Biomedical subjects

A Leviton

Publications and source records attributed to A Leviton.

220 records · Page 13Linked to original sources

PubMedDate not supplied

Children with hypoplastic enamel defects of primary incisors are not at increased risk of learning-problem syndromes.

Developmental enamel defects of primary teeth have been associated in earlier reports with motor, hearing and psychological disturbances. The relationship between hypoplastic enamel defects and learning problems had not been evaluated previously. For a total of 149 girls and 196 boys we collected a primary tooth shortly after shedding and approximately 2 years later a teacher-completed questionnaire about function in school. Children with a hypoplastic enamel defect of one of their primary incisors were no more likely than their peers without an enamel defect to have any of 7 different learning problem syndromes. In the absence of reason to suspect selection bias, confounding, or misclassification of hypoplastic defects or school problems, we conclude that hypoplastic enamel defects are not associated with teacher-identified learning problems.

Child↗

PubMedDate not supplied

Quantitative histologic factors for grouping childhood supratentorial neuroglial tumors.

The histologic heterogeneity of childhood supratentorial neuroglial tumors, when quantified, identifies relatively homogeneous subgroups for prognostic purposes and for assignment in clinical trials. Our sample consisted of supratentorial tumors in the Childhood Brain Tumor Consortium. The data consist of reliably identified histologic features and demographic, clinical, operative, and survival information. Factor analysis was used to identify uncorrelated "factors," each represented by a different combination of histologic features in 703 tumors. The defining histologic features were used to label each factor. The heterogeneity of each tumor was summarized using the factor scores for each factor. We compared the survival estimates of subgroups of tumors within common diagnostic classes. We identified five uncorrelated quantitative factors that accounted for much of the histologic variation. Our factor labels were Jumbo, Fibrillary, Proliferative, Spongy, an Oligodendroglial. Two thirds of tumors had high scores on two or more factors, indicating a high degree of heterogeneity among these tumors. Eighty-four percent of supratentorial tumors were accounted for by 19 nonoverlapping relatively homogeneous histologic groups. The five quantitative factors complement standard qualitative taxonomies by summarizing more completely the histologic feature aspects of a tumor than by diagnosis alone and quantify the histologic heterogeneity of individual tumors. Histologically homogeneous groups of tumors are essential for clinical trials, biologic research, and prognostic models.

Adolescent↗

PubMedDate not supplied

Prognosis for children with supratentorial neuroglial tumors.

Factor analysis of reliably identified histologic features in supratentorial glial tumors yielded five interpretable "factors": Spongy, Fibrillary, Proliferative, Jumbo, and Oligodendroglial. Quantitative scores can be calculated for each factor in a tumor to summarize its heterogeneity. The objective was to investigate whether factor scores are useful for prognostic purposes. The sample consisted of 703 children with supratentorial neuroglial tumors with factor scores for each of the five factors. Data were based on the presence or absence of 26 reliably identified histologic features, plus clinical and survival information. Multivariate proportional hazards models assessed each factor's contribution to survival for children who survived 1 month after operation (n = 609). Patient-specific clinical data were allowed in the models. Increased likelihood of survival is associated with greater tumor removal, later decade of surgery, and high Spongy and high Oligodendroglial factor scores. Decreased likelihood of survival is associated with high Proliferative factor scores and radiation and/or chemotherapy treatment. Gender, age, location, and Jumbo and Fibrillary factor scores did not provide additional prognostic information. Three reliable histologic features, nondefining for any histologic factor, added prognostic information: Rosenthal fibers and glomeruli are associated with improved prognosis; pleomorphic nuclei are associated with worse prognosis. A high Oligodendroglial factor score is associated with a worse prognosis for some classes of astrocytoma but with a better prognosis for oligodendroglial tumors. A high Proliferative score is associated with a worse prognosis for anaplastic astrocytomas, ependymomas, and unclassifiable tumors. A high Spongy score is associated with a better prognosis for anaplastic astrocytomas but with a worse prognosis for pilocytic astrocytomas. For giant cell astrocytomas, gangliogliomas, and miscellaneous tumors, none of the factors is prognostic. Spongy, Oligodendroglial, and Proliferative factors provide important prognostic information for children with supratentorial neuroglial tumors.

Adolescent↗

PubMedDate not supplied

Quantitative histologic factors for grouping childhood infratentorial neuroglial tumors.

We employed factors analysis to quantify the degree of histologic heterogeneity of childhood infratentorial neuroglial tumors. Our data were 26 reliably ascertained histologic features in 1068 children in the Childhood Brain Tumor Consortium database. The factor analysis identified five uncorrelated quantitative "factors," each derived from a different linear combination of the 26 histologic features, that accounted for much of the histologic variation. Histologic features differed in their importance in each factor. The most important features in each factor were used for naming using simple, histologic, familiar descriptive terms: Spongy, Proliferative, Ring, Fibrillary, and Nuclear. Each tumor has a score on each factor. Two-thirds of tumors had high scores for at least two factors, indicating frequent histologic heterogeneity among these tumors. Ninety-five percent of tumors were allocated to 1 of 11 nonoverlapping histologically homogeneous groups. The five quantitative factors complement standard qualitative taxonomies by making explicit the histologic heterogeneity or homogeneity of individual tumors and provide the pathologist with a method that takes advantage of more of the histology of each tumor than conventional nomenclatures. Histologically homogeneous groups of tumors are likely to be of value in clinical trials and biologic research. Prognostic models based on these factors have been published.

Adolescent↗