Retinoblastoma

Retinoblastoma is the most common intraocular malignancy in children and one of the very few life-threatening ophthalmic conditions. Genetically, the disease may be heritable or non-heritable. It can have unilateral or bilateral involvement and can present either sporadically or with a positive family history. Leukocoria and strabismus are the most common presentations. Diagnosis is made by indirect ophthalmoscopy aided by imaging techniques. Multidisciplinary management is aimed at saving lives, salvaging the globe and maintaining good vision. The use of neoadjuvant chemotherapy and focal treatments, such as cryotherapy, laser photocoagulation, transpupillary thermotherapy, brachytherapy and periocular chemotherapy, form the mainstay of globe preserving treatment in retinoblastoma. In developing countries, retinoblastoma is unfortunately accompanied by a high mortality rate due to delayed diagnosis made at advanced stages of the disease. Early diagnosis and timely management are vital for a good prognosis.

Coexistence of superconductivity and ferromagnetism in two dimensions

Ferromagnetism is usually considered to be incompatible with conventional superconductivity, as it destroys the singlet correlations responsible for the pairing interaction. Superconductivity and ferromagnetism are known to coexist in only a few bulk rare-earth materials. Here we report evidence for their coexistence in a two-dimensional system: the interface between two bulk insulators, LaAlO(3) (LAO) and SrTiO(3) (STO), a system that has been studied intensively recently. Magnetoresistance, Hall, and electric-field dependence measurements suggest that there are two distinct bands of charge carriers that contribute to the interface conductivity. The sensitivity of properties of the interface to an electric field makes this a fascinating system for the study of the interplay between superconductivity and magnetism.

Effect of topical anesthesia and age on pain scores during retinopathy of prematurity screening

OBJECTIVE

The efficacy of topical anesthesia during retinopathy of prematurity (ROP) screening has been a controversial issue. To determine the efficacy of proparacaine eye drops (0.5%), we compared the Premature Infant Pain Profile (PIPP) scores in 40 preterm infants undergoing ROP screening.

STUDY DESIGN

Prospective randomized double masked cross-over clinical trial. The study was conducted in the neonatal intensive units for infants undergoing routine ROP screening exams. Baseline PIPP scores and post-examination PIPP scores at 1 and 5 min were compared for: (1) those receiving saline vs proparacaine eye drops (2) first ROP screening vs second ROP screening, regardless of the type of eye drops used. Wilcoxon signed-ranks test was used to pair pain scores.

RESULT

Forty preterm infants were included in the study. Mean gestational age (GA) at first and second examinations was 33.3 and 35.3 weeks, respectively. Proparacaine use significantly lowered mean PIPP scores (P=0.027) and delta scores (P=0.013) at 1 min after examination, but there was no difference at 5 min after examination. Second examinations showed significantly lower mean PIPP scores after examination (1 min (P=0.003) and 5 min (P=0.025)), regardless of the type of drop used.

CONCLUSION

Proparacaine eye drops offer significant relief of pain that is apparently short lived. Significantly lower PIPP scores at second ROP examinations suggested that infants of older GA may have a greater ability to tolerate ROP screening. We recommend the use of proparacaine eye drops for the short term, immediate relief of pain during ROP screening in preterm infants of lesser GA.

Influences of age and mechanical stability on volume, microstructure, and mineralization of the fracture callus during bone healing: is osteoclast activity the key to age-related impaired healing?

Earlier studies have shown that the influence of fixation stability on bone healing diminishes with advanced age. The goal of this study was to unravel the relationship between mechanical stimulus and age on callus competence at a tissue level. Using 3D in vitro micro-computed tomography derived metrics, 2D in vivo radiography, and histology, we investigated the influences of age and varying fixation stability on callus size, geometry, microstructure, composition, remodeling, and vascularity. Compared were four groups with a 1.5-mm osteotomy gap in the femora of Sprague-Dawley rats: Young rigid (YR), Young semirigid (YSR), Old rigid (OR), Old semirigid (OSR). Hypothesis was that calcified callus microstructure and composition is impaired due to the influence of advanced age, and these individuals would show a reduced response to fixation stabilities. Semirigid fixations resulted in a larger DeltaCSA (Callus cross-sectional area) compared to rigid groups. In vitro microCT analysis at 6 weeks postmortem showed callus bridging scores in younger animals to be superior than their older counterparts (p<0.01). Younger animals showed (i) larger callus strut thickness (p<0.001), (ii) lower perforation in struts (p<0.01), and (iii) higher mineralization of callus struts (p<0.001). Callus mineralization was reduced in young animals with semirigid fracture fixation but remained unaffected in the aged group. While stability had an influence, age showed none on callus size and geometry of callus. With no differences observed in relative osteoid areas in the callus ROI, old as well as semirigid fixated animals showed a higher osteoclast count (p<0.05). Blood vessel density was reduced in animals with semirigid fixation (p<0.05). In conclusion, in vivo monitoring indicated delayed callus maturation in aged individuals. Callus bridging and callus competence (microstructure and mineralization) were impaired in individuals with an advanced age. This matched with increased bone resorption due to higher osteoclast numbers. Varying fixator configurations in older individuals did not alter the dominant effect of advanced age on callus tissue mineralization, unlike in their younger counterparts. Age-associated influences appeared independent from stability. This study illustrates the dominating role of osteoclastic activity in age-related impaired healing, while demonstrating the optimization of fixation parameters such as stiffness appeared to be less effective in influencing healing in aged individuals.