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Biomedical subjects

E Harper

Publications and source records attributed to E Harper.

65 records · Page 4Linked to original sources
PubMed1972

Critical role of the carbohydrate side chains of collagen in platelet aggregation.

The reaction between human platelet membrane glucosyl transferase and collagen has recently been proposed as the mechanism for pletelet-collagen adhesion. Collagen contains glucosyl-galactose and galactose side chains linked through the galactose to hydroxylysine. Oxidation of the 6-hydroxymethyl position of the galactosyl residue to aldehydes with galactose oxidase completely abolishes platelet aggregation. This enzymatic modification of collagen can be fully reversed by reduction of the aldehydes formed by NaBH(4) with complete restoration of platelet aggregating ability. Limited digestion with bacterial collagenase abolishes the ability of collagen to aggregate platelets. Removal of the N-terminal telopeptides from collagen with trypsin does not affect platelet aggregation. Tertiary structure of soluble collagen is essential for platelet aggregation. Normal collagen is less effective than lathyritic collagen, which contains only a small number of cross-links. The decreased number of aldehyde groups in the lathyritic collagen are not responsible for the increase in aggregating ability, since reduction with NaBH(4) does not alter platelet aggregation. These results suggest that integrity and accessibility of the galactose receptor site may be crucial for the formation of a ternary collagenenzyme-platelet membrane complex which must precede platelet aggregation.

Alcohol Oxidoreductases↗
PubMed1967

Electron microscopic and biochemical characterization of collagen in blattarian insects.

The occurrence of collagen in the cockroach Leucophaea maderae has been demonstrated by electron optical and biochemical techniques. Electron micrographs of tissues of this and a related species (Blaberus craniifer) are presented and they show that collagenous-type fibers occur in the stroma of nonneural as well as neural organs of these insects. Hydroxyproline and hydroxylysine, amino acids considered to be "markers" for collagen, have been shown to be present in proteins extracted from material rich in neuroglandular tissue (corpus cardiacum plus corpus allatum). Trimmed carcasses of Leucophaea maderae have been shown to contain a protein or proteins soluble in hot trichloroacetic acid, with compositional characteristics similar to those of collagens in general, including diagnostic proportions of glycine, proline, hydroxyproline, and hydroxylysine. This collagen is not soluble in dilute acetic acid or in concentrated solutions of guanidinium chloride. It is measurably digested by bacterial collagenase.

Alanine↗
PubMedDate not supplied

Respiratory rates in pediatric emergency patients.

Respiratory rates are routinely measured in pediatric emergency patients. The normal range has not been established, and commonly reported ranges seem lower than those encountered in clinical practice. This prospective study selected subjects from pediatric patients presenting for care to a suburban emergency department. All respiratory rates were measured for one full minute. Patients with complaints related to the cardiopulmonary system or with an elevated temperature were excluded. A total of 434 patients were entered into the study over a 3-month period of time. Ages ranged from 2 weeks to 18 years. Respiratory rates ranged from a high of 65 breaths/min in a 4-month-old to a low of 12 breaths/min in a 14-year-old. Respiratory rate was inversely related to age, and there was a broad range in every age group. Our study shows that a normal respiratory rate is inversely related to age and is higher than noted in previously published studies. The wide range of "normal" pediatric respiratory rates makes identification of "abnormal" more difficult.

Adolescent↗