Evaluation of paediatric osteosarcomas by classic cytogenetic and CGH analyses

Classic cytogenetic and comparative genomic hybridisation (CGH) data on osteosarcomas have been reported extensively in the literature. However, the number of paediatric osteosarcoma cases studied below the age of 14 years remains relatively small. This study reports four new cases of paediatric osteosarcoma in patients aged 3 to 13 years, evaluated by classic cytogenetics and CGH analyses. Clonal chromosomal alterations were detected in all the cases and included structural rearrangements at 1p11-13, 1q11, 4q27-33, 6p23-25, 6q16-25, 7p13-22, 7q11-36, 11p10-15, 11q23, 17p11.2-13, 21p11, and 21q11-22. The CGH analysis revealed recurrent gains at 1p, 4q, 17p, and 21q and losses at 3q and 16p. Five amplification sites were observed at 1q11-23, 6p21, 8q13, 8q21.3-24.2, and 17p. The data are discussed and compared with other cytogenetic reports in the literature.

Characterization of chromosome 17 abnormalities in medulloblastomas

Loss of portions of chromosome 17p, usually through the formation of i(17qp) is a well-known finding in medulloblastomas. Loss of heterozygosity (LOH) studies, however, occasionally demonstrate loss of the more distal portions of 17p, a pattern which is more consistent with a terminal deletion. Here we use a combination of routine karyotyping, fluorescence in situ hybridization (FISH) and LOH studies on four medulloblastoma cell lines and one xenograft to demonstrate the spectrum of chromosome 17 abnormalities which occur in these tumors. Cell line D-556 Med showed a typical dicentric i(17q) and cell line D-721 Med showed two normal copies of chromosome 17 by all methods. Cell line D-425 Med showed loss of terminal 17p by LOH, while the karyotype showed what appeared to be an i(17q). FISH and chromosome 17 painting, however, demonstrated that the abnormal chromosome 17 was actually formed through an unbalanced translocation involving two copies of chromosome 17, with breakpoints at p12 and q11-1, an explanation which reconciled the cytogenetic and LOH findings. Cell line D 581 Med had a terminal deletion at 17p11.2. The finding of two cells with i(17q) in this case by interphase FISH suggests that the terminal deletion arose from breakage of an i(17q). Finally, xenograft D 690 Med showed LOH for regions distal to 17p12, whereas karyotyping, FISH using probes on 17p, and chromosome 17 painting showed two intact copies of chromosome 17. This pattern can be explained by homologous recombination. These data support the concept that the critical deletion of 17p can occur through a variety of mechanisms in the medulloblastoma. The losses may occur through typical i(17q), as well as other mechanisms such as terminal deletions, possibly through breakage of i(17q), unbalanced translocations and homologous recombination.

Controlled Oxidation of Metallic Molybdenum Patterns via Joule Heating for Localized MoS2 Growth

High-quality two-dimensional transition metal dichalcogenides (2D TMDs), such as molybdenum disulfide (MoS2), have significant potential for advanced electrical and optoelectronic applications. This study introduces a novel approach to control the localized growth of MoS2 through the selective oxidation of bulk molybdenum patterns using Joule heating, followed by sulfurization. By passing an electric current through molybdenum patterns under ambient conditions, localized heating induced the formation of a molybdenum oxide layer, primarily MoO2 and MoO3, depending on the applied power and heating duration. These oxides act as nucleation sites for the subsequent growth of MoS2. The properties of the grown MoS2 films were investigated using Raman spectroscopy and photoluminescence measurements, showing promising film quality. This study demonstrates that Joule heating can be an effective method for precise control over TMD growth, offering a scalable approach for producing high-quality 2D materials that have the potential to be integrated into next-generation electrical and optoelectronic technologies.

Knowledge, Attitude, and Practice of E-Cigarettes of Adolescents and Adults in Saudi Arabia: A Cross-Sectional Study

E-cigarettes have gained enormous popularity, and their use has increased drastically worldwide. However, little is known regarding adolescents' and adults' knowledge, attitudes, and practices in Saudi Arabia. We conducted a cross-sectional study using a self-administered online-modified WHO GATS questionnaire on a convenience sample approach. Data were collected between January and March 2021 after the alleviation of COVID-19 lockdown measures in Saudi Arabia. Univariate and multivariate regression models were developed to identify independent factors associated with knowledge, attitude, and practice. Our sample (1335) had a mean age of 26.45 ± 10.5 years; nearly half of the participants had poor knowledge about e-cigarettes. The usage and positive attitude were reported by 18.6% and 19.4%, respectively. Around 43.5% of e-cigarette users reported starting or increased use during the COVID-19 pandemic, while 9.5% of participants would recommend it to others. Logistic regressions showed that older participants were more likely to have poor knowledge (OR = 1.02, 95% C.I. = 1.01-1.03) and positive attitudes (OR = 0.98, 95% C.I. = 0.91-0.96). Male participants and smokers (OR = 3.0, 95% C.I. = 2.3-3.8) were more likely to have a positive attitude. However, younger participants were less likely to go for e-cigarettes (OR = 0.95, 95% C.I. = 0.93-0.97), while males (OR = 2.53, 95% C.I. = 1.65-3.86) and smokers (OR = 4.63, 95% C.I. = 3.47-6.18) were more likely to use them. This study indicated a high level of poor knowledge about e-cigarettes. A considerable proportion of participants reported usage and a positive attitude towards them. Older age, male gender, and being a smoker were the main elicited predictors for e-cigarette use.