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Biomedical subjects

J A Weatherell

Publications and source records attributed to J A Weatherell.

At least 55 records · Page 3Linked to original sources
PubMed1981

Chemical changes during formation and maturation of human deciduous enamel.

The appearance and chemical composition of a number of developing human deciduous incisors indicated that the enamel passes through the following four developmental stages: 1. Partially mineralized matrix is secreted and some extracellular breakdown occurs. 2. Selective replacement of matrix proteins by tissue fluid begins. 3. Almost all of the matrix protein is replaced by tissue fluid and an influx of calcium phosphate occurs. 4. The enamel becomes almost fully mineralized, mature and hard. These stages of development are similar to those described in rat and bovine tissue. the number of stages simultaneously present in a single tooth differed from rat and bovine enamel, however, as did the rate of change in amino acid composition from developing to mature tissue.

Amino Acids↗
PubMed1979

Matrix and mineral changes in developing enamel.

An investigation of the changes taking place in the enamel and the enamel organ during enamel development has been carried out by analyzing small samples of tissue dissected from developing incisors of rat and bovine incisors. Observations showed that the synthesis of the enamel matrix and its subsequent loss were associated chiefly with a change in the major matrix components. This consisted of a selective loss of amelogenin components prior to secondary mineralization. Before this loss, some increase in the proportion of smaller molecular weight components suggested the possibility of limited breakdown. Even at the earliest stages examined, significant concentration of mineral ions was present. This increased steeply after most of the organic matrix had been removed. The Ca/P ratio of this mineral was constant throughout development. The concentration of minor inorganic ions (F, Mg and CO3) decreased as the tissue developed and a tendency was observed for certain ions (F, 32PO4) to penetrate and concentrate in the enamel, apparently as a consequence of the lost matrix being replaced by water, just prior to the steep increase in mineral content of the tissue.

Amelogenesis↗
PubMed1977

Changes in amino-acid composition of developing rat incisor enamel.

The amino-acid composition and total "protein" content of enamel particles dissected serially from the developing enamel of rat incisors have been determined. Changes in protein content and amino-acid composition occurred throughout all stages of development. The most obvious alterations occurred in the vicinity of a white opaque band. Here, protein was lost most rapidly and considerable changes in amino-acid composition occurred.

Amino Acids↗