younger than 18 months than in older children. There was no difference in the time to discharge from the post-anaesthesia care unit despite the procedure being longer in smaller children.

Depleted hexokinase1 and lack of AMPKα activation favor OXPHOS-dependent energetics in retinoblastoma tumors.

Lack of retinoblastoma (Rb) protein causes aggressive intraocular retinal tumors in children. Recently, Rb tumors have been shown to have a distinctly altered metabolic phenotype, such as reduced expression of glycolytic pathway proteins alongside altered pyruvate and fatty acid levels. In this study, we demonstrate that loss of hexokinase 1(HK1) in tumor cells rewires their metabolism allowing enhanced oxidative phosphorylation-dependent energy production. We show that rescuing HK1 or retinoblastoma protein 1 (RB1) in these Rb cells reduced cancer hallmarks such as proliferation, invasion, and spheroid formation and increased their sensitivity to chemotherapy drugs. Induction of HK1 was accompanied by a metabolic shift of the cells to glycolysis and a reduction in mitochondrial mass. Cytoplasmic HK1 bound Liver Kinase B1 and phosphorylated AMP-activated kinase-α (AMPKα Thr172), thereby reducing mitochondria-dependent energy production. We validated these findings in tumor samples from Rb patients compared to age-matched healthy retinae. HK1 or RB1 expression in Rb-/- cells led to a reduction in their respiratory capacity and glycolytic proton flux. HK1 overexpression reduced tumor burden in an intraocular tumor xenograft model. AMPKα activation by AICAR also enhanced the tumoricidal effects of the chemotherapeutic drug topotecan in vivo. Therefore, enhancing HK1 or AMPKα activity can reprogram cancer metabolism and sensitize Rb tumors to lower doses of existing treatments, a potential therapeutic modality for Rb.

A fungal epidemic amidst a viral pandemic: Risk factors for development of COVID-19 associated rhino-orbital-cerebral mucormycosis in India.

PURPOSE: To study the risk factors for development of COVID-19 associated rhino-orbital-cerebral mucormycosis (ROCM) during the COVID-19 pandemic in India. METHODS: Multi-centric retrospective case-control study conducted from October 2020 to May 2021. Cases comprised of consecutive patients of COVID-19-associated ROCM (CA-ROCM) presenting at the participating ophthalmic institutes. Controls comprised of COVID-19-positive or COVID-19-recovered patients who did not develop ROCM. Comparative analysis of demographic, COVID-19 infection, treatment parameters and vaccination status between cases and controls performed. Clinical and imaging features of CA-ROCM analyzed. RESULTS: There were 179 cases and 361 controls. Mean age of presentation in cases was 52.06 years (p = .001) with male predominance (69.83%, p = .000011). Active COVID-19 infection at the time of presentation of ROCM (57.54%, p < .0001), moderate to severe COVID-19 (p < .0001), steroid administration (OR 3.63, p < .00001), uncontrolled diabetes (OR 32.83, p < .00001), random blood sugar >178 mg/dl were associated with development of CA-ROCM. Vaccination showed a protective effect (p = .0049). In cases with intracranial or cavernous sinus extension there was history of steroid administration (OR 2.89, p = .024) and orbital apex involvement on imaging (OR 6.202, p = .000037) compared to those with only rhino-orbital disease. CONCLUSION: Male gender, active COVID-19 infection, moderate or severe COVID-19, uncontrolled diabetes, steroid administration during COVID-19 treatment are risk factors for developing rhino-orbital-cerebral mucormycosis. Vaccination is protective. Random blood sugar of >178 mg/dl in COVID-19 positive or recovered patients should warrant close observation and early detection of ROCM. Presence of ophthalmoplegia, blepharoptosis at first clinical presentation and orbital apex involvement on imaging are associated with intracranial extension in ROCM.

Selective Induction of Intrinsic Apoptosis in Retinoblastoma Cells by Novel Cationic Antimicrobial Dodecapeptides.

Host defense peptides represent an important component of innate immunity. In this work, we report the anticancer properties of a panel of hyper-charged wholly cationic antimicrobial dodecapeptides (CAPs) containing multiple canonical forms of lysine and arginine residues. These CAPs displayed excellent bactericidal activities against a broad range of pathogenic bacteria by dissipating the cytoplasmic membrane potential. Specifically, we identified two CAPs, named HC3 and HC5, that effectively killed a significant number of retinoblastoma (WERI-Rb1) cells (p ≤ 0.01). These two CAPs caused the shrinkage of WERI-Rb1 tumor spheroids (p ≤ 0.01), induced intrinsic apoptosis in WERI-Rb1 cells via activation of caspase 9 and caspase 3, cleaved the PARP protein, and triggered off the phosphorylation of p53 and γH2A.X. Combining HC3 or HC5 with the standard chemotherapeutic drug topotecan showed synergistic anti-cancer activities. Overall, these results suggest that HC3 and HC5 can be exploited as potential therapeutic agents in retinoblastoma as monotherapy or as adjunctive therapy to enhance the effectiveness of currently used treatment modalities.

Lack of Retinoblastoma Protein Shifts Tumor Metabolism from Glycolysis to OXPHOS and Allows the Use of Alternate Fuels.

Mutations in the RB1 locus leading to a loss of functional Rb protein cause intraocular tumors, which uniquely affect children worldwide. These tumors demonstrate rapid proliferation, which has recently been shown to be associated with an altered metabolic signature. We found that retinoblastoma tumors and in-vitro models lack Hexokinase 1 (HK1) and exhibit elevated fatty acid oxidation. We show that ectopic expression of RB1 induces HK1 protein in Rb null cells, and both RB1 and HK1 can mediate a metabolic switch from OXPHOS to glycolysis with increased pyruvate levels, reduced ATP production and reduced mitochondrial mass. Further, cells lacking Rb or HK1 can flexibly utilize glutamine and fatty acids to enhance oxidative phosphorylation-dependent ATP generation, as revealed by metabolic and biochemical assays. Thus, loss of Rb and HK1 in retinoblastoma reprograms tumor metabolic circuits to enhance the glucose-independent TCA (tricarboxylic acid) cycle and the intermediate NAD+/NADH ratios, with a subsequent increase in fatty-acid derived L-carnitine to enhance mitochondrial OXPHOS for ATP production instead of glycolysis dependence. We also demonstrate that modulation of the Rb-regulated transcription factor E2F2 does not result in any of these metabolic perturbations. In conclusion, we demonstrate RB1 or HK1 as critical regulators of the cellular bioenergetic profile and identify the altered tumor metabolism as a potential therapeutic target for cancers lacking functional Rb protein.

Enhanced Epithelial-to-Mesenchymal Transition and Chemoresistance in Advanced Retinoblastoma Tumors Is Driven by miR-181a.

Advanced retinoblastoma (Rb) tumors display high metastatic spread to distant tissues, causing a potent threat to vision and life. Through transcriptomic profiling, we discovered key upregulated genes that belonged to the epithelial-mesenchymal transition (EMT) and chemotherapy resistance pathways in advanced Rb tumors. Through in vitro models, we further showed that Rb null tumor cells under prolonged chemo drug exposure, acquires a metastasis-like phenotype through the EMT program mediated by ZEB1 and SNAI2 and these cells further acquires chemotherapeutic resistance through cathepsin-L- and MDR1-mediated drug efflux mechanisms. Using a miRNA microarray, we identified miR-181a-5p as being significantly reduced in advanced Rb tumors, which was associated with an altered EMT and drug-resistance genes. We showed that enhancing miR-181a-5p levels in Rb null chemo-resistant sublines reduced the ZEB1 and SNAI2 levels and halted the mesenchymal transition switch, further reducing the drug resistance. We thus identified miR-181a-5p as a therapeutically exploitable target for EMT-triggered drug-resistant cancers that halted their invasion and migration and sensitized them to low-dose chemotherapy drugs.

Ruptured retinoblastoma: management in a rare case scenario.

A preschool child presented with white reflex in left eye since 2 months. Examination under anaesthesia revealed left eye retinoblastoma group D as per international classification of retinoblastoma. In collaboration with medical oncologist, systemic chemotherapy was started. After two cycles of systemic chemotherapy, tumour ruptured into the vitreous cavity suspending the tumour cells in the vitreous jelly. After a combination of systemic and intravitreal chemotherapy with adjuvant transpupillary thermotherapy of the residual retinal tumour, retinoblastoma regressed completely with corresponding flat scar.

Integrated Analysis of Cancer Tissue and Vitreous Humor from Retinoblastoma Eyes Reveals Unique Tumor-Specific Metabolic and Cellular Pathways in Advanced and Non-Advanced Tumors.

Retinoblastoma (Rb) is a pediatric intraocular malignancy that is proposed to originate from maturing cone cell precursors in the developing retina. The molecular mechanisms underlying the biological and clinical behaviors are important to understand in order to improve the management of advanced-stage tumors. While the genetic causes of Rb are known, an integrated understanding of the gene expression and metabolic processes in tumors of human eyes is deficient. By integrating transcriptomic profiling from tumor tissues and metabolomics from tumorous eye vitreous humor samples (with healthy, age-matched pediatric retinae and vitreous samples as controls), we uncover unique functional associations between genes and metabolites. We found distinct gene expression patterns between clinically advanced and non-advanced Rb. Global metabolomic analysis of the vitreous humor of the same Rb eyes revealed distinctly altered metabolites, indicating how tumor metabolism has diverged from healthy pediatric retina. Several key enzymes that are related to cellular energy production, such as hexokinase 1, were found to be reduced in a manner corresponding to altered metabolites; notably, a reduction in pyruvate levels. Similarly, E2F2 was the most significantly elevated E2F family member in our cohort that is part of the cell cycle regulatory circuit. Ectopic expression of the wild-type RB1 gene in the Rb-null Y79 and WERI-Rb1 cells rescued hexokinase 1 expression, while E2F2 levels were repressed. In an additional set of Rb tumor samples and pediatric healthy controls, we further validated differences in the expression of HK1 and E2F2. Through an integrated omics analysis of the transcriptomics and metabolomics of Rb, we uncovered a significantly altered tumor-specific metabolic circuit that reduces its dependence on glycolytic pathways and is governed by Rb1 and HK1.

All India Ophthalmological Society - Oculoplastics Association of India consensus statement on preferred practices in oculoplasty and lacrimal surgery during the COVID-19 pandemic.

Oculoplastic surgeries encompass both emergency surgeries for traumatic conditions and infectious disorders as well as elective aesthetic procedures. The COVID-19 pandemic has brought about a drastic change in this practice. Given the highly infectious nature of the disease as well as the global scarcity of medical resources; it is only prudent to treat only emergent conditions during the pandemic as we incorporate evidence-based screening and protective measures into our practices. This manuscript is a compilation of evidence-based guidelines for surgical procedures that oculoplastic surgeons can employ during the COVID-19 pandemic. These guidelines also serve as the basic framework upon which further recommendations may be based on in the future, as elective surgeries start being performed on a regular basis.

Rates of Positive Findings on Positron Emission Tomography and Bone Marrow Biopsy in Patients With Ocular Adnexal Lymphoma.

PURPOSE: The aim of this study was to determine rates of positive findings on positron emission tomography (PET) and bone marrow biopsy performed during staging workup for ocular adnexal lymphoma (OAL). METHODS: A retrospective review of OAL patients was conducted. Demographics, primary versus secondary OAL, histologic subtype, and findings on PET and bone marrow biopsy performed as part of the initial staging workup for OAL were recorded. RESULTS: The study included 119 patients with OAL. There were 85 primary and 34 secondary OALs. The main histologic subtypes of lymphoma were mucosa-associated lymphoid tissue (n = 61), follicular (n = 26), diffuse large B-cell (n = 17), and mantle cell (n = 10). Positive PET findings were seen in 42 of 68 patients (62%) with primary OAL and 19 of 24 (79%) with secondary OAL. Positive PET findings were seen in 24 of 47 patients (51%) with mucosa-associated lymphoid tissue, 13 of 17 (76%) with follicular, 14 of 15 (93%) with diffuse large B-cell, and 9 of 10 (90%) with mantle cell lymphoma. Positive findings on bone marrow biopsy were seen in 7 of 59 patients (12%) with mucosa-associated lymphoid tissue, 4 of 23 (17%) with follicular, 1 of 17 (6%) with diffuse large B-cell, and 2 of 9 (22%) with mantle cell lymphoma. CONCLUSIONS: Our findings suggest that a significant proportion of patients with primary and secondary OAL have positive findings on PET and bone marrow biopsy at initial diagnosis, suggesting a reasonable yield for these tests as part of the initial staging workup in patients with a new diagnosis of OAL.

Role of Age and Myopia in Simultaneous Assessment of Corneal and Extraocular Tissue Stiffness by Air-Puff Applanation.

PURPOSE: To assess the correlation of age and myopia with corneal and extraocular tissue stiffness derived from air-puff applanation using a composite viscoelastic model. METHODS: This retrospective, cross-sectional study evaluated 155 normal eyes (age range: 5 to 50 years) measured on Corvis ST (Oculus Optikgeräte GmbH, Wetzlar, Germany). Manifest refraction spherical equivalent was also analyzed. A linear viscoelastic model that segregated corneal and extraocular tissue stiffness from the applanation deformation waveform was implemented. Corvis ST measured the total deformation (deformation amplitude waveform), which was simply the sum of corneal and extraocular tissue deformation. Age- and myopia-based multivariate analyses of variance between deformation parameters were performed after adjusting for intraocular pressure and central corneal thickness. Corvis ST corneal hysteresis was also calculated from the corneal deformation waveform. RESULTS: All myopia and age groups were matched for intraocular pressure and central corneal thickness. Extraocular tissue stiffness significantly increased with age (P = .03). Some other extraocular tissue deformation parameters also correlated with age, indicating age-related stiffening (P < .05). Corneal and extraocular tissue stiffness decreased with increasing myopia, but the trend was not significant (P = .10). Corvis ST corneal hysteresis increased with increasing age (P = .01) but not with increasing myopia (P = .61). CONCLUSIONS: Extraocular deformation parameters indicated stiffening of the extraocular tissues with age. Corneal deformation parameters were unaffected by age and myopia. Further studies with larger sample sizes are needed to clearly understand the effect of myopia on corneal and extraocular tissue stiffness. [J Refract Surg. 2016;32(7):486-493.].