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Biomedical subjects

E J Breen

Publications and source records attributed to E J Breen.

5 recordsLinked to original sources
PubMed1992

Length regulation in the Dictyostelium discoideum slug is a late event.

Time-lapse video light microscopy was used to study the emergence and maturation of the migratory slug from a D. discoideum aggregate. The anterior part, the tip of this simple multicellular organism, establishes migration prior to the definition of the rear, and hence the length of the slug. It was found that newly formed slugs of wild-type strain WS380B can reach lengths greater than 1 cm, yet mature slugs of this strain are rarely longer than 2-3 mumm. Often the tip extended out of the aggregation mound upon an arching pillar of cells. After the tip first touched the substratum, it commenced migration with a rapid succession of movement steps. Here we show that at the initiation of migration, a differential rate of cell movement along the developing slug axis results in a series of complicated changes, before the stable and mature shape of the slug is formed. Our results lead to new conclusions about D. discoideum slug formation and shape maintenance. Evidence is presented for regulation of slug length.

Animals↗
PubMed1992

Dynamic arrays for fast, efficient, data manipulation during image analysis: a new software tool for exploratory data analysis.

Memory reallocation is used to construct a run-time data structure for fast/efficient storage of information during collection and analysis. The data structure presented uses dynamic memory but does not require the use of pointers to link nodes of information together. It allows for simple and efficient access to data via array indexing rather than through the use of lists or tree structures and it provides flexibility for competing storage requirements that are determined dynamically. The data structure is developed in the C programming language and a suite of ANSI standard C subroutines that make up a run-time data structure management system is provided.

Abstracting and Indexing↗
PubMed1989

Hash function performance on different biological databases.

Open hashing is used to demonstrate the effectiveness of several hashing functions for the uniform distribution of biological records. The three types of database tested include (1) genetic nomenclature, mutation sites and strain names, (2) surnames extracted from literature files and (3) a set of 1000 numeric ASCII strings. Several hash functions (hashpjw, hashcrc and hashquad) showed considerable versatility on all data sets examined while two hash functions, hashsum and hashsmc, performed poorly, on the same databases.

Clinical Laboratory Information Systems↗
PubMed1988

Movement of the Dictyostelium discoideum slug: models, musings, and images.

The last 5 years have resulted in many advances in knowledge of the cytoskeleton and motility of individual cells. Here the problem of multicellular movement is addressed. The Dictyostelium discoideum slug is examined, and models for how approximately 100,000 cells become coordinated to move are briefly reviewed. Experiments that contributed to model building as well as those used to test models are considered. Four levels of experimentation are considered: (1) the extracellular matrix (ECM) is examined as a component of the system; (2) information obtained by examining the organisation of slug cells through sectioning is presented; (3) time, the 4th dimension, is considered, and approaches to studying the dynamics of cell interactions from the point of view of movement are outlined, and (4) cell adhesion molecules are addressed.

Cell Movement↗