Spectrum of pediatric brain tumors in India: A multi-institutional study

Background : Till date there is no published multi-institutional data regarding the epidemiological profile of pediatric brain tumors in India. Aim : The present retrospective study analyses the histological spectrum of pediatric age group brain tumors in seven tertiary care hospitals in India. Material and Methods : Data regarding frequencies of various primary brain tumors (diagnosed according to the World Health Organization (WHO) classification), in 3936 pediatric patients (<18 yrs of age), was collected from seven tertiary care hospitals in India. Results : The most common primary pediatric brain tumors were astrocytic tumors (34.7%), followed by medulloblastoma and supratentorial primitive neuro-ectodermal tumors (22.4%), craniopharyngiomas (10.2%) and ependymal tumors (9.8%). The most common astrocytic tumor was pilocytic astrocytoma. In comparison to adults, oligodendrogliomas and lymphomas were rare in children. Conclusions : Our study is the first such report on the histological spectrum of brain tumors in children in India. Except for a slightly higher frequency of craniopharyngiomas, the histological profile of pediatric brain tumors in India is similar to that reported in the Western literature

Loss of heterozygosity on chromosome 10q in glioblastomas, and its association with other genetic alterations and survival in Indian patients

Background: Glioblastoma multiforme (GBM) is the most common malignant central nervous system neoplasm. Loss of heterozygosity (LOH) on chromosome 10q in these tumors has been found to show variable association with prognosis. Aim: To evaluate LOH 10q status in cases of GBM, and to correlate these results with patient characteristics, other genetic alterations, and survival. Material and Methods: Fresh tumor tissue and blood samples were obtained for 25 cases of GBM diagnosed over a 2-year period. LOH 10q assay was performed on blood and tumor DNA by a PCR-based method using four microsatellite markers. TP53 mutation analysis and fluorescence in situ hybridization for epidermal growth factor receptor (EGFR) were performed. Histopathology was reviewed and clinical data were analyzed. Results: LOH 10q was identified in 17 of 25 cases (68%). Losses were frequent with markers D10S1765 (12/20 informative cases; 60%) and D10S587 (12/17 informative cases; 70.5%) in the regions of 10q23.3 and 10q26.1, respectively. D10S540 for 10q25.1 showed LOH in 4/12 informative cases (33.3%) and D10S1770 for 10q26-ter in none of the 25 cases. LOH with D10S1765 at the PTEN gene locus was found to correlate with overall LOH 10q status (P = 0.001). LOH 10q was more common in patients older than 40 years (16/19, 84.2%) than in those below (1/6, 16.7%) (P = 0.006). One of three pediatric patients included demonstrated LOH 10q. Survival rates for patients with LOH were lower than for patients with retained heterozygosity. Conclusion: LOH 10q is a frequent genetic abnormality in GBM in Indian patients, is seen more frequently in older adults, and its presence is associated with shorter survival. The single best marker to determine LOH 10q status is D10S1765 at the PTEN region

Hydrogen migration in inner-shell ionized halogenated cyclic hydrocarbons

Abstract We have studied the fragmentation of the brominated cyclic hydrocarbons bromocyclo-propane, bromocyclo-butane, and bromocyclo-pentane upon Br(3d) and C(1s) inner-shell ionization using coincidence ion momentum imaging. We observe a substantial yield of CH3+ fragments, whose formation requires intramolecular hydrogen (or proton) migration, that increases with molecular size, which contrasts with prior observations of hydrogen migration in linear hydrocarbon molecules. Furthermore, by inspecting the fragment ion momentum correlations of three-body fragmentation channels, we conclude that CHx⁺ fragments (with x = 0, …, 3) with an increasing number of hydrogens are more likely to be produced via sequential fragmentation pathways. Overall trends in the molecular-size-dependence of the experimentally observed kinetic energy releases and fragment kinetic energies are explained with the help of classical Coulomb explosion simulations

Monitoring the evolution of relative product populations at early times during a photochemical reaction

Identifying multiple rival reaction products and transient species formed during ultrafast photochemical reactions and determining their time-evolving relative populations are key steps toward understanding and predicting photochemical outcomes. Yet, most contemporary ultrafast studies struggle with clearly identifying and quantifying competing molecular structures/species among the emerging reaction products. Here, we show that mega-electronvolt ultrafast electron diffraction in combination with ab initio molecular dynamics calculations offer a powerful route to determining time-resolved populations of the various isomeric products formed after UV (266 nm) excitation of the five-membered heterocyclic molecule 2(5H)-thiophenone. This strategy provides experimental validation of the predicted high (∼50%) yield of an episulfide isomer containing a strained three-membered ring within ∼1 ps of photoexcitation and highlights the rapidity of interconversion between the rival highly vibrationally excited photoproducts in their ground electronic state